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Old Apr 05, 2007, 01:59 AM
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Coanda UFO v2.0 - a different approach

I decided to give this Coanda effect thing one more shot.

My first attempt was not very succesfull.

http://www.rcgroups.com/forums/showthread.php?t=653166

It was very dificult to fly (almost impossible) and way under powered. Actually I think it had enough power but it was so inefficient at generating lift that it barely got off the ground.

I think most of the dificulty in flying it was that the controll responce seemd to be severely delayed. You could give it a roll command and it would respond - but after a significant delay. That makes it extreemly hard to controll and tends to cause pilot induced ocilations.

I also think that the basic design was flawed in that it wasted a lot of energy and potential lifting force by haveing the outer rim curved down.

The controll surfaces were located on the vertical outer sides and I think thats why the controlls were very ineffective and delayed as well.

Notice all the "I think"'s above I've never done one of these before and as far as I know, the guy I linked to in the original thread is the only other person to get a Coanda UFO flying.

This is very new territory and all my "I think"s are really just WAG's

Any way - here is the start of Coanda UFO v2.0.

The fundamental difference in this one is that the lifting surface is completely flat. Its also going to be raised of the ground on 3 legs. It will use the same basic controll set up as the first one.

We will all get to see how it goes.....

Larry
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Old Apr 05, 2007, 04:45 AM
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Larry, AFAIK, the Coanda effect is about airflow sticking to curved surfaces. The faster air on top may provide some extra lift though. (but personally I have trouble seeing why the still air above the airflow will not equalize that pressure.)
If you remove the curvature, you have no downwash, and thus less lift. But in the end, I hope I am wrong because I'd love to see such a weird thing fly.
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Old Apr 05, 2007, 05:10 AM
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Good Onya Larry . Things went quite there for a while but I'm glad that your giving it another shot Since I'm outta my depth with this one , I'll keep watching from the bleaches and hope all goes well with V2!!!!!

Of course it will, cause you got the knack

Regards Box
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Old Apr 05, 2007, 09:04 PM
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Quote:
Originally Posted by JelleB
Larry, AFAIK, the Coanda effect is about airflow sticking to curved surfaces. The faster air on top may provide some extra lift though. (but personally I have trouble seeing why the still air above the airflow will not equalize that pressure.)
If you remove the curvature, you have no downwash, and thus less lift. But in the end, I hope I am wrong because I'd love to see such a weird thing fly.
I've been worried about that exact thing - my fingers are crossed also

Larry
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Old Apr 05, 2007, 09:05 PM
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Quote:
Originally Posted by Boxhead
Good Onya Larry . Things went quite there for a while but I'm glad that your giving it another shot Since I'm outta my depth with this one , I'll keep watching from the bleaches and hope all goes well with V2!!!!!

Of course it will, cause you got the knack

Regards Box
Thanks!

Larry
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Old Apr 08, 2007, 02:41 PM
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Ive been watching an interesting thread in the exotic planes/VTOL section about the Chanell wing or Custer wing.

http://www.rcgroups.com/forums/showthread.php?t=621903

I just did a test to demonstrate the effect.

Demonstration of lift for Chanell wing/Coanda effect (1 min 55 sec)


This test applies to the UFO as well. It clearly shows a lot more lift being generated by suction than with forced air flow.

Now Im wondering how to SUCK air over the surface instead of blow it?

Larry
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Old Apr 09, 2007, 04:06 PM
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In case you haven't seen this, here's an article from a couple days ago about the inventor of the original Coanda UFO.

http://www.dailymail.co.uk/pages/liv...icle_id=447317
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Old Apr 09, 2007, 04:36 PM
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Ah, Anatoly reads slashdot too? came here with that link in the clipboard...
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Old Apr 09, 2007, 07:13 PM
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Thanks anatoly and JelleB for the link. Interesting article.

Im putting this project on hold for a bit - Ive been sidetracked by an EDF project...

Larry
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Old Apr 11, 2007, 07:16 AM
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Intresting project.

I have some pointers, if I may:

-Check the coanda effect on wikipedia, the surface should roughly look like the front part of a wing.
Here's a more practical link: jlnlabs

The thing works because the airstream follows the surface, so as the surface diverges the airstream downwards, you get a reaction force upwards (sort of like a centripetal force)

You can think of it as a gearbox for propellers, with a small amount of fast-moving air you get a large static force, but loose the speed.

-the airstream should be laminar to follow the surface better(as on the wing of a plane), for this you need a smooth surface like solarfilm or something

-to get better stearing, you could try having a engine that's a little oversized, and build four air-brakes close to the engine. Air-brakes, as you know, destroy the laminar airstream and decrease lift (on this one it totally destroys lift for the whole circle-segment covered by the air-brake)

When you lift all four the lift decreases fast, when you lift just one the craft should tilt to that side.
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Old Apr 11, 2007, 07:59 AM
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Flying platform

A true ducted fan may be the way to go. If done correctly (airfoils on inside) not just a straight tube it is supposed to create more thrust then the propeller alone.

The Hiller Flying Platform demonstrated this. Modelling this machine might make an interesting spin-off project from the coanda effect project.
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Old Apr 11, 2007, 02:45 PM
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Quote:
Originally Posted by Larry3215
Ive been watching an interesting thread in the exotic planes/VTOL section about the Chanell wing or Custer wing.

http://www.rcgroups.com/forums/showthread.php?t=621903

I just did a test to demonstrate the effect.

http://www.youtube.com/watch?v=mhiJKTmq5Mk

This test applies to the UFO as well. It clearly shows a lot more lift being generated by suction than with forced air flow.

Now Im wondering how to SUCK air over the surface instead of blow it?

Larry

here is one way Larry ... i love your craftsmanship good job man!!

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Old Apr 13, 2007, 01:00 AM
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i submit some research done by funded peoples.. save you a copy and read through it i find it very valuable to this topic

.Mil research pdf... with pics too
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Old Apr 13, 2007, 02:23 AM
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Quote:
Originally Posted by leadfeather
A true ducted fan may be the way to go. If done correctly (airfoils on inside) not just a straight tube it is supposed to create more thrust then the propeller alone.

The Hiller Flying Platform demonstrated this. Modelling this machine might make an interesting spin-off project from the coanda effect project.
I think thats a good idea!

Larry
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Old Apr 13, 2007, 02:24 AM
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Originally Posted by iTs_jUst_sEth
i submit some research done by funded peoples.. save you a copy and read through it i find it very valuable to this topic

.Mil research pdf... with pics too
I like your sketch above - but where does the air GO when its done getting sucked??

That document is super! Finally some real engeneering data to go on.

Unfortunately it sounds like my idea isnt going to work at all based on his findings!

Ah well

Larry
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