Wake Turbulence from a Paper Airplane

It's not just something that happens with large airliner jets, the same phenomenon occurs in smaller planes, including RC models and even down to paper airplanes.

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Video Shows Wake Turbulence from Tiny Paper Airplane

Wake Turbulence happens when an object moves through the air. It's not just something that happens with large airliner jets, the same phenomenon occurs in smaller planes, including RC models and even down to paper airplanes as the video below demonstrates. Perhaps you have experienced it flying an RC model at an event with many other aircraft flying at the same time. You fly through an area where another plane just passed and you notice turbulence. That's wake turbulence.

I've experienced this indoors flying small agile planes. When flying in a tight circle, it is possible to fly through your own wake and the see the plane get rocked by the swirling air. It's not enough to be really concerned about from a safety point of view in model aircraft, but it is an interesting bit of science. The video below does a great job of explaining wake turbulence and showing it in an artistic way using a paper airplane and a fog machine. Enjoy.

Have you experienced wake turbulence flying model airplanes before?

Last edited by Jason Cole; Jun 29, 2021 at 08:01 AM..
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Jun 29, 2021, 04:03 PM
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Thank you,
It was interesting to see wingtip vortex coming off the wings on a paper airplane.

As a thought experiment: if there were propellers on the wingtips, rotating in the opposite direction to the wingtip vortex, would the air rotation from the propeller and the rotation of the vortex cancel out each other?

Yes, yes I know: how fast are the propellers moving? How fast is the plane moving? A low aspect ratio or high? Etc, etc, etc…..

But is the theory that the Vought V-173 tried with their wingtip propellers valid?

Thanks
Last edited by adamalbert; Jun 29, 2021 at 04:44 PM. Reason: typo
Jun 29, 2021, 04:29 PM
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Jason Cole's Avatar
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Would be neat to see what happens in the fog.
Jun 29, 2021, 04:42 PM
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accidental double post
Last edited by adamalbert; Jun 29, 2021 at 04:46 PM. Reason: double post
Jun 29, 2021, 06:44 PM
Wait...Say again?
Nice video! I was a little surprised to see just how big the vortices are from a little, slow-moving airplane. Also loved the fingers of smoke getting sucked out of the cloud and up into the vortices. Thanks for posting.
Jun 29, 2021, 10:44 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Very cool!

SteveT.
Latest blog entry: My shop....
Jun 30, 2021, 05:23 AM
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Quote:
Originally Posted by adamalbert
Thank you,
It was interesting to see wingtip vortex coming off the wings on a paper airplane.

As a thought experiment: if there were propellers on the wingtips, rotating in the opposite direction to the wingtip vortex, would the air rotation from the propeller and the rotation of the vortex cancel out each other?

Yes, yes I know: how fast are the propellers moving? How fast is the plane moving? A low aspect ratio or high? Etc, etc, etc…..

But is the theory that the Vought V-173 tried with their wingtip propellers valid?

Thanks
And it worked quite well. So much so that the V22 Osprey still applies the same method to reduce the wingspan needed for conventional flight. In the world of twin engined planes, if you go to the bother of having counter-rotating propellers you generally want the inboard blade to be the one moving downwards, because at a positive AOA this gets the centre of thrust closer to the centerline, reduces the amount of stuff a propeller blade could pick up from the runway and toss on the fuselage, and reduces the chance that a blade might detach and hit the fuselage in a crash landing. So there must be some compelling aerodynamic reason to have the propellers spin the opposite way. As far as I know this arrangement is only present in production airplanes in the V22 and the P38, where it was adopted as a fix to cure some issues with stability.
Jun 30, 2021, 07:37 AM
AndyKunz's Avatar
Dare I say it? Sure, what's a little baiting going to hurt?!?!

Anybody notice how the air in the middle is being "thrown down"

Andy
Jun 30, 2021, 07:58 AM
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I notice how the volume of the smoke remains the same both above and below the swirls
Jun 30, 2021, 02:33 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Quote:
Originally Posted by Brandano
And it worked quite well. So much so that the V22 Osprey still applies the same method to reduce the wingspan needed for conventional flight. In the world of twin engined planes, if you go to the bother of having counter-rotating propellers you generally want the inboard blade to be the one moving downwards, because at a positive AOA this gets the centre of thrust closer to the centerline, reduces the amount of stuff a propeller blade could pick up from the runway and toss on the fuselage, and reduces the chance that a blade might detach and hit the fuselage in a crash landing. So there must be some compelling aerodynamic reason to have the propellers spin the opposite way. As far as I know this arrangement is only present in production airplanes in the V22 and the P38, where it was adopted as a fix to cure some issues with stability.
Excuse my feeble mind, as I don’t remember which one it was, but if I remember correctly there was a twin engine plane that when first tested had the props rotating such that the blades were going up towards the fuselage and it could barely get off the ground. They changed the rotation and the plane flew much better.

SteveT
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Jun 30, 2021, 03:10 PM
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Hmm, I don't know of such a plane. Sounds unlikely, though I guess it might be possible, aerodynamics can be weird. Apparently there were a few other production planes with the "reversed" prop rotation arrangement, mostly German WW2 planes (https://en.wikipedia.org/wiki/Counte...ing_propellers). One plane that had some takeoff issues due to it's engine wake was the Me262 prototype, where the accelerated jet exhaust hitting the ground would create a low pressure area under the horizontal stabilizer, making it impossible to lift the tail. They "fixed" it by hitting the brakes during the takeoff run, and in the production plane by switching to a tricicle landing gear.
Jul 01, 2021, 04:07 AM
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gerryndennis's Avatar
Quote:
Originally Posted by AndyKunz
Dare I say it? Sure, what's a little baiting going to hurt?!?!

Anybody notice how the air in the middle is being "thrown down"

Andy
Whew, lucky there’s the same amount of air going up on the outside or all the air would end up down by the floor making it hard to breath
Jul 01, 2021, 06:58 AM
Registered User
Quote:
Originally Posted by AndyKunz
Dare I say it? Sure, what's a little baiting going to hurt?!?!

Anybody notice how the air in the middle is being "thrown down"

Andy
Absolutely. And even while the air in the vortices is moving up, the vortices as a whole move down too
Jul 01, 2021, 07:55 AM
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Coupez's Avatar
Now we just need to measure the pressure in the region above the wing upper surface...
Jul 01, 2021, 08:15 AM
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interesting. also, when looking at the contrails of prop driven aircraft, when all props turn the same way, the vortex sheet of the wing which has propellers which rotate opposing the wing vortex, is straighter. the other wing vortex sheet wraps up quicker.
i suppose the wing with straighter vortex sheet has less losses (not sure)


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