Twelve prototypes were built and used for trials by the F-15 Joint Test Force at Edwards Air Force Base using McDonnell Douglas and United States Air Force personnel. Most prototypes were later used by NASA for trials and experiments.
F-15A-1, AF Serial 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-63 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-1, AF Ser. No. 71-0290
The first two-seat prototype originally designated the TF-15A, it first flew on 7 July 1973.
F-15B-2, 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. Also used as the development aircraft for the F-15E as well as the first F-15 to use Conformal Fuel Tanks.
Research and test
NASA F-15B Research Testbed, aircraft No. 836 (AF Ser. No. 74-0141).
F-15 Streak Eagle (AF Ser. No.72-0119)
An unpainted F-15A stripped of most avionics demonstrated the fighter’s acceleration capabilities. The aircraft broke eight time-to-climb world records between 16 January and 1 February 1975 at Grand Forks AFB, ND. It was delivered to the National Museum of the United States Air Force in December 1980.
F-15 STOL/MTD (AF Ser. No. 71-0290)
The first F-15B was converted into a short takeoff and landing, maneuver technology demonstrator aircraft. In the late 1980s it received canard flight surfaces in addition to its usual horizontal tail, along with square thrust-vectoring nozzles. It was used as a short-takeoff/maneuver-technology demonstrator (S/MTD).
F-15 ACTIVE (AF Ser. No. 71-0290)
The F-15 S/MTD was later converted into an advanced flight control technology research aircraft with thrust vectoring nozzles.
F-15 IFCS (AF Ser. No. 71-0290)
The F-15 ACTIVE was then converted into an intelligent flight control systems research aircraft. F-15B 71-0290 was the oldest F-15 still flying when retired in January 2009.
F-15 MANX
Concept name for a tailless variant of the F-15 ACTIVE, but the NASA ACTIVE experimental aircraft was never modified to be tailless.
F-15 Flight Research Facility (AF Ser. No. 71-0281 and AF Ser. No. 71-0287)
Two F-15A aircraft were acquired in 1976 for use by NASA’s Dryden Flight Research Center for numerous experiments such as: Highly Integrated Digital Electronic Control (HiDEC), Adaptive Engine Control System (ADECS), Self-Repairing and Self-Diagnostic Flight Control System (SRFCS) and Propulsion Controlled Aircraft System (PCA).
71-0281, the second flight-test F-15A, was returned to the Air Force and became a static display at Langley AFB in 1983.
F-15B Research Testbed (AF Ser. No. 74-0141)
Acquired in 1993, it was an F-15B modified and used by NASA’s Dryden Flight Research Center for flight tests.
Eagle development
The Eagle’s initial versions were the F-15 single-seat variant and TF-15 twin-seat variant. (After the F-15C was first flown, the designations were changed to “F-15A” and “F-15B”). These versions would be powered by new Pratt & Whitney F100 engines to achieve a combat thrust-to-weight ratio in excess of 1:1. A proposed 25-mm Ford-Philco GAU-7 cannon with caseless ammunition suffered development problems. It was dropped in favor of the standard M61 Vulcan gun. The F-15 used conformal carriage of four Sparrow missiles like the Phantom. The fixed wing was put onto a flat, wide fuselage that also provided an effective lifting surface. The first F-15A flight was made on 27 July 1972, with the first flight of the two-seat F-15B following in July 1973.
The F-15 has a “look-down/shoot-down” radar that can distinguish low-flying moving targets from ground clutter. It would use computer technology with new controls and displays to lower pilot workload and require only one pilot to save weight. Unlike the F-14 or F-4, the F-15 has only a single canopy frame with clear vision forward. The USAF introduced the F-15 as “the first dedicated USAF air-superiority fighter since the North American F-86 Sabre”.
The F-15 was favored by customers such as the Israel and Japan air arms. Criticism from the fighter mafia that the F-15 was too large to be a dedicated dogfighter and too expensive to procure in large numbers, led to the Lightweight Fighter (LWF) program, which led to the USAF General Dynamics F-16 Fighting Falcon and the middle-weight Navy McDonnell Douglas F/A-18 Hornet.
Further development
The single-seat F-15C and two-seat F-15D models entered production in 1978 and conducted their first flights in February and June of that year. These models were fitted with the Production Eagle Package (PEP 2000), which included 2,000 pounds (910 kg) of additional internal fuel, provisions for exterior conformal fuel tanks, and an increased maximum takeoff weight up to 68,000 pounds (31,000 kg). The increased takeoff weight allows internal fuel, a full weapons load, conformal fuel tanks, and three external fuel tanks to be carried. The APG-63 radar uses a programmable signal processor (PSP), enabling the radar to be reprogrammable for additional purposes such as the addition of new armaments and equipment. The PSP was the first of its kind in the world, and the upgraded APG-63 radar was the first radar to use it. Other improvements included strengthened landing gear, a new digital central computer, and an overload warning system, which allows the pilot to fly up to 9 g at all weights.
The F-15 Multistage Improvement Program (MSIP) was initiated in February 1983 with the first production MSIP F-15C produced in 1985. Improvements included an upgraded central computer; a Programmable Armament Control Set, allowing for advanced versions of the AIM-7, AIM-9, and AIM-120A missiles; and an expanded Tactical Electronic Warfare System that provides improvements to the ALR-56C radar warning receiver and ALQ-135 countermeasure set. The final 43 F-15Cs included the Hughes APG-70 radar developed for the F-15E; these are sometimes referred as Enhanced Eagles. Earlier MSIP F-15Cs with the APG-63 were upgraded to the APG-63(V)1 to improve maintainability and to perform similar to the APG-70. Existing F-15s were retrofitted with these improvements.
In 1979, McDonnell Douglas and F-15 radar manufacturer, Hughes, teamed to privately develop a strike fighter version of the F-15. This version competed in the Air Force’s Dual-Role Fighter competition starting in 1982. The F-15E strike variant was selected for production over General Dynamics’ competing F-16XL in 1984. Beginning in 1985, F-15C and D models were equipped with the improved P&W F100-PW-220 engine and digital engine controls, providing quicker throttle response, reduced wear, and lower fuel consumption. Starting in 1997, original F100-PW-100 engines were upgraded to a similar configuration with the designation F100-PW-220E starting.
Beginning in 2007, 179 USAF F-15Cs would be retrofitted with the AN/APG-63(V)3 Active Electronically Scanned Array radar.A significant number of F-15s are to be equipped with the Joint Helmet Mounted Cueing System. Lockheed Martin is working on an IRST system for the F-15C.A follow-on upgrade called the Eagle passive/active warning survivability system (EPAWSS) was planned, but remained unfunded. Boeing was selected in October 2015 to serve as prime contractor for the EPAWSS, with BAE Systems selected as a subcontractor. The EPAWSS is an all-digital system with advanced electronic countermeasures, radar warning, and increased chaff and flare capabilities in a smaller footprint than the 1980s-era Tactical Electronic Warfare System. More than 400 F-15Cs and F-15Es will have the system installed.
In September 2015, Boeing unveiled its 2040C Eagle upgrade, designed to keep the F-15 relevant through 2040. Seen as a necessity because of the low numbers of F-22s procured, the upgrade builds upon the company’s F-15SE Silent Eagle concept with low-observable features. Most improvements focus on lethality including quad-pack munitions racks to double its missile load to 16, conformal fuel tanks for extended range, “Talon HATE” communications pod to communicate with fifth-generation fighters, the APG-63(v)3 AESA radar, a long-range infrared search and track sensor, and BAE Systems’ EPAWSS systems.