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Time to Think ?Horizontal? for Future Space Launches
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Time to Think ?Horizontal? for Future Space Launches
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Time to Think ‘Horizontal’ for Future Space Launches
On 9/23/2010 1:15 AM, Sylvia Else wrote:
Thing is, you need a structure strong enough to tolerate the aerodynamic forces of whatever speed the launch rail gives at its end point, but then you need to carry that structure to up to where the second stage is released, or orbit if you're going for SSTO. ....and God help you if there's a rabbit or rock sitting on that track considering how fast you are going to be going down it on the launch sled. You note whenever they show drawings of these things, they seem to throw in a tunnel it's going to pass through before it reaches the end of the track: http://www.g2mil.com/argus2.jpg I don't know if that's just for effect, or if it's supposed to serve some purpose - I had the thought that the tunnel might have thin sheets of plastic on either end and be pumped full of pure oxygen to help light the scramjets as the vehicle pierces the plastic walls on launch. Pat |
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Time to Think ?Horizontal? for Future Space Launches
On 9/23/2010 4:51 AM, Jeff Findley wrote:
True. Any way it was tried, the "tail sitter" mode of landing was just too dangerous to proceed to an operational vehicle. You could do it nowadays relying on GPS and automated landing control; but trying to land something as big and light as a ET in a side wind would be pure folly. The Coleoptere had one advantage over the Pogo and Lockheed "Salmon"; in it the pilot could pivot his seat ninety degrees so he ended up sitting upright and looking out a window in the bottom of the aircraft's nose during landing. One of the big problems in the Pogo was that the pilot couldn't tell how fast he was ascending or descending in vertical flight other than looking at the altimeter or a "wind vane" mounted on the wingtip that would at least tell him if he was rising or descending. The big problem was that if it started descending too fast the aircraft was going to tip over sideways under the influence of the wings going backwards into the airstream, and end up doing a power dive straight into the ground. We can thank the Germans for coming up with this goofy idea: http://www.luft46.com/heinkel/hewespe.html http://www.luft46.com/heinkel/helerche.html http://www.luft46.com/fw/fwtrieb.html Today, vertical landing with the aircraft in the horizontal position is preferred (e.g. Harrier, V-22 Osprey, and pretty much every operational helicopter). This eliminates the 90 degree rotation required by a tail sitter which eliminates the requirement for the pilot to guide the craft down with his back to the ground and his eyes pointed up at the sky. The VTOL aspect of the Coleoptere was only the start of the fun; it was going to come flying out of a silo in the ground, and once in horizontal flight the space between the circular wing and fuselage was going to turn into a ramjet...like I said, the thing was straight out of "Thunderbirds". I've got Mook killfiled, so I'm only reading what you quote from him. Is there some reason that he wants it to land vertically rather than just glide-land with the inflatable wings? If you are going to land it vertically, all you need to do is stick some parachutes in the nose and have the weight of the rear plug-nozzle engine make it fall tail-first towards the landing site. There's no need for the goofy wings then. In that case what you end up with is very similar to the SASSTO Saturn IVB stage, with the plug nozzle serving as the heatshield: http://www.up-ship.com/drawndoc/sdoc53ani.jpg Pat |
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Time to Think ?Horizontal? for Future Space Launches
On 9/23/2010 5:00 AM, Jeff Findley wrote:
Plus, if the pilot got into real trouble, ejecting from a tail sitter was more challenging than ejecting from a Harrier, again due to the orientation of the pilot's seat during the tail sitting landing. Even with its early teething problems, the Harriers were safer for the pilots than tail sitters would have been. Thankfully, the tail sitters were abandoned well before the stage where "teething problems" would likely have killed several pilots. You know, I'd never thought about that in relation to the Coleoptere, but the pilot did eject from it when it was in the vertical flight mode; they must have had a system that swung the seat back to horizontal flight position before firing. Pat |
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Time to Think ‘Horizontal’ for Future Space Launches
The title of this post suggests... something else instead of a change
in mission profiles. However, I don't think one can really recommend seducing and blackmailing influential politicians as an effective way to obtain more space funding. Although, no doubt, it could make for a plot for an exciting movie. John Savard |
#28
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Time to Think ?Horizontal? for Future Space Launches
On Sep 23, 9:00*am, Jeff Findley wrote:
In article fd456a18-e444-4b5c-b8dc-cafde4fe0203 @u4g2000prn.googlegroups.com, says... On Sep 22, 8:04*pm, Pat Flannery wrote: On 9/22/2010 12:18 PM, Jeff Findley wrote: That vertical landing on a mobile landing platform by those tail sitters was abandoned in the 1950's for a reason. *The transition from horizontal to vertical flight was tricky, and the actual "landing" onto those platforms was even trickier. The Convair Pogo could be landed on any flat surface, but its one vertical landing left its test pilot so spooked by the process that he felt he was lucky to be alive, and they never tried it again. When the French tried in in their straight-out-of-"Thunderbirds" SNECMA Coléoptère, the result was the aircraft going out of control and the pilot ejecting. Pat The tail sitting system is well defined No it's not. *It was abandoned as an R&D program before the serious problems were worked out of the system. and modern avionics and computing obviates any concern over the legends you repeat here without any analysis. * This remains unproven in flight hardware. VTOL aircraft like the Harrier had similar teething difficulties which were addressed by improved avionics and computer control. Not true. *The tail sitters were much more difficult to fly than the early Harrier, Not true http://www.youtube.com/watch?v=6-wc6-yspYw http://www.youtube.com/watch?v=9t731Y2tSqQ http://www.youtube.com/watch?v=Nh9dhBJY010 http://www.youtube.com/watch?v=XJ1D_eiHafY http://www.youtube.com/watch?v=Ja9kFc1BdT8 Get a POGO model and try it for yourself! lol. Without wings - the DCX took off and landed vertically http://www.youtube.com/watch?v=wv9n9Casp1o So did the JAXA RVT http://www.youtube.com/watch?v=-irOfrXy4N4 What I propose, is rather simple. (1) parallel staging of an existing airframe; (2) equipped with thermal protection for ballistic re-entry (3) equipped with lift systems to act as glider (4) recovery of the glider down-range (5) release of the glider near the launch center (6) transition to vertical flight (7) vertical landing The procedure and technology is simple and provides a system of minimal weight, complexity and innovation to deliver a maximum of performance. due partly to the fact that the pilot was trying to land with his back to the ground and eyes pointed up at the sky. This isn't an issue in an unpiloted craft. *At least in a Harrier, the hand-eye coordination was more natural because the pilot could easily see and feel what he was doing. This is not an issue for an unpiloted vehicle. The Hawker P-1127 had significant difficulties and design problems from the early stages in the 1950s. These difficulties led to Convair proposing a simpler easier to build alternative with far fewer problems. Plus, if the pilot got into real trouble, ejecting from a tail sitter was more challenging than ejecting from a Harrier, again due to the orientation of the pilot's seat during the tail sitting landing. * This is not an issue for an unpiloted vehicle. Even with its early teething problems, the Harriers were safer for the pilots than tail sitters would have been. In the 1950s the tail sitters were obviously less complex and dangerous than redirecting jet exhaust http://www.youtube.com/watch?v=f8W2SI4c93s The P-1127 crashed in 1963 at the Paris Air Show and the P-1154 was canceled when it became clear that its performance would never be what it was promised to be. *Thankfully, the tail sitters were abandoned well before the stage where "teething problems" would likely have killed several pilots. No tail sitters have crashed. Many Harriers have. http://www.youtube.com/watch?v=1USNC3Ozw18 http://www.youtube.com/watch?v=HB5CXlEALJ0 http://www.youtube.com/watch?v=VGE7AYe7DtY Jeff -- The only decision you'll have to make is Who goes in after the snake in the morning? |
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Time to Think ?Horizontal? for Future Space Launches
On Sep 23, 4:07*pm, Pat Flannery wrote:
On 9/23/2010 5:00 AM, Jeff Findley wrote: Plus, if the pilot got into real trouble, ejecting from a tail sitter was more challenging than ejecting from a Harrier, again due to the orientation of the pilot's seat during the tail sitting landing. *Even with its early teething problems, the Harriers were safer for the pilots than tail sitters would have been. *Thankfully, the tail sitters were abandoned well before the stage where "teething problems" would likely have killed several pilots. You know, I'd never thought about that in relation to the Coleoptere, but the pilot did eject from it when it was in the vertical flight mode; they must have had a system that swung the seat back to horizontal flight position before firing. Pat Yeah, many of Jeff's objections ignore the possibility of designing a crew seat and avionics to avoid the problems he outlines - but the use of this technology in an unpiloted vehicle makes the points moot anyway. |
#30
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Time to Think ?Horizontal? for Future Space Launches
On Sep 23, 8:51*am, Jeff Findley wrote:
In article tatelephone, says... On 9/22/2010 12:18 PM, Jeff Findley wrote: That vertical landing on a mobile landing platform by those tail sitters was abandoned in the 1950's for a reason. *The transition from horizontal to vertical flight was tricky, and the actual "landing" onto those platforms was even trickier. The Convair Pogo could be landed on any flat surface, but its one vertical landing left its test pilot so spooked by the process that he felt he was lucky to be alive, and they never tried it again. When the French tried in in their straight-out-of-"Thunderbirds" SNECMA Coléoptère, the result was the aircraft going out of control and the pilot ejecting. True. *Any way it was tried, the "tail sitter" mode of landing was just too dangerous to proceed to an operational vehicle. Today, vertical landing with the aircraft in the horizontal position is preferred (e.g. Harrier, V-22 Osprey, and pretty much every operational helicopter). *This eliminates the 90 degree rotation required by a tail sitter which eliminates the requirement for the pilot to guide the craft down with his back to the ground and his eyes pointed up at the sky. Jeff -- The only decision you'll have to make is Who goes in after the snake in the morning? Still, the tail sitter is rather simple to carry out as a method to recover through automatic means an ET sized booster with minimal added mass and minimal complexity. If you'd fly a model aircraft to a vertical landing transitioning from horizontal flight, you'd see how simple it is. Restarting an aerospike engine to carry out a landing similar to that of the DC-X provides a simple light weight approach to booster recovery. |
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