Cargo Rockets For Space Exploration

Press, Volume CII, Issue 30178, 9 July 1963, Page 16

Cargo Rockets For Space Exploration

In the not-so-distant future, when space operations are greatly intensified, there will be a need for cargo rockets far larger than any being built at present; Even the establishment of the smallest permanent space station (as outlined in this column last month) will require flights by several of the 500-ton Saturn 1 rockets now under development. Each Saturn 1 will be capable of lifting a payload of 11 tons into orbit 'above the earth, while a further improved version, the Saturn 1-B, will raise the amount to 16 tons. By 1966 the giant Saturn 5, designed to launch America's lunar expedition, will be ready to lift more than 100 tons at a time into earth orbit.

These payloads far exceed any yet orbited by either the Soviet Union or the United States, but they are decidedly marginal when the needs of future space missions are considered. Costs are also prohibitive. A single flight by a Saturn 5 will cost about a hundred million dollars—mainly because none of the rocket can be recovered for future use. Even nuclear rockets, with their potentially great weight-lifting power, will be too expensive unless recovery is feasible. When the 20-billion-dollar-plus Project Apollo lunar landings have been achieved the exploration of space will not just come to a stop. There will be no end to space activities for the simple reason that space has no boundaries. Economic pressures, however will slow the expansion of space travel unless a cheap way can be found to fight gravity and cut the cost of boosting large payloads into space. The use of rocket powered vehicles cannot be avoided and any type of rocket is bound to be expensive, so there is no escape unless the cost of a rocket can be spread over a large number of flights. Think how expensive air-fares would be if Boeing 707's were only good for a single flight! Attention must therefore be focused on the problems associated with the recovery and re-use of space vehicles if the exploration of space is not to bog down for want of funds. Various ideas for booster recovery have been put forward: one plan calls for ' a large flexible wing to unfurl from the expended first stage of the Saturn enabling it to glide back to a landing area for subsequent re-use. The requirements for any such wing are extremely severe: it must support a 40-ton rocket stage all the way from burnout on the fringe of

space at a height of 50 miles and a speed of 4000 miles an hour back to a gentle sealevel landing at a few miles an hour.

The upper stages of Saturn rockets present even more of a problem. They must be decelerated from orbital, or near-orbital speeds and survive re-entry into the earth’s atmosphere without damage. Investigations show that present rocket designs offer little hope of surviving re-entry deceleration loads. Upper stage recovery will demand radical design changes and with this need in view the National Aeronautics and Space Administration has let contracts to various aerospace companies for the study of large re-usable rocket vehicles. The Douglas Aircraft Company revealed its design last month at a meeting of the American Institute of Aeronautics and Astaomautics. Douglas’ chief advanced project engineer Philip Bono described a single-stage manned space cargo carried called ROMBUS (Re-usable Orbital Module-Booster and Utility Shuttle). It could orbit a payload of several hundred tons and return to earth for re-use 20 times or more. This, together with the basic cheapness of the ROMBUS design, would slash the cost of space missions from the present 250 dollars-plus for every pound of payload boosted into orbit to a figure of about five dollars per pound.

According to Bono, RQMBUS is lighter and more compact than any other future space boosters now on the drawing boards. It would bo only 95 feet tall compared with the 350 feet of the Saturn 5, but it would be

over twice as wide across its base. The key to its compactness and versatility is the plug-nozzle rocket motor (see illustration) which can be used for propulsion and control during all phases of the flight—lift-off, injection into orbit, retro-fire to drop out of orbit and as a braking rocket during touch-down on its four landing legs. Unlike conventional bellnozzle rocket engines the plug-nozzle design can, when cooled by some of its liquid hydrogen fuel, survive the aerodynamic heating of reentry.

For initial boost eight detachable liquid hydrogen tanks would be strapped around the tapered body of the vehicle. When empty, these tanks would be jettisoned to increase flight performance and improve manoeuvrability during the subsequent return to earth. The tanks themselves would be landed by parachute and recovered from the sea. It is estimated that the ROMBUS vehicle and its eight detachable tanks could be refurbished and returned to the launch-pad in a total turnaround time of only two and a half months. Although ROMBUS is at the moment no more than a drawing board concept for purposes of future planning it represents a change in design philosophy away from costly expendability. “No medium of transportation can long survive the extravagance of using the carrier vehicle only once,” said design engineer Bono. “Over the years to come, long-range economy, and not immediate space spectaculars, may well establish superiority in space exploration.’’