dietz@SLB-DOLL.CSNET (Paul Dietz) (02/26/86)
It looks like BAE will be going public with details on the HOTOL soon. According to reports in New Scientist and AWST, the vehicle would begin 19 test flights in 1996 and begin commercial operations sometime between 1998 and the early 2000's. Amortizing the airframe over 120 flights and the engines over 60 flights would give the HOTOL an operating cost of $5.25 million/launch. Payload size was not stated, but judging from the illustration the payload bay would be a cylinder approximately 30 feet long and 18 feet in diameter. The vehicle would be automated but could carry a manned module in its cargo bay. The internal hydrogen tank must be pressurized for structural integrity, limiting the time the vehicle could spend in orbit to 50 hours in a continuously illuminated polar orbit (the worst case). The vehicle would take off horizontally on a wheeled trolley and land on skids. (Landing weight would be much lower than takeoff weight, since most of the fuel would be gone.) The vehicle would breathe air until it reaches 26 kilometers, at this point it would have burned 18% of its hydrogen and switched over to an onboard oxygen supply. It would reach an orbit of 300 kilometers. Because the vehicle would be less massive than the shuttle less heat would be dissipated on reentry, so tiles would not be used. Instead, carbon-carbon would be used on high temperature areas and titanium and nickel sandwich elsewhere. The designers project a turnaround time of two days. The vehicle would operate autonomously in orbit (this sounds dubious) and land using conventional MLS guidance. Development cost would be somewhere around $6 billion.
silber@uiucdcsp.CS.UIUC.EDU (02/28/86)
I haven't really been keeping up with the development of HOTOL, so this may be an inane question, but was there any discussion/possibility of it being a human-piloted craft? It seems to me that if they allow humans as 'cargo', it should be possible to include a flight-deck module, at least for manned flights. On the otherhand, this may not be really necessary. I saw on PBS recently that the new generation of jet-liners are capable of flying themselves under normal conditions including take-off and landing, and that the crews spend most of their time checking the instruments and occasionally dealing with unforseen circumstances.