Message posted by willy Nammer on April 26, 2002 at 11:14:23 PST:

Strategic Nuclear Strike
Hypersonic Glide Vehicles

Beginning in the 1960s, after cancellation of the X-20 experimental DYNASOAR vehicle, the USAF renewed interest in the same type of vehicle (unmanned) for the mission of nuclear strike (strategic). Launched by Atlas and Titan ICBMs, these hypersonic glide vehicles (HGVs) could cover the same distances as the
normal ICBM, but flew shallower hypersonic glide paths
instead of ballistic trajectories, and were as fast as
the ICBMs. However, flying a shallower flight path, Soviet air defense radars could not detect the incoming HGV in time for a successful intercept. Thus the HGV had a distinct advantage over the ballistic missile - little warning time for defenses to react. The American HGV program of the 1960s (since they were launched by ICBMs) are thought to have been banned by both the SALT (I & II) and the START nuclear weapons treaties between the US and the Soviet Union. The Soviets, for their part, gave up development of their FOBS ICBM weapon program.

In order to get around such treaty restrictions, the US, instead of employing ICBMs as the HGV launcher, chose to launch such weapons from bomber aircraft, namely the B-52. The strategic HGV could therefore not be counted under those treaty provisions as cruise missiles, nor ballistic missiles. It also helped that
this HGV program kept secret (well...!!!). With this in mind, the USAF re-initiated development of the bomber-launched HGV, in the mid to late 1970s. Lockheed's Skunk Works (as usual with secret programs) won the "secret" HGV contract in 1980.

Mission: strategic nuclear strike and other missions, i.e., reconnaissance. For final development of this bomber-launched strategic HGV, work on the weapon was passed to Lockheed Missiles & Space Company. Main target(s) for the HGV was high value mobile missile and command posts in the Soviet Union.

The following (a bit modified, but accurate) is from Bill Sweetman's book "AURORA" "The HGV was designed to be launched from a B-52, at 68,000 feet, it would be rocket boosted to Mach 18 at high altitude, an could glide more than 5,000 miles to its target, arriving barely 30 minutes after launch. The main challenge was aerodynamic heating: the HGV was made of heat-resistant carbon-carbon composite skin panels on a titanium sub-structure. Its planform was triangular with the leading edges swept at 75-degree. With the response speed of the ICBM and the short warning time and terminal maneuver performance of a cruise missile, the HGV could be launched against mobile targets and hit them before they haad time to move."

The strategic bomber-launched HGV could carry 2 to 3 nuclear warheads (each shaped like the 9-ft Sandia SWERVE, which proved to be highly maneuverable during its testing in the 80s). These warheads were carried in the shrouded nose section of the fairly large HGV. The HGV, just like the Poseidon and Trident SLBMs, had an extendable spike in its nose - when extended, it would lessen hypersonic drag. The Lockheed HGV looks somewhat like the old Boeing X-20 (just a bit, not much), but it has four vertical fins.

The ground-launched (tactical) AXE, BOSS, and CADM, mentioned by Fuel Fraction, has no relation to the strategic B-52-launched HGV. The strategic HGV was tested between 1986 and 1991. Dimensions for the HGV was - length 45.96 feet, wing span 11.14 feet, correct as stated by Fuel Fraction. Launch weight, however,
was more like 25,000 pounds - not 58,000 pounds - that was the launch weight of the tactical ground-launched AXE, et. al., with a range of 350 miles while carrying an 18,000 pound payload of conventional sub-munitions. Also, the AXE, et. al., were ballistic missile types - not hypersonic glide types. Aanother facet of the AXE anf HGV difference - whereas the strategic HGV was classified "Secret," the tactical AXE was not. Plus, the solid propellant rocket motor of the HGV was an integral part of the vehicle - it was not a seperate item or add-on booster.

Another advantage of the HGV-equipped B-52 (2 HGVs, one under each wing), is that during a crisis, it could be alerted, takeoff, fly to a pre-designated area, and loiter there for hours - and it could be recalled - unlike an ICBM. Strategy flexibility!

Test launches of the HGV occurred off the California coast, and directed towards Johnston Atoll in the Pacific Ocean. The vehicle was recoverable (an expensive piece of equipment). The tests are said to have been handled by the AF's Space Command's 576th
Flight Test Squadron.

The US Navy also had in development - 1980 through 1991, a boost-glide weapon (single or cluster warhead), but it was smaller than the USAF's strategic HGV. Designed to be launched from submarines and surface warships, it could also be launched by aircraft or from ground launchers (this was not AXE either). This missile, was therefore, to be used by both the Navy and the Air Force. During 1988, the US Navy launched one of these test missiles from a submerged submarine - the missile then flying (boosted then glided) 3,000 miles, and hit its intende target, using LIDAR terminal guidance. This weapon was also a product of (again "secret" !!!?) Lockheed Missiles and Space Company. The Navy named this missile "Excaliber" but it was canceled in 1991 - end of the Cold War, ya know - no need for it (!!?)



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