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#11
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asemetrical thrust is one thing near the inboard section of the
wing... but at the outboard end of a high aspect ratio wing! All I can say is holly crap hold on for one hell of a ride when one engine shuts down early. Is my brain fading or did that huge german transport sailplane in WW2 have a jato fail and the with the yaw created by the one rocket cause it to take out the glider as well as 2 Junkers tow planes at the same time? Its a better world with centerline thrust! Mount two engines above the fusalage and angle them so the thrust is directed to the side of the tail feathers. The vector would be small and concentrated at the center of mass if one engine failed just add rudder. Rocket Science (for people that am smart like I is) Chris Ashburn wrote in message ... It might get a pit toasty for the wing runner in self-launch mode, but how about one at each wing tip? It seems most gliders these days already have some sort of interchangable tip, so make a new set with a jet built in. Fuel storage would be the main issue. If you give up the water ballast option though, there's plenty of room in the wing. Chris Slingsby wrote: I would think that mounting a couple of small jets at or just behind the wing/fuselage junction could also serve to remove some of the low speed turbulence in that area. Also, if the engine had a tight cowling around it then perhaps some water could be sprayed or drizzled onto the outside of the engine and the resulting steam would mix with the exhaust to provide some additional thrust. SWB Turbines in Neenah, WI (SWBTurbines.com)has a Mamba turbojet which puts out 11 Lbs. of thrust. It is only 3.5 inches in diameter and would fit nicely at the wing junction interface. SWB also has 45, 60 and a 100Lb thrust engine. |
#12
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Combining some of the thoughts here with the earlier message string about
electric self launching gliders, I wonder if it wouldn't be possible to use a ducted fan in the rear fuselage of a glider, exhausting thru the tail of the boom, and driven by an electric motor? Some openikngs on the side and top of the fuselage would provide inlet air. Some form of retracable tail cone would cover the end of the boom once the engine was shut down. The tail boom on most modern gliders would appear to be excellent ducts. Heat wouldn't be an issue. If the batteries were quick change and quick charge, they would only need to provide for one launch. John Scott |
#13
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#14
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Eric Greenwell wrote in message ...
[] I still think someone with a metal vee-tail glider ought to jump on this idea, and just mount the engine on a short pylon. Fiberglass forward fuselage, metal rear fuselage and metal V-tail. Hmm. Didn't Udo Rumph show us that this formula can still lead to a very high performance glider (ref. Dick Johnson's recent tests on Udo's modified HP-18 published in Soaring)? I think Eric may be onto something... -Doug |
#15
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"John Scott" wrote in message ... Combining some of the thoughts here with the earlier message string about electric self launching gliders, I wonder if it wouldn't be possible to use a ducted fan in the rear fuselage of a glider, exhausting thru the tail of the boom, and driven by an electric motor? Some openikngs on the side and top of the fuselage would provide inlet air. Some form of retracable tail cone would cover the end of the boom once the engine was shut down. The tail boom on most modern gliders would appear to be excellent ducts. Heat wouldn't be an issue. If the batteries were quick change and quick charge, they would only need to provide for one launch. This is an idea that has also been running through my mind, but a ducted fan does not have to be driven only by an electric motor. Piston or even turboshaft power would do just fine. I believe that there are now some ducted fans in the model world that are almost big enough to do the job. You would not necessarily need the retractable tail cone, swing out pressure-operated ducts on each side would also be a possibility. You could use NACA ducts for the inlet, perhaps also equipped with simple closures. Vaughn John Scott |
#16
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I still think someone with a metal vee-tail glider ought to jump on
this idea, and just mount the engine on a short pylon. Fiberglass forward fuselage, metal rear fuselage and metal V-tail. Hmm. Didn't Udo Rumph show us that this formula can still lead to a very high performance glider (ref. Dick Johnson's recent tests on Udo's modified HP-18 published in Soaring)? I think Eric may be onto something... -Doug It would be fun the to explore a sustainer jet with the HP18. A 42 lb thrust jet should do to job, provided it has the same or better reliability for starting as a conventional engine. I would reject a self launching jet version on environmental grounds. Udo Rumpf |
#17
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This is an idea that has also been running through my mind, but a
ducted fan does not have to be driven only by an electric motor. Piston or even turboshaft power would do just fine. I believe that there are now some ducted fans in the model world that are almost big enough to do the job. You would not necessarily need the retractable tail cone, swing out pressure-operated ducts on each side would also be a possibility. You could use NACA ducts for the inlet, perhaps also equipped with simple closures. I found a picture of the Funk Sirius 1 ducted fan motorglider (circa 1970) on this page: http://www.fk-lightplanes.com/FK-His...k-history.html He also built a turbojet powered glider in 1960... Marc |
#18
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"Marc Ramsey" wrote... I found a picture of the Funk Sirius 1 ducted fan motorglider (circa 1970) on this page: http://www.fk-lightplanes.com/FK-His...k-history.html He also built a turbojet powered glider in 1960... A bit more info on the Sirius I (and II which was based on the Calif), along with pictures of another Calif-based ducted fan design: http://www.gomolzig.de/englisch/antrieb/antrieb1.htm |
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