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Old Oct 26, 2015, 12:37 PM
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4 Axis Control???

So I am trying to help a guy set up his radio to do something that I admit is new to me. It seems what he wants to do is use the trailing edge to control pitch when he is in thermal mode.

So what he wants is to use the "elevator" stick to control the trailing edge such that when he pulls back on the stick (up) the trailing drops which should cause the nose to pitch up. Conversely when he pushes the "elevator" stick forward the trailing will reflex and cause the nose to pitch down. It appears to me that the elevator itself is disabled in this mode.

Like I said, this is a new one for me.Any thoughts?? This is apparently coming from an article in a French magazine, perhaps from 1998, not sure on the date.
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Old Oct 26, 2015, 01:03 PM
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Sounds like regular snap flaps with the elevator servo disabled. Sounds both weird and dangerous...
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Old Oct 26, 2015, 01:17 PM
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That is just elevator to camber mix isn't it? Not sure what the benefit of not having elevator input would be.

Tom
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Old Oct 26, 2015, 01:24 PM
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In effect that is the same as pitcheron control as used on some slope gliders. I am not sure what is going to happen when using camber changing instead of rotating the entire wing panel to change the angle of attack, though. Camber is more effective than AoA but also changes the pitching moment of the wing overall and that may lead to disaster if the horizontal stab can't overcome extra pitching moment forces.


Mark
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Old Oct 26, 2015, 07:30 PM
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Quote:
Originally Posted by Kiesling View Post
That is just elevator to camber mix isn't it? Not sure what the benefit of not having elevator input would be.

Tom
No. what this guy wants to do is to use the trailing edge position to control pitch. No elevator involved. Both flaps and ailerons either droop or reflex to control up/down pitch.

I guess it could be done using an elevator camber mix, but in his case he wants zero elevator movement.

Says it comes out of an article in a French soaring magazine.
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Old Oct 26, 2015, 07:43 PM
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This is common in VTPR (slope aerobatics). Helps with loops, inverted flight . . .

This can be set in 'camber system' with Spektrum radios using Sherman Knight's sailplane template.

Quite a bit of info on the Slope forum about vtpr you may want to put your thread there as well.
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Old Oct 26, 2015, 09:15 PM
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Originally Posted by Silent-AV8R View Post
No. what this guy wants to do is to use the trailing edge position to control pitch. No elevator involved. Both flaps and ailerons either droop or reflex to control up/down pitch.

I guess it could be done using an elevator camber mix, but in his case he wants zero elevator movement.

Says it comes out of an article in a French soaring magazine.
Right, so you would use elevator to camber mix to control the TE. Depending on the radio, you can add a second mix to counter act the elevator to cancel it out or set the elevator dual rate to almost so it doesn't move. If I remember correctly the latter method would work for the SD 10G. On my MZ-24, I would have try it to see if it works, but I think I would need to use a second mix to cancel out the elevator. But this may also kill the camber movement - not sure if the second mix would be tied to the elevator to camber mix. The other possibility is to set the end points to zero for the elevator. Again not sure if that would kill the elevator to camber mix. If you wanted to go all in, just fix the elevator physically and not use an elevator servo or just plug the elevator servo into an unused channel.

I still can't imagine eliminating the elevator movement is more efficient than using both elevator and camber to control pitch.

Tom
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Old Oct 26, 2015, 10:15 PM
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The 'snap flap' is left alone.

TE of flap and aileron is further controlled typically through the throttle stick. Camber and reflex to suit. Gives additional pitch response only when desired during certain manuvers.

That's all I know. Good luck with your project.
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Old Oct 26, 2015, 11:26 PM
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Bill,

What is your buddy trying to accomplish? Does he just want to prove to himself that it is possible to control a plane with wing only deflections? Or does he have some kind of goal in mind?

I have a good amount of time on pitcheron models, which are generally slope planes and fly fast to have good control response. They also have LOTS of throw. The VS Rotor and V-max were the planes that I flew the most, but also had lots of time on CR aircraft Turbo's, which were wingeron models.

The other end of the spectrum are obviously flying wings. They have rather unique design constraints and handling characteristics.

The key in the design of those pitcheron planes was to have an un-swept wing so that the servos don't get overpowered. If he is just thinking about eliminating the elevator movement on a standard thermal plane, sweep or multi-taper panels just adds complication to the moments that are generated by deflecting the TE. Generically I suspect that he would be able to fly the model. However given the complexities of achieving good handling with this control scheme, I have to ask why? Is this a purpose built model? What is he trying to achieve? I seriously doubt that this would show any kind of efficiency gain over a conventional layout.

It is certainly possible to design an airplane with this scheme in mind, but would it fly better than a Maxa or X3?
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Old Oct 27, 2015, 08:21 AM
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Easily do-able via flight modes, what radio is in use?

Secondly, if it was of any use or benefit it would be commonly done already.
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Old Oct 27, 2015, 08:47 AM
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Guys, I was not curious about how to do it, that is not my question. I was curious if anyone else had heard of this and what you all thought about it.

From what I was told, this fellow says that this is supposed to be more efficient in thermal.
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Old Oct 27, 2015, 08:49 AM
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Quote:
Originally Posted by Avaldes View Post
Bill,

What is your buddy trying to accomplish? Does he just want to prove to himself that it is possible to control a plane with wing only deflections? Or does he have some kind of goal in mind?
I do not know the fellow. He is just a guy asking how to do something. I have never heard of what he wants to do and I am not completely sure why he thinks it will be a better way to fly a plane.

He is talking about using this on both DLGs and F3J planes.
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Old Oct 27, 2015, 10:23 AM
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Quote:
Originally Posted by Silent-AV8R View Post
So I am trying to help a guy set up his radio to do something that I admit is new to me. It seems what he wants to do is use the trailing edge to control pitch when he is in thermal mode.

So what he wants is to use the "elevator" stick to control the trailing edge such that when he pulls back on the stick (up) the trailing drops which should cause the nose to pitch up. Conversely when he pushes the "elevator" stick forward the trailing will reflex and cause the nose to pitch down. It appears to me that the elevator itself is disabled in this mode.

Like I said, this is a new one for me.Any thoughts?? This is apparently coming from an article in a French magazine, perhaps from 1998, not sure on the date.

I think the title of your post is misleading as it implies that elevator will be used as well. 4 axis flying to my mind is elevator, rudder, aileron and trailing edge (usually controlled by a centred stick - VTPR etc).

In terms of programming it should be easy if you have a good radio and not easy if you don't!

You would assume the end result would be a lower pitch control.
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Old Oct 27, 2015, 10:47 AM
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I used that title because that is what the guy called it.

Regardless of the name, is this something you have seen used? I have not which again, is why I was asking about it.
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Old Oct 27, 2015, 12:21 PM
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Nope, never heard or seen it being used.
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