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Permalink Reply by Daniel Gru on June 2, 2011 at 8:55am

I'd forget about that, only version would be, if you could get a collective pitch quad and power it with one turbine.

Turbines in general are very slow on rpm-changes... with the quads manouverability relying alone on rpm changes, it will be very, very complicated to set a turbing quadro up...

Daniel

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Permalink Reply by charlie Soppelsa on June 2, 2011 at 9:25am

You can do it with a single turbine with 4 control vanes in the exhaust. You can get pitch,roll,yaw and some fast thrust control for altitude.

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DeveloperPermalink Reply by Olivier ADLER on June 2, 2011 at 10:51am

 

Yes, four control vanes at arms extremity, and a central air exhaust for main thrust. This is certainly done like this inside some military drones.

Seems not really complicated to do.

Nevertheless there could be some differences and code adaptation.

 

Another interesting setup is collective pitch using 4 electric motors (or 6 for Hexas). Should give faster response time, less power consumption, and the possibility to reverse thrust for acro fly.

 

Again the code should be slightly adapted for this.

 

The central motor setup for collective pitch seems complicated to me, unreliable, and weight costly.

 

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Permalink Reply by Chuck on June 2, 2011 at 1:17pm

I thought about using a turbine to power a generator and then using the generator to chargo a lipo, which powers the quads brushless motors.

This way you get the reaction and burst power of the brushless, but the power from the turbine.

 

But I doubt there is any weight gain from carrying the turbine fuel over just plain batteries.  Those turbines suck a lot of gas.

 

 

 

 

 

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DeveloperPermalink Reply by Olivier ADLER on June 2, 2011 at 1:36pm

 

You can do this with a simple methanol 2 strokes engine. Really less expensive.

 

Could be interesting for long fly, but quite noisy... I don't think that the fuel motor and methanol weight is a problem. Electric motors used on multi are very powerfull.

 

An advantage with methanol it that you can recharge in a few seconds :=) even during flight, perhaps with another multi :=)

 

I'm not sure you could keep lipo, they need to be cold to be charged again. The generator should be followed by a rectifier and a regulation circuit. Eventualy a lipo could be added for safety, if the main fuel engine stop.

 

 

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Permalink Reply by NerdyFirefighter on June 2, 2011 at 1:35pm

As previously stated... the transient response of a turbine is complete crap.   They just don't spin up and down fast enough to make appreciable differences in thrust in a short amount of time.

 

If you were dead set on using 4 turbines... I'd instead look at variable geometry turbos for inspiration.

 

 

As you can see here, the area that the gases pass through can be radially changed by rotating the external collar.

 

Clearly you'd have to manufacture your own rig to accomplish this since turbine engines are inline and a turbo is designed to sling air perpendicular to the axis of rotation.

 

Maybe vectoring could be employed as an option too.

 

Food for thought.

 

 

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Permalink Reply by valentin colon on June 2, 2011 at 2:37pm

this my next challenge,  any suggestion will be well received, the intention is to build a human  flyable jetpack

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Permalink Reply by Russell B. Sutton on June 2, 2011 at 3:48pm

I have been working on this in my head for awhile.    Use the turbine as a generator to power the aircraft and a battery backup for emergency landings.      APU  of  a small private jet would work great.

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Permalink Reply by Jack Crossfire on June 2, 2011 at 3:56pm

Someone actually did make a quad copter with a transmission that linked 4 collective pitch rotors to a single electric motor.  When it came to doing the obvious, using a gas motor to extend flight time, no-one ever thought of it.

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Permalink Reply by Chuck on June 2, 2011 at 4:25pm

Funny,m how so many people have the same thing in their head.

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Permalink Reply by Russell B. Sutton on June 2, 2011 at 5:26pm

I've done a little math on this project, it's all about the Power to Weigh ratio if you want any real filght time.  An onboard Turbine Power Unit would be the  best choice.   I would use the quadcopter X  flying configuration with 2 motors per corner counter rotating for safety.  Composite and aluminum frame with a battery landing  backup.  Must to weigh 350 lb or less and pilot needs to weigh 150 or less for a max weight of 500 lbs.  This would be ideal,  Remember Fuel weighs about 6.6 lb per gallon.

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Permalink Reply by Chuck on June 2, 2011 at 11:45pm

Pilot?

What pilot.

 

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