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VTO free flight model gets airborne

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Re: VTO free flight model gets airborne

Post  fredvon4 on Mon Dec 05, 2016 9:43 am

With this very cool design I don't see any good way to use a bladder...from a filling and starting perspective

I would be tempted to Over prop the engine and add additional dimension to the counter rotating prop...more area/ thinking width of blades but perhaps just slightly larger diameter would do

I might also be tempted to reduce a TeeDee Venturi for better fuel draw but most likely I would switch to the better for this (IMO) Medallion engine
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Re: VTO free flight model gets airborne

Post  OVERLORD on Wed Dec 28, 2016 1:59 pm

Thanks for your ideas and suggestions.

I did another test today with a smaller prop to reduce the torque reaction. I mounted a 3 bladed Cox prop from the F15.



Unfortunately, I had the same results as before. The engine stopped as soon as it started spinning. During testing, I slowed down wih my finger the spinning action to see at what rate the engine would continue running. When the counter rotating prop spins at more than 3 or 4 revs a second, the engine stops.

A few times when the engine nearly died, I blocked the engine from spinning and the engine revved up again indicating that it is the excessive centrifugal force that starves the engine.

After all,  this engine and prop did not generate enough trust to lift the plane in any conditions.

It' a definite return to the TeeDee but with a round tank without inner baffles or bulkheads.

Lieven
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Re: VTO free flight model gets airborne

Post  Marleysky on Wed Dec 28, 2016 4:27 pm

There has got to be a formula for this to fly. I know the cox helicopters take off and gain alitude....but they weigh ounces. Although the slow rotation of the larger counterbalanced blades may be the secret to success of a vertical take off.
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