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Old Feb 07, 2006, 01:10 PM
Dreaming Weasel Dreams
Tucson, AZ
Joined Sep 2003
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camber and flaperons?

Maybe I'm missing something, but what's the difference between camber and flapperons? Are they the same thing with two different names depending on the context?

-Rick (slope newb, dreaming weasel dreams)
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Old Feb 07, 2006, 01:14 PM
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Flaperons are used on the landing approach to slow down. When you lower the ailerons you tend to lose aileron authority however.

Camber is to increase the lift of your wing when the slope lift isnt cooperating.

Spoilerons (where the ailerons go up at about 45 degrees) are what I use for landing. You also will need a radio capable of mixing in a small amount of elevator compensation to correct a pitch-up or down depending on the airplane.

Reflex is raising your ailerons slightly ( like 1-2 mm) to add some speed.

All these things can de done on your average, 3 servo slope racer such as a Sparrow.
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Old Feb 07, 2006, 02:11 PM
Flagstaff, AZ
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Camber is the curvature of the wing. Most people think of "adding" camber. In general if you increase the camber of a wing you get more lift, drag, and slower speeds.

If you have Flaps, you can use them to increases the camber of the wing.

You can use your ailerons as flaps (flapperons). Both ailerons are lowered and thus increase lift, drag and slow you down... often at the expense of control (as per above).

You can also move the ailerons up ("reflex"). A little reflex reduces lift/drag for more speed, a lot of reflex (spoilerons) reduces lift and adds drag.

Some airfoils are designed to the flyer can change the curve of the wing to suit the task.... no added camber or slightly reflexed for speed/penetration, really reflexed (spoilers) for slowing down and/or landing, slightly cambered for increased lift (thermal flying) and really cambered (flaps) for landing.

Then there is "Crow" in which a four servo wing does both. Flaps are used as flaps and ailerons are used as spoilers... lots of drag, slow flight, great for spot landings.
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Old Feb 07, 2006, 02:13 PM
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My take is as follows:

Flaperons - when you only have ailerons. (yes, you can put them down just a little for "camber")

Camber - for flaps AND ailerons. (adjusting the entire rear of wing together)
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Old Feb 07, 2006, 02:31 PM
That Freeking Laird Guy
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It's basically the same thing. Camber is accomplished be dropping the trailing edge of the wing. You can drop it using the ailerons, or aileron and flaps. The primary difference betweend flaperons and camber is the amount of droop on the surfaces. When a wing is cambered it is usually only a few degrees ( 3 to 5 degrees is fairly common). When Flaperons are deployed to slow for landing the trailing edge drops considerably more (20 to 30 degrees is usually the range for flaperons). Flaperon is not used very often as it does lead to a loss of aileron control. Spoileron (ailerons up) is a more common method of landing control.

TFLG
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Old Feb 07, 2006, 03:11 PM
Dreaming Weasel Dreams
Tucson, AZ
Joined Sep 2003
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So on a 3-servo A/E ship, I could set up my flap lever to do flaperons or spoilerons, and mix in my throttle to flaps at a small percentage to get camber/reflex control? Will I actually see any advantage on a cheap foamie like a steelhead Eureka?

-Rick (slope newb, looking at kit-bashing a Eureka since it's cheap, and he already has 3 standard sized servos)
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Old Feb 07, 2006, 03:20 PM
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The Eureka actually flies great as-is. The approach control stuff like spoilerons will help slow your landings down and save wear and tear on it. A faster airframe like a Sparrow/Mach Dart, etc will make better use of mixes like this, but it couldnt hurt to learn how to do it.

A good mix for simple planes like the Eureka is to mix throttle at about 5% to your elevator, which gives you very fine elevator trim on your throttle stick. When the lift gets light close the throttle and it will milk the lift. When the lift picks up add throttle and the nose will drop slightly and it will speed up. I use this mix on lots of planes.
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Old Feb 07, 2006, 04:18 PM
Dreaming Weasel Dreams
Tucson, AZ
Joined Sep 2003
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I'd like to start playing around with this kind of stuff on a cheap airframe -- Unfortunately my Optic-6 won't let me do what I'd really like on a 4-servo wing, but I don't anticipate having a 4-servo wing any time soon (I'll be doing good to get a 2-servo wing!). I can still dream about 4 surfaces, though... all 4 acting as ailerons when flaps aren't deployed, and having the flap silder affect only the inboard surfaces, with a camber adjust affecting all 4, wheeeee!

-Rick (slope newb, dreaming weasel dreams, getting too big for his britches... time to concentrate on not crashing the weasel rather than drooling on slope ships with 4-servo wings!)
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Old Feb 07, 2006, 04:19 PM
Dreaming Weasel Dreams
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Oh, and why are spoilerons preferred for landing as opposed to flaperons?

thanks,
Rick
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Old Feb 07, 2006, 05:00 PM
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If you think about it, if you draw a line from the trailing edge to the leading edge, thats the center line of your airfoil. What you did was in effect, add a bunch of up via the wings angle of attack. The wing is close to a stall at this point. Now, you can add down trim to account for this, and mix it in to the flaperons to correct the up pitch. What happens if you need to turn on landing? The down going aileron drops further, and the plane will actually yaw the wrong way ( i.e turn left, but it yaws right), since down aileron is draggier than up.
Remember, its a glider. It has too much wing as part of its design. We need to kill lift to land. Spoilerons, on the other hand take the wing away from stall. Planes with spoilerons out still have lots of aileron authority, they just sink fast. Add some elevator trim to make it sit level with the spoilerons out and you have a plane that turns left when you say left, is hard to stall, and is descending.
Of course, all this goes out the window if you have seperate flaps.
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Old Feb 07, 2006, 05:47 PM
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Also, using flaps on a 2 servo wing will cause it to tip stall...which is not good when you are trying to land. Also, you wont have as much aileron control when using flaperons as opposed to spoilerons.

K
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Old Feb 07, 2006, 06:07 PM
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As slopemeno puts it quite well - spoilers kill the lift that the wings normally generate. This makes for a steeper glide angle / approach. While that may sound bad at first, remember that a shallow glide angle means a lot of forward velocity. Bringing a plane in at a steeper angle (within limits) means less forward velocity and therefore a smaller landing zone and less scraping / sliding / tumbling once ground contact is made.

As for the adverse yaw that slopemeno talks about with flaps or flaperons... There is extra "frontal-area" drag in putting a control-surface area either up or down (i.e. at an angle to the airflow) - but it "hurts worse" when you deploy a control-surface in the down direction because you are increasing the camber (and therefore the lift) of the wing. It all goes back to something called "induced drag". On a very basic level, it can be said that some part of the lift a wing generates ALSO pulls the plane back.

To put it another way: You know how you've always seen those drawings of an airplane or wing with the "Lift", "Drag", "Gravity", and "Thrust" arrows coming out of it at nice 90-degreee angles? Well, that drawing ain't true. Even in level flight, lift isn't generated in a purely vertical direction - it is actually "tilted" a little bit toward the trailing edge. Think of it like a right-triangle: the is an angled line which represents the "total" lift, a vertical line the represents the vertical lift, and a horizontal line that represents the induced drag. If you imagine growing or scaling up that triangle, you will see that as lift increases, so does induced drag.

Therefore, the more lift you generate, the more induced drag is pulling the wing back and trying to slow it down. With or without flaperons, this is why there is "adverse yaw" in all aileron-airplanes to a certain degree.

Think about it from another point of view: In a turn, you reduce the lift on one wing (the lower wing), so you also reduce the induced drag. However, that is the "inside" wing in the turn - it needs to travel a shorter distance than the "outside" wing (the one raised up above the horizon). BUT, that outside wing has its ailerons deployed to increase the lift (which is what caused it to raise up in the first place) - increasing the lift increases the induced drag; slowing down the "outside" wing. So whever you begin a turn, the plane actually tends to yaw _away_ from the turn, even though it is rolling into the proper bank-angle. Different airfoils and sizes/shapes of aileron can minimize this effect, but induced drag is an innate part of any airfoil.

As slopemeno points out - with flaperons you have already increased the camber (lift) of the airfoil a great degree. You are closer to a stall condition, and generating a fair amount of induced drag.

Having said all this, flaperons appeal to me in a way that spoilerons do not; but I've never owned a non-flapped plane that had either capability - so I'm not in a good position to judge.

Take care,

--Noel
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