Rocket Plane Roulette
Honolulu HI (SPX) Mar 07, 2007
I'm a supporter of private spaceflight projects for the basic reason that Government space agencies have reached a state of total intellectual stasis with NASA's plan to redo Apollo 50 years later, China's plan to redo Soyuz/Salyut at about 1/8 the pace managed by the USSR, and Russia's plan to redo Zond with billionares in place of turtles.
And at this very time of official stagnation, a variety of private firms have finally found a business model that is both within the financial capacity of private capital and attractive to the general public: Suborbital tourism.
But there is a big problem with this nascent industry that most of its supporters are glossing over: Safety.
The romantic half of my brain would really like to see these businesses succeed and prosper, but the rational half tells me that they are heading for a series of fatal accidents that will be financial and public relations disasters.
To get a handle on how dangerous suborbital winged rocket flight really is, I have examined the safety history of research rocketplanes in the US and UK. That record is not very encouraging:
Flight History of Experimental Rocketplanes
Military First Pwrd Date of Cause of Name Serial # Flight Flts Loss Loss ------- ---------- -------- -- -------- ---------- X-1 46-062 25.01.46 62 X-1 46-063(a) 11.10.46 68 (Grounded 10.51) X-1 46-064 20.07.51 1 09.11.51 Explosion X-1A 48-1384 14.02.53 23 08.08.55 Explosion X-1B 48-1385 24.09.54 24 (Grounded 01.59) X-1D 48-1386 24.07.51 1 22.08.51 Explosion X-1E 48-063(b) 12.12.55 22 (Grounded 12.58) X-2 46-674 05.08.54 1 27.09.56 Inertia coupling X-2 46-675 27.06.52 14 12.05.53 Explosion SR.53 XD145 16.05.57 31 SR.53 XD151 08.12.57 12 15.06.58 Takeoff crash X-15-1 56-6670 08.06.59 81 (Grounded 12.68) X-15-2 56-6671(a) 17.09.59 31 09.11.59 Engine failure X-15-3 56-6672(a) (none) 0 08.06.60 Engine explosion X-15-3 56-6672(b) 20.12.61 22 15.11.67 Pilot error X-15A-2 56-6671(b) 25.05.64 65 03.10.67 Overheated Sources: Jay Miller, The X-Planes Dennis R. Jenkins and Tony Landis, Hypersonic Ray Sturtivant, British R&D Aircraft
(In compiling this table, I have excluded unpowered glide flights. Accurate information on French and Soviet rocketplane programs could not be located.)
Out of 16 mostly distinct airframes, 10 were totally or largely destroyed in accidents (along with one B-50 carrier aircraft). 5 pilots were killed in these accidents and 2 were severely injured.
Two of these accidents would not have endangered passengers. The X-15-3 exploded during a static engine test and the X-15A-2 meltdown occured during a level speed run that is quite unlike any tourist rocketplane profile.
So for a prospective space tourist, the relevant record for suborbital rocketplanes is: 8 life-threatening accidents in 458 flights, for a loss rate of 1-in-57 (1.75%). This is essentially the same as the Space Shuttle's safety record. As I pointed out in a previous SpaceDaily article, this is higher than the combat loss rate of any US aircraft operating against the Nazis in WWII! It's no surprise that the USAF and RAF cancelled their projected operational rocket fighters F-91 and SR.177.
Four of these accidents were probably due to a single egregious technical blunder - the use of organic materials (leather gaskets) in contact with LOX. If we omit these four accidents, the crash rate is still 1-in-114.
Even the rocketplanes that survived catastrophic accidents had surprisingly short lives due to the intense stresses on their components. 46-063(a), 48-1385, and 46-063(b) all were prematurely grounded due to accumulated fatigue damage in propellant or pressurant tanks. The X-15 program ended with a whimper after a month of vain attempts to get the sole surviving aircraft to function. The average rocketplane made only 29 flights in its lifetime before it was wrecked or retired due to wear.
There were also frequent aborts in which the rocketplane was not dropped from its carrier aircraft due to technical defects, and a lesser number where planned flights were cancelled on the ground. In the X-15 program over 350 planned takeoffs resulted in only 200 successful drops - and 11 of these drops led to crashes or emergency landings at remote dry lakes.
The reason for this dismal safety record is that these aircraft combine four incompatible technologies. During ascent, the rocketplane is a ballistic missile; at apogee it is a spacecraft; on descent it is a reentry vehicle; on approach and landing it is a glider. The result is a nightmare of complexity in which parts essential for one phase of flight are useless or even dangerous in the other phases.
Are these safety statistics relevant to the 21st-century commercial operators? Probably not. These Cold War X-plane projects were lavishly funded and enjoyed top national priority. They were designed and operated by some of the best technical minds in the aerospace industry and consumed thousands of hours of wind-tunnel time before any metal was cut.
Most of today's potential rocketplane builders are tiny startup firms with weak technical staffs and dubious design concepts. One firm is planning to use the DC-X design which crashed, exploded, or caught fire on 25% of its flights; another is converting a subsonic business jet; a third has hired the most incompetent aircraft design team of the Cold War (Myashischev).
Burt Rutan's Scaled Composites is the only established aerospace company working in this field. But SpaceShip1 suffered serious problems on all of its flights above 100km and was retired after only 3 such flights. Clearly Rutan didn't think that it was safe enough to fly passengers instead of sandbags - or even safe enough to make a few more proving flights to explore the economics of SpaceShip2.
Those firms that are planning to use hybrid engines tout them as safer than the old X-plane engines that used liquids for both fuel and oxydizer. But the X-plane pilot could jettison both propellants in an abort situation to get down to normal landing weight. Hybrids have a solid fuel neccessarily carried in the tail and a liquid oxydizer neccessarily carried in a pressure tank further forward. The hybrid rocketplane pilot faces the choice of dumping only the oxydizer and coping with a massive trim change or retaining it for a proper CG and landing extremely fast and heavy. Such a landing after a partial fuel jettison broke the X-15-2 in half.
This is exactly the sort of problem that could be fixed by a simple FAA regulation. In this case they need only require that the solid part of the engine be ejectable in emergencies. Since the engine already needs to be removed and recast after every flight, this would be easy to accomplish without much extra hardware.
But the rocketplane promoters lobbied the US Congress into passing a law that greatly restricts regulation of their industry until 2012. Tourist rocketplanes will operate in the kind of regulatory vacuum that existed in the barnstorming era of aviation. The promoters seem to have forgotten about the huge number of people killed in that era, and the numerous airlines that failed financially or were taken over by governments.
Any ordinary aircraft has completed thousands of test flights before the FAA certifies it to carry passengers. But airliners are much cheaper to operate than rocketplanes and developed by huge corporate consortia with vastly deeper pockets than most of the players in the space tourism industry.
It is unlikely that any tourist rocket operator will be able to afford a comprehensive test program. Different firms have suggested they will fly from 25 to 200 test flights before paying passengers are accepted. These numbers are both too small to reveal all the potential failure modes and so large relative to the average rocketplane lifetime that a crash in the test program is likely.
So there is no getting around the fact that the first generation of tourist rocketplanes are going to be far more dangerous than any other aircraft. The fatal crash rate will be at least 1-in-200 and probably more like 1-in-50. How does this affect the prospects for this industry?
Most skeptical commentators have emphasized the effect of unfavorable publicity on a business that has basically been created by publicity. The first few commercial rocketplane accidents will be front-page news around the world. Any video clips will be played over and over on our TV screens, just like the last moments of Hindenburg, Challenger, and Columbia.
I'm more concerned about the financial aspects of rocketplane crashes. It is not clear that the prospective operators have included the extra costs of accidents in their business plans.
First, the initial cost of the vehicles cannot be amortized over thousands of flights as it is with normal airliners. Given the safety statistics cited above, each revenue flight must recover at least 2% of the construction cost in addition to all the operating costs and profit margin. There will also be a significant number of aborted flights for which the passengers will not pay.
Second, there is the potential costs of lawsuits and damage claims resulting from rocketplane accidents. This problem is usually explained away by claiming that the passengers will have signed all sorts of releases before they board their fatal flight.
But anybody rich enough to pay $200,000 for 5 minutes in space will have rich relatives, rich business partners and greedy heirs who will not have signed releases. In many cases these associates will not share the passenger's mania for space and will have opposed the passenger's decision to fly. Many of them will be able to demonstrate financial or emotional losses from the passenger's death and will be able to afford good lawyers.
And that libertarian regulatory environment has two features that make rocketplane operators extremely vulnerable to damage suits:
1) There is no statutory limit on the size of damage judgements such as the airline industry has under the Warsaw Convention of 1929 and the Montreal Convention of 1999.
2) Defense lawyers will not be able to use compliance with government regulations as a defense. They will not be able to call FAA inspectors or NTSB investigators as witnesses to testify that the crashed rocketplane met all applicable safety rules.
Liability insurance? Forget it. No insurance company is likely to sell policies to rocketplane operators at acceptable rates. The very richest operators like Sir Richard Branson may choose to self-insure - but their ultra deep pockets will attract the very best tort lawyers.
Many Space Cadets excuse the dangers of space flight by emphasizing the dangers of the past. They are always talking about how few of Magellan's men got back, or how many of the pioneer aviators broke their necks - and citing these dreadful statistics as examples to be emulated in the 21st century.
The problem with this rationalization is: That was then, this is now. The public's tolerance for violent death is a lot lower in 2006 than it was in 1536 or even 1906. That's why we see hard hats, safety goggles, and steel-toed boots at every construction site. That's why seat belts are compulsory in cars and fighter jets have ejection seats.
Recall that the V-22 Osprey tilt-rotor VTOL transport aircraft was nearly cancelled in 2000 after two fatal crashes in operational testing. The public has come to expect that even radically new aircraft won't kill anyone. And this same public will be in the jury box at the first rocketplane liability trial.
How does the space tourism industry deal with these problems? Mostly with wishful thinking and blind hostility to the skeptics. Even Supreme Rocketplane Guru Burt Rutan has been in trouble since he pointed out some of these issues at a conference. A few operators have vague plans to operate from nations not ruled by lawyers, but most seem to be sticking with the US.
So the rational side of my brain has stopped the romantic side from buying any stock in rocketplane firms. The current situation reminds me of two other periods when excessive enthusiasm for rocket propulsion led to tragedy.
The first golden age of reckless rocketry was in Germany during the Roaring 20s. Primitive black-powder rockets roared on automobiles, gliders, railroad cars, and even sleds. Nothing useful was accomplished and one of the principal rocket promoters died. After Max Valier was killed by rocket shrapnel, the German Rocket Society found it almost impossible to raise money for serious rocketry research and the Nazis had a perfect excuse to shut down all private groups and absorb their more useful members into their military rocket program.
The second period of amateur enthusiasts occurred in the wake of Sputnik I when nerdy teenagers all over the world rushed to their basements and began working on model rockets. This era was brilliantly recalled in Homer Hickham's novel "Rocket Boys" and the movie "October Sky".
Hickham's amateur rocketeers managed not to kill anybody in their sparsely populated part of West Virginia, but other such groups suffered deaths and serious injuries. Many US states and European nations passed laws banning home-made rockets, and the hobby only survived because commercially manufactured solid rocket mini-motors became available.
I fear that the space tourism industry is headed for a third cycle of unnecessary deaths followed by a regulatory crackdown -- exactly the opposite of what the would-be space tycoons are trying to achieve.
Jeffrey F. Bell is a former space scientist and recovering pro-space activist.
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