"SpaceShipTwo could be single stage to SUBorbit"
in [Physics]
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From: Jeff Findley on 13 May 2010 15:53 "J. Clarke" <jclarke.usenet(a)cox.net> wrote in message news:hshi7c030ls(a)news4.newsguy.com... > On 5/13/2010 1:10 PM, LSMFT wrote: >> Robert Clark wrote: >> What happened to the X-30? > > Clinton. 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. Jeff -- "Take heart amid the deepening gloom that your dog is finally getting enough cheese" - Deteriorata - National Lampoon
From: Jeff Findley on 13 May 2010 16:04 "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). The fact of the matter is that LOX and liquid fueled rocket engines are really good at accelerating vehicles to orbital velocity. Air breathers, not so much. The machinery required to compress enough air for use in an engine optimized for rocket like acceleration would be large and heavy. So much so that just bringing your own LOX in a tank turns out to be a net win. Jeff -- "Take heart amid the deepening gloom that your dog is finally getting enough cheese" - Deteriorata - National Lampoon
From: J. Clarke on 13 May 2010 17:59 On 5/13/2010 6:50 PM, Pat Flannery wrote: > On 5/13/2010 9:10 AM, LSMFT wrote: > >>> "... the UK firm came to the conclusion that the volume within which >>> SS2 carries its solid rocket motor and nitrous oxide supply could >>> equally hold a liquid chemical propulsion system capable of providing >>> enough thrust for long enough for a horizontal take-off and ascent to >>> 50,000ft and above without the need for WK2." >>> http://www.flightglobal.com/blogs/hyperbola/2010/04/spaceshiptwo-could-be-single-s.html >>> >>> >>> >>> If you also filled up the passenger compartment with fuel leaving only >>> a pilot's cabin could it even become orbital? >>> >>> >>> Bob Clark >>> >> >> 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? Geez, a Lear 45 has a rated service ceiling of 51,000. You can _rent_ those.
From: J. Clarke on 13 May 2010 18:09 On 5/13/2010 3:53 PM, Jeff Findley wrote: > "J. Clarke"<jclarke.usenet(a)cox.net> wrote in message > news:hshi7c030ls(a)news4.newsguy.com... >> On 5/13/2010 1:10 PM, LSMFT wrote: >>> Robert Clark wrote: >>> What happened to the X-30? >> >> Clinton. > > 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.
From: J. Clarke on 13 May 2010 18:08
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? > The fact of the matter is that LOX and liquid fueled rocket engines are > really good at accelerating vehicles to orbital velocity. No, actually they aren't. They can do it, but "really good"? No. > Air breathers, > not so much. The machinery required to compress enough air for use in an > engine optimized for rocket like acceleration would be large and heavy. So > much so that just bringing your own LOX in a tank turns out to be a net win. X-30 was intended for Mach 20 cruise. At Mach 20 orbit isn't that far away. You don't need "rocket like acceleration" if you are cruising at speeds that high. And you don't need any "large and heavy machinery" to "compress enough air". Scramjets work. Get used to it. |