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Bill Daniels wrote:
Have you math whizzes figured out how far the wing runner will have to run before this dog whistle is going fast enough to have aileron control? Well, we've got a name for the project! Project Dog Whistle. LOL And Bill rightly points out that if the thrust is behind the CG, any yaw at low speeds means a ground loop on takeoff unless the tailwheel is firmly tracking. One more reason why the twin Cri-cri version had it right, with the two engines well ahead of the CG, and with exhaust away from anything that might burn. |
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Alan Baker wrote:
Project Dog Whistle. LOL And Bill rightly points out that if the thrust is behind the CG, any yaw at low speeds means a ground loop on takeoff unless the tailwheel is firmly tracking. No it doesn't. The thrust is always directed through the centre of mass. It's position of the main wheel with respect to the CM that matters for a ground loop... Alan Baker Correct. I'm mixing apples and oranges. In our Sparrowhawk design, the engine(s) thrust is through the center of mass, so this doesn't matter. I wonder about the Genesis mock-up, where this may not be the case. |
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![]() "Mark James Boyd" wrote in message news:4004fb99$1@darkstar... Bill Daniels wrote: One more reason why the twin Cri-cri version had it right, with the two engines well ahead of the CG, and with exhaust away from anything that might burn. But introduces the possibility (certainty?) of asymmetric thrust! I saw a Cri-cri (piston) lose power on TO one year at Oshkosh, it crashed almost at the crowd line. Vaughn |
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Vaughn wrote:
One more reason why the twin Cri-cri version had it right, with the two engines well ahead of the CG, and with exhaust away from anything that might burn. But introduces the possibility (certainty?) of asymmetric thrust! I saw a Cri-cri (piston) lose power on TO one year at Oshkosh, it crashed almost at the crowd line. Vaughn Probably because the Cri-cri is such a terrible glider... A lot in common with the BD-5: rotation speed = Vne = Va = Vmc = Vs... (or nearly so). ;( The Gruman Yankee also had critical speeds close together, and the Speed Canard had a real high stall speed too. One of the reasons I LOVE gliders is the generally low stall speed. Some full size regional jets, and the RC models that use the little turbines, have placed the twin turbines very close together and near the rear with no blast towards surfaces. It would be great to put turbine(s) on the tail of the Sparrowhawk, but the CG would never, ever work... Alas, back to the drawing board... |
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![]() "Mark James Boyd" wrote in message news:40057f22$1@darkstar... Vaughn wrote: One more reason why the twin Cri-cri version had it right, with the two engines well ahead of the CG, and with exhaust away from anything that might burn. But introduces the possibility (certainty?) of asymmetric thrust! I saw a Cri-cri (piston) lose power on TO one year at Oshkosh, it crashed almost at the crowd line. Vaughn Probably because the Cri-cri is such a terrible glider... Probably so, but I see I was not clear in my above post. The Cri-cri apparently lost power in one engine only, the one towards the crowd. We were sitting at the crowd line, but at the other end of the field, so we were not among the menaced. Looking at the Cri-cri, the engines look close enough together that you would think that asymmetric thrust would not be a problem; apparently not so. Vaughn |
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