Flaperon with pot

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Adrenax
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Flaperon with pot

Post by Adrenax »

Hello everybody, first of all thanks to all for the great job you're doing here, I follow you since years but I write just now because i'm stuck on a mix I cannot create, my understanding of advanced mixing is really too low, so I ask your help if possible. All my planes have no flaps (aerobatics), so I wish a flaperon mix to try it but slightly different from the ones I've found around. My idea is: ID0 no flaperon, ID1 activate flaperon and say pot 2 decide the amount, from 0 to 30, but at the same time aileron should keep the positive travel to 100% and set the negative from -100 to -70 based on pot 2 value to avoid excessive range of servo, and same with ID2 but this time pot 2 should set from say -30 to -60, and again aileron should keep positive to 100 and negative from -70 to -40 depending on pot 2 setting. This is mainly because I never had flaps on my models, so I'm pretty scared to crash my 2 meter Katana or Extra (or whatever) for a bad setting, hence I'd like to find the correct ones with pot, and in a second time I'd put them as fixed values (somehow lol). What I've always find are mix that set the servo like 100+100, and I don't like that because it's too much, and if 50+50 results in a too short travel on the positive side, hope you get what I mean. Playing with offset and curves I just made it work for say -60/60, never from 100 to -100 minus pot setting, that I think should be used like GVAR, but like I said, my knowledge here is not good enough to make it on my own.
Thanks in advance for your help, but please I not just wish a mix, but also to understand how it works, to be able to learn how programming on my own for my needing. I know I'm missing something in my thinking but I don't know where, all I know is that I'm not able to tell the radio what I want it to do.
Sorry for the long writing :)

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MikeB
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Re: Flaperon with pot

Post by MikeB »

Try the following:
First set up a logical switch:
L1: v<val Ail 0, AND switch = RUD
This detects the aileron going down (or up).
Now, assuming you have a mix like:
CH01 +100% Ail
add a second mix
* +15%P1 Switch(L1) Offset 85% [This is a MULTIPLY multiplex mix]
85% +/- 15% is 70% to 100%
This scales the aileron movement by the amount P1 is moved on one side only when the RUD switch is ON.
Finally add a third mix:
+15% P1 Switch(RUD) Offset(-15%)
This adds in the flap movement also based on the RUD switch being ON, and controlled by P1.

If you don't have eepe installed, then please install it as you may quickly test this, and experiment with the settings on your computer.

Mike.
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Adrenax
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Re: Flaperon with pot

Post by Adrenax »

Hi Mike and thanks for the answer. The positive side of the movement is lower than expected, in fact it is correct in the -100 (it doesn't exceed -100) but on the positive side it stops at 70 when flaperon are down, but I wish it always go to 100, in other words the "flap" position should affect just the negative travel but the "0 / +100" part should be untouched, is it possible?
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Re: Flaperon with pot

Post by MikeB »

There are some possibilities, although you are getting +100% movement from the -30% flap down position. Do you really need to get to the +100% position when the flaps are down?

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Adrenax
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Re: Flaperon with pot

Post by Adrenax »

Well, i'm not sure i "need" it, but I don't like to have short travel, just in case things go wrong for some reason, I'd like to be able to have full range aileron to get out of troubles. I was thinking, isn't possible to split the mix in lower and upper parts? So the lower side would be affected by the pot/reduction, while the upper (positive) would not, got what I mean?

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jhsa
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Re: Flaperon with pot

Post by jhsa »

When you lower the flaps, you are offsetting the center point but the amount of travel remain the same. That means the aileron won't go as far up as without flaperon. What you want is to increase the travel over 100% when flaps are down then. not sure that is a good thing :)

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Adrenax
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Re: Flaperon with pot

Post by Adrenax »

Hi Jhsa, I've been watching your video tutorials, very well done! :)
I understand what you mean, for this I was thinking in a "splitted half" solution, to influence just the down side of servo movement and leave intact the upper half, but maybe is not possible
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Re: Flaperon with pot

Post by jhsa »

Possible, i'm quite sure it is.
I'm just not sure how good (or bad) that might be aerodynamically speaking :)

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Re: Flaperon with pot

Post by Adrenax »

Ok, so I'll stay with 70% up aileron and will give it a try
I use to fly with high range movements and use thumbs in the old way, I like to have too much and use just what I need, mainly in aerobatics or 3D I'm used to that, so I'm a bit scared to have not enough response, but probably is just a stupid fear lol
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Re: Flaperon with pot

Post by jhsa »

I have always been told that when I try new things my model should be at least 2 mistakes high..
In other words, try the flaperon high so you have enough time to recover the model if something goes wrong. You can fly slow high and "feel" how the plane behave.

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Re: Flaperon with pot

Post by Adrenax »

I'll do that, thanks
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Flaperon with pot

Post by Daedalus66 »

jhsa wrote:I have always been told that when I try new things my model should be at least 2 mistakes high..
In other words, try the flaperon high so you have enough time to recover the model if something goes wrong. You can fly slow high and "feel" how the plane behave.

João
Good principle.
When I was learning to fly aerobatics in a Citabria years ago, we flew at 3000 feet to stay under the traffic for Vancouver Airport but allow for two 1000 foot mistakes and still have 1000 foot margin.
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Re: Flaperon with pot

Post by ReSt »

You can try, if the following mix is doing what you want

Assume channel 01 and channel 04 to be the right and left aileron

CH01 +80%Ail Diff(50)
-90Thr Switch(ID2) Curve(x<0)
+100%CH10


CH04 -80%Ail Diff(-50)
-90%Thr Switch(ID2) Curve(x<0)
-100%CH10


CH10 -90%Thr Switch(ID2) Curve(x<0)
* +100%Ail (This is a Multiply Mix)


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Re: Flaperon with pot

Post by KAL »

Besides of all the programming:
Does the plane you want to use for testing have symmetrial or asymmetrical airfoil?

Keep in mind that with using flaperons a plane with asymmetrical airfoil is prone to tip stalling.
This is one reason for differential aileron throw (more throw upward than downward).
In this case it's worth to test also spoilerons (both ailerons go upward).

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Flaperon with pot

Post by Daedalus66 »

The big problem is created when ailerons are inset at the tip, rather than being along most of the trailing edge. When the ailerons are drooped to create flap action it's like twisting the wing tips to higher incidence. The result is that the tips stall before the inner portion of the wing and cause a snap roll followed by spin (if there's any height left).

If you look at how flaperons are used on full size aircraft, you will see that they normally work in conjunction with inboard flaps. On the Beaver, for example, the flaps go down about twice as much as the ailerons in landing configuration.

As Reinhard suggests, spoilerons (raised ailerons) are often much more useful and manageable than drooped ailerons. They generate drag while reducing lift and maintaining aileron control, which is exactly what is needed for most models. Extra lift is seldom a benefit, except for models with very high wing loading.
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Adrenax
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Re: Flaperon with pot

Post by Adrenax »

Thanks all for your reply
The planes are all symmetrical airfoil, like I said I'd like to test on a katana and/or extra 300, I tried on a simulator and it was pretty useful, no snap or stall, but it was a simulator...
Wing load is not so high, katana, for example, it's a 2 meter plane weight about 5,5 kg, less than 6 full tank, load should be about 70 gr/dmq (don't have the surface dmq here so not sure numbers, but should be something alike) and I didn't consider spoileron because I always though at them as a sailplane thing, in all the models I've seen around (talking about many years now...) I've always just seen flaperon, but is something I can try, thanks for the idea :)
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Re: Flaperon with pot

Post by jhsa »

Flaperon obviously only works if the Aileron is the full length of the wing, not only at the wing tip..
I guess most 3D planes have a full length aileron. I would certainly not use a spoileron on these models. All the lift I can get on landing is very welcome. More lift, the slower I can land in most cases.
If I destroy lift with spoilers, I will have to land the model faster.
Not a problem with gliders as their wings normally produce loads of lift. It can even be a problem on landing. It floats, and floats, and floats, and keeps floating.. :mrgreen: Therefore destroying lift is a good thing in this case :) :)

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Re: Flaperon with pot

Post by Daedalus66 »

Yes, I skipped a few points. You might think it's obvious that flaperons shouldn't be used on tip ailerons (alone) but most of the questions from non-glider flyers relate to models with tip ailerons.

A good example of where tip spoilerons work well is the Habu EDF. It has lots of wing area and the problem in landing is that it doesn't want to slow down. Our runway is about 120m and it's a bit of a challenge not to run off the end. Setting up spoilerons so ailerons rise about 25 degrees helps a lot. The model can be brought in at higher angle of attack and steeper approach and slows down better during the flare.
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Re: Flaperon with pot

Post by Adrenax »

AFAIK all aerobatic and 3D planes have full wing ailerons, mine use to have about from 20% to 30% wing surface just for ailerons, also F3A full wing aileron.
I always knew what jhsa said, spoileron reduce lift, opposite action of flaperon (in fact they go on the opposite way), so not what I want, and also talking about real planes, I don't remember to have ever seen a motor plane using spoileron on landing, but the fact I don't remember doesn't mean is not possible of course! Anyway I'll try the mix you guys gave me ASAP and will tell you the results.
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Re: RE: Re: Flaperon with pot

Post by jhsa »

Adrenax wrote: I don't remember to have ever seen a motor plane using spoileron on landing, but the fact I don't remember doesn't mean is not possible of course!
There is at least one plane that as far as I know uses spoilers for roll control. The B52.
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Re: Flaperon with pot

Post by Daedalus66 »

The B52 is the classic example, but there are many others. Boeing airliners use spoilers to reduce total lift that also function one at a time as spoilerons to supplement the ailerons. You can watch them in action during landing if you sit over the wing.
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Re: Flaperon with pot

Post by jhsa »

yes, that is true..
You lift one of those things on a wing, and that wing will go down for sure :mrgreen:

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