Re: Polythene tanks?

From: Rüdiger Klaehn (klaehn_at_gamemakers.de)
Date: 02/04/05 

To: sci-space-tech@moderators.isc.org
Date: Fri, 04 Feb 2005 11:24:25 +0100

Peter Fairbrother schrieb:
> Henry Spencer wrote:
>
> Why?

You still have not answered why wings and wheels are the only safe
technology for landing. Even if we accept the very unrealistic
assumption that a space transport must be safe as commercial airliners,
there is no technical reason that you can not get very high safety with
rocket powered landing.

The key to high safety is redundancy. A capsule with many small rocket
engines for landing can be very reliable. For maximum reliability you
would run all rocket engines on idle during the landing and then
throttle up some of them to decelerate and land. If you have 12 rocket
engines and need only 4 of them to land, the chances of a failure are
extremely low. You just have to make sure that the engines do not have a
catastrophic failure mode.

You might argue that relying on complex active systems for a safe
landing is unacceptable, but then a starting airplane would be
unacceptable too. When a starting airplane were to lose all engines
during takeoff, it would certainly crash. But the chances of this are
extremely small with multi-engine airplanes. And (especially
pressure-fed) rocket engines are much less complex and less dependent on
the environment than aircraft turbofan engines. At least you don't have
to worry about birdstrike :-)

Relevant Pages

  • Re: Space Access Update #112 9/19/05
    ... The ignition detection system is set in such a way that while it might ... If you actually want to learn a bit about how to make reliable rocket ... > They've done over 2000 firings total of all their engines without a hard ... > it as safe as one powered by a Lycoming piston engine. ...
    (sci.space.policy)
  • Re: Lunar airbags
    ... > landing manuever. ... If you already have working rocket engines, ... With airbags, the only throttle you need are some pyros to ... The complexity of maintaining a critical two-way comm link for landing ...
    (sci.space.tech)
  • Re: Mojave airport is not a spaceport
    ... JC> A BDB can do a powered landing with little more than software changes ... JC> a boat out to fish your rocket out of the ocean is going to suck. ... AN> ...The best design for the second stage is my engine cluster... ... If the coolant pressure is lower than its critical pressure, ...
    (sci.space.policy)
  • Re: Skylon SSTO
    ... use air breathing engines up to high subsonic speeds and moderately ... our earlier, airbreathing, subsonic carrier concepts. ... practical landing and ferry operations. ...
    (sci.space.policy)
  • Re: Mojave airport is not a spaceport
    ... > JC> sounds like an inefficient staging strategy, since the upper stage ... > A winged rocket does not need as strong propellant tank as ... > it may crash during landing. ... design that will works over a guess. ...
    (sci.space.policy)