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Author Topic: What is this new little mini wing on aerobatic designs??  (Read 492 times)
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Dan Snow
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« on: August 28, 2018, 02:56:35 PM »

I used to fly pattern way back when I flew RC about 15-20 years ago, so I still occasionally look at the planes they are flying today, and I have to admit, this new design with the little mini wing on the top of the fuselage located just slightly forward of the wing trailing edge has me flummoxed!!   Can someone please explain what it is, and what the advantages might be?
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What is this new little mini wing on aerobatic designs??
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Starduster
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« Reply #1 on: August 28, 2018, 03:31:57 PM »

Just a guess, but I'd say it has to do with so-called "3D" flight. So, that during vertical "hovering", the small wing is in the prop-wash and gives a little more control, whereas the wing tips are outside of the prop wash.

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piecost
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« Reply #2 on: August 28, 2018, 04:03:53 PM »

I recall reading that it somehow helps knifedge flight.
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mike
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« Reply #3 on: August 28, 2018, 04:54:42 PM »

Try searching for  'canaliser' - that's what they call them.  They have been fashionable for a while now.
Here's a reference - look under rudder... http://www.modelflying.co.uk/news/article/the-f3a-aerobat/25967

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Dan Snow
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« Reply #4 on: August 28, 2018, 06:46:26 PM »

Thanks Mike. I had no idea what the little doohickey was called, had only seen a couple of pictures of models with it. The technology sure advances fast. When I flew you almost needed a new airframe and engine every year just to keep up!!
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mike
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« Reply #5 on: August 28, 2018, 07:02:14 PM »

Try a Google image search on 'F3A canaliser'.  They're sprouting out of a lot of F3A models - I spotted one with 'ailerons'.  It's a biplane with a tiny upper wing isn't it?
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Konrad
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« Reply #6 on: August 28, 2018, 09:01:13 PM »

It is not a biplane.

Its main function is to direct air over the rudder so that for any given yaw input one needs less rudder deflection. This comes into effect when in knife edge. The idea is that with a more effective rudder one needs less deflection. Less rudder deflection means less rudder elevator mix. I have not seen any wind tunnel data showing the effectiveness of this. I will say that on my ships I set the angle of the incidence at negative 0.5 degrees. And my canalizer's (french for tunnel?) have had the surface area 12% that of the wing area.

Can't really say as I've seen a noticeable impact from these. But I think that on the bottom 3/4 of a knife edge loop that planes with the canalizer may not go off heading as much.

I would think ailerons (gap) would negate the effect of smoothing out the airflow off the side of the fuselage

Konrad 
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mike
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« Reply #7 on: August 29, 2018, 03:49:24 AM »

I think, 'Canaliser', given a French origin, would translate as 'Channeller' in English.
(The French word for 'tunnel' is 'tunnel'.)

Would making the tail end of the model symmetrical top-to-bottom avoid rudder/elevator mix?
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mike
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« Reply #8 on: August 29, 2018, 07:35:37 AM »

Found on the GBRCAA site....
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Konrad
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« Reply #9 on: August 29, 2018, 10:39:52 AM »

I haven’t seen any papers describing the wing mounted canaliser.

One of the few things I like about foam models is the ease in which one can experiment with ideas. One of the problems with building models to explore phenomenon is that it introduces the “phycology of aerodynamics” into the experiment. With foam one can change configurations very easily, and test the hypothesis rather quickly. This eliminates the emotional investment clouding the observation.

I’m showing my E-Flite Tribute FX that I used as a test bed. It was very easy to change the size and location of features. I liked the Tribute FX as it had an airfoiled wing and vertical fin. Many foam models have just flat plate surfaces. Surprise, surprise airfoiled surfaces do respond differently than just flat plates.

The Tribute FX with its curved LE presented very bad wing rock in high alfa flight. It was thought that wing fences would help flight the span wise flow. They did, but the fences where susceptible to hanger rash. So the wing tip was changed to a saw tooth.

Tribute FX shown with Canaliser based on my reading of the writings of Quique Somenzini.
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piecost
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« Reply #10 on: August 29, 2018, 12:34:34 PM »

Did you notice the effect of the device?
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Konrad
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« Reply #11 on: August 30, 2018, 09:33:22 AM »

As mentioned in reply #6 the effect is minimal at best. I can’t say as it helped with pilot load. I tried larger and larger Canaliser ending with 4 times larger than the one shown. While they had an effect on trim I saw no real reduction on the rudder elevator coupling.

The wing fences had a dramatic reduction on wing rock during high alpha flight (on swept  LE). The saw tooth wing tip had no noticeable effect on flight performance other than the fence effect. But added great durability to the fences. I feared that the added mass out on the tips would effect roll response but with my flying skills I didn't notice it.

All the best,
Konrad

P.S.
Seaweed aside it should have read "Psychology of Aerodynamics"
« Last Edit: August 30, 2018, 09:53:54 AM by Konrad » Logged

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piecost
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« Reply #12 on: August 30, 2018, 11:43:27 AM »

Thanks for the detailed response. It might be that your particular plane is not sensitive to the device, its geometry was not optimum or if the device is more of a fashion statement!
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Konrad
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« Reply #13 on: August 30, 2018, 07:18:00 PM »

Thanks for the detailed response. It might be that your particular plane is not sensitive to the device, its geometry was not optimum or if the device is more of a fashion statement!
While I'm sure the geometry is not optimum, it is the latter. I've added and removed this feature on three other ship with similar results, no substantial changes. Pattern is full of follow the leader type engineering. You old timers might recall the Curare-itus anhedral tail of the 70's and 80's All to help with the knife edge pull to the canopy or gear. When CofG placement and rigging of the ailerons was more effective than the bent tail.

While I encourage experimentation have a set of objective criteria defined to show if the change was effective.

All the best,
Konrad
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