Sounds about right, I usually run my Sims with 500-600psi Cp, pressure fed engines, it tops out at ~ 340 seconds Isp . A 200:1 expansion ratio is pretty close to "infinite" ! If you can AVERAGE 300 seconds Isp , you need a mass ratio of ~24 . Not too difficult with composites.
Kevin Bollinger ----- Original Message ----- From: "David Weinshenker" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Friday, February 28, 2003 3:15 PM Subject: Re: [ERPS] blowdown SSTO > John Carmack wrote: > > > > At 01:49 PM 2/28/2003 -0800, you wrote: > > > Yup , another thing to think about is if you have a lot of nozzles in your > > >100 ratio plug , after 50,000 ft you shut off 1/2 of them , Instant 200 > > >ratio ! ( Isp 300 to 340 ) > > > > I don't think you get to 340 with even an infinite expansion in vacuum. > > Well, using isp.exe, the available specific impulse with > 100%HTP / RP1 (o/f ratio 7.0:1 appears to be close to optimum) > is as follows, for various chamber/exit combinations: > > 400/14.7 252 > 400/10.0 263 > 400/4.0 286 > 400/0.5 323 > > -dave w > _______________________________________________ > ERPS-list mailing list > [EMAIL PROTECTED] > http://lists.erps.org/mailman/listinfo/erps-list > _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
