Randall Clague wrote:
On Tue, 17 Dec 2002 04:13:12 +0000, Ian Woollard
<[EMAIL PROTECTED]> wrote:
When you have a vehicle capable of orbital velocity, $10k won't be a
problem.
Probably, possibly, maybe. I'm currently looking at how small a vehicle
can be made, with a payload and still make orbit and hopefully come
back. $10k is actually significant, and I may lose a few... The guidance
looks to be the most expensive subsystem at the moment, but that
probably just means I haven't understood my problems yet.
Let me make sure I understand this: you're looking to launch a small
vehicle into orbit for some small multiple of $10,000?
But hey look buster, don't put words in my mouth; I only said I was 'looking
at' it, I never said 'looking to', whether I do 'looking to' depends how
the 'looking at' phase goes ;-)
First thing, orbital vehicles don't scale down well. Many components
you need to get to orbit come in a minimum size & mass, and as the
vehicle gets smaller, their relative contribution to dry mass
increases. Before too long, you can't make orbit; you just don't have
the mass fraction.
Yup, minimum gauge, I hate it. Atmospheric drag is a big pain too. I did
consider a doomsday bomb to remove the atmosphere but it would add to my
development schedule rather, but it looks like it isn't stopping me making
orbit, so I leave it right now.
Second thing, you'll need liquid fuel rockets to get you there, and
liquid fuel rocketry is basically fancy plumbing with a bunch of
constraints put on it (can't be heavy, can't use much power, etc). You
don't have time to develop Swagelok's expertise in making plumbing
connectors, and you can't live without it.
Yeah, lots a lots of valves and connectors at the very least. I've got a
trick for a lot of the plumbing, but if I can get that trick to work, I can
probably get a doctorate thrown in for free.
Ditto valves, solenoids,
transducers, attitude sensors of whatever stripe, GPS, A/D boards,
radios... It's a long list when you're going to orbit.
Yup, that was about the list I had, although I may leave out GPS.
If you try to
make those things yourself, you'll bog down in details, and they'll be
too heavy anyway. If you want reliable light components, you have to
buy them. That's going to take you past any small multiple of $10,000
before you even get an orbiter off the test stand.
I don't want to build anything, unless there's nothing suitable out there.
Unless there's a market for it in its own right I guess.
To offer another perspective: we've spent over $10,000 on KISS, and it
doesn't _have_ a guidance system. When you start building flight
vehicles, things get expensive. We expect to spend another $10,000 to
get POGO flying, and no one will be surprised if we go over budget
again.
For what you're doing that doesn't sound expensive to me. It's good going
to keep it down to that. If my project came to 4x that I would be the cleverest
person ever (I don't think I am); and if it were 100x or more I would not
be in any way surprised.
I don't wish to rain on your parade, but the first step in any project
is set user expectations. I believe yours are unrealistic.
Actually I think you're unrealistically expecting me to have high expectations.
;-)
I would be thrilled to be proven wrong. :-)
Me too.
-R
--
"Is this a bagel?"
"It's the Guardian of Forever!"
"Well yes. But is it a bagel?"
--Overheard at Loscon 29
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