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Help with my own creation

Old 03-20-2010, 01:21 AM
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whereismyisland
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Default Help with my own creation

Greetings guys.

As a complete newcomer here, I hope I am posting in the correct forum.
Below is a creation of mine I would like to turn into reality. It is modelled in Blender 3d and hopefully sometime in the near future also in balsa/foam etc. Before I hear comments regarding the practicallity of it all, let me assure you that I am well aware of the problems regarding counter rotating props, flying planks etc. Who was it that said we do things 'not because they are easy, but because they are hard' ...

Needless to say I have created a few problems for myself. If it is unclear on the picture let me explain a bit. The propellers are counter rotating, sort of in the middle of the fuselage, this obviously creates a problem as the fuselage in front of and behind the propellers are stationary. How can I connect the twofuselage parts, with the spinning bits in the middle?
Has anybody got an idea of a good wing airfoil for a flying plan?

I would like to go electric initially, because I think it would be the easiest and cheapest approach. Once the hickups are ironed out, I would realy like to build a gas/nitro version. What would be a good approach to match electric motor to model size?

Thanking everybody in advance
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Old 03-20-2010, 08:48 AM
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Lnewqban
 
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Default RE: Help with my own creation

The main problem I see is the structure connecting the two-part fuse.
That structure must be internal, then your propellers must be mounted on two floating rings, actuated by belts of gears to the motor/motors.

Being a tailess, your airfoild should be reflexed, for pitch stability.

Good challenge!!!
Old 03-20-2010, 01:50 PM
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SeamusG
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Default RE: Help with my own creation


ORIGINAL: whereismyisland

As a complete newcomer here, I hope I am posting in the correct forum.
I would suggest re-posting in the "Scratch Building, Aircraft Design, 3D/CAD"forum.

I love your creativity. Like Lnewqban commented, Iwonder about "pitch" management without elevator or "V" tail configuration.

Good luck!

Old 03-25-2010, 12:32 PM
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MinnFlyer
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Default RE: Help with my own creation

The term that comes to mind is, "Form Follows Function"

In other words: you design an airplane to perform a particular function, not because it looks cool.

What function does this design hope to accomplish over more familiar designs?
Old 03-25-2010, 03:35 PM
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ARUP
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Default RE: Help with my own creation

Do a 'Google' search for Galludet aircraft. He did the same thing. The propellor 'hub' was a large ring that fit over a corresponding tube portion of the fuselage. The hub was driven by gears. Very neat design that was ahead of its time.The technology and metallurgy couldn't cope. Skyways magazine may have reprints of various articles on these unique aircraft. Tailwinds, ARUP
Old 03-25-2010, 05:43 PM
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Default RE: Help with my own creation

I would think those props would cause too much turbulence with each other to work. The design also is going to be severely nose heavy and will have no pitch control. You might consider building a proven design first to learn about aircraft construction and learn how to fly before striking out on your own. That way your creativity will have some roots to give you a chance at succeeding.
Old 03-25-2010, 06:53 PM
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Default RE: Help with my own creation

Slide the wings back and add canards
Old 03-26-2010, 03:38 AM
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whereismyisland
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Default RE: Help with my own creation

Thanks ARUP

Did a search and found the Gallaudet D-1. A truly amazing aircraft for its time. And exactly the thing I was looking for!!
On the US patents office' website there is also a PDF document regarding the engine and propeller installation. If anybody is interested let me know I will gladly share it.

The counter rotating propeller is not a necessity, I merely considered it for its 'coolness' factor. It has however an added bonus that no torque effects will be present. Open throttle and it should track straight down the runway.

MinnFlyer, I totally agree with principle of form following function, the reasoning behind my design? I don't know ... I started doodling something on paper, then modelled it in Blender and eventually thought ... 'hey will this thing fly?' I went as far as modelling it in Plane X and it flew ... quite well actually. In this case I suppose the function will have to follow the form. What that function is? Who knows? Satisfying my curiosity ....
For interest sake Plane X is a full Flightsim package, even approved in some form by the FAA. It includes a nice modelling package 'PlaneMaker' that has quite advanced aerodynamics. Only downside, it is quite expensive to buy, the demo is free however ...

I will post some updates here shortly, hopefully with a working animated demo ...
Old 03-28-2010, 11:41 AM
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Default RE: Help with my own creation

YOU dreamed it up, YOU think it's cool, YOU want to see it fly. In my book, that is a perfectly valid function for a model airplane. FWIW, I think it's cool too!!!

The airfoil does not necessarily have to be reflexed, a symmetrical airfoil will also work. Pitch stability would be neutral, also valid for a model, particularly for a "fighterish"-looking design like this.
Old 03-29-2010, 05:52 AM
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whereismyisland
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Default RE: Help with my own creation

Hi Bruce

Thanks for the kind words. Had a look at your website and found the Elliptica. Nice!! Do you offer plans via download after purchasing, or do you only ship them? I am located in Namibia, Southern Africa. Could you advise about shipping costs?
I realy like the look of an elliptical wing, buthave not been able to find any decend plans though.

I am currently raiding all kinds of hobby shops for pieces to try and build my 'propulsion system'.
Old 03-29-2010, 10:24 AM
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Default RE: Help with my own creation

whereis, please send me a quick email (address at bottom of every page on my site) and we can take care of all your questions. The Elliptica plans may be a useful reference for you. I can send the files if you contact me via email...
Old 03-29-2010, 11:27 AM
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Charlie P.
 
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Default RE: Help with my own creation

Do you intend to set the ailerons or flaps as elevators? Biggest problem I see is you will lack any kind of pitch control. The elevators are too close to the center of gravity/axis of rotation. Down elevator will produce added lift to the wing, raising the aircraft. Up elevator will stall it, bringing the nose up and eventually down rapidly.

Sounds like not much fun to fly.

Plus, it's gonna be a pain to transmit power to two rotating propeller collars. It will need to be a tricycle gear, adding complication to get prop clearance for the ground.

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