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> <9186edb5.0311111736.6a47d1a9@posting.google.com> NNTP-Posting-Host: 209.88.68.230 Message-ID: <9186edb5.0311151754.68720ff8@posting.google.com> henry@spsystems.net (Henry Spencer) wrote in message news:... > Likewise the rocket motors. At 700RPM, the centrifugal force on the > Juno I second-stage motors was 180G! Ouch, this hurts. High G thrust may not take any extra motor strength if the internal pressure is high enough, which for a solid I think it is. But high RPM is just additional stress on your case, and so you will need additional strength and mass. So your mass ratios will be worse with high RPM spin stabilized motors. So you won't get as good a delta-V per stage. This is probably the big drawback to spin stabilization. I don't find anything in my books explaining how you would decide what RPM you needed to spin your rocket at. Do you know of anything on this? -- Vince