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The F-15 Eagle
The F-15 Eagle is an all-weather fighter designed to gain and maintain air supremacy. As the first US fighter with engine thrust greater than its basic weight, the F-15 can accelerate while in a vertical climb.
As told by Bertie Simmonds in his book F-15 Eagle, much was initially made of the F-15 Eagle’s amazing speed and — indeed — thanks to the threat of the MiG-25 Foxbat, its dash speed of Mach 2.5 was much trumpeted in the early 1970s. This was, however, a bit of an irrelevance as with a decent war load, the F-15 couldn’t go much faster than Mach 1.7.
However, both the USAF and McDonnell Douglas knew that the speed of a fighter could be headline news. In late 1974, they got together to come up with an idea for an event to show the world this new fighter and show the US taxpayer what they were getting for their dollar.
The F-15 Streak Eagle
Therefore — at an expense of more than $2 million — a ‘show’ was put on, where a stripped and lightened early F-15 would take a series of time-to-height records. Five of these records were held by the F-15’s predecessor, the F-4 Phantom II, from 1962, while the higher-altitude ones were held by the Soviets with their Foxbat. Three USAF pilots were to take part in these attempts and they would break all eight records over a period of 17 days, between Jan. 16 and Feb. 1, 1975, over Grand Forks Air Force Base, North Dakota.
But first — what was ‘Streak Eagle’? It was the 19th preproduction F-15 called ‘F-17’ and was stripped of all non-essential materials and equipment. All the radar and associated avionics, the Vulcan cannon and ammunition ‘bin’ and feed chutes, flap and speed-brake actuators, radios, one hydraulic system, some cockpit displays and a generator were removed. Some equipment was added, such as a pressure suit for the pilot on some of the attempts, a pitot boom to give more information to the pilot and instruments to help measure the speed and acceleration of the aircraft.
With all attempts beginning with a standing start, the arrestor hook was replaced with a hold-down hook which would be released when the timer was begun. Also, the entire surface of the aircraft was left unpainted, to save yet more weight (and gain around 15mph). The changes meant that Streak Eagle was 1,800lb or 817kg lighter than a production F-15A and, to ensure the best performance, only the correct amount of fuel for the attempt would fill the Eagle’s tanks. It was estimated that the Streak Eagle had a thrust-to-weight ratio of around 1.5:1.
Five F-4-held records broken in one day
On Jan. 16, the five F-4-held records were broken all in one day. The first record to go was ‘Time to 3,000m (9843ft)’ which Major Roger Smith bear by a 20 per cent margin. The previous best was 34.52 seconds with the Streak Eagle setting a time of 27.57 seconds. The aircraft was taken to full throttle under the hold-back system and the Streak Eagle — when released — took off after only a 400-metre take-off roll. So fast was the acceleration that the pilot had to be quick to get the undercarriage tucked away before the associated gear and doors went past their ‘never-exceed speed’ as the aircraft went almost vertically upwards in a 5g climb. Some attempts were actually aborted due to this issue.
The next three records were beaten in a single flight, with times being taken at the requisite altitudes. In the ‘Time to 6,000m (19,685ft)’ attempt Major Willard Mac’ Macfarlane beat the F-4’s time by 19 per cent (48.79s vs 39.33s.) The ‘Time to 9,000m (29,528ft)’ saw the F-4’s 61.68s record beaten by 21 per cent with the Streak Eagle getting to the required altitude in just 48.86s. For the 12,000m (39,370ft) attempt, the Eagle beat the F-4’s best by 23 per cent: 77.14s compared to the Eagle’s 59.38s.
Faster than the Saturn V moon rocket
The last of the three flights that day saw Major Dave Peterson beat the old ‘Time to 15,000m (49,212ft)’ record by 33 per cent: the F-4 could manage the height in 114.50 seconds but was thrashed by the Eagle’s 77.02s time. For this attempt and all the later flights, pilots would be wearing a full pressure suit. And he’d need it … as Peterson lifted to around 50ft over the runway, at around Mach 0.65 he pulled hard on the F-15’s control column and hit the target altitude some 10 seconds quicker than the time to that height set by the Saturn V moon rocket!
Now it was time to beat the Soviet MiG-25 Foxbat’s 1973 records. On Jan. 19, Smith would shatter the ‘Time to 20,000m (65,617ft)’ by some 28 per cent, with the MiG-25 clocking 169.80 seconds and the Eagle 122.94. The Streak Eagle would start ‘on the deck’ at around Mach 0.65, before pulling up at just 2.5g into an Immelmann over the top at 32,000ft before accelerating in the opposite direction to take-off, then pulling a 4g, 55° climb, supersonic, until it went through the requisite altitude. The same technique would be used on these higher altitude record flights.
On Jan. 26, Peterson would take the 25,000m (82,021 ft) record from the Soviet aircraft, beating it by some 16 per cent: 192.60s versus the Eagle’s 161.02. Smith would be back in the saddle for the 30,000m (98,425ft) record on Feb. 1, where the Streak Eagle’s winning advantage would be 15 per cent, thanks to their 207.80s ‘to-height’ time compared to the MiG’s 243.86s.
Sukhoi Su-27 beats the F-15 Streak Eagle
These records would prove to be a significant PR coup for both the USAF and McDonnell Douglas. So successful were the records set that they wouldn’t fall until the 1980s, when — between 1986 and 1988 — a similarly stripped Sukhoi SU-27/T-10 (or P-42 as it was known) bettered the records, apparently boasting an almost 2:1 thrust-to-weight ratio!
The Streak Eagle itself — being a preproduction aircraft and one stripped of all non-essential equipment — was never made into a production F-15A (that was considered too costly) so instead it was painted in air-superiority grey — to prevent corrosion — and then delivered to the National Museum of the United States Air Force at Wright-Patterson Air Force Base, Ohio, in December 1980.
F-15 Eagle is published by Mortons Books and is available to order here.
Photo credit: U.S. Air Force