tag:blogger.com,1999:blog-8809438035746342262.post5168005492308211657..comments2023-10-27T19:34:05.946-07:00Comments on NEW PAPYRUS: Funding NASA's FutureMarcel F. Williamshttp://www.blogger.com/profile/16245086958213100840noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-8809438035746342262.post-83070820739392243142009-09-28T11:31:11.422-07:002009-09-28T11:31:11.422-07:00NASA has contemplated developing ET derived rocket...NASA has contemplated developing ET derived rockets without SRBs in the past. But I assume that such concepts required more structural reinforcement of the fuel tanks. <br /><br />I agree that a SD-SSTO vehicle would not be as fuel efficient as a multistage rocket. But fuel cost are tiny relative to the cost of the vehicle itself. The advantages would be in the safety, simplicity and lower cost of a single stage rocket booster relative to a multistage vehicle which might be very attractive to the emerging commercial launch companies. <br /><br />I should also note that it may turn out that any LAS (launch abort system) may not be fast enough to escape from the fragments of a solid rocket booster explosion. Of course there hasn't been a serious solid rocket booster malfunction on the shuttle in more than 20 years. But the LAS in a Sidemount or DIRECT configuration may ultimately only give us the illusion of enhanced safety beyond the inherent safety SRBs already have. <br /><br />Gary Hudson argued that such a shuttle derived SSTO vehicle could possible launch up to 36 tons into low earth orbit. However, Hudson wrote this article before the development of the Super Lightweight Tank which is about 3 tons lighter. That would mean 39 tons of lifting capability (35 metric tonnes). So if 10 tonnes of this mass was utilized to enhance the support structure of the fuel tank, then at least 25 tonnes could be lifted into orbit-- enough to launch the Orion CEV. This would also be the first demonstration of a SSTO vehicle which could be the first major step towards the dream of a totally reusable SSTO vehicle. <br /><br /><br />Gary Hudson has discussed this interesting concept in the past:<br /><br />http://www.spacefuture.com/archive/a_single_stage_to_orbit_thought_experiment.shtmlMarcel F. Williamshttps://www.blogger.com/profile/16245086958213100840noreply@blogger.comtag:blogger.com,1999:blog-8809438035746342262.post-23575465980572063672009-09-28T06:51:15.792-07:002009-09-28T06:51:15.792-07:00The problem with SDLV SSTO without SRBs is that th...The problem with SDLV SSTO without SRBs is that the SRBs are the structural supports for the rocket on the launch pad. The ET lacks the strength to hold itself upright.<br /><br />LOX / LH2 engines (SSME) are not very efficient as first stage propulsion. That's why they stuck SRB's on the Shuttle. If you want a totally liquid fuel first stage, you would want a kerolox engine.<br /><br />Dr Dave<br />nssphoenixAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8809438035746342262.post-9343839741309453312009-09-27T01:10:04.053-07:002009-09-27T01:10:04.053-07:00It would have been nice if the Augustine Commissio...It would have been nice if the Augustine Commission had done a proper and serious evaluation of both the SD-HLV and DIRECT concepts.<br /><br />If the Ares1/Ares V configuration is rejected, I think Obama and Bolden will choose the SD-HLV (NASA's back up plan) over NASA's secret plan (DIRECT).<br /><br />I think the DIRECT advocates made a mistake by not advocating a Jupiter SSTO (without the SRBs) as part of the DIRECT rocket family. A Jupiter SSTO booster with 6 SSME could be the simplest and safest manned and unmanned rocket booster ever developed, IMO.Marcel F. Williamshttps://www.blogger.com/profile/16245086958213100840noreply@blogger.comtag:blogger.com,1999:blog-8809438035746342262.post-76144140982039109842009-09-26T21:00:44.267-07:002009-09-26T21:00:44.267-07:00Marcel,
Having followed the Direct Team effort fo...Marcel,<br /><br />Having followed the Direct Team effort for quite a while (I had the pleasure of talking with Ross Tierney and other Direct members in Cocao Beach during the 30 July 2009 public meeting), I have worked over the budgets and time tables (now verified by the Aerospace Corp's engineers) and the Augustine Commission has sliced and diced the Direct architecture to NASA's disadvantage.<br /><br />As you point out, the existing budget can accomplish most of the VSE, if one takes Direct seriously.<br /><br />Dr Dave<br />nssphoenixDavehttps://www.blogger.com/profile/13748895633134916275noreply@blogger.com