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On October 3, 1967, the North American X-15A-2, piloted by
USAF Major William J. "Pete" Knight, was released from its
NB-52 mother plane at 35,000 feet above the Mojave Desert to
begin its dash for an absolute speed record of 4,520 miles
per hour, a record which stood unbroken until exceeded by
the Space Shuttle.
Because of the lack of oxygen at the altitudes at which the
X-15 flew, the XLR99 rocket engine used anhydrous ammonia as
fuel and liquid oxygen as the oxidizer. Fitted with external
fuel tanks to prolong engine burn up to 70%, the A-2 climbed
to 102,000 feet and reached a speed of Mach 6.7.
A-2 differed from previous Marks in that it had an ablative
coating to protect it from the high temperatures encountered
at the high Mach velocities. It also had a dummy scram-jet
engine fitted to the stub ventral fin to test the
feasibility of the engines for sustained high-Mach flight.
The X-15 expanded the envelope of manned, winged flight to
the very limits of the atmosphere and opened aviation to
horizons only dreamed of previously. In all its variants,
X-15 will be remembered as one of the most successful
As a direct result of test data obtained by early X-plane
flights, and advances in stealth technology, super fighters
have been developed that will carry America and her Allies
well into the 21st Century. Using exotic fuels and
oxidizers, these aircraft will operate at extreme altitudes
and be capable of speeds approaching Mach 30, or 17,500
miles per hour, which speed will allow these aircraft to be
placed into orbit after unassisted lift-off from their
As aircraft technology advances, airplanes are beginning to
look more and more like ovate ellipsoids, or 'Flying
Saucers." The newest stealth fighters will most certainly be
capable of vertical takeoff and landing and may, until the
orbital goal is met, operate at speeds approaching Mach 8 or
even Mach 10 with ease.
Because of the constraints inherent in protecting the pilot
from death during severe maneuvers, many of these aircraft
will be capable of only straight and level flight or shallow
dives and climbs when operating at their Mach limits. As new
data is evaluated, this problem may be solved by designing
the aircraft to stop in mid-air, hover, or change directions
quickly (but not instantly), or they may be flown remotely
from simulators on the ground thousands of miles away.
But while we occasionally see glimpses of these new aircraft
or hear rumors of their development, even more remarkable
aircraft and devices are being tested in complete secrecy in
underground facilities in the American Southwest deserts. If
the rumors are correct (and there is no reason at this time
to doubt them), galactic travel and even time-travel may be
only weeks away!
This information is provided as a public service, but we cannot guarantee that the information is current or accurate. Readers should verify the information before acting on it.