View Full Version : Don't try this at home
06-23-2008, 06:17 AM
A friend and i build Paramoters, and we thought about a design that was shown on Myth busters. Two horizontal props driven of one engine. You stand or sit on a platform, then the 2 props are above you, one each side about 6 foot up.Then with weight shift, you move back and forth. 2 small rudders under each prop for turning. We have built paramotors that weigh 15 kg and producing 70 kg thrust. So theoritacally, 140 - 30- airframe. It should lift 90 kg. The mythbusters showed that the airforce had one in a museum. And the one the mythbusters built was to heavy. They used ducted props, and an industrial stationary engine. It did lift 1 inch though.
06-23-2008, 08:33 AM
Igor Bensen built such a thing perhaps half a century ago. It used two McCulloch engine-prop packages mounted on a crude frame to produce vertical thrust. Ken Brock compared the frame to a sawhorse with an engine on each end and the "pilot" in the middle.
The two prop disks were at the correct height to cut the "pilot" to ribbons if a prop ever shattered. The noise must have been beyond belief... especially for the pilot/victim riding on the thing.
Of course, machines with such high disk loadings don't autorotate in any meaningful sense. Control responses when using rigid props (without flap hinges) will be a bit weird, thanks to the lag built into a gyroscope's inertia reactions.
Many of the problems with such designs were addressed in the development of "flying platforms" for the military in the 1950's. Even they won't glide, though.
06-28-2008, 06:47 AM
no ... they was with rotax
07-04-2008, 11:15 PM
Get of. When are these spammers going to learn we are NOT INTERESTED.
... to cut the "pilot" to ribbons if a prop ever shattered.
Many of the problems with such designs were addressed in the development of "flying platforms" for the military in the 1950's.
The same appears to hold for those interested in those "strap on" helicopter packages, in that should the "landing gear" (one or both of the pilot's legs) fail for any reason - the same sickening result. That the blades were wood or metal would be irrelevant.
As for those "flying platforms" (which appear to be making a come-back due to the advances currently being made with unmanned vehicles of that nature) if I'm not mistaken the DeLackener machine of some fifty years agao, while traveling forward at thirty or thirty five MPH, had two or more of the counter-rotating blades clash but (and for reasons known only to God) the pilot survived with only a few bruises - probably scared the devil out of him though.
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