The XB-70 Valkyrie, with its planned cruise speed of Mach 3 and operating in an altitude of 70,000 feet, was supposedly the ultimate high-speed, high-altitude manned strategic bomber.
The events that followed afterward, however, caused it to play a far different role in aviation history.
Start of the Valkyrie Program
The US Air Force issued a contract known as the General Operational Requirement No. 38 for a new bomber that could fly as far and carry as much as the B-52 but with a maximum top speed of Mach 2.
Boeing and North American Aviation both came up with designs of their own, but it was North America who came to the proposal stage swinging.
Their design concept incorporated highly experimental and theoretical features such as canards, variable wing geometry, as well as a combined high-pressure inlet system for six massive engines powering the plane.
One Detail That Stood Out
But one design detail stood out from the rest that secured the contract for North American Aviation – the XB-70 could down its wingtips. This took advantage of a newly discovered phenomenon called the “compression lift.”
But what is it, exactly? Well, an aircraft that moves at supersonic speeds generates shockwaves. If these shockwaves’ high pressure could be captured beneath the wing of the aircraft, then it generates additional lift.
In the aircraft design, the sharp point was the leading edge of the engine intake splitter. To trap these shockwaves, Valkyrie had wing tips that could fold down.
Soviets’ Role in the Program
The Soviets helped the Americans with the XB-70 program quite a bit. Although they didn’t know this, the high drag area of the planes (like the nose cone and inlet) had to be made out of titanium.
The US had no titanium, so they needed to use shell companies and other third parties to acquire titanium from the Soviets, which was used in high-tech planes like the SR-71 and the XB-70.
What Killed The Program?
The downing of the U-2 planes was one of the first things that put a dent in the XB-70 Program. Until that point, the Pentagon thought that no Soviet anti-air systems could reach a plane flying at 70,000 feet, which is the altitude U-2 spy planes usually operated at.
During that time, nuclear first-strike capability was also shifting from bomber planes to ICBMs, making the nuclear bomber concept obsolete.
At this point, the XB-70 Program was dead at its inception.
How Did It Create the F-15?
Funnily enough, it was the XB-70 Program that gave the US the F-15.
Initial reports that the US was working on the XB-70 scared the Soviets, and in response, they started to work on the MiG-25 Foxbat, which was specifically designed to counter the XB-70.
Ironically, news that the Soviets were working on a plane to intercept the XB-70 scared the Americans. This forced the US to make a counter to the Soviet’s counter – that aircraft is now known as the F-15 Eagle.