"SpaceShipTwo could be single stage to SUBorbit"
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From: Robert Clark on 12 May 2010 02:57 On May 12, 4:41 am, Pat Flannery <flan...(a)daktel.com> wrote: > On 5/11/2010 4:57 AM, Jeff Findley wrote: > > > > > SpaceShipTwo is designed to fly high, not fast. You need both to make it > > into orbit. > > One gets the feeling with SpaceShipTwo that if they could have kept the > fight upwards subsonic, they would have gone for it. > I still like that loopy idea to shoot the X-15 into orbit atop some sort > of rocket booster, and have it reenter and crash into the Gulf of > Mexico, with the pilot ejecting on the way down:http://www.astronautix.com/craft/x15b.htm Thanks for that. Hadn't heard of that one before. Bob Clark
From: J. Clarke on 12 May 2010 06:24 On 5/12/2010 5:13 AM, Pat Flannery wrote: > On 5/11/2010 12:17 PM, Bob Myers wrote: >> On 5/11/2010 6:57 AM, Jeff Findley wrote: >>> >>> Actually, ignorant can be fixed. Stupid can't. In most cases, it's easy >>> enough to explain that orbital velocity is so fast that you really do >>> need a >>> huge amount of fuel and oxidizer to get into orbit. The X-15 example >>> helps >>> somewhat too. The X-15 could fly high or fast, but could not do both >>> on the >>> same mission. And even the X-15's high speed flights only achieved a >>> small >>> fraction of orbital velocity. >> >> It would seem we need an explanation akin to something Douglas Adams >> might have written - you know, comparable to "Space is big. You just >> won't >> believe how vastly, hugely, mind- bogglingly big it is. I mean, you may >> think >> it's a long way down the road to the chemist's, but that's just peanuts >> to space." >> >> However, I seem to recall that there was an idea, part of the old Air >> Force "Man In Space, Soonest" proposals, that did involve basically >> strapping on some additional boost to an X-15 and getting the thing into >> orbit, no? Not sure how they were planning on dealing with the "getting >> it back down" problem, either... >> > > They did one X-15 test flight with a spray-on ablative TPS coating that > was supposed to be easily cleaned off and replaced after the flight. > What the pilots thought of this, as the aircraft was now pink*, has not > been recorded. > After the flight they found the ablative coating had cooked itself right > on to the skin of the aircraft and was almost impossible to remove, so > the concept was dropped. > > * I keep picturing it covered in pencil eraser rubber: > http://www.dfrc.nasa.gov/gallery/photo/X-15/Small/ECN-1736.jpg That X-15 is in the Air Force Museum, with ablative coating still in place. The best laid plans . . . But that's why they flew such things on X-planes instead of just putting them in service without a flight test. Now if they'd done that for the Shuttle's thermal tiles . . . There was indeed a plan to strap a bunch of solid rockets to an X-15 and put it in orbit, with a heat shield. The Powers That Be decided that humans couldn't function under the stresses of space flight though and went with a fully automated "capsule". Would be a different world if the X-15B had been flown and worked.
From: Robert Clark on 12 May 2010 08:57 On May 10, 2:47 pm, Robert Clark <rgregorycl...(a)yahoo.com> wrote: > Interesting article here: > > SpaceShipTwo could be single stage to suborbit says ESA firm. > By Rob Coppinger > on April 29, 2010 4:24 PM > "Virgin Galactic's SpaceShipTwo could be a single stage to suborbit > vehicle using liquid chemical propulsion according to independent > research carried out by a company that has been contracted by the > European Space Agency for suborbital and hypersonic transport > studies." > "... 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-coul... > > If you also filled up the passenger compartment with fuel leaving only > a pilot's cabin could it even become orbital? > The usefulness of just using a single stage for the suborbital flights is to save on costs. Using two vehicles would cost twice as much to develop and twice as much in per flight costs. Note that XCOR is the leading suborbital tourism venture after Virgin Galactic. They plan to take off with a single craft from the ground rather than using a two-stage system. The reason they can do this is because they are using a higher performance liquid-fueled engine rather than VG's hybrids. Note, also they will charge $100,000 for the suborbital flight, half of what VG is charging. Bob Clark XCOR Lynx suborbital vehicle animation. http://www.youtube.com/watch?v=3a-l1tb1rPg
From: Robert Clark on 12 May 2010 09:14 On May 10, 2:47 pm, Robert Clark <rgregorycl...(a)yahoo.com> wrote: > Interesting article here: > > SpaceShipTwo could be single stage to suborbit says ESA firm. > By Rob Coppinger > on April 29, 2010 4:24 PM > "Virgin Galactic's SpaceShipTwo could be a single stage to suborbit > vehicle using liquid chemical propulsion according to independent > research carried out by a company that has been contracted by the > European Space Agency for suborbital and hypersonic transport > studies." > "... 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-coul... > > If you also filled up the passenger compartment with fuel leaving only > a pilot's cabin could it even become orbital? > Take a look at this diagram to get an idea of the volume you could fill with propellant for SS2: SpaceShipOne and SpaceShipTwo comparison. http://a52.g.akamaitech.net/f/52/827/1d/www.space.com/images/061221_spaceshiptwo_02.jpg It's a roughly cylindrical space about 40 feet long. Divide this by 3.28 to get the length in meters, 12.2 meters. You could estimate the diameter also from this diagram but this page gives the fuselage diameter as 2.28 meters: SpaceShipTwo - Wikipedia, the free encyclopedia. http://en.wikipedia.org/wiki/SpaceShipTwo Then the cylindrical volume is PI*(radius^2)*length = (3.1416)*(1.14^2)*12.2 = 49.8 m^3. Take the overall density of kero/ LOX propellant as 1030 kg/m^3. Then this amounts to a propellant mass of 51,300 kg. The fuselage does taper off towards the end so you should get a more accurate estimate by modeling this volume as a conical frustum: Conical Frustum. http://mathworld.wolfram.com/ConicalFrustum.html The question is what is the dry mass of SpaceShipTwo? Bob Clark
From: Jeff Findley on 12 May 2010 09:36
"Bob Myers" <nospamplease(a)address.invalid> wrote in message news:hscd7e$qev$1(a)usenet01.boi.hp.com... > However, I seem to recall that there was an idea, part of the old Air > Force "Man In Space, Soonest" proposals, that did involve basically > strapping on some additional boost to an X-15 and getting the thing into > orbit, no? Not sure how they were planning on dealing with the "getting > it back down" problem, either... True there were orbital X-15 proposals (e.g. X-15B), but it essentially amounted to straping a several rocket stages to the X-15. Drawings showed one to 3 Navaho's boosting an X-15, but the Navaho was such an early (i.e. inefficient) vehicle that it would have actually taken four of the G-38 version to put an X-15B into orbit. Based on hte empty/full mass values, it appears that the X-15 itself didn't provide much, if any, of the launch delta-V in this configuration. However, it would have had to have provided all of the deorbit burn. X-15B http://www.astronautix.com/craft/x15b.htm G-38 Navaho Booster http://www.astronautix.com/stages/g38oster.htm Jeff -- "Take heart amid the deepening gloom that your dog is finally getting enough cheese" - Deteriorata - National Lampoon |