SonexBuilders.net

I have seen some talk about roll rate in cruise or during aerobatics with the large and original ailerons. My question is do the large ailerons improve control authority substantially at landing speeds?

Rich Mercurio
Sonex hopeful

Welcome to the forum! See some of these threads.
viewtopic.php?f=3&t=4213

viewtopic.php?f=21&t=647&p=4632

Rich,

The short answer is no, the larger ailerons don't improve control response during landing. This is really because the standard ailerons are very effective all the was thru landing and into the stall. The Sonex isn't like a Cessna where you can deflect the ailerons side to side as much as you want when slow and nothing much really happens. With the Sonex, you get immediate control well before the plane is flying. Adding the larger ailerons doesn't appreciably affect this.

The large ailerons will feel slightly heavier due to the added surface area that you'll have to deflect, but the increase in aileron heft isn't a problem. In exchange you'll get a 20%-30% increase in roll rate during aerobatics. I always tell people that if they don't care about aerobatics choose the standard ailerons - they are light and responsive, and give you wonderful control feel. If you just have to have the best roll rate possible for acro, then go with the large ailerons.

Jeff

I walked around at my local airport recently and saw many aerobatic airplanes with extra large aileron to maximize roll performance.
I am wondering if anyone ever tried deviating from the plan and enlarge the aileron of a sonex to use the entire wingspan?

I doubt anyone has done a full span aileron on a Sonex. If you are wanting to build a Sonex for acro, I'd say go for it. Full span ailerons are the way to go for acro. My previously owned One Design had them and it rolled so fast it makes rolls in my RV-6 feel like I am flying a dump truck.

Slips can replace flaps for landing. Or with long runways no slips or flaps needed.

Then I built a Xenos. With those ailerons and long wings, an aileron roll started 60 deg nose up finishes the roll 60 deg. nose down. It rolls sooo slooow. Flying slow on final in gusty crosswinds, when the wind lifts the windward wing, full aileron slooowly brings it back down. This is a limiting factor of the design as any much stronger gust or longer duration could overpower aileron authority and then it becomes out of control while low and slow on final. If I had known this, I would have a least thought about when building that I should add more aileron deflection than the design currently allows. That is not possible now the the wings are finished.

And these ailerons require a lot of arm strength. Total opposite to the acro planes I am used to flying.

Rick Caldwell
Xenos 0057 26 hrs into ph. 1

Just a few thoughts:

A full length aileron on a Sonex, I would guess, would probably exceed the design strength of the components involved in the control system. Think about the various points that the pushrods transfer control pressure to the aileron (the attach point on the aileron, the control horn in the wing, etc) and the bending forces on each.

I've only flown 1 other aerobatic airplane than the Sonex/Waiex, a Citabria, and I recall it had aerodynamic assist (don't remember what the feature was called) that actually reduces control force required the larger the deflection. I.e. it would "assist" in deflection. It wasn't a servo-tab, more of an aerodynamic counterweight that enforces more control deflection the larger the pilot-demanded deflection, resulting in lighter control feel.

This is just my opinion (everyone has one, right?), but if I were to build my own Sonex, I would go with the Acro ailerons even if I didn't want to do aerobatics. The reason has nothing to do with the ailerons, and everything to do with the flaps. The standard Sonex flaps are HUGE, and I talk to many Sonex pilots who say they never (or almost never) use full flaps on landing. The smaller flaps used with the acro ailerons seem to me to be the perfect size, and they are still very effective. But you can use full flaps at will and it's not a hard pull to deploy them. I found them to be much more useful than the standard flaps. And the larger ailerons are fun for doing rolls too!!

I like my aerobatic size flaps. I wouldn't want the flaps to be any bigger, they are plenty effective, and I almost always use full flaps.

I also like that if I have to go around there is less drag.

I have the standard large flaps and fly from a hilltop airport with no good off field landing options and also occasionally fly into an airport with houses and trees at approach end of runway. In both cases, I often approach a bit high and fast (90 MPH) so as to be sure to make the field if any engine problems, but then pull nose up to drop speed and apply full flaps, with that configuration, at speeds of 65 -70 MPH, well above stall, the plane has the glide angle of a brick and can land in a very short space. Having electrically operated flaps (now standard) rather than the old lever is a great help in that and makes retracting for go around easier as well. (With a CAMIt 3300 it will takeoff or go around with full flaps, but do not recommend that.) For my purposes, it still does aerobatics quite nicely, but I fly aerobatics only for fun, not competition.

David A.

Legacy Sonex, Standard flaps and ailerons. Aileron roll rate is about 120 degrees per second.

Landings are power off 180's from abeam the touchdown point.
Abeam the numbers slowed to Vfe - and Flaps 10
Start the 180 semicircle and half way around the curve in the base position - Flaps 20
Turn final and I want to be a little high and not in need of power.
Fly final, slipping as needed and as I line up to land - a mixture of stick in right hand and flaps in left - pulling more than 20 flaps to apply correct amount of drag. With the plane at about 60-65KIAS - I never have a problem pulling full flaps. As I touch down - flaps 0 to kill lift.

If a go around IS needed - drop flaps into the 20 degree detent to free hand and full power. I never put the flaps into the 30 detent in the air.

If demonstrating full flaps in slow flight - a forward pop on the stick to unload the wing a moment to get the lever out the 30 detent.