Use of spoilerons

[Wayne]

@Red (and others), have you ever seen a full scale plane that uses spoilerons with the flap deployment? (Butterfly) I have now seen a few of the STOL Drags racers drooping their ailerons to gain more flap and I have to shake my head as this seems like the wrong solution that actually would be working against them..? (Ok, it might help them pop off the ground on the takeoff, but seems it would just extend the landing roll.)

I guess the large CRAB and high bank angle on the landing approach is their solution to cutting the lift out of the wing, but then they level out for the final flare and are back into float mode in ground effect.

From my RC glider and smaller electrics experience I seem to get the best performance out of spoilerons when compared to flaperons.

Thoughts?

 

[Red]

Wayne,

I'm with you when it comes to spoilerons vs, flaperons. I've been preaching it for years. Two of the benefits I see is killing adverse yaw and less deck angle to deal with to get to flare attitude.

As to your question, no I don't think I have seen any full scale planes using butterfly (crow). Drooping the ailerons with flaps seems to be the norm, however it is not a new idea. The earliest example that I know of is the Fieseler Fi-156 Storch of WWII. It was STOL before it was cool, and one of my favorite planes. I can think of a couple reasons that this might be the case. One, full scale aircraft usually carry a much higher wing (and cube) loading than our models. The extra lift can be really helpful getting the landing speed slower. Spoilerons kill lift, we can just deal with it easier on models due to the lighter wing loading tolerating a higher AoA prior to stall. Also, full scale are less dynamic than our models, so the piloting workload is less, so any adverse yaw is a bit easier to deal with.

Red

 

[Wayne]

I can see the advantage of drooped ailerons for takeoff, but still seems like the ability to flip that over to spoilers for landing would be a worthy benefit. The few small single engine planes that I have seen with any form of spoiler seems to use them only for glide slope control. Like a Mooney or some of the motor glider planes out there.

 

[Mucksmear]

This jumped out at me on my flight back from Orange County earlier this summer. The United CRJ I was on was holding what looked like about 15 deg +/- a few deg, up ailerons during landing, while the flaps were deployed. Of course don’t know what the other aileron was doing but I’m assuming it was also up. As far as I could tell, we were not landing in significant crosswind conditions and that aileron was holding a fairly steady up deflection with the occasional small corrections as we landed.

 

[rcsoar4fun]

Funny, one of the guys that wings a lot of STOL stuff just crashed locally. He is okay, but I have seen him fly a bit.

Flaps on r/c work a little different because of the load involved and the power available, IMHO.

Flaps on something like even a C172 provide a ton of lift and let you get really slow and controllable. The Super Cubs and the like have HUGE flaps that are controlled by a lever that allows rapid deployment and retraction. When you retract the flaps the loss of lift is impressive. Doing it on a C172 on a go around incorrectly is an eye opening experience. An older C172 with 40 degrees of flaps will pretty much not climb at full power.

On a STOL bird it allows the airplane to immediately stop flying. If you are dropping in on a short roll it will immediately make the airplane 10knts too slow to fly and plant the wheels.

 

[Wayne]

On full scale there are a lot of fatal accidents with pulling off the flaps at too low a speed for a go around. Cirrus has a bad track record for example. (Ok, not fair, Cirrus wing has a number of issues..)

 

[rcsoar4fun]

On full scale there are a lot of fatal accidents with pulling off the flaps at too low a speed for a go around. Cirrus has a bad track record for example. (Ok, not fair, Cirrus wing has a number of issues..)

I think Cirrus has some issues based on pilot overconfidence.

If you are on approach with a C172 with 40 degree flaps and push full throttle, it will stop descending. It will not climb. You have to pull to 30 degrees, accelerate, climb, then begin retract/climb game.

The first time you attempt a go around it is very eye opening.

 

[Doc J]

I design my models' control volume, and set my models up, and then test them so that with ailerons up - normally about 20 or so degrees, and flaps down as much as I can get; and a bit of elevator compensation they will park stationary in a 15 to 20Mph wind and can be 'helicoptered down" for landings with no actual forward speed.

I like to land (Plonk my model) at the front of the slope if I can, by walking off a bit, out of the pilot area, but where I'll still be very visible. I dont actually like the rear of slope landings on small slopes where the model is headed towards a bunch of flying or spectating people. With some people that makes me a bit nervous.

I dont actually like spoilers because they tend to eliminate a bar of lift acoss the wing rather than be a 'controllable' force in slowing down like flaps. Also the older types can be prone to mechical problems theat might leave them stuck up or down at the wrong times.

But like everything its up to the flyer. To each his own.

Doc.