Mfcttrf

I should preface that I'm by no means an aviation person. I'm just in a aircraft knowledge obsession phase and daydreaming about designing my own ultralight (will never happen).

The idea would be to simplify and lighten a small aircraft using the flaps as spoilers. As a practical example, the same handle could be used in one movement to get from flaps raised just before touchdown to spoiler raised just after it, making it fast and intuitive.

Basically you would have on a single axis :

high lift + high drag <-> normal lift + low drag <-> low lift + high drag

Is that possible? I guess not because I couldn't find anything like that, but why?

I name them flapoilers.

The Fairey-Youngman flaps seem to do that but all I could find as explanation is "so that the aircraft could be dived vertically without needing excessive trim changes" and I'm not sure how to understand that.

One reason is that any device you want to use as a lift dumper needs to be able to be instantly retracted and this is really difficult to do with a flap. On an airliner when the lift dumpers come up, if you slam the thrust back up to TO, they immediately come back down. A flap system with its slow moving drive line can't do this, and it's enough that it has to be retracted from landing to takeoff setting for a balked landing like that.

Plus, even in a normal landing, you would be landing with the flaps at the landing setting, and when you touch down they would need 10-20 seconds a typical drive system would need to move up past 0 to a fully up position. You'd be stopped by then, and deciding to take off again on the rollout is out of the question.

So you can see that any system like this would require flaps that can move up and down rapidly like ailerons. A really difficult engineering problem.

You might do this on a small airplane with manual flaps operated by a lever, but now you have to cater to twice the movement range as regular flaps, and you'd lose the mechanical leverage you'd need for manual flaps to work unless you made the lever move twice as far (by say having it move in a 180 degree arc - but now the lever handle is in the back seat).

Lots of gliders use flaps - without any spoilers - and they can in most cases be "reflexed" up a small amount, but this feature is done only to unload the trailing edge region for high speed running which has an effect similar to reducing wing area and pitching moment to reduce both induced drag and trim drag.

For approach control and landing, they actually do the opposite of what you would think; you drop the flaps down to near 90 degrees when you want to come down steeply and for the landing roll. Not everybody likes that kind of system because you have the same problem - you can't bring them up and down quickly like spoilers so you can't work the flap lever like a throttle on approach the way you normally do with regular spoilers/dive brakes, and they require different flying techniques, on which a pilot used to spoilers needs to be carefully briefed to avoid trouble.

What is created by deflecting a flap (or aileron) up is a reflexed airfoil, which, at higher angle of attack actually might create LESS drag and contribute a lower pitching up tendency. This design is used on flying wings, while others prefer to have pitch control duties handled by a separate tail.

Conceptually, "flapoilers" are a good idea, but aerodynamics requires spoilers to be placed further forward on the upper wing surface to be effective.

There for, they are usually a separate control surface from flaps, although a "clamshell" arrangement is seen as a speed brake. Model gliders, as AEhere mentioned, put both ailerons up and (closer to fuselage) flaps down in the "crow" configuration to achieve spot landings in competition.

But keep spoilers in mind as the (old and new B-52) makes very effective use of them as
"spoilerons" to bank and turn the aircraft.

But, with exception of some gliders, most aircraft want to land at as low an airspeed with as much drag as possible. This favors the flap.

For radio- controlled gliders, it is common to deflect both (outboard) ailerons upward while also deflecting both (inboard) flaps downward. This combination is called "crow", and it makes lots of drag to allow for a steeper glide path for easier landings, with no increase in stall speed.

Something similar would surely be possible with some full-scale aircraft, though as other answers have noted, there may be some engineering challenges.

Actually what you are trying to do is INCREASE the stall speed when the surface is deployed. (So after the wheels touch, the flaps suddenly snap to the raised-upward position.) My point is just that in the R.C. world it is possible for a control surface to be fast-moving AND to hold position in the face of heavy aerodynamic loading, so there must be SOME way scale this up. Whether that would ever be considered an optimal or good approach, is another matter.

Current designs do not support that. In planes with Fowler style flaps for example, the flaps extend down and back on a curved track. The top back of the wing extends over the top of the flap when retracted to make a smooth surface. The track would have to be redesigned to allow the flap to go up.

I have not felt the need for spoilers in my 4-seat plane. Any big altitude losses, generally when coming in too high on final, can be accomplished by side slipping the plane - lots of right rudder while banking left with the ailerons for example. Makes the plane nice and draggy to enhance vertical descent rate.

Probably not since spoilers are located further up the wing (leading edge) to "spoil the air" that is moving faster over the top of the wing rather than after it falls off the back of the wing hitting the air from underneath. None the less, the idea sounds logical. My glider has spoilers do to the huge amount lift the wings produce and can send you rising past 15K feet before you know it and needing O2!! The spoilers are a separate lever and lift the flaps that are centered over the middle area of the wings and give equal "spoiling" allowing the aircraft to slow down evenly without tipping the nose up or down like control surfaces on the trailing edges do.