By reacting to Soviet propaganda rather than reality, the Americans built the premier air superiority fighter of the 20th century.
Conceived to intercept the North American B-70 Valkyrie Mach 3 Bomber, the Mikoyan-Gurevich MiG-25 (NATO reporting name: Foxbat) supersonic interceptor is still among the fastest military aircraft to have ever entered service. It was the last plane designed by Mikhail Gurevich before his retirement.
Because of the thermal stresses incurred in flight above Mach 2, the Mikoyan-Gurevich OKB had difficulties choosing what materials to use for the aircraft. They had to use E-2 heat-resistant Plexiglas for the canopy and high-strength stainless steel for the wings and fuselage. Using titanium rather than steel would have been ideal, but it was expensive and difficult to work with. The problem of cracks in welded titanium structures with thin walls could not be solved, so the heavier nickel steel was used instead. It cost far less than titanium and allowed for welding, along with heat-resistant seals. The MiG-25 was constructed from 80% nickel-steel alloy, 11% aluminum, and 9% titanium. The steel components were formed by a combination of spot welding, automatic machine welding, and hand arc welding methods.
The Foxbat was built the way it was in order to achieve several goals:
- It had to be able to reach the speed and altitude of American B-70 bombers, which were projected to enter Soviet airspace at Mach 3 and at an altitude of 21,000m (70,000 feet). There was also the possibility the B-70 would be escorted by F-108 Rapier fighters as well.
- It needed to survive in a nuclear environment.
- It had to be built and serviced by Soviet industry and aircrews of the Voyska PVO.
According to an interesting article appeared on Quora, steel construction was a useful, low cost method of building a rugged airframe capable of performing the interceptor missions at an acceptable cost. It would be unlikely for the MiG-25, or indeed any PVO interceptor, to have a long service life in a nuclear war. The vacuum tube electronics may have been all the Soviets had initially, but turned out to be just the thing to survive in a very hot environment. They also proved resistant to EMP effects from nearby nuclear weapons. Much like Swedish SAAB warplanes, the MiG needed to be maintained by short-term conscript airmen, so simplification was the order of the day.
It is interesting to see how the F-15 (and indeed all fighters of that time period) were influenced by the MiG-25. It’s appearance at Soviet airshows and flypasts on May Day parades was impressive, and the Soviets made frightening claims as to its performance, claims which could not be independently verified. The F-15 Eagle, was designed with countering the claimed performance of the MiG-25. Western examination of the MiG-25 did not occur until a MiG-25 pilot defected and landed in Japan, after the F-15 was already in production. In reality, the MiG-25 was a purpose built interceptor with a very narrow niche role, while the F-15 was designed to be a powerful, all-weather, extremely maneuverable, tactical fighter aimed to permit the US Air Force (USAF) to gain and maintain air supremacy over the battlefield.
By reacting to Soviet propaganda rather than reality, the Americans built the premier air superiority fighter of the 20th century. F-15’s have served in multiple air forces and fought in several wars, with a startling record of no F-15’s ever having been shot down by enemy aircraft.
So in the end, the MiG-25 was designed and built for a certain role, and built around the industrial and military capabilities which existed at the time. It certainly does not look or behave like a Western jet (indeed, perhaps the closest Western analogue to the MiG-25 is the English Electric Lightning, a Mach 2 jet which was closer to a point interceptor than an all around fighter jet). It may not be pretty or “sophisticated”, but it does the job it was designed to do.