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Aviation History
1964
1964 - 1140.PDF
fUCHT International, 23 April 1964 641 25,000 m.p.h. RE-ENTRY POSTPONED from April 7, the suborbital flight of NASA's firstProject Fire re-entry spacecraft was made on April 14 from Cape Kennedy. Launched by an Atlas D vehicle, the 2001b craft was accelerated to a re-entry speed of 25,000 m.p.h. by an Antares 2 rocket motor in an experiment to obtain direct measurements of re-entry heating. The scheduled flight was based on a 32min ballistic flight path, with major events concentrated at the beginning and near the end of the flight, separated by a 21min coasting period. After lift-off, the Atlas was to follow its standard operating sequence, which includes booster engine cut-off; booster jettison; and sustainer engine cut-off. Following sustainer cut-off, the heat shroud was to be jettisoned. Spacecraft separation was to take place after 5min 6sec of flight at an altitude of 190 miles and 490 miles downrange. A series of explosive nuts were to be detonated to separate the velocity package from the launch vehicle, with retrorockets on the Atlas completing the separation. Coasting flight was to begin with the velocity package under control of an inertially referenced guidance and stabilization system. Six cold-gas attitude-control jets used nitrogen stored at 3,001b/sq in in four spherical tanks. The velocity package was to reach an apogee of approximately 500 miles about 2,500 miles downrange after 15min 41 sec of flight. At the end of the 21min coast period, the re-entry package was to be accelerated to the correct speed for the beginning of re-entry. These planned events were as follows :— (1) Three spin rocket motors are ignited by a timer in the velocity package shell after 26min 14sec. (2) At 26min 17sec the velocity package shell is jettisoned. (3) Ignition of the Antares 2 motor occurs at 26min 20sec. (4) The Antares 2 burns for 30sec, with separation scheduled after 27min 20sec of flight. At that point a pyrotechnic device releases a coil spring which expands to separate the re-entry package from the adapter that remains attached to the Antares 2. The re- entry package moves away from the spent rocket case and adapter at 6ft/sec and, after a 6sec delay, a small rocket fastened to the adapter is fired to ensure positive separation. At that time, the re-entry package should be on a flight path inclined 15° below horizontal, moving at 25,000 m.p.h. on a south- easterly heading about 100 miles due west of Ascension Island. Splash was calculated to occur after 32min 17sec of flight, at a point approximately 5,200 miles downrange. A Nike Apache sounding rocket was to be launched from Ascension Island on the South Atlantic within an hour after the Fire spacecraft re-entry, in order to measure the atmospheric conditions at that time. Project Fire re-entry spacecraft is tested in Republic Aviation's space environment chamber Illustrated on this page, the instrumented re-entry package for Project Fire is a blunt-faced vehicle with a conical afterbody, 26in in diameter across the face, 21 in long and weighing 2001b. The adapter which supports the re-entry package and connects it to the Antares rocket motor weighs an additional 501b. The blunt end of the re-entry package consists of three beryllium calorimeters (devices for measuring absorbed heat) interleaved with three phenolic asbestos ablative heat-protection layers. All but the last two layers will be burned away or jettisoned during the 45sec flight through the high re-entry heating period. Choice of the layer design was dictated by the fact that the calorimeter material, beryllium, will survive only seconds of intense re-entry heat. Hence a number of calorimeters are used, one during the earliest portion of the re-entry, one when heating rises to a peak, and the third near the end of the heating period. Two of the ablative heat-protection layers are jettisoned at pre-set times to expose a fresh calorimeter to the hot gas region. Within the re-entry package are three radiometers. Two are single devices to measure total radiant energy and the third is a Wie re-entry package weighs 2001b and mea- sures 21 in x 26in maxi- mum diameter. The beryl- lium calorimeters are exposed in turn (see text) AFTERBODY (66° CONE) -AFTERBODY OPTICAL WINDOW BERYLLIUM HEAT SHIELD BERYLLIUM HEAT SHIELD BERYLLIUM HEAT SHIELD OPTICAL WINDOW PHENOLIC HEAT SHIELD PHENOLIC HEAT SHIELD PHENOLIC HEAT SHIELD K/P SEPARATION SYSTEM • COOLER ASSEMBLY C-BAND ANTENNA
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