Encyclopedia Astronautica
Phoenix C

Phoenix C
Credit: Gary Hudson
Phoenix E-L-LP-C
Credit: Gary Hudson
American SSTO VTOVL orbital launch vehicle. The larger 180 tonne Phoenix design of the 1980's was envisioned in two versions -- the Phoenix C (Cargo, unmanned) and Phoenix E (Excursion -- for use as a lunar or Mars lander and personnel transport to earth orbit). The earlier versions used liquid oxygen oxidiser and two fuels (hydrogen and propane) but later iterations used only oxygen and hydrogen (varying the oxidiser to fuel ration during ascent). The designs used an 'aeroplug' in place of the 'aerospike' of earlier SSTO designs. Gary Hudson and Maxwell Hunter spent several years trying to interest investors in the designs before the company folded.

In 1982 Gary Hudson and his partners founded Pacific American Launch Systems to develop VTOL SSTOs for the commercial marketplace. The proposed Phoenix family included two large vehicles. The earlier designs used mixed-mode dual-fuel propulsion to achieve higher propellant mass fractions and a more compact vehicle. Twenty-four individual bell nozzle rocket engines were chosen to allow abort even if several engines failed. The use of smaller engines was also aimed at reducing the cost to develop the propulsion system. Both keroesene and propane were considered as the second fuel. Propane was finally chosen for density, cost, storage at close to the lox boiling point, and reduced engine development and maintenance problems since the coking caused by kerosene would be reduced.

Later versions of the design were drastically different. Study showed that most of the gains of dual-fuel could be achieved by changing the mixture ratio of a lox-hydrogen rocket engine during ascent. Later designs also used water-cooling of the aluminum skin for thermal protection during reentry, in place of a passive heat shield. The individual engines were replaced with a new-concept 'aeroplug' engine. The aeroplug differed from earlier aerospike designs in that all but a few percent of the plug surface was removed, providing a smooth base for reentry. This meant a loss of performance that was more than compensated for by a ligher structure. The aeroplug used J-2S turbomachinery and could operate at 1200 psia combustion pressure and a vacuum area ratio of about 200:1. Steering would be by differential throttling.

Status: Study 1982-1988.
Gross mass: 180,000 kg (390,000 lb).
Height: 17.40 m (57.00 ft).
Span: 9.80 m (32.10 ft).
Thrust: 2,840.00 kN (638,450 lbf).

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See also
  • SSTO Category of launch vehicles. Single Stage To Orbit. More...
  • VTOVL The concept of a reusable single-stage-to-orbit Vertical Take-Off Vertical Landing (VTOVL) launch vehicle that would reenter and return to its launch site for turnaround and relaunch was first proposed by Philip Bono in the 1960's. The appealing simplicity of the concept has been offset by the technological risk in developing it. The problem with any single-stage-to-orbit concept is that if the empty weight of the final vehicle has been underestimated it will not be able to deliver any payload to orbit, or even reach orbit. Since weight growth of up to 20% is not unknown in aerospace projects, this is a very real threat which has made both NASA and private investors reluctant to invest the billions of dollars it would take to develop a full-scale flight vehicle. More...

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