What are you all doing now with the High Torque servos on 40% aerobatic airplanes

[Cam Shahrdar]

What are you all doing now with the High Torque servos on 40% aerobatic airplanes

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Question for you all?


What are you all doing now, on your 40% aircraft

if you have stepped up and using the newer very high torque servos

each servo that has over 800 or 1000 ou/in of torque

DO you still use two of those on the rudder?

DO you still use two on the ailerons?

Just think using one less set up on an 40% airplane cuts down the price of the servos by over 200 dollars.

But that is just as an aside.

[Rich Whitlow]

I have not used them. But I would use them on my rudder, not much different than ganging servos. I would be leery of the ailerons because you lose that second point of contact (unless you have that tube setup like the Comp Arf)

[Earle Andrews]

Cam....although only a 35% Extra I'm using 3 of the Futaba A700 servos on my Krill. One each on the ailerons and rudder (pull/pull). These composite ailerons are pretty stiff plus I've added a center span CF rib. Haven't maidened it yet....although tomorrow (May 5th) is looking good here. This much servo power is overkill on a 35%, but WTH...🤣

I will say this....keep your fingers out of any pinch-point areas when you fiddling with these.....or you may be fiddling with one less digit!!!

[Ty Lyman]

A single HP A700 would be fine on ruder IF you can afford to lose the weight of a servo in the tail, which will be tough to do with a 200 on the front. If you need to tail weight you might as well make it functional. I would not go with a single on the ail though. It's not an issue of moving force but that a foam ail with that much surface area just does not have the torsional rigidity to handle being articulated from a single point.

[Toby Slihavy]

You can get ailerons as stiff as you want by using cf veil and cf strips running down the ailerons. Use a 0.5 x 10mm cf strip. Use one on top of wing and one at bottom. I just got done doing this veil/strip combo and it’s as stiff as a 2x4. I showed this technique in one of my tip discussions in our newsletters.

[Cam Shahrdar]

So Earle, I saw the maiden video. SO on that 35% beauty, only one servo per aileron?

[Earle Andrews]

So Earle, I saw the maiden video. SO on that 35% beauty, only one servo per aileron?

Hi Cam....yes, just one on each at the inboard location. These ailerons, while already pretty stiff span-wise, have also been reinforced at their centers with an internal carbon fiber/balsa laminate rib. The aileron horns are also solid,....dual aluminum horns captured to the base plate with a hidden cross-pin and then epoxied into the hardwood block in the aileron....machine screws and all.

Other than the 10 min maiden I have not had other opportunities yet to expand the flight envelope and fine-tune the setup. It also has spades (aerodynamic boosters) that will be mounted mid-span....after more flight testing. Those big servos don't need anymore power, the spades, while probably somewhat functional, are more for scale than anything else.

In the attached photo you can see the aileron horn and linkage (HD ball links, titanium turnbuckles, aluminum horns), and further towards mid-span the internal rib extension for the spade.

This plane was built for scale competition (not IMAC), although could serve as a back-up if needed. My goal is to fly it in a manner than closely replicates the full scale on....gotta cut back on that throttle ALOT!

[Charles Edwards]

So correct me if I am wrong here. This is not a true comparison or example of determining if one servo is a viable solution on ailerons. This is a 35% aircraft that is being flown in a scale like manner, not high energy 3D or high energy snap and roll combinations.

There was a gentleman on FG that went by the name of fixedwing that was a PRO builder of Cardens back a few years ago. One of the last build threads I remember him doing was an ultra light Carden 124 pro with short ailerons and utilizing 1 servo per surface. He ultimately converted it back to 2 servos and full span ailerons.

[Earle Andrews]

So correct me if I am wrong here. This is not a true comparison or example of determining if one servo is a viable solution on ailerons. This is a 35% aircraft that is being flown in a scale like manner, not high energy 3D or high energy snap and roll combinations.
......

Yes Chuck that is correct, although no one implied that it was a "true comparison or example....". It was an answer to Cam's question on my 35% Extra. I would not be surprised if handles high energy snap and roll combinations as well. Flight testing and time will determine that.

[Charles Edwards]

Definitely should not have any issues with a 35% especially with composite wings. Cool scale build by the way!

[Earle Andrews]

Thanks Chuck. Here's the important part

[Charles Edwards]

Very nice!

[Daniel Powell]

On my Carden Pro that was originally built for A DA200 I had a heavy Hub and the batteries all the way forward for the 170 Conversion. My rudder servos were mounted on the bottom of the plane ganged in push pull. I switched to single A700 for rudder push pull in the tail and removed the heavy Hub, also upgraded elevator and aileron servos to A700. 10oz savings and WOW the plane flies soo much better, granted the removed servos were around 580in/oz and had over 1000 flights. Plenty of rudder authority!

[Cam Shahrdar]

anyone else have experience with single servo on the rudder or on ailerons on 40%

[Steve Sides]

I'd be interested it putting one on the rudder a dumping that extra weight in the tail for sure. Ailerons though ???? As previously mentioned you have the stiffness issues of the ailerons to consider going to a single servo. But also consider the mount on the aileron itself. Basically taking all the force generated by 2 servos and 2 mounts and now concentrating that force into a single point. Earle had done an admirable job of beefing up his mount. I'm concerned about the mount giving up the fight. Not so much in complete failure but more of a loosening leading to flutter and all the consequences of that. I'm not sure I want to go down that path to save a few ounces of weight / wiring, etc.