|Paracone Retrofire - Douglas Paracone personal orbital escape system of the 1960's|
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The Douglas Paracone was one of the most minimal schemes for bail-out from orbit. The objective was to hit a continental land mass; for such purposes totally manual re-entry operations were used. After separation from the spacecraft, the undeployed Paracone consisted of essentially the pilot in his seat, with a small solid retrorocket motor mounted on struts above the pilot's chest. The astronaut would first roughly orient himself and the seat facing forward along the direction of orbital motion using cold gas thrusters. Then he would ignite the solid rocket motor. The motor had 18 seconds of low level 'vernier' thrust (9 kgf), during which time the pilot could correct its allignment using hand holds on the motor. It then went into 60 seconds of full thrust (44 kgf). The Paracone was designed to handle re-entry angles resulting from up to 30 degrees misallignment of the motor. Accuracy was within 800 km of the planned impact point.
After retrofire the empty motor was discarded and a large light-weight re-entry shell was deployed from the seat by gas pressure. The same gas supply was used for the reaction control thrusters. With a low ballistic coefficient the Paracone could be made of Rene-41 alloy fabric, with a teflon coating. Heat loads were calculated to be within the heat rejection capacity of the astronaut's portable life support system. A ballistic re-entry followed, with a peak of 9.6 G's. No parachute was required. The terminal velocity of the Paracone was 42 km/hour and impact was absorbed by the crushable structure of the cap of the cone. The total mass of the Paracone system compared favorably with that of conventional ejection seats.
The mass breakdown (in kg) was:
|Paracone Re-entry - Douglas Paracone with the heat shield deployed|
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|Astronaut & Suit||88.9|
|Seat & Restraints||13.6|
|Life Support Pack||13.6|
|Re-Entry Vehicle Structure||56.7|
|Retro Motor Mounts||2.7|
16,621 bytes. 261 x 304 pixels.
Craft.Crew Size: 1. Design Life: 3 hours. Total Length: 1.0 m. Maximum Diameter: 2.0 m. Total Mass: 227 kg. Total Payload: 89 kg. Total Propellants: 11 kg. Total RCS Impulse: 2.00 kgf-sec. Primary Engine Thrust: 44 kgf. Main Engine Propellants: Solid. Main Engine Isp: 255 sec. Total spacecraft delta v: 168 m/s.
A 'flying carpet' escape system from orbital space stations had been proposed by Douglas Aircraft Company. The escape system would be a saucer shape that would expand into a blunt-nosed, cone- shaped vehicle 7.6 m across at its base. The vehicle would act as its own brake as it passed through the atmosphere. Reentry heating problems would be met by using fabrics woven with filaments of nickel-based alloys.
|Douglas Bailout - Douglas Bailout System Cutaway|
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