Saturday, July 20, 2013

McDonnell Douglas F-15 Eagle

McDonnell Douglas F-15 Eagle

The McDonnell Douglas (now Boeing) F-15 Eagle is a twin-engine, all-weather tactical fighter designed by McDonnell Douglas to gain and maintain air superiority in aerial combat. It is considered among the most successful modern fighters, with over 100 aerial combat victories with no losses in dogfights.[3][4] Following reviews of proposals, the United States Air Force selected McDonnell Douglas' design in 1967 to meet the service's need for a dedicated air superiority fighter. The Eagle first flew in July 1972, and entered service in 1976.
Since the 1970s, the Eagle has been exported to Israel, Japan, Saudi Arabia, and other nations. The F-15 was originally envisioned as a pure air superiority aircraft. Its design included a secondary ground-attack capability[5] that was largely unused. The design proved flexible enough that an all-weather strike derivative, the F-15E Strike Eagle, was later developed, and entered service in 1989. The F-15 Eagle is expected to be in service with the U.S. Air Force past 2025.[6]

 

Origins

Following studies in 1964–1965, the U.S. Air Force developed requirements for an air superiority fighter in October 1965. Then on 8 December 1965, the service issued a request for proposals (RFP) for the new fighter. The request called for both air-to-air and air-to-ground capabilities. Eight companies responded with proposals. In the following study phase, four of these companies developed some 500 design concepts. Typical designs featured variable-sweep wings, weighed over 60,000 lb (27,200 kg), included a top speed of Mach 2.7 and a thrust-to-weight ratio of 0.75.[7] The designs were not accepted by the Air Force as they compromised fighter qualities for ground attack qualities.[8] Acceptance of the Energy-Maneuverability (E-M) theory by the Air Force led to a change in requirements for improved maneuverability by the spring 1967. The design mission weight was reduced to 40,000 lb (18,100 kg), top speed reduced to Mach 2.3–2.5 and thrust-to-weight ratio increased to 0.97.[7]
In 1967 U.S. intelligence was surprised[9] to find that the Soviet Union was producing a large fighter aircraft, the MiG-25 'Foxbat'.[10] It was not known in the West at the time that the MiG-25 was designed as a high-speed interceptor, not an air superiority fighter,[11] so its primary asset was speed, not maneuverability. The MiG-25's huge tailplanes and vertical stabilizers (tail fins) hinted at a very maneuverable aircraft, which worried the Air Force that its performance might be better than its U.S. counterparts. In reality, the MiG's large fins and stabilators were necessary to prevent the aircraft from encountering inertia coupling in high-speed, high-altitude flight.[citation needed]
The McDonnell Douglas F-4 Phantom II of the USAF, U.S. Navy and U.S. Marine Corps was the only fighter with enough power, range, and maneuverability to be given the primary task of dealing with the threat of Soviet fighters while flying with visual engagement rules.[10] As a matter of policy, the Phantoms could not engage targets without positive visual identification, so they could not engage targets at long ranges, as designed. Medium-range AIM-7 Sparrow missiles, and to a lesser degree even the AIM-9 Sidewinder, were often unreliable and ineffective at close ranges where it was found that guns were often the only effective weapon.[12] The Phantom did not originally have any guns or cannons, but experience in Vietnam led to the addition of an internally mounted cannon in later versions.

Overview

Gray jet fighter taking off at steep angle of attack, with full afterburner, as evident by hot gas ejected from its engines.
F-15C executing a maximum performance takeoff.
The F-15 has an all-metal semi-monocoque fuselage with a large cantilever shoulder-mounted wing. The empennage is metal and composite construction, with twin aluminum/composite honeycomb fins with boron-composite skins, resulting in an exceptionally thin tailplane and rudders with all-moving composite horizontal tail surfaces outboard of the fins. The F-15 has a spine-mounted air brake and retractable tricycle landing gear. It is powered by two Pratt & Whitney F100 axial-flow turbofan engines with afterburners mounted side-by-side in the fuselage. The cockpit is mounted high in the forward fuselage with a one-piece windscreen and large canopy to increase visibility.
The F-15's maneuverability is derived from low wing loading (weight to wing area ratio) with a high thrust-to-weight ratio enabling the aircraft to turn tightly without losing airspeed. The F-15 can climb to 30,000 ft (10,000 m) in around 60 seconds. The thrust output of the dual engines is greater than the aircraft's weight, thus giving it the ability to accelerate in a vertical climb. The weapons and flight control systems are designed so that one person can safely and effectively perform air-to-air combat.[13] The A and C-models are single-seat variants; these were the main air superiority versions produced. B and D-models add a second seat behind the pilot for training. E-models use the second seat for a weapon systems officer. Visibly, the F-15 has a unique feature vis a vis other modern fighter aircraft in that it does not have the distinctive turkey feather aerodynamic exhaust petals covering its engine nozzles. This is because the petal design on the F-15 was problematic and could fall off in flight; therefore they were removed, resulting in a 3% drag increase.[29]

Avionics

A multi-mission avionics system includes a heads-up display (HUD), advanced radar, inertial guidance system (INS), flight instruments, ultra high frequency (UHF) communications, and Tactical Air Navigation (TACAN) and Instrument Landing System (ILS) receivers. It also has an internally mounted, tactical electronic-warfare system, identification, friend or foe (IFF) system, electronic countermeasures suite and a central digital computer.[30]
A wing over maneuver displays the clean lines and high-wing design of an F-15E from Elmendorf AFB, Alaska.
The heads-up display projects, through a combiner, all essential flight information gathered by the integrated avionics system. This display, visible in any light condition, provides the pilot information necessary to track and destroy an enemy aircraft without having to look down at cockpit instruments.[31]
The F-15's versatile APG-63/70 pulse-Doppler radar system can look up at high-flying targets and down at low-flying targets without being confused by ground clutter. It can detect and track aircraft and small high-speed targets at distances beyond visual range (the maximum being 120 nautical miles (220 km) away) down to close range, and at altitudes down to treetop level. The radar feeds target information into the central computer for effective weapons delivery. The capability of locking onto targets as far as 50 nautical miles (90 km) with an AIM-120 AMRAAM missile enables true beyond visual range (BVR) engagement of targets. For close-in dogfights, the radar automatically acquires enemy aircraft, and this information is projected on the heads-up display. The F-15's electronic warfare system provides both threat warning and automatic countermeasures against selected threats.[32]

Weaponry and external stores

M61 Vulcan mounted on the side of right engine intake
A variety of air-to-air weaponry can be carried by the F-15. An automated weapon system enables the pilot to perform aerial combat safely and effectively, using the head-up display and the avionics and weapons controls located on the engine throttles or control stick. When the pilot changes from one weapon system to another, visual guidance for the required weapon automatically appears on the head-up display.[33]
The Eagle can be armed with combinations of four different air-to-air weapons: AIM-7F/M Sparrow missiles or AIM-120 AMRAAM advanced medium range air-to-air missiles on its lower fuselage corners, AIM-9L/M Sidewinder or AIM-120 AMRAAM missiles on two pylons under the wings, and an internal M61A1 20 mm Gatling gun in the right wing root.[34]
F-15C external stores stations
Low-drag conformal fuel tanks (CFTs) were developed for the F-15C and D models. They can be attached to the sides of the engine air intake trunks under each wing and are designed to the same load factors and airspeed limits as the basic aircraft.[34] They degrade performance by increasing drag and cannot be jettisoned in-flight (unlike conventional external tanks). Each conformal fuel tank can hold 750 U.S. gallons (2,840 L) of fuel.[35] These tanks increase range and reduce the need for in-flight refueling. All external stations for munitions remain available with the tanks in use. Moreover, Sparrow or AMRAAM missiles can be attached to the corners of the conformal fuel tanks.[20] The 57 FIS based at Keflavik NAS, Iceland was the only C-model squadron to use CFTs on a regular basis due to its extended operations over the North Atlantic. With the closure of the 57 FIS, the F-15E is the only variant to carry them on a routine basis. CFTs have also been sold to Israel and Saudi Arabia.

Upgrades

F-15E with speed brake deployed and conformal tanks fitted
The F-15E Strike Eagle is a two-seat, dual-role, totally integrated fighter for all-weather, air-to-air and deep interdiction missions. The rear cockpit is upgraded to include four multi-purpose CRT displays for aircraft systems and weapons management. The digital, triple-redundant Lear Siegler flight control system permits coupled automatic terrain following, enhanced by a ring-laser gyro inertial navigation system.[36] For low-altitude, high-speed penetration and precision attack on tactical targets at night or in adverse weather, the F-15E carries a high-resolution APG-70 radar and LANTIRN pods to provide thermal imagery.[32]
The APG-63(V)2 Active Electronically Scanned Array (AESA) radar has been retrofitted to 18 U.S. Air Force F-15C aircraft.[37] This upgrade includes most of the new hardware from the APG-63(V)1, but adds an AESA to provide increased pilot situational awareness. The AESA radar has an exceptionally agile beam, providing nearly instantaneous track updates and enhanced multi-target tracking capability. The APG-63(V)2 is compatible with current F-15C weapon loads and enables pilots to take full advantage of AIM-120 capabilities, simultaneously guiding multiple missiles to several targets widely spaced in azimuth, elevation, or range.

Basic models

Gray jet aircraft flying above missile following firing of the weapon.
USAF F-15C fires an AIM-7 Sparrow in 2005.
F-15A
Single-seat all-weather air-superiority fighter version, 384 built 1972–1979.[69]
F-15B
Two-seat training version, formerly designated TF-15A, 61 built 1972–1979.[69]
F-15C
Improved single-seat all-weather air-superiority fighter version, 483 built 1979–1985.[69] The last 43 F-15Cs are being upgraded with AN/APG-70 radar.
F-15D
Two-seat training version, 92 built 1979–1985.[69]
A view of an F-15E cockpit from an aerial refueling tanker.
F-15J
Single-seat all-weather air-superiority fighter version for the Japan Air Self-Defense Force 139 built under license in Japan by Mitsubishi 1981–1997, two built in St. Louis.[69]
F-15DJ
Two-seat training version for the Japan Air Self-Defense Force. 12 built in St. Louis, and 25 built under license in Japan by Mitsubishi during 1981–1997.[69]
F-15N Sea Eagle
The F-15N was a carrier-capable variant proposed in the early 1970s to the U.S. Navy as an alternative to the heavier and, at the time, considered as "riskier" technology program: Grumman F-14 Tomcat. The F-15N-PHX was another proposed naval version capable of carrying the AIM-54 Phoenix missile. These featured folding wingtips, reinforced landing gear and a stronger tailhook for shipboard operation.[70]
F-15E Strike Eagle
See McDonnell Douglas F-15E Strike Eagle for F-15E, F-15I, F-15S, F-15K, F-15SG, and other F-15E-based variants.
F-15SE Silent Eagle
See Boeing F-15SE Silent Eagle for a recent proposed F-15E variant with a reduced radar signature.

Prototypes

71-0280 the first prototype
Twelve prototypes were built and were used for trials by the F-15 Joint Test Force at Edwards Air Force Base using McDonnell Douglas and United States Air Force personnel. Many of the prototypes were later used by NASA for trials and experiments.
F-15A-1, AF Ser. No. 71-0280
Was the first F-15 to fly on 11 July 1972 from Edwards Air Force Base, it was used as a trial aircraft for exploring the flight envelope, general handling and testing the carriage of external stores.
F-15A-1, AF Ser. No. 71-0281
The second prototype first flew on 26 September 1972 and was used to test the F100 engine.
F-15A-2, AF Ser. No. 71-0282
First flew on 4 November 1972 and was used to test the APG-62 radar and avionics.
F-15A-2, AF Ser. No. 71-0283
First flew on 13 January 1973 and was used as a structural test aircraft, it was the first aircraft to have the smaller wingtips to clear a severe buffet problem found on earlier aircraft.
F-15A-2, AF Ser. No. 71-0284
First flew on 7 March 1973 it was used for armament development and was the first aircraft fitted with an internal cannon.
F-15A-3, AF Ser. No. 71-0285
First flew on 23 May 1973 and was used to test the missile fire control system and other avionics.
F-15A-3, AF Ser. No. 71-0286
First flew on 14 June 1973 and was used for armament trials and testing external fuel stores.
F-15A-4, AF Ser. No. 71-0287
First flew on 25 August 1973 and was used for spin recovery, angle of attack and fuel system testing, it was fitted with an anti-spin recovery parachute. The aircraft was loaned to NASA from 1976 for engine development trials.
F-15A-4, AF Ser. No. 71-0288
First flew on 20 October 1973 and was used to test integrated aircraft and engine performance, it was later used by McDonnell Douglas as a test aircraft in the 1990s.
F-15A-4, AF Ser. No. 71-0289
First flew on 30 January 1974 and was used for trials on the radar, avionics and electronic warfare systems.
F-15B-3, AF Ser. No. 71-0290
The first two-seat prototype originally designated the TF-15A, it first flew on 7 July 1973.
F-15B-4, AF Ser. No. 71-0291
First flew on 18 October 1973 as a TF-15A and used as a test and demonstration aircraft. In 1976 it made an overseas sales tour painted in markings to celebrate the bicentenary of the United States.


General characteristics
Performance
Armament
Avionics
  • Radar:



 From Wikipedia, the free encyclopedia

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