XF-108 Rapier: Impressive USAF Interceptor That Never Flew

The era of what was known as the Jet Age in the 1950s saw the biggest boom of advancements in terms of aircraft technology. After the internal combustion era in the 1940s, what followed post-war was the revolution of the aircraft industry that slowly developed after engineers saw its potential. In what was deemed the golden age of aircraft design, no idea was too odd or weird. It saw the birth of aircraft like the Lockheed XFV and the pancake-looking VZ-9 Arvocar. Another proposal, although it never really flew, was the XF-108 Rapier.

The XF-108 Rapier

The North American XF-108 Rapier was manufactured by North American Aviation, the same company that conceived the P-51 Mustang. It was a proposed long-range, high-speed interceptor aircraft that was intended to use as the United States’ protection against the threat of supersonic Soviet strategic bombers armed with nuclear weapons. If it actually flew, the XF-108’s long-range and extremely high-speed design would have been one of the most advanced and highest performing aircraft of its time.

The idea was for it to fly fast and intercept Soviet bombers before they could drop their bombs. The designers hoped that the XF-108 would accompany the XB-70 Valkyrie bomber as well as an escort, which was also developed by North American Aviation. The problem with XB-70 at that time was it was too fast for any existing fighter to escort on a bombing mission.

XF At a Closer Look

The main thing about Rapier was its speed. Rapier was powered by General Electric YJ93 engines that could produce 29,300 pounds of thrust on each side with afterburners. This was expected to give the XF-108 a speed of around 2,000 MPH.  This was in the 1950s too!

It was also equipped with AN/ASG-18 prototype radar that would enable the aircraft to detect approaching bombers. At that time, the infrared search and tracking system was the cutting edge for the radar system with a range of up to 300 miles and could detect bomber-sized targets at about 100 miles with accuracy.

As it was an interceptor, the XF-108 Rapier was armed with three GAR-9 missiles to take down enemy bombers. Along with the AN/ASG-18 radar, they had a range of roughly 100 miles at a speed of around 3,000 mph. Because of the long-distance range of the missile, a radar-guidance system had to be installed in its internal bay on a rotary launcher so that it could still reach its target even while it was already out of range of the aircraft that launched it.

The size of the interceptor was large compared to the other aircraft at that time. It was even longer than the F-22 Raptor and B-17 Flying Fortress at its 27 meters length.

No Longer Needed

You might be wondering why an impressive XF-108 would be canceled despite its outstanding potential and capabilities?

The answer to that was it wasn’t the Rapier. It was the development of the intercontinental ballistic missiles (ICBMs). Both the United States and the Soviet Union had been working to develop their own ICBMs since World War II, after being heavily inspired by the V-2 rocket of Nazi Germany.

ICBMs had the capability to deliver nuclear weapons faster and with greater yields in kilotons than bombers could. They were also easy to hide and could reach their target in just 30 to 40 minutes. Its speed could reach around 4 miles per second, which was virtually impossible to intercept.  And they were cheap compared to the cost of building and manning whole squadrons of bombers.

When the Soviets successfully made their first ICBM and launched it in August 1957 with the R-7 missile, it shook the nations around the world and made them change their priorities. Bombers were no longer needed, which means interceptors to shoot down these bombers were also obsolete. Two years after the R-7 was launched, the XF-108 program was canceled.