XB-70A: The bomber was built for a nuclear war against Soviet Russia. And yet,
it seems technology made her obsolete before her time. Here is her the story and why she
failed – On display at the National Museum of the United States Air Force at Wright-Patterson
Air Force Base (AFB) outside of Dayton, Ohio is the sole surviving prototype of an aircraft
that was originally conceived in the 1950s as a high-altitude, nuclear strike bomber that
could fly at Mach 3 (three times the speed of sound). What makes this especially impressive
is that the futuristic-looking XB-70 “Valkyrie” took to the skies just a mere six decades after
the Wright Brothers made their first flight. It was a testament to the progress made in
aviation design in the first half of the 20th century.
The XB-70A, built by the North American Aviation (NAA) Los Angeles Division for the U.S. Air Force,
was an experimental high-speed, delta-wing aircraft designed to fly at Mach 3 – three times
the speed of sound – and higher than 70,000 feet (21,000 kilometers). The goal of the program was
to develop a high-altitude, nuclear strike bomber that could outrun any interceptor sent against it.
The planned B-70 was to be a nuclear-armed,
deep penetration supersonic strategic bomber for the Strategic Air Command.
With its delta-wing profile, it isn’t hard to see the similarities in the
overall design of the experimental XB-70 and the British-French turbojet-powered Concorde
supersonic passenger airline that was operated from 1976 until 2003. However, the B-70 had
been conceived well before any consideration was likely given to the high-speed passenger airliner.
As initially planned, the XB-70A – which was powered by six General Electric YJ93s of 30,000
lbs. thrust each with an afterburner – was to have a maximum speed of Mach 3.1 (2,056 miles per hour,
or 3,309 kilometers per hour). At 35,000 feet (10,668 meters), it could reach Mach 1.90
(1,254 miles per hour, or 2,018 kilometers per hour), while at its service ceiling of
75,550 feet (23,012 meters), it had a maximum speed of Mach 3.00 (1,982 miles per hour,
or 3,190 kilometers per hour). The planned combat range of the B-70 was to be 3,419
miles (5,502 kilometers) with a maximum range of 4,290 miles (6,904 kilometers).
The belief among military planners was that the bomber could simply fly so high and fast
that any enemy, notably the Soviet Union, couldn’t have easily defended against it.
However, the one thing that the XB-70 Valkyrie couldn’t outrun
was the progress that was being made with missile technology.
In fact, by the early 1960s, Surface-to-Air Missiles (SAMs) technology had vastly improved,
which in turn threatened the survivability of even high-speed,
high-altitude bombers. At the same time, less costly, nuclear-armed
ICBMs (Intercontinental Ballistic Missiles) were entering service. As a result, in 1961,
the expensive B-70 bomber program was canceled before any Valkyries had been completed or flown.
It was also expected that each aircraft would cost an estimated $24.5 million (nearly
$240 million in today’s money), which proved simply far too expensive for such an aircraft.
That could have been the end of the line for the Valkryie, but the United States Air Force
still moved forward with the program and bought two XB-70As to test aerodynamics, propulsion,
and other characteristics of large supersonic aircraft. The XB-70 Valkyrie proved to be a
perfect testbed for SST research, which was being conducted jointly by NASA and the Air Force.
It was the same size as the projected SST designs and used similar structural materials, such as
brazed stainless steel honeycomb and titanium. The first XB-70A – which is now on display at
the National Museum of the United States Air Force – first flew in from Air Force Plant 42,
Palmdale, California, to Edwards Air Force Base in September 1964,
with Chief Test Pilot Alvin S. White and Colonel Joseph F. Cotton, U.S. Air Force, at the controls.
The aircraft achieved Mach 3 flight in October 1965,
and the prototype continued to fly and generate valuable test data in the research program
until it was retired after conducting its final research flight on Feb. 4,