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Old Nov 27, 2012, 02:59 AM
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Naudins Coanda Saucer


Seven months ago I was surfing the internet and came a cross a picture of a coanda saucer, I did not have a clue about coanda effect and started digging and found some interesting stuff. Anyway the idea of building one of these was the one thing that got me back in RC and so I bought lots of gyros, a radio, motors and batteries ext.I even learnrd about Depron. So the journey started back into RC. After discovering RCGroups and reading lots of threads I got side tracked and the thing that got me interested in the first place was pushed to the side and other projects started to evolve.

So this is an atempt to start and finnish this build and to see if i can get it to work.
I have seen some atempts that did not go to well.

I'm going to trat this as an educational effert in what can go wrong and try to find salutions as I go along.
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Old Nov 27, 2012, 03:19 AM
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In the beginning i read through all the material on naudins site and watched all the videos.I found this craft mechanicaly simple in design and new i had to give it try. So i went shopping and bought lots of goodies. I now realized that the Gyros I bought needs to run on Digital servos so I had to buy some of those.here is a collection of some hardware.
Old Nov 27, 2012, 04:56 AM
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DIY Mania from Taiwan
Nice try,it's always good to try something new
hope you can lift this saucer up in the air soonest and share vid with us
regards
Sam
Old Nov 27, 2012, 07:34 AM
Gary Mortimer is offline
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I have seen some wind tunnel work on these and tucking under (maybe tripping over itself is a better description) in forward flight is the big issue. Will watch with interest from NMR land.
Old Dec 06, 2012, 08:51 PM
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sweet, my friends dad built one of those
Old Dec 07, 2012, 01:03 AM
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Thanks for the interest guys.
One week before I go on leave, then I'll have plenty time to finnish this project and hopefully some of the others.
Old Dec 24, 2012, 08:11 PM
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Very interesting! I just want to see how Coanda effect goes! One guy claimed it can multiply lift by factor of 3, another one claimed worse than the same powered propeller (rotor) Certainly the diamete of the rotors count! What I am interested is if I put a Coanda dome under the propeller
is it will sufficiently boost the lift (thrust) or none effect at all (certainly I have to count dome weight loss
Old May 29, 2013, 07:51 AM
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Well it is time to continue with this little project.
Got side lined with alot of foamies and just wanting to get flying.
Well it is time to finnish this ,got some digital servos and a 3007 donkey motor to complete this.So in the next few days hope to have some photos to share.
Old May 29, 2013, 06:28 PM
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I am not sure how they control yaw on these things unless we assume separately powered counter rotating propellers. Alternatively those flow straighteners could be tilted, but it looks like they are just glued on. I imagine it will just spin, slowly, in the direction opposite the propeller and be unflyable unless your flight controller has a "carefree mode". Feel free to prove me wrong :-)
Old May 30, 2013, 08:10 AM
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Hi Ran D.
The stabilizer fitted so far is the static ones ,the rotating stabilizers still need to be fitted.They rotate to counter the torque of the prop and controls the yaw.
Got my ST3007-1100 Donkey motor to day.Have got 2 Park 480's that I want to use for my next coanda craft or if this does not work out to well use it for a bi-copter.
Old May 30, 2013, 10:53 AM
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Thanks for the explanation. I can see how that could work.

On a separate note, if there is any sort of a lift multiplication effect I would be cureous to understand the physics of it. Off the top of my head, F = M x A, where the mass relates to the volume of air that is accelerated by the prop. If the net effect is to simply redirect that air from a roughly circular cross section (the prop disk) to a ring shaped cross section (the exit path along the lower skirt of the craft) then it is the same air volume and the same acceleration with skin friction losses as the air is redirected, so the net thrust should be less, not more, than the thust of the propeller alone.

There might, however, be some mixing with the surrounding air, which could result in a higher volume of air being accelerated to a lower velocity (conservation of momentum still applies). From basic disk actuation theory, it takes less power to produce a given amount of thrust the more air you can grab on to. Hence, all other things being more or less equal, a larger rotor diameter, will lift more for the same power than a smaller rotor, (or combined rotor area for a multi-rotor). The same basic concept applies for a fixed wing aircraft inversely relating the wing span to the induced drag.

So, somewhere among the infinity of things I don't know, is whether the coanda effect effectively increases the rotor diameter. I am pretty sure that the area inside the skirt does not count, unless it is slightly pressurized somehow, but I doubt it is, so it's just the ring of air flowing down the outside of the skirts that counts.

If someone has any real data, or an accepted theory, I would love to hear it. Vague theories, such as my own, don't add any real value.
Old May 30, 2013, 11:01 AM
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That is exactly the reason for this build, I am very curious how all this works and what the possibilities are with the coanda effect device.I want to take some measurements during the coarse of the build to make up my mind what the positives and negitives are and if it is wurth experimenting more.
The prove will be in the pudding or not.
Old May 31, 2013, 11:02 AM
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I think the idea is to convert impulse into static thrust. The shape of the disc causes air to accelerate, which lowers the pressure and "drags" in more air from the surrounding. As the shape curves downwards again the pressure increases and the speed lowers, but the prop is affecting a greater air mass than that going through its disk. That's my impression, I'd like to see a CFD analysis of this setup.
Old Jun 01, 2013, 08:28 AM
jiberk is offline
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Vacuum Tubes Forever BCT2/BCR3
The GFS-UAV project
A Coanda effect flying saucer

Link

http://jlnlabs.online.fr/gfsuav/index.htm

JohnB
Old Jun 01, 2013, 12:14 PM
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DIY Mania from Taiwan
thanks for the link,interesting stuff
regards
Sam


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