On several occasions after the breakup of the Space Shuttle Columbia on February 1st, I found myself in conversations about the safety of the space program. Actually, my knowledge is limited to much lower altitudes and speeds and much more prosaic equipment. On a few occasions, nevertheless, I felt obliged to put in my two cents when someone commented that the Shuttle was obviously unsafe, given its record of one fatality for every 10 or so flights.
It’s hard to define an expected level of safety for something like the Space Shuttle. Considering the extreme difficulty of what it does, it has succeeded very well, though, like Concorde, it has been an economic failure. The appearance of safety depends a lot on the numbers that you select to represent it. The one-in-10 figure sounds awful; if you say one accident per 60 launches it sounds a bit better. But try putting it in terms of passenger miles. A week-long Shuttle flight with seven aboard racks up some 20 million passenger miles, and if you think of 1.2 billion passenger miles per disaster, it starts to sound almost good. That’s the equivalent of 4,000 transcontinental flights of a half-empty 757.
NASA’s jolly publicity photos of smiling orange-suited astronauts (what a lovely name-star sailors!) seem intended to suggest that space flight is a walk in the park. Well, maybe Central Park. It’s risky, and it’s going to remain risky for a long time. The astronauts know it. The technology of the Shuttle is comparatively ancient, but various projects for replacements have come and gone, including ones that dispense with the now-famous insulating tiles, while the old Shuttle soldiers on.
With an ever-shrinking budget, NASA has attempted to shift some of the burden of space vehicle development to private industry. Shuttle operations are now managed by a private contractor, a subsidiary of Boeing. Lockheed-Martin benefited from a period of NASA enthusiasm for a proposed single-stage-to-orbit vehicle called VentureStar, a huge lifting body that was supposed to launch vertically into orbit, glide back, and be ready for reuse in the twinkling of an eye, unlike the Shuttle, which requires the ministrations of armies of technicians for weeks or months between flights. A fundamental part of the VentureStar concept was its so-called linear aerospike rocket engines. An ingenious departure from the familiar mushroom-shaped design, the linear aerospike looks a little bit like an automotive V-8. Rows of combustors eject hot gas against two curved surfaces that form an aft-pointing vee. The outer sides of the exhaust plume are free to adjust their shape to ambient pressure and velocity. Despite high expectations of increased efficiency and many promising ground tests, the linear aerospike had not reached flight status when NASA, with the fiscal belt, or noose, growing ever tighter, cancelled the program.
Another abortive NASA/industry project was the X-34. An unmanned booster system for small to medium-sized payloads, it was essentially a scaled-up version of Orbital Sciences Corporation’s successful Pegasus, a rocket-powered spaceplane launched from under the wing of a high-flying L-1011. The business end of the partnership foundered because one of the participants, Rockwell, refused to use the most suitable engine available, which happened to be of Russian manufacture. Rockwell wanted to use its own brand, though it was less powerful and would have made for a less capable booster. Eventually, citing irreconcilable differences, Rockwell withdrew from the program in 1996. The remaining partner, Orbital Sciences, decided to go it alone under a new NASA contract, but that one was cancelled as well for the usual reason-money. Such are the vicissitudes and ignominies of privatizing the Last Frontier.
As time and habit take the bloom off the rose of space exploration, the messy financial aspects become more and more prominent. When Kennedy announced 40 years ago that the United States would put men on the moon, nobody asked why or how much it would cost. Now those questions are being asked, especially about manned space flight, which is much more difficult and expensive than the unmanned variety and has (arguably, at least-these things, like safety, are hard to measure) yielded proportionately fewer benefits to the earthbound citizens of this world. In the past few decades, a number of ambitious technological initiatives-the American SST, the National AeroSpace Plane, VentureStar-have been shelved in the face of runaway costs, unanticipated technical difficulties and doubts about their real value. Against that background, the Space Shuttle and Concorde are triumphal twin peaks of technological daring and of national pride for their creators; both, however, are discouragingly costly to operate.
One school of thought has it that space travel will not become a practical reality until it is taken out of the hands of governments and large corporations and turned over to the ingenuity of private individuals and small businesses. Indeed, at Mojave today one sees a bizarre airplane-it looks like two anteaters yoked to a polkadotted balloon-that is intended to help loft wealthy thrill-seekers into suborbital space. Almost certainly, it will try to do so during this, the centenary year of powered flight. Its funding is entirely private, and on a microscopic scale compared with NASA and industry projects.
The same newspapers that brought news of the Columbia accident reported, on their inner pages, a train wreck in Zimbabwe that had killed 14. Its victims were obscure, ordinary people, however, and train wrecks are to be expected, so there was no agonized reappraisal of the suitability of trains for human transportation. But a Shuttle accident is a full-fledged disaster, not only because of the loss of life it entails, but because of the wreckage of ambitions and dreams that falls to earth with it. Citizens normally lulled by the barely publicized routine of launches and landings, and occasionally entertained by 10-second televised images of smiling weightless astronauts swimming about like so many seals, are suddenly roused to ask, “Why?”
It’s a difficult and, at times like this, a bitter question to answer. For some Americans, outer space holds an attraction so powerful, and the analogy to the old West is so clear, that the question makes no sense at all. For others, to sacrifice even one life to gain a foothold on some inconceivably distant airless rock seems insane. Is space travel the manifest destiny of mankind? Or is it just a bread-and-circuses distraction from deteriorating conditions here on Earth? What do you think? Would you go?
Unbearable HeavinessThe rather sudden and dramatic rejection of the Williams EJ22 mini-turbofan by Eclipse Aviation must have given many people the impression the Williams engine had failed to live up to its promised performance. Actually, Williams says the engine is progressing well and has run at a higher thrust level than required by the contract with Eclipse. Nevertheless, Williams “accept[s Eclipse’s] need for a larger, higher thrust engine.”
This is as much as to say that the problem was not that the Williams engine failed to live up to expectations, but that the Eclipse jet did-specifically, that it failed to be as light as it was intended to be.
Failure to be light is endemic among airplanes. Even experienced designers are often seized by an irrational optimism when faced with a clean sheet of paper. At last rumor, the Eclipse was weighing in at around 4,800 pounds gross. This is several hundred pounds above the original (rumored, again) target weight, but still reasonable for a pressurized six-seat airplane, especially one intended to operate at FL 410. There was no reason to think the Eclipse would be lighter than other airplanes of similar capacity. The Williams engines are much lighter than recips-less than 100 pounds each-but their hourly fuel burn is two or three times greater, and so the net powerplant weight comes out about the same. The structural material is conventional aluminum. Where else are you going to save weight?
The rated thrust of two EJ22s, 1,600 pounds, is ample to get a 4,800-pound airplane off a runway. The problem comes in Aspen on a hot day with a failed engine. Hot and high, an EJ22’s thrust probably drops to 600 pounds or less, and because of its very small mass the engine couldn’t support any kind of “war emergency” power setting for more than a few seconds.
The Williams engine could be a great, in fact a revolutionary powerplant, for a four-seat personal twin-jet weighing 3,500 pounds-something like the old Morane-Saulnier Paris (which, by the way, had a gross weight of 8,650 pounds!)-or possibly even for a single-engine airplane in the Mooney class. But before we get carried away with dreams of a new generation of jet-powered general aviation airplanes, we should reflect that jets are in their element only at high altitude, and they therefore have to be pressurized; and they and their pilots need full IFR capability, not only in hardware but also in proficiency. Furthermore, they cover so much ground so fast that there’s no point in having them unless you really have somewhere to go, and often. A jet-powered Skyhawk for Sunday pilots may sound seductive, but it’s a contradiction in terms. For ordinary general aviation operations involving ordinary families taking ordinary trips, the reciprocating engine still has a bright future.
