"SpaceShipTwo could be single stage to SUBorbit"
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From: Greg D. Moore (Strider) on 13 May 2010 23:12 J. Clarke wrote: > > Scramjets work. Get used to it. Really? How many flight hours do they have? How many have been flown more than once? -- Greg Moore Ask me about lily, an RPI based CMC.
From: Greg D. Moore (Strider) on 13 May 2010 23:14 J. Clarke wrote: >> X-30 was way too much for NASA to do in one huge leap and would have >> required billions more dollars just to try to make it work. The >> state of the art in hypersonic propulsion still isn't where it would >> need to be to build X-30 today (note that X-30 was cancelled more >> than two decades ago). Hypersonic propulsion is one of those >> promising looking technologies that's been "only a few years away" >> for many decades. > > Uh, it's not there because Clinton pulled the plug on it. Really? Amazing. I didn't realize Clinton whas that powerful. You mean no one else was capable of doing research on Hypersonic propulsion? Hypersonic propulsion was " a few years away" before Clinton and is still a few years away. -- Greg Moore Ask me about lily, an RPI based CMC.
From: Jorge R. Frank on 14 May 2010 00:05 On 05/13/2010 05:08 PM, J. Clarke wrote: > On 5/13/2010 4:04 PM, Jeff Findley wrote: >> "Pat Flannery"<flanner(a)daktel.com> wrote in message >> news:6vGdnRW146eIxXHWnZ2dnUVZ_tOdnZ2d(a)posted.northdakotatelephone... >>> On 5/13/2010 9:10 AM, LSMFT wrote: >>>> What happened to the X-30? >>> >>> And since when did 50,000 feet become outer space? >>> I like the part about it using a "liquid chemical propulsion system", >>> without specifying what those chemicals are exactly. >>> You could certainly make a ground takeoff rocket plane that could >>> climb to >>> 50,000 feet, but since numerous types of jet aircraft are capable of >>> flying to 50,000 feet also, what would be the point of doing this? >> >> The promises made by X-30 were absolutely silly, in retrospect. A vehicle >> which can cruise at hypersonic speeds is going to be very different >> than a >> vehicle which can accelerate to orbital speeds, yet somehow X-30 was >> being >> sold as able to do both (makes me think of the SNL skit for Shimmer, a >> floor >> polish and a dessert topping). > > So let's see, a vehicle that can cruise at Mach 20 is going to be > different from one that can accelerate to Mach 25 how, exactly? If you haven't figured it out on your own, it is not going to be worth anyone's time to explain it to you. But the quick-and-dirty is that cruising at Mach 20 with an airbreather is going to require remaining at an altitude where there is enough O2 to keep the engine going, which radically increases the total heat load. Whereas a Mach 25 accelerator will only spend a brief amount of time in the Mach region where a scramjet will do any good, so it will need two additional propulsion systems: one to accelerate to the minimum speed to light the scramjet, another (necessarily rocket-based) to take over for the final boost to orbit once the scramjet is useless. The additional weight of having three propulsion systems more than outweighs the advantages of the airbreather. IMO scramjets are daft for either mission. It's at times like this that I really miss Henry Spencer. He could explain this far more eloquently than I could.
From: Pat Flannery on 14 May 2010 06:39 On 5/13/2010 7:14 PM, Greg D. Moore (Strider) wrote: >> Uh, it's not there because Clinton pulled the plug on it. > > Really? Amazing. I didn't realize Clinton whas that powerful. You mean no > one else was capable of doing research on Hypersonic propulsion? > > Hypersonic propulsion was " a few years away" before Clinton and is still a > few years away. Some suggest that the entire X-30/NASP program was a sham designed to make the already nearly bankrupt USSR spend even more money on its military to cause it to collapse...as it soon did. We knew the concept wouldn't work, but the Soviets would think we had made some major breakthrough, and try to build things to counter it - as they would assume it was a hypersonic bomber. The fact that there were classified programs related to developing technology for it (SCIENCE REALM, SCIENCE DAWN, HAVE REGION, COPPER CANYON) would further reinforce that idea. Pat
From: Pat Flannery on 14 May 2010 07:15
On 5/13/2010 8:05 PM, Jorge R. Frank wrote: > On 05/13/2010 05:08 PM, J. Clarke wrote: >> On 5/13/2010 4:04 PM, Jeff Findley wrote: >>> "Pat Flannery"<flanner(a)daktel.com> wrote in message >>> news:6vGdnRW146eIxXHWnZ2dnUVZ_tOdnZ2d(a)posted.northdakotatelephone... >>>> On 5/13/2010 9:10 AM, LSMFT wrote: >>>>> What happened to the X-30? >>>> >>>> And since when did 50,000 feet become outer space? >>>> I like the part about it using a "liquid chemical propulsion system", >>>> without specifying what those chemicals are exactly. >>>> You could certainly make a ground takeoff rocket plane that could >>>> climb to >>>> 50,000 feet, but since numerous types of jet aircraft are capable of >>>> flying to 50,000 feet also, what would be the point of doing this? >>> >>> The promises made by X-30 were absolutely silly, in retrospect. A >>> vehicle >>> which can cruise at hypersonic speeds is going to be very different >>> than a >>> vehicle which can accelerate to orbital speeds, yet somehow X-30 was >>> being >>> sold as able to do both (makes me think of the SNL skit for Shimmer, a >>> floor >>> polish and a dessert topping). >> >> So let's see, a vehicle that can cruise at Mach 20 is going to be >> different from one that can accelerate to Mach 25 how, exactly? > > If you haven't figured it out on your own, it is not going to be worth > anyone's time to explain it to you. You are in fine pissed-off form today, aren't you? Excuse anyone else for even existing, much less asking a question. > It's at times like this that > I really miss Henry Spencer. He could explain this far more eloquently > than I could. Henry Spencer was the guy who thought a SSTO vehicle with over 100 RL10 engines on it was a rational idea. Do you have any idea what the propellant plumbing weight on something like that would be? :-D Pat |