X
تبلیغات
نظامی وهوایی

نظامی وهوایی

دستاورد نظامی وهوایی ایران وجهان

F-22

-

F-22 Raptor Lockheed Martin
F-22 Raptor
Air Superiority Fighter

DESCRIPTION:
The F-22 won the Air Force's Advanced Tactical Fighter contest over the Northrop YF-23 in April 1991. While the aircraft's primary mission remains air superiority, for which it can carry up to 8 air-to-air missiles internally, a secondary ground-attack role has also been developed. This capability was highlighted when the Raptor was briefly renamed the F/A-22 in late 2002, though it has been redesignated as the F-22 since December 2005. The F-22 was designed primarily to supplement and replace the F-15 by incorporating the latest in stealth features and propulsion technology. These advances include its angular design, use of radar-absorbant composite materials, and the ability to "supercruise" at supersonic speeds without using an afterburner. The F-22 also emphasizes agility through the use of thrust vectoring nozzles and a sophisticated fly-by-wire control system.

Other advanced systems aboard the Raptor include an integrated avionics suite built around a powerful flight computer with three times the memory and 16 times the speed of that used on the F-15. The F-22 also uses a nav/attack system that incorporates artificial intelligence to filter information to the pilot reducing his workload as well as improving his situational awareness.

Two prototypes of both the YF-22 and YF-23 were constructed, one example of each aircraft being powered by Pratt & Whitney F119 turbofans and the other by the General Electric F120 turbofans. These various combinations allowed the Air Force to select the best airframe/propulsion combination. The second YF-22 prototype, fitted with Pratt & Whitney engines, soon demonstrated the ability to cruise at Mach 1.58 without afterburner and Mach 1.7 with afterburner. This combination was deemed the most desirable, and both Lockheed and Pratt & Whitney were issued contracts to proceed with production. The production F-22 Raptor includes a number of modifications when compared to the YF-22 prototype, including greater wingspan, reduced wing sweep, a shortened fuselage, and a relocated cockpit to improve visibility.

Despite its advanced systems and exceptional performance, few examples of the F-22 may be purchased due to the aircraft's high price that has been estimated as high as $250 million apiece. Costs have been decreasing as F-22 production methods have improved, however, and the flyaway cost was estimated at $133 million in 2005. Lockheed Martin has also indicated that F-22 unit cost may drop below $100 million in future production lots. Regardless, even these cost reductions may be insufficient as Congress continues to limit funding for the Raptor program. The Air Force had originally hoped to purchase 750 examples of the F-22 and still states a requirement for at least 380 planes. Nevertheless, current budget plans have slashed the anticipated F-22 fleet to about 185 aircraft and production is scheduled to end in 2011. The Air Force continues to fight for additional funding and may succeed in increasing the production run given groundings of the F-15 fleet due to structural aging issues. By late 2008, some 130 F-22 Raptors had been delivered to the Air Force out of 183 ordered.

The Raptor program was set back by numerous delays in manufacturing, software development, and flight testing that pushed service entry back by several years. Operational Testing finally commenced at Nellis and Edwards AFB in October 2003, and a pilot training squadron was established at Tyndall AFB. The first operational squadron is the 27th Fighter Squadron at Langley AFB that reached initial operational capability in December 2005. Upon entering service, the Raptor has been cleared to carry the AIM-120 AMRAAM medium-range air-to-air missile, the AIM-9M Sidewinder short-range air-to-air missile, and the GBU-32 JDAM 1,000-lb GPS-guided bomb. Other weapons planned for integration aboard the F-22 in the near future include the GBU-39 SDB GPS-guided bomb and the latest AIM-9X variant of Sidewinder.

The US Congress has so far voted to deny export of the F-22 to foreign countries, but Japan and Israel have expressed strong interest in purchasing the plane. Australia also made a bid but has instead chosen to buy the F-35.

Last modified 20 November 2008

HISTORY:
First Flight (YF-22) 29 September 1990
(F-22A) 7 September 1997
Service Entry

15 December 2005

CREW: one: pilot

ESTIMATED COST:

$142 million [2008$]

AIRFOIL SECTIONS:
Wing Root NACA 64A?05.92
Wing Tip

NACA 64A?04.29

DIMENSIONS:
Length 62.08 ft (18.92 m)
Wingspan 44.50 ft (13.56 m)
Height 16.42 ft (5.00 m)
Wing Area 838 ft² (78.0 m²)
Canard Area

not applicable

WEIGHTS:
Empty 43,340 lb (19,660 kg)
Normal Takeoff 60,000 lb (27,215 kg)
Max Takeoff 83,500 lb (37,875 kg)
Fuel Capacity internal: 20,650 lb (9,365 kg)
external: 15,865 lb (7,195 kg) in four 600 gal (2,270 L) tanks
Max Payload

3,915 lb (1,775 kg) [internal]
approximately 19,000 lb (8,620 kg) [external]

PROPULSION:
Powerplant two Pratt & Whitney F119-100 afterburning turbofans
Thrust 70,000 lb (310 kN)

PERFORMANCE:
Max Level Speed at altitude: 1,355 mph (2,180 km/h) at 30,000 ft (9,150 m), Mach 2 [afterburner]
1,070 mph (1,725 km/h) at 30,000 ft (9,150 m), Mach 1.6 [supercruise]
at sea level: 920 mph (1,480 km/h), Mach 1.2
Initial Climb Rate unknown
Service Ceiling 50,000 ft (15,240 m)
Range typical: 2,000 nm (3,700 km)
ferry: unknown
Endurance unknown
g-Limits +9.0 / -3.0

ARMAMENT:
Gun one 20-mm M61A2 Vulcan cannon (480 rds)
Stations four internal weapons bays and four external hardpoints
Air-to-Air Missile AIM-9M Sidewinder, AIM-120A/C AMRAAM
AIM-9X Sidewinder planned
Air-to-Surface Missile none
Bomb GBU-32 JDAM
GBU-39 Small Diameter Bomb planned
Other unknown

KNOWN VARIANTS:
YF-22 Prototype evaluated under the Advanced Tactical Fighter competition; 2 built
F-22A Production model with a slightly shorter fuselage, reduced wing sweep, and the cockpit shifted forward to improve visibilty; 183 to be built
F/A-22A Designation given to the F-22A in 2002 to highlight the plane's air-to-ground combat capabilities, but dropped upon service entry in 2005 when the model was again called the F-22A
F-22B Proposed two-seat combat-capable trainer; cancelled
F-22E Lockheed proposal for an upgraded version based on the F-22A but with improved ground attack capability
F-22N Proposed navalized variant with variable-sweep wings for operation from US Navy aircraft carriers; not developed
F/A-22X Proposed advanced variant that would add a synthetic aperture radar, moving target indicator, and additional ground attack capability
FB-22 Lockheed concept for a long-range high-altitude bomber based on the F-22; design would eliminate all tail surfaces, incorporate a new delta wing with increased fuel capacity, and employ a longer fuselage with room for stretched weapons bays carrying two AIM-120 missiles and up to 24 small diameter bombs; the Air Force has indicated that it will not order the design

KNOWN COMBAT RECORD:

US Homeland Security - Operation Noble Eagle (USAF, 2006-present)

KNOWN OPERATORS:

United States (US Air Force)

3-VIEW SCHEMATIC:

F-22 Raptor


+ نوشته شده در  شنبه ششم تیر 1388ساعت 20:14  توسط نوید  | 

Airbus A380

- - - -

Airbus A380 Airbus
A380
Long-Range Jetliner

DESCRIPTION:
The Airbus A380 was developed in response to the growing problems of airport congestion and air traffic control systems struggling to cope with the number of aircraft in operation. Originally known as the A3XX, the enormous design was re-christened as the A380 following the official launch of the program in late 2000. Upon entering service, the A380 will become the first full triple-decked super jumbo-jet as well as the first true competitor to the Boeing 747. Though many argue that the aviation industry is not ready for such a giant, Airbus believes that by commiting to the A380 now, the company will be in excellent position to take advantage of such a need by 2020. By then, Airbus estimates a potential need for 1,200 passenger and 300 freighter models.

Despite its large size, the A380 adopts a conventional airliner design with a cylindrical fuselage slightly wider than that of the 747. The A380 also features a standard low-mounted swept-wing configuration with four podded engines along its span. The landing gear include 22 wheels so that the load per wheel is comparable to that of the Boeing 747 and 777. This design makes the A380 compatible with most existing runways at major airports. However, the large wingspan requires most airports to widen taxiways so that two A380 aircraft can pass each other. Many airports must also build additional jetway bridges to accomodate the large number of passengers, and baggage handling systems also need to be upgraded. A handful of airports at major international hubs are investing millions of dollars to complete these improvements by the time the A380 enters service. Even so, delays in funding these improvements at some key airports could be a significant problem for A380 operators.

The internal layout of the A380 is of typical configuration with passengers seated on the two upper decks and cargo located on the lower deck. Airbus has also proposed configuring some cargo compartments as shops, lounges, or even casinos, although economy-minded airlines are unlikely to adopt such gimics. The flight deck is very similar to that of the A330/A340 family to ease A380 pilot training and promote commonality across the Airbus production line. Furthermore, the cockpit is located in between the upper and main decks at a height comparable to that of smaller airliners for easier pilot familiarity.

Two basic models are currently being marketed, the A380-800 passenger model seating up to 555 in three classes and the A380-800F freighter version. Additional extended range, passenger/cargo, and stretched models are also under consideration. A total of 17 airlines had placed orders for 195 aircraft by February 2008, and a Saudi prince has also ordered a VIP model.

Unfortunately, difficulties in manufacturing have delayed A380 deliveries and pushed service entry back by at least two years to late 2007. The majority of these delays have been blamed on difficulties installing over 300 miles (500 km) of wiring throughout the aircraft. Initial A380 testing also uncovered a rupture in the wing that required minor redesign, and rumors have surfaced that flaws may exist in the landing gear as well as the cabin pressurization system. If true, these difficulties could delay the plane's service entry even further.

Several customers like Singapore Airlines, Qantas, Virgin Airways, Emirates, Malaysian Airlines, and Thai Airways have already expressed frustration over the program's pace and rising costs, forcing Airbus to pay millions of dollars in compensation to the airlines. Some customers have also threatened to reduce or cancel their A380 orders. The only cancellations so far were from cargo operators FedEx and UPS when both companies cancelled their orders for up to 20 A380-800F frieghters apiece. The move left no customers for the freighter model and further development of this variant has been postponed indefinitely.

Production delays have created a significant cost overrun of over $3 billion driving up A380 unit cost by at least 25%. These delays and cost increases may deter future orders, and Airbus must sell a total of at least 420 aircraft to break even on the program.

Data below for A380-800 and A380-800F
Last modified 15 January 2009

HISTORY:
First Flight (A380-800) 27 April 2005
Service Entry

(A380-800) 25 October 2007 (with Singapore Airlines)

CREW: two flight crew: pilot, co-pilot

PASSENGERS: (A380-800) 555 in three classes, 840 in one class

ESTIMATED COST:

$327.4 million [2008$]

AIRFOIL SECTIONS:
Wing Root unknown
Wing Tip

unknown

DIMENSIONS:
Length (A380-800) 238.67 ft (72.75 m)
Wingspan 261.83 ft (79.80 m)
Height 79.00 ft (24.08 m)
Wing Area 9,095.5 ft² (845.0 m²)
Canard Area

not applicable

WEIGHTS:
Empty (A380-800) 610,680 lb (277,000 kg)
(A380-800F) 555,565 lb (252,000 kg)
Normal Takeoff unknown
Max Takeoff (A380-800) 1,234,590 lb (560,000 kg)
(A380-800F) 1,300,725 lb (590,000 kg)
Fuel Capacity internal:
(A380-800) 575,185 lb (260,900 kg)
(A380-800F) 575,185 lb (260,900 kg)
external: not applicable
Max Payload

(A380-800) 185,190 lb (84,000 kg)
(A380-800F) 330,695 lb (150,000 kg)

PROPULSION:
Powerplant (A380-800) four Rolls-Royce Trent RB-967 turbofans
or four Engine Alliance GP-7267 turbofans
(A380-800F) four Rolls-Royce Trent RB-975 turbofans
or four Engine Alliance GP-7275 turbofans
Thrust (A380-800 RB-967) 272,000 lb (1,210 kN)
(A380-800 GP-7267) 326,000 lb (1,450 kN)
(A380-800F RB-975) 299,435 lb (1,332 kN)

PERFORMANCE:
Max Level Speed at altitude: 595 mph (955 km/h) at 35,000 ft (10,675 m), Mach 0.89
at sea level: 390 mph (630 km/h)
cruise speed: 560 mph (900 km/h) at 35,000 ft (10,675 m), Mach 0.85
Initial Climb Rate unknown
Service Ceiling 42,980 ft (13,100 m)
Range (A380-800) 8,000 nm (14,815 km)
(A380-800F) 5,600 nm (10,370 km)
g-Limits unknown

KNOWN VARIANTS:
A380-700 Originally known as the A3XX-50 or A3XX-50R, proposed extended range model with a shortened fuselage for 481 passengers
A380-800 Originally known as the A3XX-100, first production model seating 555 passengers
A380-800C7 Proposed combination passenger/cargo model based on the A380-800 with space for 7 cargo pallets
A380-800C11 Proposed combination passenger/cargo model with space for 11 cargo pallets
A380-800F Originally known as the A3XX-100F, dedicated freighter based on the A380-800 model with a capacity of 25 pallets on the upper deck, 33 pallets on the main deck, and 13 pallets on the lower deck; development had been underway but was postponed in March 2006 after both launch customers cancelled their orders
A380-800R Proposed extended range model based on the A380-800 for 555 passengers
A380-800S Proposed reduced range version of the A380-800
A380-900 Originally known as the A3XX-200, proposed stretch model with a longer fuselage for 656 passengers
A380-900S Proposed reduced range version of the A380-900

KNOWN OPERATORS: Aerolineas Argentinas
Air Austral
Air Comet
Air France
British Airways
China Southern Airlines
Doric Asset Finance
Emirates Airlines
Etihad Airways
International Lease Finance Corporation (ILFC)
Kingfisher Airlines
Korean Air Lines
Lufthansa
Malaysian Airline System (MAS)
Qantas
Qatar Airways
Singapore Airlines
Thai Airways
Virgin Atlantic Airways

3-VIEW SCHEMATIC:

Airbus A380


+ نوشته شده در  شنبه ششم تیر 1388ساعت 20:13  توسط نوید  | 

Concorde History 1

This week, we decided to focus our attention on a number of questions we have received about the Concorde. Though the supersonic airliner made its final flight nine months ago, the historic aircraft remains one of the most popular and most asked about on our site.


    How much did it cost to build Concordes? How many were built?
    - question from Aaron Gaite
A total of 20 Concordes were built between 1966 and 1979, and 14 of these were passenger models that entered airline service. Two prototypes were initially built, one each in France and the UK. The next two planes were pre-production prototypes used primarily for ground testing. The cost to develop and build these first four aircraft was about £1.134 billion and was funded entirely by the French and British governments.

First flight of the second Concorde prototype
First flight of the second Concorde prototype

The production run included 16 aircraft. The first two were initial production models that never entered service. These planes were used to test production methods and airline training techniques. The two planes also conducted airworthiness flight testing and extensive route planning operations. Five of these first six test planes were soon placed on display at museums while the remaining British initial production model was given to British Airways as a spare parts aircraft.

In 1977, British Airways and Air France purchased the first production aircraft. Five were bought by British Airways and four by Air France at an estimated cost of £23 million ($46 million) each in 1977 prices. The British and French governments built another five aircraft but could find no airlines willing to buy them. These remaining Concordes were given to the two airlines between 1979 and 1980 for the grand total of 1 French franc or £1 respectively. The total cost of the 16 production aircraft was £654 million, but the two governments recouped only £278 million through sales to the airlines. This loss came on top of the initial development cost and had to be written off by the governments. In addition, the two governments continued to subsidize the operating costs of Concorde to the tune of tens of millions of pounds per year until 1984.

The 14 Concordes that ultimately entered service were split equally, seven each between the airlines. British Airways continued to operate its seven planes until the fleet was grounded in 2000. Air France retired one of its planes in 1982 to provide spare parts for the rest of the fleet, and another was lost in a fatal crash during takeoff from Paris in July 2000.

Following that accident, the airlines spent a considerable sum of money to modify the remaining planes to meet new safety requirements before they were allowed to fly again. Air France completed these upgrades on four of its five remaining aircraft and the fifth was retired. British Airways returned five of its seven planes to service and kept the other two in storage. All production aircraft have now been retired and put on display in various museums around the world.
- answer by Jeff Scott, 25 July 2004


    When did Concorde make its first commercial flight?
    - question from Rita Peters
The Concorde entered commercial service on 21 January 1976 with both airlines that operated it. The first Air France flight was completed between Paris and Rio de Janeiro. British Airways flew its first flight from London Heathrow to Bahrain. Both of these locations remained regularly scheduled destinations for a short time, but the vast majority of Concorde service was between London or Paris and New York City. This service was delayed until 1977 because of protests by environmental groups that opposed allowing Concorde to operate from New York's John F. Kennedy Airport.

Destinations regularly serviced by Concorde during its operational life included:

British Airways

  • New York City two to four times per day, 1977-2003
  • Barbados once per week during the winter, 1977-2003
  • Bahrain three times per week, 1976-1980
  • Dallas-Fort Worth three times per week (via Washington Dulles), 1979-1980
  • Miami three times per week (via Washington Dulles), 1984-1991
  • Singapore three times per week (via Bahrain), 1977-1980
  • Toronto during summer months
  • Washington Dulles three times per week, 1976-1994
Air France
  • New York City five days per week, 1977-2003
  • Caracas once per week (via Azores), 1976-1982
  • Dallas-Fort Worth five times per week (via Washington Dulles), 1979-1980
  • Mexico City twice per week (via Washington Dulles or New York), 1978-1982
  • Rio de Janeiro twice per week (via Dakar), 1976-1982
  • Washington Dulles once per day, 1977-1982
A number of other locations were frequent destinations for charter flights, particularly to tropic regions like the Carribbean and Mediterranean. It was one of these charter flights that crashed at Paris in 2000 while carrying German tourists to New York to join a cruise ship.
- answer by Joe Yoon, 25 July 2004


    What airlines operated the Concorde? Was it ever offered to the British or French military services?
    - question from Graham Richardson
The only true operators of Concorde were Air France and British Airways. Nevertheless, there were a couple cases of joint operations with other airlines. One of these was Singapore Airlines that briefly flew a Concorde between Bahrain and Singapore from 1979 to 1980. The aircraft was painted in British Airways markings on the right side and Singapore Airlines markings on the left. The service did not last long because of problems obtaining rights to fly over countries along the route and insufficient interest from passengers.

Concorde in Singapore Airlines livery
Concorde in Singapore Airlines livery

A similar arrangement was made with the American airline Braniff. Both British Airways and Air France forged agreements with Braniff to operate service between Europe and Dallas via Washington Dulles Airport. Crews would switch at Dulles so that Braniff pilots would fly the Concorde to and from Dallas Fort Worth.

Postcard commemorating Concorde service with Braniff
Postcard commemorating Concorde service with Braniff

The Concordes used on this route retained the markings of their parent airlines and were not modified to display Braniff livery. However, the Concordes were forced to change registration numbers when the flight crews changed. This feat was accomplished by simply covering over the G or F in the registration number on the exterior of the plane with white tape and replacing it with the N used for US registered planes. The Braniff service only lasted from January 1979 to May 1980 when it was cancelled due to high costs and lack of passenger traffic.

I've been unable to find any information regarding a possible military version of Concorde. I don't believe any such proposal was ever made to or requested by the military services.
- answer by Molly Swanson, 25 July 2004


    How many passengers could the Concorde hold?
    - question from Ted Walton
The Concorde was designed to carry about 100 passengers, though it was certified to carry as many as 128. The theoretical maximum that the aircraft could accommodate was 144 in a very cramped cabin configuration.

Typical Concorde seating layouts
Typical Concorde seating layouts

Air France aircraft were arranged to carry 92 passengers while British Airways normally carried 100. The flight crew included a pilot (or captain), a co-pilot, and a flight engineer and cockpit seats were also available for two additional observers. The cabin crew could contain as many as six flight attendants.

British Airways estimated that more than 2.5 million passengers flew aboard Concorde between 1976 and 2003 over the course of about 50,000 flights.
- answer by Molly Swanson, 25 July 2004


    What was the spray guard used in the landing gear of the Concorde?
    - question from Diwahar
The spray guard, sometimes also called the tire guard, was a small metal strip located on the rear of the nose and main landing gear. As the wheels turned, they often threw water or other debris up from the runway and towards the underside of the aircraft. Since the Concorde had much faster takeoff and landing speeds than other airliners, this debris had significant momentum and could potentially do significant damage to the aircraft.

Spray guard on the Concorde nose landing gear
Spray guard on the Concorde nose landing gear

The purpose of the spray guard was to deflect that debris away so that it would not threaten the plane. However, the guard turned out to cause as much damage as it was intended to prevent because it would often break off and impact the aircraft. A number of such cases were reported by the airlines in which the spray guard caused fuel leaks after breaking off and penetrating the wing fuel tanks.

The problem was so prevalent that British Airways modified the spray guards on its planes to insure that they could not break off and damage the aircraft. Air France had not made the modification before its Concorde crashed in 2000, which made the guard one of the prime suspects in the accident. It turned out that the spray guard was not the culprit in this case, but the accident was instead caused by a piece of metal debris on the runway.
- answer by Greg Alexander, 25 July 2004


    What are the reasons for the failure of Concorde? What improvements could be made to it?
    - question from Harpeet
Your question is unclear as to whether you are asking why the Concorde failed to become a success in the first place or why the airlines decided to retire the plane in 2001. In any case, the reasons are largely similar.

The design of what ultimately became Concorde began in the late 1950s when commercial air service was just beginning to become the dominant form of long-distance travel. During the late 1950s and early 1960s, technology was progressing so rapidly that the public believed high speed aircraft and even commercial space travel would become commonplace in the near future. It was this mindset that made the Concorde possible, and it was shared by other nations as well. Both the Soviet Union and the United States were also developing their own equivalents to Concorde called the Tupolev Tu-144 and the Boeing SST.

Artist concept of the 1967 Boeing SST with variable-geometry wings
Artist concept of the 1967 Boeing SST with variable-geometry wings

Unfortunately, the politics and economy of the world changed substantially between the early 1960s and the mid-1970s when Concorde was finally ready to enter service. One of the challenges that confronted Concorde was the growth of the environmental movement that bitterly fought against the plane. Chief among the complaints of environmentalists was the noise pollution that supersonic aircraft threatened to bring. It was because of this concern that most nations banned supersonic air travel over their territories to eliminate the danger of sonic booms. This legislation forced Concorde to seek out intercontinental routes across oceans. The routes that did travel over land, such as Washington DC to Dallas and London to Bahrain, were forced to remain subsonic and cruise at Mach 0.95. This cruise speed significantly increased fuel consumption and caused the cost per flight to skyrocket, which was one of the primary reaons why both routes were abandoned within a couple of years.

A second problem that plagued Concorde was the rise in oil prices that struck the West so forcefully during the 1970s. Supersonic flight requires powerful engines that consume much more fuel than traditional airliners flying at Mach 0.8. Oil was inexpensive in the early 1960s, so the airlines had little need to worry about fuel costs when the Concorde was being designed. As the airline industry changed in the 1970s and 1980s because of deregulation and increased competition, cutting costs became necessary simply for survival. Airlines just could not afford the cost of fuel needed for supersonic aircraft, so they had no interest in planes like Concorde.

Regardless, British Airways and Air France were able to overcome these challenges as best they could and eventually turned a profit on Concorde flights. They did so by abandoning the idea of supersonic travel for the masses and instead adopting a premium service catering to the elite. Concorde was most often flown by wealthy business executives and celebrities who needed to cross the Atlantic rapidly or who were simply attracted by the special treatment offered on Concorde flights. These upper class passengers could also afford to pay exorbidant ticket prices that could be as high as $10,000 one way. This business model allowed Concorde to generate a profit for its operators until the fleet was grounded following the Air France crash in 2000.

The accident investigation that followed lasted for an extended period and revealed a number of troubling safety concerns. Both British and French authorities revoked the Concorde's airworthiness certificates and mandated several modifications to the remaining fleet before Concorde would be allowed to fly again. Both airlines felt the aircraft could still be profitable and invested millions of dollars to return Concorde to service. Once authorities had agreed that the plane was again safe to fly, passenger service resumed in September 2001.

By this time, however, the air travel industry was in a serious downturn following the September 11 terrorist attacks. The slump in business caused passenger traffic on Concorde to drop so low that the airlines were having difficulty turning a profit. The situation only became worse when Airbus, the maintenance and parts supplier for Concorde, announced that the aircraft would no longer be supported after October 2003. The loss of this support meant that the airlines would be forced to acquire all the spare parts and complete all maintenance on their own, which was simply too expensive. The Airbus decision to stop supporting Concorde coupled with the loss of passengers doomed the aircraft to retirement. As the chief executive of Airbus, Noel Forgeard, said, "The costs of operating Concorde, and in particular maintenance and support, have become such that operations are unrealistic for any operator."

As for the second part of your question, there are a number of improvements that could potentially make supersonic travel more economical. One of the most important concerns to airlines is the cost of operating an aircraft per the number of passengers it carries per mile it travels, or the "cost per seat-mile." Concorde never proved to be a commercial success because it cost too much to operate and carried too few passengers. To be a success, any future SST will need to carry at least twice as many passengers as Concorde and its fuel consumption will have to be comparable to a competing subsonic airliner.
- answer by Jeff Scott, 25 July 2004

+ نوشته شده در  شنبه ششم تیر 1388ساعت 20:12  توسط نوید  | 

Concorde History II

Though the Concorde has been retired for the past year, the supersonic transport remains a frequent source of questions. This week's article answers several of the questions we have received and is a continuation of those covered in Part I.


    How did Concorde get its name?
    - question from Diwahar
When the supersonic transport project began in the early 1960s, it was a joint effort between the French firm Sud-Aviation and Bristol Aircraft in the UK. Bristol soon became part of the British Aircraft Corporation (BAC), which is today part of British Aerospace (now called BAE Systems). The name Concorde was reportedly first chosen by a BAC executive during a discussion with his family in 1963. The name was selected after glancing through a thesaurus, and "concorde" seemed a perfect fit being a synonym for agreement, friendship, and cooperation.

Rollout of the first Concorde prototype
Rollout of the first Concorde prototype

The suggestion was accepted by the British government and forwarded on to the French for their consideration. The name received informal approval, but it took some time before French president Charles de Gaulle officially announced the name of the project as Concorde, using the French spelling with an "e." Unfortunately, the British government by this time had decided that the name should be spelled using the English form Concord without an "e." The seemingly insignificant issue remained a bone of contention between the two nations for several years. Finally, at the rollout ceremony for the first prototype in 1967, British Minister of Technology Tony Benn announced that the British government had officially accepted the name Concorde for the new aircraft.
- answer by Molly Swanson, 24 October 2004


    Can you give me some information about Concorde's fuel transfer at transonic speeds?
    - question from Tignol Fabien
The Concorde had a total of 13 fuel tanks with a maximum capacity of 31,510 gallons (119,280 liters). These tanks were located throughout the wings and fuselage, as shown below.

Concorde fuel tanks
Concorde fuel tanks

Having multiple fuel tanks is not unusual for any aircraft, especially for very large planes like commercial airliners. What made the Concorde unique was that it required a fuel management system to transfer fuel between the various tanks during flight. Such a system was required because of an aerodynamic effect that occurs around the speed of sound. At these speeds, the point where the lift acts on a wing tends to move around by a large amount. As an aircraft transitions from subsonic to supersonic speeds, the point where the lift generated by the wing acts tends to move further back. Aerodynamicists refer to this behavior as a shift in the center of pressure, and it is caused by the creation of shock waves on the surface of the wing.

The changing center of pressure has a tremendous impact on the stability and controllability of a plane. All planes are equipped with some method of balancing the lift to keep the aircraft flying level. Most conventional planes use a control surface called an elevator to adjust the pitch angle of the aircraft and keep the nose level. The angle of the elevator can be increased or decreased to compensate for changes in the lift generated by the wing and maintain level flight. When the wing and elevator balance each other to keep the plane flying straight and level, we say that the aircraft is in a trim condition.

Keeping the aircraft trimmed becomes more complicated when the center of pressure moves around because it requires much larger and more frequent adjustments to the elevator position. Many aircraft are equipped with a device called a mach trim that is designed specifically for this purpose. When flying near Mach 1 at conditions where the wing center of pressure tends to move a lot, a mach trim system automatically adjusts the position of the elevator to compensate for the movement and keep the plane level. Such a system is common on commercial airliners since these craft usually fly around Mach 0.8 where center of pressure movement starts to become a problem.

Concorde suffered the effects of a shifting center of pressure even more so than traditional airliners. At its cruise speed of Mach 2, the center of pressure had moved a full 6 ft (1.8 m) aft of its location at subsonic speeds. While the plane could have used a traditional elevator control surface to balance the lift, designers decided against it because a horizontal tail would generate too much drag at supersonic speeds. Concorde instead made use of a device called an elevon, which is a control surface that acts like a combination of a traditional elevator and an aileron. A series of these elevons were located along the trailing edge of the wing. Depending on how they were deflected, these elevons could control the Concorde's pitch, like an elevator, or its roll, like an aileron.

The disadvantage of elevons was their inability to compensate for the changes in center of pressure between low speed and high speed flight. Concorde's designers instead adopted a more sophisticated solution. Rather than adjusting aerodynamic forces to keep the plane level as on a traditional plane, engineers chose to adjust the weight distribution of the plane to balance out the changes in aerodynamic lift. Their solution was to pump fuel between different tanks to move the plane's center of gravity forward or aft. The tanks used in this process were known as "trim tanks" since their purpose was to keep Concorde in a trim condition during different phases of flight.

Transfering fuel aft to shift the center of gravity aft
Transfering fuel aft to shift the center of gravity aft

During acceleration through the sound barrier, the aerodynamic center of pressure shifts aft. This effect was compensated for by pumping fuel from the forward trim tanks towards the rear of the plane, as pictured above, to move the center of gravity aft. A total of about 20 tons (40,000 lb or 18,145 kg) of fuel was transferred aft, shifting the center of gravity by 6 ft (1.8 m) in the process.

Transfering fuel forward to shift the center of gravity forward
Transfering fuel forward to shift the center of gravity forward

Once the cruise portion of flight was concluded and the plane began to decelerate back to subsonic speeds, the center of pressure started shifting forward again. Fuel was then pumped back into the wing transfer tanks or forward trim tanks to move the center of gravity forward. Additional fuel was also often pumped forward after landing to keep the plane balanced during the unloading of passengers and cargo.

Concorde center of gravity limits vs. Mach number
Concorde center of gravity limits vs. Mach number

The above graph illustrates how the Concorde's center of gravity was moved over the different phases of a typical flight. Also note the dashed lines showing the furthest forward or aft the center of gravity could be at a given speed for the plane to continue flying safely. The task of properly managing the fuel distribution during flight was the most important duty of the flight engineer.
- answer by Joe Yoon, 24 October 2004


    When will there be a replacement for Concorde? What is the future of HSCTs?
    - question from Mary Lynn Seremet
We hate to sound pessimistic, but it does not appear likely that a true replacement for the Concorde will ever fly. Concorde was originally designed and built in an era when the airline business was very stable and profitable. Since that time, the industry has become far more competitive and airlines must focus on minimizing their expenses to stay alive. Concorde and its competitors failed to become a success because they were simply too costly to operate when compared to more conventional airliner designs.

Perhaps the best hope for a Concorde replacement came in the 1990s when NASA conducted its High Speed Civil Transport (HSCT) research effort. The goal of HSCT was to investigate new technologies that could potentially reduce the operating costs of a supersonic transport to be competitive with a typical subsonic airliner.

Artist concept of the High Speed Civil Transport
Artist concept of the High Speed Civil Transport

The most important hurdle addressed by NASA was to reduce the fuel consumption problems that plagued Concorde. Although Concorde's builders were justifiably proud of the plane's ability to cut transatlantic travel times by more than half, the problem was that the plane burned three times as much fuel in the process. The high price of oil over the past 30 years made the Concorde so expensive to fly that the airline market could not afford it. NASA investigated new advances in jet engine technology that might be able to reduce fuel consumption to more acceptable levels.

Furthermore, the Concorde's engines generated a large amount of pollutants like nitrogen oxide, particulates, and ozone-depleting substances during cruise flight. These engines were also notoriously loud during takeoff generating noise pollution complaints from those living near airports. Both forms of pollution have become increasingly restricted under more recent environmental laws. NASA's researchers looked at ways of reducing these forms of pollution to reduce the environmental impact of a future supersonic plane.

High Speed Civil Transport undergoing wind tunnel tests
High Speed Civil Transport undergoing wind tunnel tests

The HSCT program also looked at a number of other technological solutions to reduce costs and improve performance. For example, researchers studied the development of advanced composite materials and new methods of structural design that could improve the plane's ability to survive high temperatures while reducing weight and manufacturing costs. NASA also studied possible methods of reducing the effects of sonic booms as well as electronic displays to eliminate the need for cockpit windows and the complicated drooping nose mechanism.

NASA had hoped that its investment in these advanced technologies would encourage commercial aircraft manufacturers to build a more efficient and cost effective replacement for Concorde that would revolutionize airline travel. In particular, NASA formed a partnership with Boeing to share research and reduce the development costs of such an ambitious project. Unfortunately, Boeing's market research indicated that the airlines had little interest in such a plane because it would still be much more expensive than traditional subsonic aircraft. This lack of success prompted NASA to discontinue HSCT research in 1999, and Boeing has shelved the concept indefinitely.

Model of the Tupolev Tu-244
Model of the Tupolev Tu-244

Other nations have also investigated developing a Concorde replacement, including Europe's Airbus consortium, Japan, and Russia. Russia's Tupolev had previously developed its own rival to Concorde called the Tu-144 and proposed a more advanced Tu-244 during the 1990s. The concepts for this plane look very similar to the American HSCT, and the Tu-244 incorporates many of the same advanced technologies to improve economy and impact on the environment. Though Tupolev has attempted to generate interest in such a plane, response from airlines has been poor and the idea appears to have all but died.

Concept for a hypersonic airliner
Concept for a hypersonic airliner

More extreme proposals for Concorde "replacements" are far more ambitious, such as hypersonic transports cruising at Mach 5 or better. Test programs like the X-43 and pulse detonation engine experiments are already developing the basic technologies needed to make hypersonic aircraft a reality. However, building large hypersonic planes safe enough for airline travel is an enormous leap beyond the Concorde or HSCT that will likely take decades to develop.
- answer by Jeff Scott, 24 October 2004

+ نوشته شده در  شنبه ششم تیر 1388ساعت 20:8  توسط نوید  | 

JetBlue A320 Emergency Landing

    Did the JetBlue Airbus A320 that had to make an emergency landing because of a landing gear problem have the ability to eject fuel in flight? If so, why did they fly around for three hours?
    - question from Gilles Laroche & Jonathan Britz
The incident in question occurred on 21 September 2005. JetBlue Flight 292 left Burbank, California, carrying 139 passengers and six crew on a transcontinental flight bound for New York City's John F. Kennedy International Airport. Shortly after takeoff, the pilot of the Airbus A320 received two warning lights as he tried to retract the plane's landing gear. The lights indicated there were problems with the shock absorber and steering on the nose gear.

Unsure of the exact nature of the problem, the pilots contacted maintenance personnel at the airline's headquarters in New York to discuss the meaning of the warnings. The experts agreed to divert the A320 south towards Los Angeles where JetBlue operates a maintenance hub in the nearby city of Long Beach. As Flight 292 made a flyby of the control tower at Long Beach Airport, controllers discovered the nose gear had rotated 90° and become locked in the down position.

JetBlue A320 with its nose landing gear jammed
JetBlue A320 with its nose landing gear jammed

As plans were made for the A320 to make an emergency landing, the plane remained in a circular flight pattern over Long Beach, Santa Catalina Island, and Newport Beach. The aircraft continued in this pattern for about three hours before attempting an emergency landing at Los Angeles International Airport (LAX). The landing was made here because of the airport's longer runways compared to Long Beach and Burbank.

The flight crew and experts on the ground decided to keep the plane airborne for so long to burn off fuel. We have previously described the emergency fuel dump that many planes use to release fuel during flight prior to making an emergency landing. The purpose of this system is to lower the plane's weight so that it can land safely without risking possible damage to its landing gear and internal structure. However, these systems are typically only needed on larger commercial widebody airliners like the A340 or Boeing 747. Smaller narrow body planes such as the A320 or 737 weigh considerably less and are able to make a safe landing immediately after takeoff even when fully loaded. As a result, they are not equipped with and do not require an emergency fuel dump system.

Map of the area where the JetBlue emergency occurred
Map of the area where the JetBlue emergency occurred

In the JetBlue case, however, personnel felt uncomfortable allowing the plane to land with its full load of fuel for a transcontinental flight while the nose gear was locked sideways. The plane instead remained airborne for several hours to reduce its weight until the pilots felt ready to make the landing attempt. The flight attendants also used the opportunity to move passengers and carry-on luggage toward the rear of the aircraft. This movement shifted as much weight as possible aft to minimize the load on the nose gear once the plane finally landed.

The aircraft also remained flying for such a long period to give the pilots time to consult with as many experts on the ground as possible. Besides the airline's maintenance personnel, it is likely that engineers at Airbus and Messier-Dowty, manufacturer of the landing gear, were contacted to provide their input on the situation.

JetBlue A320 about to touch down for its emergency landing
JetBlue A320 about to touch down for its emergency landing

Once the decision to land had been made and emergency equipment was in place along the runway, the JetBlue pilots followed their training and gradually eased the plane onto the ground. The A320 touched down on Runway 25L at 120 knots about 2,500 ft (760 m) down the 11,000 ft (3,350 m) runway. The plane rolled along the runway on its main gear for as long as possible as its speed decreased. About 15 seconds passed before the nose of the plane finally tilted down and the nose gear touched the ground. The gear's rubber tires rapidly shredded away until the metal wheel hubs scraped the runway pavement. This friction sent up a trail of white smoke, a shower of sparks, and finally bright flashes of flame that spread behind the gear while the plane continued barreling down the runway.

The pilot applied brakes at 90 knots and shut down the two turbofan engines at 60 knots. Observers became concerned about the plane's ability to stop as it continued its ground roll, but the A320 finally came to rest just 1,000 ft (305 m) short of the end of the runway. The nose gear had ground into the runway surface for about 20 seconds before the plane finally came to a halt. Once the smoke cleared, it was apparent the front wheels had been reduced to a flattened mangle of metal and rubber. The rest of the plane remained undamaged, however, and no one aboard the A320 was injured during the landing.

Sparks and fire from the twisted nose gear as the A320 lands
Sparks and fire from the twisted nose gear as the A320 lands

The A320 involved in the emergency landing was only three-years old and had been through a routine maintenance check just five days earlier. Following the incident, the plane was moved to a Continental Airlines hangar for inspection by investigators from the National Transportation Safety Board (NTSB) and by Airbus engineers. The NTSB also removed the plane's cockpit voice recorder and the digital flight data recorder for review in Washington DC and planned to conduct a thorough review of the plane's maintenance history. Additional reports indicated the entire nose landing gear assembly might be removed and dismantled before trying to recreate the malfunction. NTSB officials estimated the investigation would last about six to nine months.

This particular accident received extensive coverage because it was so well-covered by the local Los Angeles media whose news helicopters must circle the city 24 hours a day hoping to cover the next high-speed car chase. However, landing gear problems are actually relatively common and rarely result in serious damage or loss of life. Nose gear problems are the most common form of landing gear malfunctions, and pilots regularly train on how to perform an emergency landing like that conducted aboard JetBlue Flight 292. This type of landing minimizes the loads on the nose gear to reduce the potential for serious damage. Experts estimate an accident of this kind causes the nose gear to collapse and the fuselage itself to scrape along the runway perhaps 1% of the time. Even under these extreme conditions, the passengers are able to safely escape the plane and injuries are rare.

What does concern experts in the field is the fact this type of landing gear problem has occurred so frequently on the Airbus A320 and related A318, A319, and A321. Although the A320 family has an excellent safety record overall, a Canadian report released in 2004 documented 67 cases of nose landing gear failures aboard the A320 series worldwide since 1989. At least seven cases involved the nose gear becoming locked at a 90° angle as occurred on JetBlue Flight 292. The A320 has never been grounded as a result of these accidents because none has resulted in injury and Airbus has made several improvements to the nose gear design.

JetBlue A320 during its emergency landing
JetBlue A320 during its emergency landing

The nose gear is controlled by a computer that sends commands to an electrical system. This system in turn operates hydraulics that retract and deploy the gear. The failure aboard JetBlue Flight 292 could have resulted from a malfunction in any one of these systems or other mechanical components of the landing gear. A hydraulic problem had caused a similar malfunction on an America West flight in 1999. The flaw was blamed on a faulty valve seal that was already known because of an earlier nose gear failure. Airlines flying the A320 had been alerted about a repair, but the fix had not yet been implemented on the America West aircraft. The Federal Aviation Administration (FAA) then issued a mandatory order to complete this fix on all A320 series planes in the United States.

The same type of nose gear failure also occurred in four other cases, including two foreign aircraft and another JetBlue flight to New York in November 2002. A United Airlines flight to Chicago had to make an emergency landing due to the same problem just three weeks later. In all four cases, the fault was blamed on improper installation of a hydraulic shock absorber. Both US incidents had occurred shortly after the planes underwent maintenance, and the FAA issued advisories to the airlines warning about incorrect maintenance procedures that could result in the failure. The French landing gear manufacturer Messier-Dowty had redesigned the backplate onto which the shock absorber is attached to prevent future occurrences of the problem, but the redesign was still awaiting approval as of April 2004. It is unknown whether the new part had been approved or installed on the JetBlue A320 involved in the most recent incident.

Damaged A320 wheels removed from the Jetblue plane
Damaged A320 wheels removed from the JetBlue plane

Readers wanting to learn more about landing gear design should check out Aircraft Landing Gear Design: Principles and Practices by Norman Currey. Those interested in aircraft accident investigations might want to look at Shari Krause's Aircraft Safety: Accident Investigations, Analyses, & Applications or Aircraft Accident Analysis: Final Reports by Robert Sumwalt and Jim Walters. Another good book on airline safety and regulations is Commercial Aviation Safety by Alexander Wells and Clarence Rodrigues.
- answer by Jeff Scott, 2 October 2005

+ نوشته شده در  شنبه ششم تیر 1388ساعت 20:6  توسط نوید  | 


5-موشك سانبرن(SS-N-22 Sunburn,Moskit)

موشك جهت شكست دادن سيستم راداری دفاعی آمريكا طراحی شده است . يك ناو آمريكايی در حالت دفاعی به هر صورت در جريان شناسايی موشك SUNBURN كه به طرف آنها در حركت است تنها زمان كافی برای محاسبه و پيدا كردن راه حل شليك را دارد نه وقت كافی برای منهدم كردن موشك SUNBURN را. به همين خاطر از نوعی اسلحه جديد كه می‌تواند 3000 گلوله اورانيوم را در يك دقيقه شليك كند ولی اين سلاح بايد هماهنگی دقيقی را برای نابودی موشك به موقع انجام دهد كه بسيار مشكل است .
تركيب سرعت مافوق صوت و اندازه بمب آن انرژی تخريبی زيادی را هنگام برخورد با كشتی ايجاد می‌كند . يكعدد از اين موشك‌ها می‌تواند يك كشتی جنگی را غرق كند. تنها راه ناوهای آمريكايی برای دفاع از خودشان در مقابل سلاحهای مهيبی چون SUNBURN اين است كه قبل از رسيدن جنگنده پرتاب كننده بمب به محدوده پرتاب موشك آن را نابود كنند. SUNBURN می‌تواند يك بمب اتمی 200 كيلو تنی يا يك كلاهك 750 پوندی را در حدود 100 مايل حمل كند. بيش از دو برابر ميزانی كه EXOCET می‌تواند. SUNBURN می‌تواند سرعتی دو برابر سرعت صوت داشته و با قابليت تنظيم مسير پروازی كه می‌تواند از كنار موانع عبور كند تا خود را به استحكامات دشمن برساند. اين موشك قابليت شليك از زير دريايي ساحل و ناوهاي جنگي را بر خوردار است.مدل هوايي ان نيز قابليت شليك از جنگنده su-27k يا su-33 رادارا ميباشد كه نام ديگر ان Kh-4 مي باشد.
مطابق گزارش وزير دفاع ايران "علی شمخانی” در سال 2001 هنگام بازديد از مسكو در خواست پرتاب آزمايشی آن را كرد كه روسها هم با روی باز ترتيب آن را داده و علی شمخانی كه مجذوب آن شده بود سفارش تعداد نا محدود از اين موشك را به روسها داد.
از تعداد موشك هاي ايران اطلاعاتي در دست نيست.
مشخصات:
طول: 9 متر
وزن:450كيلوگرم
وزن كلاهك:320 كيلوگرم
سرعت: 3 ماخ
برد نهايي: 250 كيلومتر
نوع رادار: فعال




6-موشك اگزوسه(Exocet)

طراحي موشك اگزوسه در سال1967 اغاز گرديده و نوع دريا پايه ان كه با كد MM 38 شناخته مي شود در سال 1975 وارد خدمت گرديد.نوع هواپايه ان كه با كد AM 39 شناخته مي شود طراحي ان از سال 1974 اغاز گرديد و در سال 1979 تحويل نيروي دريايي فرانسه گشت.اين موشك در جنگ فالكلند از يك جنگنده ارژانتيني شليك شده و باعث غرق شدن ناو جنگي انگلستان گشت و در جنگ اول خليج فارس جنگنده هاي نيروي هوايي عراق اين موشك را به سمت يك ناوچه امريكايي شليك كرد و قبل از اينكه ناو امريكايي بتواند كاري از پيش ببرد موشك به ان برخورد كرده و ان را به دونيم ميكند.
ايران درسال 2003 سفارش تعداد نامحدودي از اين نوع موشك را به فرانسه داده است.از دريافت سفارس ايران اطلاعاتي در دست نيست ولي منابع مطلع تعداد اين موشك هاي ايران را 500 عدد اعلام كرده اند.اين موشك به وسيله جنگنده هاي ميراژ فرانسوي كه در اختيار نيروي هوايي قرار دارد قابل شليك است.
مشخصات:
سال ورود:1979
انداره: 580 سانتيمتر
وزن: 855 كيلوگرم
وزن كلاهك:168 كيلوگرم به همراه زره تاخير انداز در انفجار
سرعت: 0.93 ماخ
برد: 63 كيلومتر
رادار:ESD ADAC رادار فعال



7-موشک ضد کشتی رعد(HY-2)

در سال 2004 ایران یک مدل جدید از موشکهای
ضد کشتی را بر مبنای موشک چینی کرم ابریشم را با برد و سرعت بیشتر طراحی نمود و به تولید انبوه رساند
این موشک با توجه به سرعت زیاد آن یکی از خطرناک ترین موشک های ضد کشتی است که امکان هر گون تحرکی را از حریف صلب میکند
مشخصات:
نوع: موشک ضد کشتی
سرعت: بین0.8 تا 1 ماخ
طول:7.8 متر
وزن: 2998 کیلوگرم
برد: 135 تا 200 کیلومتر
ارتفاع پرواز:30 تا 50 متر
نوع سیستم راداری: رادار مونو پالس (فعال)
وزن سر جنگی: 512 کیلوگرم
موتور: یک موتور سوخت مایع بهمراه یک بوستر سوخت جامد
این عکس کوچک شده است برای مشاهده ی سایز اصلی کلیک کنید


+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:57  توسط نوید  | 

4-موشك حوت

4-موشك حوت
در سال 1385 و در رزمايش پيامبر اعظم(ص) موشكي را ازمايش كرد كه باعث حيرت بيش از پيش جامعه جهاني گشت.ايران در اين رزمايش موشكي با سرعت 100 متر بر ثانيه را ازمايش كرد.موشك انداز هاي اين موشك كامل رادار گريز بوده و از ديد رادارهاي دشمن مخفي ميمانند.توان رزمي اين موشك برابر با موشك VA-111 Shkval ساخت روسيه است و تنها دو كشور ايران و روسيه فناوري لازم را براي ساخت چنين موشك هاي به دست اورده اند.هنوز مشخص نيست كه آيا "حوت" بر پايه shkval ساخته شده است يا خير.سرعت متوسط اين موشك 4 برابر اژدر معمولي زير ابي است.
اين موشك با توليد حبابهاي بخار كه از نوك دماغه و پوسته خود خارج مي كند لايه اي از گاز در اطراف خود شكل مي دهد و بدين ترتيب خود را از تماس مستقيم با آب و پساي قابل ملاحظه ناشي از آن دور مي كند.
اين موشك قابليت پرتاب از روي شناور و يا زيردريايي در عمق 100 متري را دارد. با سرعت حدود 50 نات (93 كيلومتر بر ساعت) كپسول پرتاب خود را ترك مي كند. با فرو رفتن در آب و رسيدن به عمق مناسب، موتور خود را روشن كرده و به سمت هدف راهي مي شود.
از چالش هاي فني توسعه چنين موشكي مي توان به كاويتاسيون اشاره نمود كه لازم است ميزان حبابهاي كاويتاسيون براي حفظ و پايدار نگهداشتن لايه گاز اطراف موشك ونيز رسيدن به كمترين پسا كنترل شود. در همين رابطه توجه به تداخل گازهاي خروجي از راكت و نيز سطوح كنترل موشك با لايه گاز ايجاد شده در اطراف آن، پيچيدگيهاي اين مساله را روشن تر مي سازد. به ويژه زمان شروع به كار موتور و شرايط گذار (Transision) ناشي از آن از اين حيث قابل توجه است.
سيستم هدايت چنين موشكي نيز با چالشهاي خود روبرو است. تغيير محيط سيال اطراف موشك، شكست امواج و نيز سرعت خودموشك از مواردي است كه هدايت آن را با مشكلات عديده اي مواجه مي سازد
این عکس کوچک شده است برای مشاهده ی سایز اصلی کلیک کنید


+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:56  توسط نوید  | 

3-موشك كروز دريايي نور(بهينه شده c-802)


موشك كروز نور از جمله موشك هاي ساخت داخل ميباشد كه با الگو برداري از موشك هاي چيني c-802 توسط متخصصان داخلي توليد شده .اين موشك در ايران در سال 80 به صورت توليد انبوه در اختيار نيروهاي مسلح قرار گرفت.در سال 1385 و در رزمايش پيامبر اعظم(ص) نوع بهينه شده اي از موشك نور مورد ازمايش قرار گرفت و با موفقيت ازمايش شد.موشك بهينه نور بدون نياز به سيستم OTHT با حداكثر برد به سمت اهداف سطحي شليك مي‌شود.جمهوري اسلامي ايران اولين كشوري است كه توانست موشك نور(c-802) را بر روي بالگرد نصب كند و ما نخستين كشوري هستيم كه اين تكنولوژي را دارا مي‌باشيم.
مشخصات:
برد:120 كيلومتر
ورن كلاهك جنگي:165 كيلوگرم
این عکس کوچک شده است برای مشاهده ی سایز اصلی کلیک کنید



+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:56  توسط نوید  | 

2-موشك كروز دريايي كوثر(C-701)


اين موشک ترکيبي از تکنولوژي بومي و برداشتهايي از نمونه ي چيني C-701 است اين موشک به يک سرجنگي الکترو اوپتيک مجهز است که به همراه يک رادار جستجوي ميليمتري کنترل آن را انجام ميدهد
موشک کوثر مناسب براي شليک از شناور هاي گشتي کوچک تا متوسط لانچر هاي زميني هليکوپتر ها و جنگنده ها يا هواپيماهاي گشت درياييست (مانند اوريون)
از توانايي هاي اين موشک ميتوان به اصلاح اتوماتيک مسير شليک انتخاب اتوماتيک هدف بعدي(نزديک ترين هدف در صورت خارج شدن هدف اول از دسترس يا قفل رادار بطور کلي بازيافت البته امکان هدايت اپتيکي تلوزيوني هم هست)

مشخصات:
نوع: موشک ضد کشتي
برد بيشينه:15 تا 19 کيلومتر
طول:2.6 متر
وزن سرجنگي: 29 کيلوگرم با توانايي ضد زره براي ورود به قسمت هاي داخلي تر(تاخير در انفجار)
وزن کلي: 100 کيلوگرم
موتور: يک بوستر سوخت جامد با سوخت ذخيره
سرعت: 0.8 ماخ
نوع کنترل گر: کنترل گر تصويري يا رادار موج ميليمتري به همراه رادار خانگي Sea skimmer
این عکس کوچک شده است برای مشاهده ی سایز اصلی کلیک کنید
+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:55  توسط نوید  | 

موشکهای ضد کشتی ایران

موشك هارپون(AGM-84 Harpoon)
موشک هارپون یکی از معروفترین و قویترین سلاح های ضد کشتیست که با وجود عمر طولانی آن هنوز یکی از موشک های اصلی ضد کشتی در نیروی دریایی آمریکا و بسیاری از کشورهای جهان از جمله ایران است(هارپون به معنی نیزه ی شکار نهنگ است)
موشک هارپون بسور اختصاصی و تنها برای مقابله با کشتی ها ساخته شد و اولین بار به خدمت نیروی زمینی و دریایی آمریکا در آمد موشک هارپون بدلیل نیاز شدید نیرو های هوایی و دریایی در مدل های مختلف به تولید انبوه رسید بعدها موشکSLAM که به معنی (Stand-off Land Attack Missile) است از روی آن تولید گردید
در 1965 نیروی دریایی بصورت آزمایشی در قالب یک طرح پژوهشی بر روی موشک برای مقابله ی سطحی با زیر دریایی ها و با برد 45 کیلومتر شروع به بررسی نمود پس از نابودی رزم ناو اسرائیلی Eilat توسط دو ناوچه ی موشک انداز ساخت روسیه در 1967 احمیت این پروژه دوچندان شد چرا که نیاز به یک موشک ضد کشتی قوی در برابر اهداف سطحی بسیار حس میشد با سرعت گرفتن رشد پروژه در 1970 اولین نمونه ی هارپون تحت عنوان ZAGM-84A مورد آزمایش قرار گرفت با این وجود نتیجه ی آزمایشات رضایت بخش نبود در نتیجه سال بعد این قرار داد طی مناقصه ای به شرکت McDonnell-Douglas اعطا گردید بدنبال این امر مکدانل داگلاس طی مدت کوتاهی سه مدل مختلف از این موشک را تدوین نمود و سریعا اولین تست ها انجام شد نمونه ی اولیه در 1972 آزمایش شدمدل هایی که مکدانل داگلاس ارائه کرد به این ترتیب بود موشک هوا به دریا مدل پایه AGM-84A و موشک دریا به دریا RGM-84A و زمین به دریا UGM-84A ولی طرح ایراداتی نیز داشت از جمله برد کم در حالی که حد اقل نیاز به دامنه برد 90 کیلومتر می بود که بعدها اصلاح شد
اولین مدل در 1977 وارد خدمت شد و اولین نمونه هم نمونه ی دریا به دریا بود پس از آن اولین نمونه ی هوا به دریا (AGM-84A ) در 1979 بر روی هواپیما های P-3 اوریون نصب شد اولین نمونه ی زمین به دریا هم در 1981 وارد خدمت گردید.
از تعداد و امادگي اين نوع موشك در نيروي دريايي ايران اطلاعات زيادي دردست نيست و سياست ايران در ضمينه موشك هاي دريايي برپايه موشك هاي كروز قرار دارد.موشك هارپون در مدلهاي مختلفي توليد گشته و ما مشخصات موشك هاي تحت اختيار ايران را در زير قرار مي دهيم.
مشخصات:
نوع: موشك ضد كشتي
طول: 4 متر 55 سانتيمتر
وزن: 5/661 كيلوگرم
برد: 60 مايل
سرعت: 855 كيلومتر بر ساعت


+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:54  توسط نوید  | 

AURORA 2

AURORA / SENIOR CITIZEN

Reports of plans for a high-performance piloted replacement for the SR-71 date back more than a decade. In 1979 it was reported that a:<41>

"... Mach 4, 200,000-ft.-altitude aircraft that could be a follow-on to the Lockheed SR-71 strategic reconnaissance vehicle in the 1990s has been defined by the Air Force Aeronautical Systems Division and Lockheed."

As previously noted, reports of the existence of a successor to the SR-71 surfaced repeatedly during the debate over termination of the SR-71. Subsequent observations of mysterious aerial phenomena have been connected with the 1988 reports that Aurora was a Mach 6 stealthy reconnaissance aircraft that was being developed to replace the SR-71.<42>

Noted aerospace analyst Wolfgang Demisch, of First Boston Company, suggested that the $10 billion program would result in the production of about 30 aircraft.<43> More recently, Kemper Security analyst Lawrence Harris concluded that Lockheed was involved in a:<44>

"... hypersonic replacement for the Mach 3 plus SR-71 reconnaissance aircraft. Circumstantial evidence suggests that this project has been underway since 1987 and that a first flight occurred in 1989... Aurora could be operational in 1995, six years after the probable first flight."

This analysis suggested that the total development costs for Aurora might range from $4.4 billion to $8 billion, with the procurement of 24 aircraft costing an additional $10 billion to $24 billion.

According to another report, by mid-1992:<45>

"... Aurora was being flown from a base in the Nevada desert to an atoll in the Pacific, then on to Scotland to refuel before returning to the US at night. Specially modified tanker aircraft are being used to top up Aurora's tanks with liquid methane fuel in mid-air... The US Air Force is using the remote RAF airbase at Machrihanish, Strathclyde, as a staging point... The mystery aircraft has been dropping in at night before streaking back to America across the North Pole at more than six times the speed of sound... An F-111 fighter bomber is scrambling as the black-painted aircraft lands, flying in close formation to confuse prying civilian radars."

The rationale used most frequently by the Department of Defense for the SR-71's termination was financial. The Blackbird's operation and maintenance costs were very high. According to some reports, the SR-71's O&M costs were nearly $710- million in FY-90 and FY-91.<46> Furthermore, they argued, imaging satellites could now conduct worldwide surveillance more efficiently and less expensively than manned reconnaissance aircraft.

Independent aerospace analysts, however, deflated this argument somewhat by pointing to the unique advantages aircraft bring to the reconnaissance arena. Aircraft, for example, are inherently flexible and unpredictable. Though not as fast as satellites, they can fly lower and the interval between over the horizon arrival and time-over-target is just as short. Aircraft have a wide choice of routes, so tracking ships are unlikely to see it on the way in. Application of low observable technology could further reduce warning time.<47> Thus, it appears plausible that aircraft may still have a role in global reconnaissance.

Another analyst has considered the possibilities of "Aurora's" characteristics and capabilities. A long-range reconnaissance follow-on to the SR-71 would be a blended delta with 75 degree leading-edge sweep and retractable low-speed foreplanes. It would be powered by two regenerative air-turboramjet (RATR) engines of 180 kN sea-level static thrust. It would carry a crew of two and use a synthetic aperture radar with real-time datalink for reconnaissance (Figure 4). It is suggested that this type of platform could be very responsive, much more easily maintainable than the SR-71 and could deliver imagery of most points of interest within six hours of the decision to go. A speed between Mach 5 and Mach 6 and a cruising altitude of 40 kilometers would make the aircraft invulnerable to any current missile system.<48>

The Public Record

Beginning in the mid-1980s, the Air Force and NASA have supported a number of studies of aircraft that are consistent with accounts of the Aurora project. Although these studies have not been linked to actual development efforts, they provide some insight into the potential configuration and capabilities of Aurora.

In 1985 McDonnell Douglas conducted studies of a Mach 5, 12,000 km range 305 passenger HSCT (hypersonic commercial transport) powered by regenerative ATR (air turboramjet) engines. Initial research led to claims that this type of aircraft was not only feasible, but remarkably efficient. According to these studies, a ramjet was the best option at Mach 5, and that methane was the preferred fuel. Hydrogen was also considered, but it takes up to five times as much space. If the large HSCT was scaled down to the dimensions of an SR-71, the aircraft could have a range of approximately 10,000 miles with a crew of two and a 1 ton sensor suite.<49>

Lockheed's renowned Skunk Works has been the incubator of several programs that could evolve, or could already have evolved, into an SR-71 replacement. Presently, Lockheed engineers are reportedly studying the development of a liquid methane- fueled aircraft that could penetrate enemy airspace in order to perform reconnaissance missions.<50>

"The sleek aircraft would cruise at Mach 5 (3,350 mph) speed at a maximum altitude of about 100,000 feet. The aircraft would be made primarily of titanium with its outer edges constructed of Inconel, a heat-resistant stainless steel. At Mach 5 speed the leading edges of the air-frame would glow red above 1,000 degrees Fahrenheit. Power for this futuristic airplane would come from four turbo-ramjets. The engines would operate as turbojets at low speeds, but at higher speeds the compressor and turbine would be overridden so the engines would operate as ramjets."

Other aircraft designs that would fly between Mach 4 and Mach 8, fueled by hydrocarbon or liquid hydrogen are also being considered.<51> And in the mid-1980s, Lockheed proposed a Mach 7-8 "transatmospheric vehicle" or TAV as an SR-71 replacement. Intriguingly enough, the name "Aurora" was also used in conjunction with this proposal.<52>

TABLE 1
>Aurora Advanced Aircraft Characteristics

Source			Lockheed	Sweetman	Lockheed	Boeing		Boeing
Date			1985		1990		1990		1990		1990

Figure			1		2		3		4		5	

Dimensions:
  Length - meters	?		 35		30.6		26.0		42.7
  Span - meters		?		 20		13.6 / 25	14.7		13.5
  wing area - m2	-		300		-		-		95

Weights: tons
  Empty			?		32.5		-		19.3		-
  Fuel 			?		44.0		-		19.5		12.6
  Payload		?		 2.0		-		 1.5		-
  Max T/O		?		78.5		-		40.3		34.5

Propulsion:
  Thrust - kN		?		?		?		267		?
  Fuel				Methane			MCH		MCH		LH2

Performance:
  Cruise - Mach		5		5-6		5		5.5		6
  Ceiling - km		30		40		27		32		33
  Range - km		?		17,000		1,900		5,000		27,750

------------------------------

MCH = methylcyclohexane
LH2 = liquid hydrogen

FIGURE 1



FIGURE 2

<57>

FIGURE 3

<58>

FIGURE 4

<59>

FIGURE 5

<60>

In 1986, the Directorate for R&D Contracting, Wright-Patterson Air Force Base, issued an RFP for aircraft propulsion integration technology. The<61>

"... purpose of the proposed investigation is to develop an improved foundation for manned aircraft air-breathing propulsion integration technology in the Mach 4 to 6 regime."

Under an Air Force contract, Boeing Military Airplane Co. designed an interceptor capable of sustaining supersonic speeds. It was reported that wind tunnel tests would be conducted under a 26 month $572,000 follow-on contract.<62> This effort also included detailed studies of aircraft subsystems.<63> Similar studies were conducted by Lockheed<64> and General Dynamics.<65>

Keeping an aircraft sufficiently cool during extreme speeds is a primary challenge of hypersonic flight. According to studies done by General Dynamics and Boeing, an aircraft travelling at between Mach 5.5 and Mach 6 would have an average skin temperature of approximately 1100-1300 degrees Fahrenheit.<66> One potential solution incorporated in the Air Force studies, also being explored by researchers at NASA's Langley Research Center and Wright-Patterson Air Force base,<67> is the use of Methylcyclohexane (MCH) as both the fuel and the thermal management medium of the vehicle.

MCH has several advantages over other possible hydrocarbon or cryogenic fuels. Unlike standard hydrocarbon fuels, MCH has a very high capacity to absorb heat prior to combustion, up to 1800 Btu per pound of fuel, which is ten times the capacity of most hydrocarbon fuels.<68> Cryogenic Methane and Hydrogen have high heat absorbtion capacities as well, but their use as an aviation fuel is limited by the logistical difficulties of handling, storage and fuel boil off.<69>

The principle behind MCH thermal management is based on a catalytic reaction transforming MCH into Toluene and Hydrogen, which are then used to fuel the aircraft:<70>

A fuel pump pressurizes the fuel to... avoid boiling. The preheater heats the fuel to the proper reaction temperature while removing heat from a secondary coolant...After preheating, the fuel passes through the catalytic heat exchanger/ reactor...

The secondary coolant, Syltherm, circulates to the hot spots to maintain skin temperatures to within specified tolerances.<71>

One aerospace journal says that an aircraft travelling at Mach 6 would be inside the combustion envelope of a subsonic-combustion ramjet. It suggests that the aircraft would thus need an accelerator to get it moving. One type of accelerator would be a ducted-rocket cycle into the engine. A fuel-rich, liquid rocket exhaust would be injected into a ramjet duct, pumping air through it even at rest. A second combustion then takes place, using atmospheric oxygen.<72> (This second combustion could produce the loud rumbling noises heard recently in California, discussed below).

Budget and Financial Data

The first suggestion that these studies might be translated into operational hardware appeared in the Fiscal Year 1986 procurement program document, colloquially known as the P-1, dated 4 February 1985. A line item in this document, labeled "Aurora," was slated to receive $80 million in 1986, and over $2.2 billion in 1987.<73> Since this line item appeared next to the line funding the TR-1 reconnaissance aircraft, it stirred up a hornet's nest of conjecture that a secret aircraft was being developed to replace the aging SR-71.

The Air Force quickly denied the existence of a secret program, and said the "Aurora" budget line was simply one site for B-2 bomber funds when that program was highly classified.<74> One Air Force official commented, "I wish I could say it is (an SR-71 follow-on), because we'd love to have it. But it's just accounting, I'm afraid."<75>

Others disagreed. One journal reported that "the general consensus now is that the item did not refer to the B-2 bomber but to another effort."<76> Other analysts placed the SR-71 follow-on at both Edwards Air Force Base and Nellis Air Range.<77>

Other publications saw a more complicated, more expansive black world. These periodicals posited that Aurora was one of several code names "nested within other code names, all referring to a class of aircraft designed for multiple missions."<78>

However, the discussions of the Aurora budget line item overlook one very crucial fact:

No money was ever appropriated for Aurora!

In the February 1985 submission of the FY 1986 budget, the Aurora line item projected a request of over $2 billion in the FY 1987 budget. But one year later, when the FY 1987 budget was submitted, the Aurora line item had vanished as mysteriously as it had first appeared. Indeed, FY 1987 request for the overall Air Force aircraft procurement account was several billion dollars less than had be projected in 1985, and there were no line items in the FY 1987 request that could have been used to conceal a request for funding for Aurora.

Much of the subsequent speculation on Aurora has implicitly assumed that there was an identifiable source of funding for the program. Although this is not obviously the case, there nonetheless remains one tantalizing, and previously unremarked, hint that the Aurora program was in fact funded, though at a significantly reduced scale.

As previously noted, the case for the existence of all mystery aircraft, including Aurora, must be predicated on identifiable sources of funding. Thus the proper identification of the programmatic content of the major elements of the black budget is essential to assessing the status of mystery aircraft, such as Aurora. A not-implausible accounting has already been given that suggests an identifiable source of funding that may be attributed to the TR-3A stealth aircraft program. But where in the budget might other aircraft programs be funded?

Some have assumed that the funding for the CIA and NRO is entirely hidden from view -- completely off-budget, or widely dispersed among a large number of accounts in many government agencies, or disguised in some obscure accounting transaction of the Federal Financing Bank, or perhaps secreted somewhere among the subsidy programs of the Agriculture Department. Under such assumptions, the billions of dollars appropriated each year for such programs as "Selected Activities" or "Special Programs" would provide more than enough money to finance a vast fleet of exotic aircraft.

But a more detailed consideration of the classified budget provides little basis for believing that these line items might provide funding for such purposes.

While the structure of the classified budget is obscure, it is not perverse. Line items in the budget may be given opaque names, like Selected Activities, which obscure their programmatic content, but there are no activities that are not included in some budget item, however obscurely. There are no off-budget programs. Other line items, such as "Special Programs" (the nomenclature used for the National Reconnaissance Office) may omit the value of the budget. But in such cases, a fair approximation of the omitted value may be obtained by subtracting the sum of those lines for which values are given from the total provided for the budget category which includes the omitted values. It may also be fairly assumed that the multitudinous Navy classified budget items, such as Chalk Coral and Retract Amber, are funding only Navy projects, rather than Air Force programs. And it may also be assumed that Aircraft Procurement accounts fund only aircraft, and that Missile Procurement accounts fund only missiles or space vehicles, though the more generic Other Procurement accounts clearly fund a wide range of programs.

The Other Procurement Air Force account includes a line item opaquely labeled "Selected Activities," which typically accounts for about half of the total budget of this account. Analysis of the outlay rates for this and other budget accounts reveals an interesting anomaly. Procurement accounts, which fund the purchase of hardware, typically spend about 5% to 15% of their appropriation in the first year, with outlays rising to 20% to 40% in the second and third years, and declining thereafter. This reflects the contracting process, in which several years are required to complete manufacture of hardware. In contrast, personnel and operations and maintenance accounts, which are largely for payroll and supplies, typically have first year outlay rates of 50% to 80%.

Uniquely, the Other Procurement Air Force account has a first year outlay rate that has ranged from over 40% to nearly 60%. The only possible explanation for this anomaly is that the "Selected Activities" half of the Other Procurement Air Force account is in fact not a procurement activity, with a low first-year outlay rate, but rather funds personnel and operating expenses, with their characteristic high first-year outlay rate.

Table 2
Classified Aircraft Budget

		AIRCRAFT		OTHER      
		PROCUREMENT		PROCUREMENT							
		Aurora		Special	
				Update Program
		FY86			FY86			
			
						
1980 		 		 50 	
1981 		 		123 
1982 		 		554 	
1983 		 		217 	
1984 		 		656 	
1985 	 	    --		928 	
1986 	 	    80 		 84 	
1987 	 	(2,272)		851 	( 139 )
1988 	 	    --		121 	
1989 			 	126 	
1990 			 	122 	
1991 			 	105 	
1992 			 	162 	
1993 			 	176 	
									
Millions of Dollars							
Numbers in parentheses are FY86 projections				
All others are actual appropriations



In recent years, the budget for the "Selected Activities" line item has been somewhat in excess of $5 billion annually. This value is consistent with the roughly $3 billion that is the reported budget of the Central Intelligence Agency, as well as the personnel and operations and maintenance budget of the National Reconnaissance Office. There is no reason to doubt this conclusion.

However, the next line down from "Selected Activities" in the Other Procurement Air Force account is an item dubbed, "Special Update Program." This proximity in the budget is suggestive of some relationship in mission as well. It is plausible that this line item includes procurement of intelligence collection systems of interest to the CIA or Air Force, other than satellites, which are funded elsewhere in the budget. Funding for this line item peaked at over $900 million in 1985, then dropped to $84 million in 1986. This suggests that whatever activity was funded under this account in the early 1980s had been concluded. The same FY 1986 procurement program document, that included the $2.2 billion funding projection for Aurora in FY 1987 also projected that the FY 1987 funding for Special Update Program would be $139 million.<79>

But when the actual FY 1987 budget was submitted a year later, not only had Aurora disappeared, but the Special Update Program budget request was $851 million, over $700 million more than had been projected a year earlier.

It is not implausible that this reflected a decision not to proceed with production of an operational system which would have been funded under the Aurora line item, but instead to conduct some sort of prototype propulsion test program, funded under the Special Update Program line. The $1.5 billion appropriated for this account since 1987 would be consistent with such a prototype effort.

Although this analysis is necessarily speculative, the coincidental behavior of these two budget line items is certainly highly suggestive. This also identifies a not- implausible source of funding for an experimental high-speed, high-altitude aircraft with primarily intelligence applications.

Observer Reports

A wide range of reports of observations of mysterious aerial phenomena have been associated with the Aurora aircraft. These observations are also in many regards consistent with the suggested Exotic Propulsion Aircraft. Those reports relating to both possibilities are discussed here, while those reports unique to the Exotic Propulsion Aircraft are discussed subsequently. These unexplained phenomena have led some to conclude that:<80>

"...the US Government has secretly developed and deployed a hypersonic reconnaissance aircraft, probably as a replacement for the SR-71."

There are two classes of reports relating to Aurora: those that are consistent with a limited experimental test program; and those that are suggestive of the existence of an operational capability.

Edwards Air Force Base in southern California is the primary facility used by the American military for the flight testing of experimental aircraft. In addition, the Groom Lake facility at Nellis Air Force Base in Nevada was used for developmental testing of the F-117A, and has been associated with reports of other advanced aircraft. Given this geographical concentration, it would not be surprising if secret aircraft undergoing flight tests were to be observed in the Southwestern United States.

In October 1990 Aviation Week & Space Technology published reports of:<81>

"A high altitude aircraft that crosses the night sky at extremely high speed.... The vehicle typically is observed as a single, bright light -- sometimes pulsating -- flying at speeds far exceeding other aircraft in the area, and at altitudes estimated to be above 50,000 ft.... Normally, no engine noise or sonic boom is heard."

More recently, a sighting by two British Airways pilots and other witnesses at Manchester Airport on January 6 1995 has been attributed to the Aurora aircraft.

Probably the most compelling evidence for such flight tests are the series of unusual sonic booms chronicled above Southern California, beginning in mid to late 1991. On at least five occasions, these sonic booms were recorded by at least 25 of the 220 US Geological Survey sensors across Southern California used to pinpoint earthquake epicenters. The incidents were recorded in June, October, November, and late January 1991.<82> Seismologists estimate that the aircraft were flying at speeds between Mach 3 and 4 and at altitudes of 8 to 10 kilometers. The aircraft's flight path was in a North North-East direction, consistent with flight paths to secret test ranges in Nevada. Seismologists say that the sonic booms were characteristic of a smaller vehicle than the 37 meter long shuttle orbiter. Furthermore, neither the shuttle nor NASA's single SR-71B were operating on the days the booms were registered.<83>

One of the seismologists, Jim Mori, noted:<84>

"We can't tell anything about the vehicle. They seem stronger than other sonic booms that we record once in a while. They've all come on Thursday mornings about the same time, between 6 and 7 in the morning."

These "skyquake" are a continuing phenomenon, with the most recent report over Orange County, CA coming on 20 July 1996. It is reported that the "quake" occurred around 3pm PST, fitting the "skyquake" pattern in the following respects:
  1. It occurred in a coastal area.
  2. Described as similar to an earthquake in some respects (rattling of loose objects, etc) but also like a boom (but no distinct double bang as far as is known).
  3. Severe enough to light up government and media switchboards, but no known damage.
  4. Not an earthquake (CalTech sensors saw nothing)
  5. Local military bases deny any knowledge.
  6. No known other source (eg explosion)

Intercepted radio transmissions are equally intriguing:<85>

"On Apr. 5 (a Sunday) and Apr. 22, radio hobbyists in Southern California monitored transmissions between Edwards AFB's radar control facility (Joshua Control) and a high-altitude aircraft using the call sign "Gaspipe." The series of radio calls occurred at approximately 6 a.m. local time on both dates.

"Controllers were directing the unknown Gaspipe aircraft to a runway at Edwards, using advisories similar to those given space shuttle crews during a landing approach. The monitors recorded two advisories, both transmitted by Joshua Control to Gaspipe: "You're at 67,000, 81 mi. out," and "Seventy mi. out, 36,000. Above glide slope."

Reported sightings of unusual high performance aircraft are not confined to the Southwestern United States. More recently, such observations have also been reported in other parts of the United States, as well as in Europe. These reports are particularly intriguing because they are difficult to reconcile with an experimental test program, since there would be no reason for test flights to be conducted in Europe. Rather, these reports would have to be understood in the context of the deployment of an operational aircraft.

One unexplained set of observations was reported at Beale Air Force Base, the California facility that was long home to the SR-71. On two consecutive nights in late February 1992, observers reported sighting a triangular aircraft displaying a distinctive diamond-shaped lighting pattern, comprised of a red light near the nose -- similar to the F-117 configuration -- two 'whitish' lights near what would be conventional wingtips and an amber light near the tail.<86> While the wing lights are reportedly much brighter than normal navigation lamps, they do not illuminate the aircraft's planform. Observers claim the vehicle's wing lights are approximately twice as far apart as those on the F-117, and nose-to-tail light spacing is about 50 percent longer than that on the stealth fighter.<87>

Reports of "unusually loud, rumbling sonic booms" near Pensacola, Florida in November 1991 have also been associated with the Aurora program.<88> At least 30 unexplained sonic booms have been reported in Southern California in late 1991 and early 1992.<89> By mid-1992 noted aviation observer Bill Sweetman concluded that, "The frequency of the sonic booms indicates that whatever is making them is now an operational aircraft."<90>

In early 1992 it was reported that:<91>

"... RAF radars have acquired the hypersonic target travelling at speeds ranging from about Mach 6 to Mach 3 over a NATO-RAF base at Machrihanish, Scotland, near the tip of the Kintyre peninsula, last November and again this past January."

aurora_fake.jpg - 10.1 K

It was recently reported than on 27 September 1995 David Morris of Walsall, Cornwall UK took a picture of a triangular shaped plane being refueled by a KC-135, and flanked by a pair of F-111s. The unknown aircraft appeared to be about three-quarters the size of the KC-135. This picture has been widely distributed. However, the "refuelling" picture is a hoax -- it was montaged by Bill Rose for the October 1995 issue of Astronomy Now (UK) magazine. There, it is captioned "A simulation of the refuelling of the top secret 'Aurora'. Photo composition by Bill Rose."<92a>

Interpretation

In 1990, it was suggested that the Aurora (also reportedly designated "Senior Citizen") had been intended to be the SR-71's successor, but it had been canceled along with the "Blackbird" in 1989.<92> One report suggested that:<93>

"Congress, in addition to killing the SR-71 late last year [1989], voted to terminate a $100 million "related classified activity" that may have been the follow-on effort."

According to the Senate Armed Services Committee, in 1989:<94>

"... the Congress directed the Department [of Defense] to develop a viable long-term roadmap for airborne reconnaissance. The Department has not done that and will not have that roadmap available until next year. Even then, the Department has proposed to initiate an extraordinarily expensive effort to reproduce the capabilities inherent in the SR-71. The committee cannot endorse that request..."

Representative Robert Livingston (R-LA) noted during a January 1990 House Appropriations Committee hearing that:<95>

"The possible follow-ons (to the SR-71), which again we can't even talk about, even if we were going ahead with them, wouldn't be available for many years, six or seven years, and we are not going ahead with them."

Addressing the prospects for an SR-71 follow-on, Air Force Chief of Staff Lawrence Welch noted that:<96>

"There are a couple of programs... Frankly, we have not found them too promising."

These official pronouncements are difficult to reconcile with other forms of evidence suggesting the existence of an SR-71 follow-on.

Byron Salisbury has built an aircraft model of a conceptual design based on eye witness sightings and information from highly reputable sources. He believes the model to be 95%+ accurate of the "aurora" plane sighted in the North Sea and South Eastern and South Western United States. The model kit is made entirely of white plastic resin and is easy to assemble. The measurements are 12" long x 9" wing span x 2" high. The cost per model is $75.00 plus $15.00 shipping and handling. If you would like to place an order or have any questions he can be reached at cromlich@iag.net or by snail mail at B.M. Salisbury, 4620 E. Michigan Street #103, Orlando, Fl. 32812.

REFERENCES

<41> "Mach 4, 200,000-Ft.-altitude Aircraft Defined," Aviation Week & Space Technology, 29 January 1979, page 141.

<42> Sweetman, Bill, "Mystery contact may be Aurora," Jane's Defense Weekly, 29 February 1992, page 333.

<43> "Evidence Points to Stealth Spy Plane," High Technology Business, April 1988, pages 8-9.

<44> "Skunk Works Revenues Point to Active Aurora Program, Kemper Says," Aerospace Daily, 17 July 1992, page 102.

<45> Campbell, Christy, "Secret US Spy Plane is Kintyre's Dark Visitor," Sunday Telegraph, 26 July 1992, page 1.

<46> "Air Force Battle Brews over using unmanned vehicles for coveted spy mission," Inside The Pentagon, 9 June 1989, page 8.

<47> Sweetman, Bill, "Aurora - is Mach 5 a reality?" Interavia Aerospace Review, 11 1990, page 1009.

<48> ibid.

<49> Sweetman, Bill, "Aurora - is Mach 5 a reality?" Interavia Aerospace Review, 11 1990, p.1010.

<50> Artists Rendering, US Air Force, Washington, DC, 12 November 1985.

<51> ibid.

<52> "Secret Advanced Vehicles Demonstrate Technologies For Future Military Use," Aviation Week & Space Technology, 1 October 1990, page 21.

<53> Sweetman, Bill, "Aurora - is Mach 5 a reality?" Interavia Aerospace Review, 11 1990, page 1009.

<54> Petley, Dennis, "Thermal Management for a Mach 5 Cruise Aircraft Using Endothermic Fuel," Journal of Aircraft, vol. 29, no. 3, May-June 1992, pages 384-38

<55> Woods, E.J. et al, "Advanced Aircraft Secondary Power System Design," Proceedings of the 25th Intersociety Energy Conversion Engineering Conference, Reno, Nevada, 12-17 August 1990, volume 1, pages 505-510.

<56> Kaufmann, H.G., et al, "Control Strategy for Maximizing Reconnaissance Range of Hypersonic Cruise Vehicles," Journal of Aircraft, vol. 29, no. 3, May- June 1992, pages 360-365.

<57> Sweetman, Bill, "Aurora - is Mach 5 a reality?" Interavia Aerospace Review, 11 1990, page 1009.

<58> Petley, Dennis, "Thermal Management for a Mach 5 Cruise Aircraft Using Endothermic Fuel," Journal of Aircraft, vol. 29, no. 3, May-June 1992, pages 384-389.

<59> Woods, E.J. et al, "Advanced Aircraft Secondary Power System Design," Proceedings of the 25th Intersociety Energy Conversion Engineering Conference, Reno, Nevada, 12-17 August 1990, volume 1, pages 505-510.

<60> Kaufmann, H.G., et al, "Control Strategy for Maximizing Reconnaissance Range of Hypersonic Cruise Vehicles," Journal of Aircraft, vol. 29, no. 3, May- June 1992, pages 360-365.

<61> "Air Force Issues RFP for Mach 4-6 Aircraft Propulsion Development," Star Wars Intelligence Report, 21 January 1986, page 10.

<62> "Boeing Designs Interceptor Aircraft Capable of Sustained Supersonic Speeds," Aviation Week & Space Technology, 11 February 1985, page 61.

<63> Woods, E.J. et al, "Advanced Aircraft Secondary Power System Design," Proceedings of the 25th Intersociety Energy Conversion Engineering Conference, Reno, Nevada, 12-17 August 1990, volume 1, pages 505-510.

<64> Petley, Dennis, "Thermal Management for a Mach 5 Cruise Aircraft Using Endothermic Fuel," Journal of Aircraft, vol. 29, no. 3, May-June 1992, pages 384-389.

<65> Gasner, James, et al, "Evaluation of Thermal Management for a Mach 5.5 Hypersonic Vehicle," AIAA/SAE/ASME/ASEE 28th Joint Propulsion Conference, 6-8 July 1992, Nashville, TN, AIAA paper 92-3721.

<66> Gasner, James et al. "Evaluation of a Thermal Management System for a Mach 5.5 Hypersonic Vehicle." AIAA/SAE/ASME/ASEE 28th joint conference and exhibit, July 6-8, 1992. page 2.

Woods, E.J. et al. "Advanced Aircraft Secondary Power System Design." Proceedings of the 25th Intersociety Energy Conversion Engineering Conference, August 12-17, 1990. volume 1, pages 506-507.

<67> "Endothermic-Fueled Jet could Break Mach 5," Popular Mechanics, August 1991, page 15.

<68> Gasner. ibid. page 3.

<69> ibid.

<70> Petley, Dennis H. and Stuart C. Jones. "Thermal Management for a Mach 5 Cruise Aircraft Using Endothermic Fuel." Journal of Aircraft. May-June 1992, page 385.

<71> ibid.

<72> "Update on Aurora," Aerospace World Weekly, 9 March 1990, page 5.

<73> Department of Defense, Procurement Programs (P-1), 4 February 1985, page F-6, line 28.

<74> "Secret Advanced Vehicles Demonstrate Technologies For Future Military Use," Aviation Week & Space Technology, 1 October 1990, page 20.

<75> "Aurora Myth," Aerospace Daily, 9 October 1990, page 34.

<76> "Update on Aurora," Aerospace World Weekly, 9 March 1990, page 5.

<77> Pope, Gregory, "America's New Secret Aircraft," Popular Mechanics, December 1991, page 35.

<78> "Secret Advanced Vehicles Demonstrate Technologies For Future Military Use," Aviation Week & Space Technology, 1 October 1990, page 20.

<79> Department of Defense, Procurement Programs (P-1), 4 February 1985, page F-31, line 308.

<80> Sweetman, Bill, "Mystery contact may be Aurora," Jane's Defense Weekly, 29 February 1992, page 33

<81> "Secret Advanced Vehicles Demonstrate Technologies For Future Military Use," Aviation Week & Space Technology, 1 October 1990, page 20.

<82> ibid.

<83> ibid.

<84> Marshal, Jonathan, "In Plane Sight? Washington City Paper, 3 July 1992, page 12-13.

<85> Scott, William, "New Evidence Bolsters Reports of Secret, High-Speed Aircraft," Aviation Week & Space Technology, 11 May 1992, pages 62-63.

<86> "Possible Black Aircraft Seen Flying In Formation With F-117s, KC-13s," Aviation Week & Space Technology, 9 March 1992, page 66.

<87> ibid, page 67.

<88> "Blast From The Past," Aviation Week & Space Technology, 25 November 1991, page 23.

<89> Scott, William, "New Evidence Bolsters Reports of Secret, High-Speed Aircraft," Aviation Week & Space Technology, 11 May 1992, pages 62-63.

<90> Campbell, Christy, "Secret US Spy Plane is Kintyre's Dark Visitor," Sunday Telegraph, 26 July 1992, page 1.

<91> Rogers, Jim, "RAF Radar Tracked 'Aurora' Over Scotland at Speeds From Mach 3 to Mach 6," Inside the Air Force, 24 April 1992, pages 1, 10-11.

<92> "Successor Relies on Stealth Not Speed," Defense Daily, 30 May 1990, page 503.

<92a> From: mdembinski@delphi.com (Mike Dembinski), Newsgroups: rec.aviation.military,alt.war,sci.space.policy,alt.conspiracy.area51 Subject: Re: Mary Shafer: What about "Aurora"?, Date: Mon, 05 Feb 1996 21:37:05 +0000, Message-ID:

<93> "Classified System Seen Providing Timely Intelligence Data," Aerospace Daily, 17 January 1990, pages 92-93.

<94> United States Senate Armed Services Committee, National Defense Authorization Act for Fiscal Year 1991, 101st Congress, 2nd Session, 20 July 1990, page 138.

<95> "Classified System Seen Providing Timely Intelligence Data," Aerospace Daily, 17 January 1990, pages 92-9

<96> ibid.

+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:51  توسط نوید  | 

Aurora

-

Aurora Aurora
Strategic Reconnaissance

DESCRIPTION:
The name "Aurora" first appeared in a 1985 budget document with a line by that name slated to receive $80 million in FY 1986 and $2.2 billion in FY 1987. Since the item appeared just after the TR-1, many conjectured this project was a high-speed reconnaissance aircraft to replace the SR-71. As early as 1979, the Air Force had begun studying a "...Mach 4, 200,000-ft.-altitude aircraft that could be a follow-on to the Lockheed SR-71 strategic reconnaissance vehicle in the 1990s."

The Air Force, NASA, and several aerospace contractors undertook design studies of Mach 5 aircraft throughout the early and mid-1980s that may have supplied the basic information needed to develop such a concept. The principal difficulties these studies had to address were the development of engines able to power an aircraft at speeds exceeding Mach 5 and developing structures capable of surviving the intense aerodynamic heating experienced at such high speeds (see the Aerospaceweb.org Hypersonic Waverider site to learn more about high-speed flight).

If it does exist, many conjecture the Aurora may look something like the Mach 3 XB-70 Valkyrie or NASA's cancelled X-30 National Aerospace Plane (NASP). Both vehicles were wedge-shaped with delta wings of small area. Both combated heating issues by circulating onboard fuel along surfaces experiencing the greatest heat fluxes. While the XB-70 was propelled by conventional jet engines, the X-30 was to have been powered by advanced ramjet or scramjet engines using cryogenic fuels to operate at speeds exceeding Mach 5.

Based on this technological progression and close scrutiny of the US budget, many observers are convinced the US Air Force was able to develop, build, and test a large high-speed aircraft by the early 1990s. Shortly thereafter, reports of loud sonic booms and sightings of strange contrails over Great Britain and southern California began to surface. Some believe these reports provide further evidence of a very high-speed aircraft using some exotic form of propulsion. It is interesting to note, however, that these reports rapidly trailed off after 1996 suggesting that whatever vehicle mentioned in these sightings may have been only an experimental prototype no longer in use.

The US government has repeatedly denied the existence of an aircraft called Aurora or any similar follow-on aircraft to replace the SR-71. Since the evidence supporting the Aurora is circumstantial or pure conjecture, there is little reason to contradict the government's position.

Data below estimated and completey conjectural
Last modified 21 October 2008

HISTORY:
First Flight possibly late-1980s
Service Entry

existence unconfirmed

CREW: possibly two: pilot and systems officer

ESTIMATED COST:

unknown

AIRFOIL SECTIONS:
Wing Root unknown
Wing Tip

unknown

DIMENSIONS:
Length 115 ft (35 m)
Wingspan 65 ft (20 m)
Height 19 ft (6 m)
Wing Area 3,200 ft2 (300 m2)
Canard Area

not applicable

WEIGHTS:
Empty 65,000 lb (29,480 kg)
Typical Load unknown
Max Takeoff 157,000 lb (71,215 kg)
Fuel Capacity internal: 88,000 lb (39,920 kg)
external: not applicable
Max Payload

4,000 lb (1,815 kg)

PROPULSION:
Powerplant possibly turbofan engines for subsonic flight and
ramjets, scramjets, or pulse detonation engines for supersonic flight
Thrust unknown

PERFORMANCE:
Max Level Speed at altitude: possibly Mach 5 to Mach 8 (some suggest up to Mach 20)
at sea level: unknown
Initial Climb Rate unknown
Service Ceiling 131,000 ft (40,000 m)
Range 8,000 nm (15,000 km)
g-Limits unknown

ARMAMENT:
Gun none
Stations none
Air-to-Air Missile none (although some suggest a long-range AAM like the AIM-54 Phoenix might be carried)
Air-to-Surface Missile none
Bomb none
Other cameras, IR sensors, other recon sensors

KNOWN VARIANTS:
Aurora Possible high-speed advanced reconnaissance platform

KNOWN COMBAT RECORD:

existence unconfirmed

KNOWN OPERATORS:

United States (US Air Force)

3-VIEW SCHEMATIC:

Aurora


+ نوشته شده در  شنبه ششم تیر 1388ساعت 19:47  توسط نوید  | 

هواپیمای بی 1بی

هواپیمای بی 1بی، از خانواده بمب افکن های سنگین وزن آمریكایی است که به عنوان جایگزینی برای هواپیمای بی 52 تولید شد. مدتها تفکر بر این بود که باید جانشینی شایسته که بتواند به خوبی از عهده وظیفه بمب افکن قدیمی و پا به سن گذاشته بی 52 بر آید، طراحی و تولید شود.


بمب افكن سنگین وزن B1-B در نمایی از روبرو


چرا که هواپیمای بوئینگ 52، بمب افکنی بسیار قدیمی و متعلق به دهه پنجاه بود که تکافوی نیازهای نیروی هوایی را نمی کرد و همه روزه چند عدد از آن ها به جمع هواپیماهای از رده خارج شده با بازنشسته به موزه های هوایی سپرده می شدند. به خصوص با اعلام طرحی جدید برای بمب افکنی مدرن ملقب به بلک جک توسط شوروی سابق، دیگر برای نیروی هوایی آمریکا بمب افکن های پیر بی 52 حرفی برای گفتن نداشتند. در این جا بود که با ارئه طرح هواپیمای فوق مدرن B1-A، کارخانه راک ول اینترنشنال وظیفه تولید آن را بر عهده گرفت، اما پس از چندی، متخصصان متوجه آسیب پذیری بسیار بالای این بمب افکن در مقابل رادار شدند و در نتیجه تصمیم بر آن گرفته شد که گونه ای جدیدتر با امکانات بیشتر و ویژگی رادار گریزی بیشتر عرضه شود.

نهایتاً موجب طراحی و تولید هواپیمای B1-B شد. هواپیمای B1-B یک بمب افکن دوربرد و میان قاره ای است که قابلیت شلیک انواع موشک های هوا به سطح ASM مانند کروز و بازه گوناگونی از بمب های همه منظوره و یا هدایت شونده و بمب های هسته ای را نیز دارا است. این بمب افکن بسیار پیشرفته، می تواند بدون سوخت گیری مجدد، از یک قاره به قاره ای دیگر سفر کند، ماموریت خود را انجام داده و سپس مراجعت کند. یکی از ویژگی های چشم گیر این بمب افکن، بالهای متغیر آن است که از تکنولوژی جمع شوندگی برای سرعت های بالا استفاده می کند.


بمب افكن B1-B یك هواپیمای رادار گریز است


در این فناوری، با عقب رفتن بال ها در سرعت های بالا، فشار وارده بر آنها کم شده در نتیجه از میزان پسای اضافی که بالها در سرعت های بالا تولید می کنند کاسته می شود. مزیت دیگر بال متغیر این است که برای برخاست، می تواند بالهای خود را به میزان حداکثر باز کرد تا با سرعت کمتری توانایی تیک آف وجود داشته باشد. هواپیمای B1-B از چهار موتور توربوفن F-101 GE با سیستم پس سوز استفاده می کند که توانایی کشش هر یک حدود 13500 کیلوگرم است. به دلیل داشتن چنین موتورهای قدرتمندی است که این هواپیما را می توان جز هواپیماهای مافوق صوت به حساب آورد، چرا که این بمب افکن می تواند با سرعت حداکثر 1.2 ماخ در سطح دریا پرواز کند که از این لحاظ نیز برتری قابل توجهی نسبت به هواپیمای B-52 دارد. این هواپیما طولی قریب به 44 متر داشته و عرض آن با بالهای کاملا باز حدود 40 متر بوده و با بالهای بسته به حدود 23 متر می رسد. حداکثر وزن برخاست این هواپیما بالغ بر 200 تن است که رقم جالبی است.

اولین مدل این هواپیما در سال 1985 تحویل شد و بعد از آن از سال 1986 به خدمت نیروی هوایی آمریکا در آمد و تا به امروز در سمت خود باقی است، هر چند که به تدریج ظهور بمب افکن هایی چون B-2 عرصه را بر وی تنگ کرده اند. این هواپیما برای پرواز به چهار خدمه شامل خلبان اصلی، افسر تهاجم، افسر دفاع نظامی و فرمانده هواپیما نیاز دارد. همچنین سقف پروازی این هواپیما، یعنی حداکثر ارتفاعی که هواپیما قابلیت پرواز را دارد) حدود 9100 متر یا 30,000 فوت است. قیمت این هواپیما حدود 200 میلیون دلار است که رقم واقعاً سر سام آوری برای دارنده آن است و هزینه نگهداری آن نیز نسبتاً چیزی از قیمت آن کم ندارد. البته برنامه هایی برای بهینه سازی و بهبود بخشی از امکانات و توانایی های این بمب افکن قدرتمند و مخوف در دست تکمیل است که تا چند ماه آینده کامل شده و باز شاهد هواپیمای بمب افكن پیشرفته تر و توانمندتری از پیش باشیم

+ نوشته شده در  پنجشنبه بیست و هشتم خرداد 1388ساعت 11:48  توسط نوید  | 

شهاب ٣ پيشرفته ترين سلاح ايران؟!


شهاب ٣ پيشرفته ترين سلاح ايران
شهاب ٣ پيشرفته ترين سلاح ايران؟!

آزمايش موشك حيتس توسط اسرائيل براي نابودي موشك ضد رادار شهاب ٣ ايران

آي آر نيو (irnew.com) - روزنامه اسراییلی معاریو نوشت: «موشک‌های حیتس برای ردیابی موشک شهاب 3 هدف آزمایش قرار خواهند گرفت، چرا که شهاب 3 مجهز به سیستم ضد رادار است و به همین سبب نیاز به تقویت و آزمایش موشک‌های حیتس وجود دارد. اسراییل، شهاب 3 را پیشرفته‌ترین سلاح ایران خوانده است. به گزارش پرس تي وي در همين زمينهT در جریان این آزمایش مووشک «انکور شاحور» ساخت اسراییل که شباهت فراوانی به شهاب 3 دارد، توسط جنگنده‌های F15 به سمت سرزمین‌های اشغالی شلیک شده تا میزان توانایی موشک حیتس برای مقابله و نابودی آن در هوا مشخص شود. این موضوع همچنین مورد بررسی قرار خواهد گرفت که موشک حیتس در چه مرحله‌ای قادر به شناسایی و نابودی شهاب 3 خواهد شد. معاریو به نقل از یک منبع آگاه امنیتی نوشت: «موشک‌های حیتس همواره مورد بازسازی و اعمال تغییرات قرار می‌گیرند و آزمایش جدید، خلل‌های احتمالی بیشتر این نوع موشک‌ها را مشخص خواهد کرد». منبع مذکور افزود: «مرحله دوم آزمایش موشک‌ حیتس که در پایان سال جاری صورت خواهد گرفت، تنها امکان ردیابی موشک شهاب 3 را هدف قرار نخواهد داد بلکه امکان نابودی آن در هوا را نیز مد نظر دارد». اضافه می‌شود اسراییل موشک‌های حیتس را با حمایت مالی آمریکا تولید کرده و موسسات امنیتی اسراییل ماه گذشته تصمیم گرفتند که نسل سوم این موشک‌ها را به مرحله بهره‌برداری برسانند. معاریو افزود: «تغییر در موشک‌های حیتس منوط به حمایت مالی و فراهم شدن بودجه لازم برای این کار است که ده‌ها میلیون دلار تخمین زده شده است. اسراییل با شرکت بویینگ آمریکا در این روند شریک شده است تا لابی شرکت بویینگ بتواند بودجه لازم را برای اسراییل در کنگره آمریکا و کاخ سفید تامین کند».

+ نوشته شده در  پنجشنبه بیست و هشتم خرداد 1388ساعت 11:43  توسط نوید  | 

هواپیما


هواپیما هواگردی سنگین‌تر از هوا است.

در هواپیما اختلاف فشار هوائی که از روی بال و زیر بال می‌گذرد ایجاد نیروی برآر می‌کند و با خنثی شدن نیروی وزن، هواپیما به پرواز درمی‌آید.از نظر طرح و عملکرد هواپیماها را می‌توان به دو دسته هواپیما با بال ثابت و هواپیما با بال متحرک تقسیم کرد.از نظر پیش‌رانش هواپیماها به دو دسته موتوردار و بی‌موتور تقسیم می‌شوند.هواپیماهارا می‌توان از نظر کاربرد به دو دسته‌ بخش کرد: هواپیمای نظامی و هواپیمای غیرنظامی.

















 

 

 

 

 

 

 

 

هواپیما با بال ثابت
بیشتر هواپیماهای امروزی به‌ویژه هواپیماهای مسافری در این دسته جای دارند.

منظور از بال ثابت آن است که بال هواپیما (بر خلاف هلیکوپتر) فقط در اثر پیش‌رانش نیروی برآر ایچاد می‌کند. اگرچه بال در بعضی هواپیماها برای جاگیری کمتر یا ملاحظات هواپویشی ممکن است باز و بسته شود ولی این‌گونه هواپیما را نیز دارای بال ثابت می‌شمارند چون باز وبسته شدن بال ایجاد نیروی برآر نمی‌کند.

 

برآر یا نیروی برآر

 

برآر یا نیروی برآر، نیرویی است که در اثر حرکت ماهیواره در شاره (سیال) ایجاد می‌شود. پرواز هواپیما در اثر نیروی برآری است که حاصل از شکل مقطع آیرودینامیکی بال‌ آن است، که اصطلاحاً مقطع ماهیواره دارند، نیروی برآر بال هواپیما به عواملی مانند سرعت هواپیما، مساحت بال، چگالی هوا، و شکل ماهیوارهٔ بال بستگی دارد و مطابق با فرمول زیر محاسبه می‌شود.

L=\frac{1}{2}\rho V^2 S C_L

 

که در این فرمول

L نیروی برآر هواپیما،
ρ چگالی هوا،
V سرعت پرواز هواپیما،
S مساحت بال، و
CL ضریب برآر است.
برآر را در فارسی «برآ» هم می‌گویند. واژه «برآر» پیشنهاد فرهنگستان است.


 

هواپیما با بال متحرک
در بال‌گردها نیروی برآر ناشی از چرخش بال یا پروانه در هوا است. هلی‌کوپتر یا بالگرد شناخته‌شده‌ترین هواپیما با بال متحرک است. هواچرخ نوع دیگری از این‌گونه هواپیما است. بعضی از هواپیماها مثل و-۲۲ آسپری ویژگی‌های بال ثابت و بال متحرک را یکجا دارند.

هواپیمای موتوردار
موتور هواپیما وظیفه تأمین نیروی پیش‌رانش (در هواپیماهای با بال ثابت) یا چرخاندن پروانه و پیش‌رانش (در هواپیماهای با بال متحرک) را دارد.

تا اواخر جنگ جهانی دوم موتور هواپیماها از نوع پیستونی یا موتور احتراق داخلی بود. اکنون بیشتر هواپیماها از موتور جت استفاده می‌کنند. در بعضی هواپیماهای آزمایشی و نظامی از موتور موشکی استفاده می‌شود.

هواپیمای بی‌موتور
در هواپیمای بی‌موتور برای پیش‌رانش از نیروی گرانش زمین استفاده می‌شود. بادپر (گلایدر) نوع رایج هواپیمای بی‌موتور است. هواپیمای بی‌موتور را باید پیش از شروع پرواز با ابزاری جدا از آن به ارتفاعی مناسب رساند و پس از آن هواپیما می‌تواند با استفاده از نیروی گرانش و جریان‌های هوائی پرواز کند.

هواپیماهای نظامی
اصطلاح هواپیمای نظامی طیف وسیعی از هواپیماها را، از هواپیمای مدل گرفته تا بزرگ‌ترین هواپیمای جهان، در بر دارد. بسیاری از این هواپیماها فقط در اختیار ارتش‌ها و نیروهای هوائی کشورها است ولی بعضی از هواپیماهای نظامی با تغییر دادن هواپیماهای غیرنظامی به کارهای گمارده می‌شوند. جنگنده‌ها و هواپیماهای ترابری نظامی دو دسته شناخته شده‌تر هواپیمای نظامی هستند.

 

 

 هواپیماهای غیرنظامی

 

هواپیماهای غیرنظامی نیز گستره وسیعی دارند و برای جابجائی مسافر یا بار و نیز تفریح و پژوهش و خدمات به‌کار می‌روند. استفاده نظامی از هواپیمای غیرنظامی برپایه قانون‌های بین‌المللی ممنوع است ولی گاه کشورها مخفیانه چنین می‌کنند.

برخی از هواپیماهای نظامی قدیمی با تغییراتی برای تفریح و پژوهش به هواپیمای غیرنظامی تبدیل شده‌اند.

 

 

 تاریخ هواپیما
مخترع هواپیما به معنی امروزی را برادران رایت می‌دانند ولی با توجه به کوشش‌های هم‌زمان دیگران، برخی این نکته را قبول ندارند.

به‌هرحال کوشش برای پرواز سابقه‌ای بسیار دورتر از کار برادران رایت دارد. ذکر وسیله پروازی که با استفاده از چند پرنده ساخته شده در اساطیر ملل مختلف شاید اولین کوشش بشر برای طراحی هواپیما به‌شمار رود. مواردی که افرادی با بستن بال یا پارچه به‌خود برای پرواز از بلندی به پائین پریده‌اند نیز در تاریخ آمده‌است.

لئوناردو داوینچی نابغه ایتالیائی طرح‌های زیادی برای وسائل پرنده (مثلاً هلیکوپتر)از خود به‌جا گذاشته‌است.

اوتو لیلینتال آلمانی را اولین کسی می‌دانند که توانست با بستن بال به خود پروازی کوتاه را انجام دهد ولی چهل سال قبل از او سر جرج کی‌لی انگلیسی همین کار را با یک هواپیمای بی‌موتور ساخت خودش کرده بود.

در اواخر قرن نوزدهم و اوائل قرن بیستم کوشش برای ساخت هواپیمائی که قابل کنترل باشد (یعنی به خواست خلبان به چپ و راست و پائین و بالا برود) در فرانسه و آمریکا شدت گرفت. اولین پرواز کنترل شده به نام برادران رایت ثبت است.

 

+ نوشته شده در  پنجشنبه بیست و هشتم خرداد 1388ساعت 11:38  توسط نوید  |