Hi Pilots

I'd like to know what spoilers do and how they operate. Do they sit on the leading or trailing edge of the wing, and do they move up, or down? I suppose they sit on the trailing edge, hence one also gets spoilerons, which I assume, would be the ailerons with a dual function.

Thanks in advance 4 ur comments.

Spoilerons are made possible by a 2-servo aileron setup. both ailerons go up to lessen the lift of the wing (they can also be set up to both travel down [flaperons])... in either direction the ailerons still function to some degree.

Spoilers are control surfaces on the wing that lessen the lift of the wing.

either configuration helps bleed off extra speed for a smoother landing.

On sailplanes, spoilers are generally located at or near the spar. They come up to create drag to help slow the plane and to decrease the lift of the wing in this area.

As stated above, spoilerons are a function provided by a computer radio that turns both ailerons up. Not as effective as the top mounted spoilers, or so I am told, but they do have an impact and help to settle the plane down in a shorter distance.

Photo is of one of my sailplanes with spoilers rasied.

I've also heard that you need to put in a little elevator mixing for either spoilerons or flaperons... I believe spoilerons will tend to give you some up pitch, so you will need to have a little down elevator mixed in to compensate, and flaperons would be the opposite...

Flaperons (as functioning in the place of flaps) tend to increase lift--thus allowing the plane to fly more stable at lower airspeeds. This usually tends to pitch the nose of the plane up when deployed, therefore most people will mix a little down elevator with their flaps or flaperons. Spoilers, on the other hand, are designed to kill lift, and should therefore tend to pitch the nose down. Up elevator would be needed to maintain level flight. Of course, some planes are different. I've seen planes that pitch down severely when flaps are deployed. It depends upon the design. But, as a general rule, flaps--nose pitch up.

I believe the spoilerons help kill lift by providing some down force to counter the lift of the airfoil. This downforce is behind the CG of the plane, so I believe it should give you some pitch up... almost like elevons would with up elevator. I had a plane with the ailerons up a little too high (equivalent of a little spoiler mixed in), and when it was trimmed out, the elevator was down quite a bit for level flight. Turns out the plane was also a little too tail heavy, so that would cause some down elevator to be required too...

Spoilers - on top of the wing, tend to drop the nose, but spoilerons, being on the back of the wing but ahead of the tail .... not sure.... gotta try that.

I look in some other spoileron/flaperon threads, and the mixing I described seems to be what most guys use. Here's a quote from one guy who uses spoileron/flaperon and elevator mixing...
I believe the "proper" spoilers on top of the wing actually kill the lift of the top airfoil, while these "spoilerons" just produce some down force (behind the CG) to counter it... probably why you get some down pitch with the conventional spoilers and some up pitch with spoilerons...

Spoilerons will will cause a nose down pitch upon application, & flapperons will cause the nose to pitch up.

Hi all.. I'm not sure if this has anything to do with this thread but....

I have tried flapperons on my 4*60 which it did not do what I wanted
to use it for(flat spins)... the flaps, tho not needed on my 4*60, worked
great.. Anyway I was finishing up on my used UCD 46, trimming all, range
check etc.. and had both elev. and ail. on dual chennels each and all
was looking good except my throttle cut, it was not working right.. No
movement off of low throttle, but it would move while the sticks was in
the high throttle position. I thought all was set right on my Airtronics RD
8000.. Anyway I gave up and called Airtronics and explained my problem..
he right away said you have spoilerons activated, deactivated the
spoilerons and activate flapperons and all should work.. And they did...
Just thought I'd post this for those that may have the same radio and
the same problem... Thought I give my used UCD it's first flight with me,
but No Can Do.... My tanks is leaking.. Hopefully I can pull the YS-63
and just tighten the tank screw.... I'm hoping it'll work... If not have to
wait for a new tank...

Spoilers are devices on top of the wing that kill lift by breaking the continuity of the top wing skin. If they are near the thick point of the airfoil, they act very non-proportionally. That is, the effect is either being "on" or "off", even if not extended all the way. This is because as soon as they are deployed a bit, the air over the wing behiind them is separated. So most of the effect occurs as soon as they are extended just a bit.

Move spoilers back towards the trailing edge and they get a much more proprtional effect, because the amount of air they desturb is more proportional to the amount of deflection.

The term spoilerons can apply to any surface that combines spoiler effect and roll control. In the RC world, it's most commonly used to describe ailerons that deflect upwards like spoilers. However, spoilers that deflect defferently on each side for roll control are also spoilerons.

AS for pitch change with spoilers & spoilerons; The pitch change is caused by the combined effects of two things. The pitch change of the wing airfoil caused by the deflection and the effect of the change in airflow angle that's hitting the tail. If ailerons are deflected up - spoileron style, you will get a pitch-up tendency. This is bacause they effect the pitching moment of the wing, but being outboard they do not effect the air going over the tail. If you deflect spoilers that are inboard, like on a glider, you will often get a pitch down. That is because the spoilers are often ahead of the horizontal tail, and since they disturb the air going over the wing, that wing is no longer directing air at a downward angle relative to the tail. Less downforce on the tail means the tail goes up, nose goes down. Xombinations of ailerons that continue inboard or spoilers that are closer to the TE will give combined results...

Thanks for all the info, guys! Much appreciated!!! :-)

Johng,

Thanx for the explanation. Now I have another one for you.

On my Ugly Stik (built from a copy to the original version plans), I tried flaperons as an experiment. When deployed the nose pitched down considerably. After flying it that way for about 6 months, I decided to re-cover to change scheme and get rid of hanger rash, nicks, etc.. While I had the wings open, I installed flaps and when deployed the nose now pitches up. Why the difference in pitch between flaperons and flaps? They both deploy fully to 30 degrees.

Ed

The pitch changes with flaps, flaperons, spoilers, and spoilerons are essentually "random" in sport models. I've never seen anyone able to predict 100% which way a particular airplane will go when something is deployed, at least by eyeball looking at a plane.

Factors that I KNOW change the pitching tendancy of an airplane include (but aren't limited to) (and, in no particular order):

- tail moment. Longer tail moment planes tend to pitch up with flap, but with a short tail moment, you start to ack more like elevons, and you pitch down. (flying wings are the extreme of "short tail moment", as are many combat planes)
- CG location. If the CG is more aft, the tail isn't working has hard. If the CG is back enough, the tail starts to lift "up" rather than down. This means that messing with the airflow over the tail can cause either pitch up or pitch down, depending on your CG location!
- Size, shape, and location of device. Due to changes to airflow over the tail, and weither you are creating or destroying lift, how much lift, and where on the wing the lift is changing.
- Angle of deflection. I've seen planes where a little flap caused nose up due to increase in lift. But lots of flap caused nose down, probibly due to a combination of drag and "elevon" effect, though I'm not 100% sure exactly why.
- Airfoil. Differnet airfoils have differnet pitching moments. Changing the TE of the airfoil often changes the pitching moment. That might or might not cause the tail to have to provide more or less lift to balance it out.
- AOA. dropping flaps increases the AOA of the wing. Espeically with very small flap movements, this can change the lift, but you can also actually stall part of the wing this way.

Also, keep in mind that there is often a momentary or trasient pitch change, and a possibly differnet long term pitch change. It's quite possible to have a situation where if you dropped flaps (or raise spoilerons), the plane will balloon upwards (or downwards), with a quick pitch change. But after a couple of seconds, it might stabalize out, and there could be a net trim change effect that could go in the opposite direction. So you might get a momentary pitch in one direction, and a long term trim change in the other. Or in the same direction, but to a different degree. Often deploying the flaps/spoilers in a slower manner, and at slower airspeeds, avoids overly dramatic transients.

Flaperons, Spoilerons typically in RC aerobatics planes is talking about ailerons that react via a mix to what the elevator is doing.

With Flaperons (Elevator/Flaps moving opposite one another) if the elevator goes up, the ailerons move downward together and vice versa according to the proportion set in the mix. But they STILL work together as ailerons at the same time to maintain roll control. This provides more lift at lower speeds.. But what its normally being used for is to tighten up looping maneuvers like waterfalls and knife edge spins.

With spoilerons (Elevator/Flaps moving the same direction) if the elevator goes up, the ailerons go up and vice versa proprtionally to the mix. This is a DANGEROUS mix because it severly magnifies the wings stall tendencies as up elevator is applied. It can be used to slow a fast plane down for a landing approach or for aerobatic purposes. If you use spoilerons you better know EXACTLY what you are doing because they will crash you and there wont be anything you can do to stop it if you dont know what you are doing.

Really spoilerons defy logic for anything considered normal flight. Using the ailerons for spoilers is fine but not really on a mix with elevator. Having a switch that will put a small amount of up ailerons(reflex) for landing is fine but you need to understand what it does to lift because the plane is going to sink faster and stall at a higher speed. Most guys I have seen use spoilers flip the switch just as they flare to slow the plane as it touches down and slows to a stop.




NOW, Spoilerons from a 3D standpoint can be a BLAST! Typically the proportion is very high so that the mix raises/lowers the ailerons a lot *****g out the reflex at 20-60 degrees as you move the elevator to full high rate 3D deflection![8D] But you better know how to use them and whats happening.


For an "elevator" maneuver (3D manuever) they will increase the descent rate and slow or stop wingrock BUT at the bottom of the maneuver, if you leave them in and pull up elevator to fly out, you will probably crash. Spoilerons are NOT conducive to flight and the plane will not fly with spoilerons worth a ,,,, well,,,, it just wont fly. I have mine on the spring loaded trainer switch so that I pull the switch, do the maneuver and then let the switch go(kills the spoileron mix) and fly out with normal flight control.

Ned is talking about various uses of mixing, ie elevator->flap or elevator->spoiler mixing, which is not the same as just having flaperons or spoilerons or what have you.

Having flaperons on a plane does not imply that they are mixed elevator->flaperon as Ned describes. Though, as Ned says, it's a common thing.

I was playing with flaperons and spoilerons on a Funtana 40. I have switches set up to turn on elevator->flaperon mixing, elevator->spoileron mixing, or no mixing at all (which enabled the flap knob for manual adjustments).

Right,

Thats why I opened with this statement



Now real planes that actually had flaps but the scale model is only equipped with ailerons or I suppose anywhere a preson wanted to take advantage of ailerons working on independant servos, sure flaperon/spoilerons can be used as an on/off thing and varied via a slider or dial.

I was strictly referring to how they are typically used for aerobatics.

Ned,
Somehow I missed that part of your message, though I knew that's what you meant.

A while back, there was someone else on this forum who was insisting that "flaperons" always meant the mixing with elevator. So I was covering the bases there a bit, and trying to clarify for anyone else reading who might have gotten the wrong idea. Looks like that would be me in this case. Hope I didn't offend.

I think that's called "flapervator" mixing...

noway Kirk!
I know you are always trying to be constructive in what you say so I dont sweat it if we misunderstand or even disagree. Heck, I know I have been wrong at times and ultimately I do want to make sure I get it right,, so feel free to speak up if you think I missed something or mis-speak..

Mike