This video was made possible by CuriosityStream. Watch thousands of high-quality documentaries
and get access to my streaming service, Nebula, using the link in the description. In the fall of 1964, the Air Force begins
testing a radical new machine that looks like it’s come from outer space. It’s one of the fastest aircraft to ever
fly, a massive intercontinental bomber that can outrun any fighter jet. An aircraft so groundbreaking, it rides its
own supersonic shockwave. It was going to be the future Amerca’s bomber
force. But efforts to develop such an advanced aircraft
would be marred by tragedy. By the mid 1950s, tensions between the United
States and Soviet Union were reaching an all time high. Both sides had strategic bombers that could
fly half way around the world to strike targets deep within enemy territory. The United States had developed a state-of
the-art, all-jet bomber force. The newly introduced B-52 could carry large
payloads over long distances, and the soon-to-be-introduced B-58 would dash to supersonic speeds. But in an all-out conflict, neither of these
would really cut it against Soviet air defenses. While the B-52 could fly all the way to the
Soviet Union, it flew too slow to stand a chance against the latest generation of Soviet
interceptors. The supersonic B-58 could just fly as fast
as any interceptor, but had limited range and payload. What the Air Force urgently needed was a new
kind of plane. A heavy bomber fast enough to outrun anything
the Soviets could throw at it. But in 1955, many doubted whether such a plane
was even possible. Because it would mean having to turn to some
pretty radical solutions. Like using nuclear power to extend an aircraft’s
range, or exotic high-energy fuels to boost the performance of jet engines. The most practical solution seemed to be an
aircraft that would fly subsonically most of the way to its target before jettisoning
the outer portions of its wings and fuel tanks to make a supersonic dash. But aviation technology in the 1950s progressed
at a breakneck speed, with rapid advances in aerodynamics, engine performance, and exotic
materials. And it meant that the dash concept could be
shelved in favor of a design that would cruise supersonically over its entire mission. So in 1957, the Air Force began development
of a next generation bomber. And the performance targets were ambitious. It would have to fly more than three times
faster than the B-52, twenty five thousand feet higher, and have a similar payload and
range. Leading aircraft builders Boeing and North
American Aviation were invited to compete on a design. Boeing and North American submitted radical
concepts that looked similar on the surface. Both featured cunards and slender delta wings
optimized for supersonic flight. But Boeing was widely expected to win. After all, they had built the venerable B-52
and a series of iconic bombers during the Second World War. North American was the underdog. But during development, their engineers stumbled
upon research that would give them a huge advantage. A little known report that detailed a phenomenon
called compression lift. When flying faster than the speed of sound,
shockwaves typically travel away from an aircraft. But if they could be redirected underneath
the wings, the shockwaves would help generate additional lift. Using this principle, North America's entry
promised to fly more efficiently at high supersonic speeds. And the Air Force was impressed. To the shock of Boeing, in 1957, North American’s
design was selected for development. The new bomber would given the name Valkyrie
and designationed as the B-70. Engineers used cutting edge technologies to
build a 260 ton bomber that could outrun a fighter jet. To make this feat possible, six afterburning
turbojets were fed air through a sophisticated intake. The engines were optimized to run most efficiently
at high supersonic speeds. And they were powerful enough so that even
if one were to fail, the Valkyrie could maintain Mach 3 and still complete its mission. But clever aerodynamics were also key to performance,
with compression lift giving the Valkyrie one of the highest lift-to-drag ratios of
any manned aircraft. Variable geometry wings improved stability
and enhanced compression lift. On takeoff and landings could be fully extended. At low supersonic speeds, angled downwards
25 degrees, and at multi-mach speeds, a full 65. But flying at three times the speed of sound,
kinetic heating the airframe would be so intense, it would soften conventional aircraft aluminum. So engineers developed a revolutionary fuselage
skin and circulated fuel throughout the airframe to cool the aircraft’s interior. Even at an altitude of seventy-five thousand
feet, the Valkyrie’s cockpit was fully pressurized and featured an innovative encapsulated escape
system. It meant that the bomber’s crew of four
wouldnt have to put on bulkly flight suites, allowing a Valkyrie crew to get airborne only
20 minutes. Capable of delivering a nuclear payload to
anywhere in the world in just hours, the Valkyrie’s performance was truly out of this world. And the bomber would embody America’s strategy
of deterrence through strength. The first experimental XB-70 prototype was
unveiled in May of 1964 with flight testing to begin in the following months. And it would soon be joined by a second and
third prototype, both already under construction. But from the start, it was clear that things
wouldn't go so smoothly. During initial ground tests, there were so
many technical problems, the first flight was delayed for months while engineers sorted
through a laundry list of issues. It wouldn't be until September 21st that the
XB-70 was finally ready to make its first flight. And cheers could be heard as the space-aged
bomber lifted off for the very first time. But celebrations were short-lived. Because a hydraulic leak prevented the landing
gear from retracting. And soon one of the engines surged, forcing
a shutdown. As the prototype came back in for a landing,
a brake locked up causing a tire to blowout and catch fire. It seemed just as one problem was solved,
more would emerge. On October 12th, the XB-70 crossed the sound
barrier for the very first time, just barely inching above Mach 1. But as flight tests continued, paint began
peeling off the fuselage and control surfaces and soon the aircraft looked like it had flown
through a sandblaster. The paint was patched up, and the XB-70 pushed
on to higher speeds. But with each test flight, it seemed the faster
it flew, the more serious the issues became. On its twelfth test flight, as the prototype
reached Mach 2.6, The horizontal splitter tore off and was sucked into the engine duct,
knocking out four engines. The pilots landed safely, but all of the engines
had to be replaced. Finally on October 14th, the aircraft was
cleared to reach Mach 3. But just two minutes in, a large portion of
the wing’s leading edge broke off, forcing yet another emergency landing. From that point on, the first prototype was
limited to flying no more than Mach 2.5. In developing such a state-of-the-art aircraft,
there were bound to be setbacks. But there was a much bigger problem looming
over the program. From the very start, there were serious doubts
about whether the Valkyrie would really be safe from Soviet air defenses. Because surface to air missiles, introduced
in the mid-1950s, were quickly becoming the most effective way to guard air space. And by the 1960s, the Soviet Union had thousands
of them, which could hit targets beyond even XB-70's altitude. The introduction of ICBMs in the late 1950’s
also meant that nuclear warheads could now be delivered much more quickly and economically. In the span of just a few years, missile technology
had rendered the world’s most advanced bomber virtually obsolete. With XB-70’s strategic value in serious
question, engineers scrambled for ways to keep the plane relevant. Seketching out radical concepts to repurpose
the bomber into missile launcher, an aerial launch platform for spacecraft, or even a
supersonic aerial refueler. Even more outlandish was a proposal that would
turn the bomber into a Mach 3 supersonic transport. But these concepts proved to be a bridge too
far. And the program was dramatically scaled back,
eventually reduced down to a bare minimum research project involving just two aircraft. But with millions already spent on development,
the program pushed forward. And in 1966, NASA joined the Air Force in
flight testing. Using the prototypes to gather valuable research
into supersonic flight. By that point the second prototype had proven
to be a much more capable plane. On May 19th, 1966 it reached speeds beyond
Mach 3, demonstrating its ability to cruise at 3 times the speed of sound over 30 minutes. After nearly a decade of development, one
of the world’s most ambitious aircraft was finally living up to expectations. But tragedy would strike just weeks later. On June 8, the second prototype was joined
by four other aircraft for a formation flying photo-op. But minutes into the flight, without warning,
one of the trailing aircraft collided with the XB-79, instantly destroying it and severely
damaging the Valkyrie's vertical stabilizers. For 16 seconds, the Valkyrie continued flying
straight and level before spiraling back to earth. In a matter of seconds, two test pilots and
a billion dollar aircraft were tragically lost. It was a devastating setback for the program,
and it meant NASA and the Air Force would have to continue research with the much less
capable original prototype. The XB-70 was an engineering marvel. And while it never joined America’s bomber
force, it still had a profound impact on the Cold War. Because in 1955, when the Soviet Union learned
that the Americans were developing a supersonic long range bomber, they scrambled to develop
an equivlant. And it would end up as one of the most fearsome
looking aircraft ever built. But looks can be deceiving. In an effort to match Americans, the Soviets
ended up producing an embarrassing failure. One that they would keep hidden for decades. You can learn more about the M-50’s dramatic
failure in my latest video available right now on Nebula. Nebula is where you watch more Mustard videos,
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