From: vince@offshore.ai (Vincent Cate)
Newsgroups: sci.space.tech
Subject: Re: Unguided orbital insertion (cheap upper stages)
References: <9186edb5.0311101839.1d56c610@posting.google.com> <20031113104913.163a5845.smithm@SPAMBLOCK.com.au>
NNTP-Posting-Host: 209.88.68.230

Michael Smith <smithm@SPAMBLOCK.com.au> wrote in message news:<20031113104913.163a5845.smithm@SPAMBLOCK.com.au>...
> The only thing is that these days a guidance system doesn't have 
> to be that expensive. Computers and GPS chipsets are pretty cheap 
> now.

I can see that the electronics are easier (cheaper and less mass) 
these days.  But what mechanisms do you want to use to control
the aim/spin of a very small guided rocket?  Like do you want to
use fins while there is air and then paddles in the exhaust
when you are too high?  What sort of servos/actuators?  How
much will servos, wires, fins add to your mass?  Imagine you 
have a small 3 stage solid rocket (like 150 Kg, 30 Kg, 0.5 Kg, 
with a 4 Kg payload) and are starting at 90 to 100 km high.  What 
approaches would be reasonable to control a rocket like this?  

  -- Vince