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Subject: 
Re: We're here to go
Newsgroups: 
lugnet.off-topic.debate
Date: 
Thu, 24 Jun 2004 01:29:25 GMT
Viewed: 
520 times
  
In lugnet.off-topic.debate, Larry Pieniazek wrote:
In lugnet.off-topic.geek, Larry Pieniazek wrote:

Now the X prize vehicle doesn't give you manrated orbit capability per se, it's
a suborbital vehicle, at least at the 3 person payload that you needed to win
the prize. But I'm assuming (big assumption) some stretchability with loss of
payload so that instead of 3 people to suborbital, you stretch the vehicle a bit
with what you learned and can get it to get one person in LEO instead.(1)

The above assumption is massively invalid, apparently. The velocity achieved by
SpaceShipOne is way way too low to be stretchable to LEO by leaving a few
passengers out.

It's not just the challenge of the order of magnitude increase in velocity
that's required, but significant issues in handling rentry and hypersonic flight
in general. I don't believe SS1 has a thermal protection system that's anywhere
close to what's needed. Furthermore designing a robust flight control system for
stable hypersonic flight isn't exactly trivial.

Despite huge expenditures of money and effort, portions of the FCS for the space
shuttle had to be rewritten after STS-1 revealed that some of the stability and
control derivatives were way under predicted by analytical modeling & wind
tunnel testing. At one point John Young had to briefly take manual control of
the orbiter during rentry because the FCS limits had been exceeded. I'm not sure
how much aerothermochemisty modeling has advanced since then, but Rutan will
have to ratchet up the engineering work considerably on a number of fronts to
make orbit and return safely. Not impossible, but no small task either.

Spencer



Message is in Reply To:
  Re: We're here to go
 
(...) The above assumption is massively invalid, apparently. The velocity achieved by SpaceShipOne is way way too low to be stretchable to LEO by leaving a few passengers out. I hadn't done my homework when I posted this, and I'm perfectly fine with (...) (20 years ago, 23-Jun-04, to lugnet.off-topic.debate)

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