Thursday, July 23, 2009
Friday, July 10, 2009
The gunship's sole user is the United States Air Force, which uses AC-130H Spectre and AC-130U Spooky variants. The AC-130 is powered by four turboprops and has an armament ranging from 20 mm Gatling guns to 105 mm howitzers. It has a standard crew of twelve or thirteen airmen, including five officers (two pilots, a navigator, an electronic warfare officer and a fire control officer) and enlisted personnel (flight engineer, electronics operators and aerial gunners).
The US Air Force uses the AC-130 gunships for close air support, air interdiction, and force protection. Close air support roles include supporting ground troops, escorting convoys, and flying urban operations. Air interdiction missions are conducted against planned targets and targets of opportunity. Force protection missions include defending air bases and other facilities. Stationed at Hurlburt Field in Northwest Florida, the gunship squadrons are part of the Air Force Special Operations Command (AFSOC), a component of United States Special Operations Command (SOCOM).
Wednesday, July 01, 2009
The AN/APG-63 and AN/APG-70 are a family of all-weather multimode radar systems designed by Hughes Aircraft (now Raytheon) for the F-15 Eagle air superiority fighter. These X-band pulse-doppler radar systems are designed for both air-air and air-ground missions; they are able to look up at high-flying targets and down at low-flying targets without being confused by ground clutter.
The systems can detect and track aircraft and small high-speed targets at distances beyond visual range down to close range, and at altitudes down to treetop level. The radar feeds target information into the aircraft's central computer for effective weapons delivery. For close-in dogfights, the radar automatically acquires enemy aircraft and projects this information onto the cockpit head-up display.
The APG-63 was developed in the early 1970s and has been operational since 1973, and was installed on all F-15 A/Bs. In 1979, it received a major upgrade and became the first airborne radar to incorporate a software programmable signal processor (PSP), and the PSP allowed the system to be modified to accommodate new modes and weapons through software reprogramming rather than by hardware retrofit. The APG-63 with PSP is one of the most important feature that disguishes earlier F-15 A/Bs from the F-15 C/Ds it arms, and with the exception of the final 43 (which is armed with APG-70), all F-15 C/Ds are armed with APG-63 with PSP.
The APG-70 was a 1980s redesign of the APG-63 for greater reliability and easier maintenance. Additionally, gate array technology enabled the APG-70 to incorporate new modes with enhanced operational capabilities. To reduce production costs, many of the upgraded radar's modules are common with the APG-73 (F/A-18) radar, while the computers / processors are 85% in common with that of APG-71 (F-14) radar.
Friday, June 19, 2009
The An-225 was designed for the Soviet space program as a replacement for the Myasishchev VM-T. Able to airlift the Energia rocket's boosters and the Buran space shuttle, its mission and objectives are almost identical to that of the Airbus Beluga and the United States' Shuttle Carrier Aircraft.
The An-225 first flew on 21 December 1988. The aircraft was on static display at the Paris Air Show in 1989 and it flew during the public days at the Farnborough air show in 1990. Two aircraft were ordered, but only one An-225 (tail number UR-82060) is currently in service. It is commercially available for carrying ultra-heavy and oversize freight, up to 250,000 kg (550,000 lb) internally or 200,000 kg (440,000 lb) on the upper fuselage. Cargo on the upper fuselage can be 70 m long. A second An-225 was partially built during the late 1980s for use by the Soviet space program. If the second An-225 is completed, it will be built with a rear cargo door and the tail will be redesigned as a single tail. It would then be more effective for cargo transportation. Following the collapse of the Soviet Union in 1990 and the cancellation of the Buran space program, the lone operational An-225 was placed in storage. The six Ivchenko Progress engines were removed for use on An-124s, and the second An-225 airframe (nearing completion and awaiting engines) was also mothballed.
The An-225 is an extension of Antonov's earlier An-124. To meet the needs of its new role, fuselage barrel extensions were added fore and aft of the wings, which received root extensions. Two more Ivchenko Progress D-18T turbofan engines were added to the new wing roots, bringing the total to six, and an increased-capacity landing gear system with 32 wheels was designed. The An-124’s rear cargo door and ramp were removed to save weight, and the empennage was changed from a single vertical stabilizer to a twin tail with an oversized horizontal stabilizer. The twin tail was essential in order to enable the plane to carry very large and heavy external loads, which would otherwise disturb the aerodynamics of a conventional tail. Unlike the An-124, the An-225 was not intended for tactical airlifting and is not designed for short-field operation.
With a maximum gross weight of 600 tonnes (1,300,000 lb), the An-225 remains as the world's heaviest and largest aircraft, being even bigger than the current double-decker Airbus A380 even though Airbus plans to pass their current maximum landingwieght with 591,7 tons.The Hughes H-4 Hercules, known to most as the "Spruce Goose", had a greater wingspan and a greater overall height, but was considerably shorter, and due to the materials used in its construction, also lighter. In addition, the Hercules only flew once and never climbed above 21.3 m (70 ft), making the An-225 the largest aircraft in the world to take off multiple times.The An-225 is not only larger than the Airbus A380 airliner, it is also considerably bigger than the Antonov An-124, Boeing 747 Large Cargo Freighter, and Lockheed C-5 Galaxy, the nearest equivalent heavy airlifters.
In September 2001, carrying a record load of 253.82 tonnes of cargo, the An-225 flew at an altitude of two kilometers (6,500 feet) over a closed circuit of 1,000 km (620 mi) at a speed of 763.2 kilometres per hour (474.2 mph).
In November 2004, FAI placed the An-225 in the Guinness Book of Records for its 240 records.
Monday, May 04, 2009
An aircraft engine is a propulsion system for an aircraft. Aircraft engines are almost always either lightweight piston engines or gas turbines. This article is an overview of the basic types of aircraft engines and the design concepts employed in engine development for aircraft.
Engine design considerations
The process of developing an engine is one of compromises. Engineers design specific attributes into engines to achieve specific goals. Aircraft are one of the most demanding applications for an engine, presenting multiple design requirements, many of which conflict with each other. An aircraft engine must be:
* reliable, as losing power in an airplane is a substantially greater problem than an automobile engine seizing. Aircraft engines operate at temperature, pressure, and speed extremes, and therefore need to operate reliably and safely under all these conditions.
* lightweight, as a heavy engine increases the empty weight of the aircraft & reduces its payload.
* powerful, to overcome the weight and drag of the aircraft.
* small and easily streamlined; large engines with substantial surface area, when installed, create too much drag, wasting fuel and reducing power output.
* repairable, to keep the cost of replacement down. Minor repairs should be relatively inexpensive.
* fuel efficient to give the aircraft the range the design requires.
* capable of operating at sufficient altitude for the aircraft
Unlike automobile engines, aircraft engines run at high power settings for extended periods of time. In general, the engine runs at maximum power for a few minutes during taking off, then power is slightly reduced for climb, and then spends the majority of its time at a cruise setting—typically 65% to 75% of full power. In contrast, a car engine might spend 20% of its time at 65% power accelerating, followed by 80% of its time at 20% power while cruising. The power of an internal combustion reciprocating or turbine aircraft engine is rated in units of power delivered to the propeller (typically horsepower) which is torque multiplied by crankshaft revolutions per minute (RPM). The propeller converts the engine power to thrust horsepower or thp in which the thrust is a function of the blade pitch of the propeller relative to the velocity of the aircraft. Jet engines are rated in terms of thrust, usually the maximum amount achieved during takeoff.
The design of aircraft engines tends to favor reliability over performance. Long engine operation times and high power settings, combined with the requirement for high-reliability means that engines must be constructed to support this type of operation with ease. Aircraft engines tend to use the simplest parts possible and include two sets of anything needed for reliability. Independence of function lessens the likelihood of a single malfunction causing an entire engine to fail. For example, reciprocating engines have two independent magneto ignition systems, and the engine's mechanical engine-driven fuel pump is always backed-up by an electric pump.
Aircraft spend the vast majority of their time travelling at high speed. This allows an aircraft engine to be air cooled, as opposed to requiring a radiator. In the absence of a radiator, aircraft engines can boast lower weight and less complexity. The amount of air flow an engine receives is usually carefully designed according to expected speed and altitude of the aircraft in order to maintain the engine at the optimal temperature.
Aircraft operate at higher altitudes where the air is less dense than at ground level. As engines need oxygen to burn fuel, a forced induction system such as turbocharger or supercharger is especially appropriate for aircraft use. This does bring along the usual drawbacks of additional cost, weight and complexity.
Thursday, April 16, 2009
The aircraft is a modernized version of the Su-27UB and has several variants. The Su-30K and Su-30MK series have had commercial success. The variants are manufactured by competing organizations: KNAAPO and the IRKUT Corporation, both of which come under the Sukhoi group's umbrella. KNAAPO manufactures the Su-30MKK and the Su-30MK2, which were designed for and sold to China and later Indonesia. Irkut makes the long-range, multirole Su-30MK series. The series includes the Su-30MKI developed for the Indian Air Force and its derivatives, the MKM, MKA and MKV for Malaysia, Algeria and Venezuela respectively.
Wednesday, April 08, 2009
Its primary missions are fighter escort, fleet air defense, suppression of enemy air defenses (SEAD), interdiction, close air support and reconnaissance. Its versatility and reliability have proven it to be a valuable carrier asset, though it has been criticized for its lack of range and payload compared to its contemporaries.