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> NNTP-Posting-Host: 209.88.68.33 Message-ID: <9186edb5.0311121913.39739203@posting.google.com> Henry Spencer: >Vincent Cate vince@offshore.ai wrote: >>One trick (from Henry Cate) is that you could have your apogee >>kick motor in front of the payload aimed the opposite way so >>that when your spin stabilized vehicle got to the other side of >>the Earth it would be aimed the right way. I did this in one >>sample below. If spin stabilizing something can last for 40 >>minutes this could work. > > Spin stabilization can last much more than 40 minutes, if the thing >is balanced properly and is spinning around the right axis. Trying >to spin a long skinny stack of hardware around its long axis, in >particular, is a disaster. This may be a problem with two solids >underneath the payload and an apogee motor on top. Since we are start high up (like 90 to 100 km maybe), we don't need to be long and skinny. A short fat stack would not hit too much air. How short and fat can small (like 150 kg) solids get? This method can have lots of margin for directional error by having extra delta-V in the stages. The alternative of spin stabilized and then electric thruster will not have as much margin for directional error. So this method might be the easiest way to send something into orbit from an X-prize vehicle? -- Vince