Rocket sled



A rocket sled is a test platform that slides along a track (e.g. set of rails), propelled by rockets. A rocket sled differs from a rocket car in not using wheels; at high speeds wheels would spin to pieces due to the extreme centrifugal forces. Apart from rare examples running on snow or ice (such as Max Valier's RAK BOBs of the late 1920s ), most rocket sleds run on a track. Although some rocket sled tracks use single beams or magnetic levitation, most use railway track. Sliding pads, called "slippers", are curved around the head of the rails to prevent the sled from flying off the track. The rail cross-section profile is generally that of a Vignoles rail, commonly used for railroads.

A rocket sled holds the land-based speed record for a vehicle, at Mach 8.5.

Usage
A rocket sled is reported to have been used in the closing days of World War II by the Germans to launch a winged A4b strategic rocket from a tunnel on March 16, 1945. Rocket sleds were used extensively early in the Cold War to accelerate equipment considered too experimental (hazardous) for testing directly in piloted aircraft. The equipment to be tested under high acceleration or high airspeed conditions was installed along with appropriate instrumentation, data recording and telemetry equipment on the sled. The sled was then accelerated according to the experiment's design requirements for data collection along a length of isolated, precisely level and straight test track. Testing ejection seat systems and technology prior to their use in experimental or operational aircraft was a common application of the rocket sled at Holloman Air Force Base. Perhaps the most famous, the tracks at Edwards Air Force Base were used to test missiles, supersonic ejection seats, aircraft shapes and the effects of acceleration and deceleration on humans. The rocket sled track at Edwards Air Force Base was dismantled and used to extend the track at Holloman Air Force Base, taking it to almost 10 miles (16 km) in length.

Unmanned rocket sleds continue to be used to test missile components without requiring costly live missile launches. A world speed record of Mach 8.5 (6,416 mph / 10,325 km/h) was achieved by a four-stage rocket sled at Holloman Air Force Base on April 30, 2003, the highest speed ever attained by a land vehicle.

Murphy's law first received public attention during a press conference about rocket sled testing.

Rocket Sled Tracks
Other former rocket sled tracks include those at the following locations:
 * Peenemünde, Germany (V-1 launch ramp)
 * Base B1, Colomb-Béchar, Algeria (HB3 track (330 m) of CIEES, built by Hotchkiss-Brandt )
 * PISQ, Salto di Quirra, Sardinia, Italy (660-ft supersonic sled track with 8° inclination )
 * Satory, France
 * Istres-Le Tubé Air Base, France (used by René Leduc for the SE 1910)
 * Cazaux Air Base, France (HB1 (200 m) and HB2 (600 m) tracks of the DGA Centre d'essais en vol, built by Hotchkiss-Brandt )
 * Aberdeen Proving Ground, Maryland, USA
 * Institute of Aviation Medicine, Farnborough, UK