by Richard Sheffield
Development of the Air Force Type F-15 Aircraft
The process of developing a military aircraft is a long and complicated affair. Often, the final product bears little resemblance to the original concept. Such was the case with the F-15.
The F-15 program came out of the Air Force's experience during the early 1960s when it was felt that a new fighter plane was needed to replace the aging F-4 Phantom. While the F-4 was one of the most versatile aircraft ever developed, the Air Force believed there was a need for a pure air-combat fighter in the tradition of the P-51 Mustang and the F-86 Sabre.
Project FX (Top Secret)
The FX program (Fighter eXperimental) was the result. The first FX proposals were very heavy (60,000 pounds) and employed the then-fashionable swing-wing design. This being too much like the ill-fated F-111 design, the momentum swung in the other direction until 1967 when the conceived aircraft was down to 30,000 pounds.
This 30,000-pound aircraft might have been developed had it not been for the Soviet Domodedovo Air Show in July 1967. It was there that the Soviets unveiled their new MiG-25, later designated Foxbat by NATO. The MiG-25 was capable of speeds up to Mach 2.8 and had an operational ceiling of 80,000 feet. It was immediately obvious that the current U.S. aircraft, the F-4 Phantom, was no match for the MiG-25.
As a result, the FX project was expedited, and bids to develop and build the new jet fighter were received from many aircraft manufacturers. By December 1968, the field had been narrowed to three manufacturers: McDonnell Douglas Aircraft Company, Fairchild Hiller, and North American. The project aircraft was then officially designated the F-15.
The name Eagle, however, wasn't immediately chosen. James McDonnell (or “Mr. Mac,” as he was known) preferred names derived from his interest in the occult—Phantom, Voodoo, Banshee, Demon, and the like. When he agreed to consider bird names, Eagle was proposed. Since the F-15 was designed to be an all-weather fighter, Eagle was chosen—someone had read in a wildlife book that eagles could hunt in bad weather.
It was during this period that the possibility of using a modified version of the Navy's F-14 was first proposed. Congress wanted the Air Force and Navy to use the same aircraft; commonality was the latest buzzword. A number of studies, however, drew some conclusions: The F-14 wasn't maneuverable enough and required a two-man crew, something unacceptable to the Air Force. The idea of adapting the F-15 to function as a Navy carrier plane was also scrapped—costs would have increased while performance decreased with the addition of systems to use the Navy's Phoenix long-range missile.
In December 1969, McDonnell Douglas was named the winner of the F-15 contract, which called for 20 aircraft. Officially, the purpose of the program was “to efficiently acquire a fighter capable of gaining and maintaining air superiority through air-to-air combat.” The designers' philosophy became “not a pound for air-to-ground.” In other words, they were to build a pure dogfighter.
The design-concept paper for the F-15 stated that the general mission of the aircraft was that of air superiority, broken down into subheadings of escorting strike forces over unfriendly airspace, fighter sweeps ahead of those strike forces, combat air patrol, and tactical intercept and defense of friendly territory.
The most difficult of these missions, and the one most preferred by F-15 pilots, is the escorting or protecting of strike forces over enemy territory. Here exists the threat of antiaircraft artillery and surface-to-air missiles as well as enemy fighters directed by ground control.
Delivery and ITP (Initial Test Program)
On 27 July 1969, the F-15 made its first flight from Edwards Air Force Base in California. The initial test program went fairly smoothly, mainly due to the extensive wind-tunnel testing that was performed. The main changes made were increasing the size of the airbrake and changing the pressure required to operate the control stick.Figure 1-1. The F-15 Eagle
Two F-15 Eagles flying in close formation. Note the AIM-9L Sidewinder missiles beneath each aircraft's wings.
The initial weapons proposals also proved to be a problem. The F-15 was to have been fitted with the new GAU-7 25mm cannon, which used caseless ammunition—there were no metal shell casings that would have to be stored or ejected. Also, the new AIM-82 infrared missile was to be utilized. Both of these systems had numerous problems. The designers decided that since they were using a totally new airframe, new engines, and new avionics, they would do best to stick to tried-and-true weapons systems. The General Electric M61 20mm gun and the AIM-9L Sidewinder missile were selected because they had been used effectively for years.
On 16 June 1972, the first manufactured F-15 rolled out of the McDonnell Douglas production plant in St. Louis.
Replacement Comparison: F-15 Versus F-4
The final design of the F-15 is a vast improvement over its predecessor, the F-4, and many of its systems are much easier to maintain and service. The F-15 has 67 quick-access doors, for instance—four times the number on the F-4. Also, the re-launch turnaround time is 12 minutes—45-percent faster than that of the F-4.
Head-to-Head: The F-15 and F-4
|Flight control devices||9||16|
|Fuel system connectors||97||281|
|Types of fasteners||1200||2800|
|Drag chute needed||No||Yes|
The F-15's safety record is also extraordinary: It's the only fighter to complete its first 5000 hours of flight time without an accident.
The F-15 in Active Service
The first probation F-15 was delivered for active service to Luke Air Force Base on 14 November 1974. Since then, the F-15 has been deployed at United States Air Force (USAF) bases around the world. It also has been sold to Israel, Japan, and Saudi Arabia. Currently, the F-15 is being deployed to select units of the Air National Guard.
F-15 Streak Eagle
Computer projections at McDonnell Douglas predicted that the F-15 would easily beat many of the current time-to-altitude records. In early 1975, the Streak Eagle program went into operation, and at Grand Forks Air Force Base in North Dakota, a modified F-15 broke all existing time-to-altitude records. This one had been stripped of its gun, its radar, some avionics, the tail hook, one generator, some of the hydraulic system, and the flap and speedbrake actuators. Even 40 pounds of external paint were removed.
After achieving the 30,000 meter record (98,425 feet), the F-15 continued up to over 102,000 feet before falling over and starting its descent. This made it the obvious choice for delivering the ASAT antisatellite weapon.
Streak Eagle Records
|Altitude||Previous Time*||Type of Aircraft||F-15 Time*||Improvement|