Balanced Control Forces

[Jim Meade]

I am not fully satisfied with the balance of the control forces on the SW. I'm not sure what I would change, but feel that roll, pitch and yaw inputs take different input forces to get a similar result. For example, in a climbing left turn, the amount of back pressure, left stick and left rudder that I put in don't seem to be in consonance. I don't think any of the forces are too light.

 

I wish I could be more precise in explaining my dissatisfaction.

 

Are you happy or not with the balance of your control forces? Have you changed anything? What would you change, if anything?

 

 

 

 

 

 

 

 

[Jim]

I'd prefer less stabilator authority. With the exception of soft-field work and practice stall recovery, I never use anything like the full range of authority. Ideal would be something similar to variable-ratio power steering, where the center range has reduced authority compared to the ends. I believe this would make landing a lot easier.

 

Any change like this would probably require a full complement of test flights, especially recovering from stalls with CG at the limits. Seems like it would not be practical as an experimental mod.

[Runtoeat]

It is hard to pin down what forces I don't like but personally I feel that my CTSW elevator and rudder efforts seem to be out of balance (lower) than the ailerons and the efforts in general seem to be more than I'd like. In particular, sometimes I get the feeling that my rudder has an "overcenter" feel to it and the efforts for this are also higher than my elevator. I don't know if there was a group of developers who agreed on the final setup for the CTSW or if there may have been one individual who set these up. Seems like if I took a poll of those who have flown my CTSW, the results would come out that most would like less effort in the controls. I have flown the Remos GT for a few hours and I liked the efforts on this aircraft. The controls felt much lighter and took much less effort than my CTSW. Those who have flown my plane have not complained but have commented that they were surprised that the controls weren't as "light" as they imagined they would be. Yesterday I gave a ride to a guy who's flown his Piper Cub hundreds of hours and he said he was surprised that the CTSW's controls took a little more effort than he thought they would..

[Jim]

It is hard to pin down what forces I don't like but personally I feel that my CTSW elevator and rudder efforts seem to be out of balance (lower) than the ailerons and the efforts in general seem to be more than I'd like. In particular, sometimes I get the feeling that my rudder has an "overcenter" feel to it and the efforts for this are also higher than my elevator. I don't know if there was a group of developers who agreed on the final setup for the CTSW or if there may have been one individual who set these up. Seems like if I took a poll of those who have flown my CTSW, the results would come out that most would like less effort in the controls. I have flown the Remos GT for a few hours and I liked the efforts on this aircraft. The controls felt much lighter and took much less effort than my CTSW. Those who have flown my plane have not complained but have commented that they were surprised that the controls weren't as "light" as they imagined they would be. Yesterday I gave a ride to a guy who's flown his Piper Cub hundreds of hours and he said he was surprised that the CTSW's controls took a little more effort than he thought they would..

 

The rudder has an over-center feel to it because it does. Sit at the controls and have a friend push the tail down to get the nose gear off the ground then try the rudder. There's a definite center detent.

[FredG]

The rudder and the aileron control mechanisms use a spring to overcome aerodynamic forces for the trim mechanism. The stabilator has an adjustable surface in the airstream to maintain trim so no spring is needed. That is why, on the ground, the rudder and the ailerons return to center after being moved from center while the stabilator does not. Forces needed to deflect the ailerons or the rudder, while in flight, are a combination of aerodynamic forces acting on the control surface and the force exerted by the centering spring. Spring forces can be changed with a change in the centering spring. My plane has a stronger rudder return spring, resulting in higher rudder forces, as a fix for insufficient rudder trim "authority" .

 

So, it may be possible to modify aileron and rudder forces, somewhat, by modifying the strength of the return spring in the system. Since you are experimental, I would think doing so is within your authority. To the extent that control forces are also a function of the leverage of the control mechanism against the slipstream, some of the force required will be much harder to alter (doing so would require structural changes to the control surfaces or to the operating mechanisms to alter the overall "leverage" of the stick or rudder pedals, which seems like uncharted territory.).

 

It will be interesting to see what you learn.

[Runtoeat]

Jim, the centering detent is what I feel. My personal impression of this is that it is overdone, same as the spring induced resistance of the ailerons.

 

Fred, I am also curious as to how one might change the feel of the control surfaces by adjusting the spring tensions. As you say this is uncharted territory and is not something I will do for fear of upsetting the aerodynamics of my CT. It sure would be nice to be able to talk this over with those who set up the CTSW at FD Germany and get the pros and cons of spring changes.

[FastEddieB]

 

Fred, I am also curious as to how one might change the feel of the control surfaces by adjusting the spring tensions.

 

Not spring tensions, but here's one thing that can possibly be done.

 

When I bought my Sky Arrow, I had had one test flight of another Sky Arrow. Someone delivered my plane to me in N GA from Atlanta, and I had to fly him back.

 

As soon as I flew it, I knew something was not quite right. The ailerons were very light, to the point that if you gave them a sudden input, or hit a bump, they'd oscillate for a few cycles before settling down. Felt like incipient flutter and I didn't like it at all.

 

I mentioned this to the dealer. He adjusted the ailerons so that they were slightly "reflexed". IOW, each is down ever so slightly when the ailerons are neutral. This provided just a tiny bit of damping and the ailerons feel normal now.

 

As a caveat, I would be VERY careful messing around with control "feel". It might not take much to end up in flutter territory. The settings in the AMM are probably there for a reason.

[Jim Meade]

Not to induce thread drift, but as a point of comparison, how do the LS controls feel compared to the SW? I have not flow an LS.

 

I flew a Tecnam 2008 and think it's control coordination and forces are far superior to the CT SW. I flew a Jabiru 250 and thought it had even heavier forces than the SW. Compared to an RV-6, which was more like the Tecnam, the SW is like driving a cement truck.

 

I appreciate everyone's concern for changing the control system. I whole-heartedly agree this is not a trivial exercise.

 

 

[Ed Cesnalis]

The LS came out with stiffer controls by design. I suspect the CTSW forces were incrementally changed. My early 2006 SW stick forces seem quite light.

[FlyingMonkey]

Be a little cautious with adjusting the spring tensions. Stronger spring rates may also be in place as an anti-flutter measure.

[Tom Baker]

Having flown both in the recent past I can say the LS controls are heavier. There are several different control set ups in the CTSW and a couple in the CTLS. The late 07 SW's had a spring on the elevator pulling towards the nose down position, and I know there have been a couple different stabilator, trim tab designs. For the most part they are lighter and touchier than the LS. The rudder and sub fin on the SW went through some changes as well in size and the tension on the centering spring. Some of the airplanes with the light spring could be yawed and would stay in that yawed position. The LS from the begining was designed to have heavier control forces to make it less twitchy. The rudders difinitely stiffer. The evlivator is not much stiffer, but with the longer tail moment it is less touchy. The first ailerons were very heavy, like OMG there heavy if you have not been flying one for a while. in mid 2008 they slowed production and changed to something like the Sw for aileron control force.

[coppercity]

I have over 600 hrs in the SW and 800hrs in the LS plus a few hours in the MC. The LS is less twitchy then the SW as mentioned, but I have to say the controls to me feel well balanced at cruise speeds. Things tend to get out of balance as you slow below about 70 knots, this is where the MC shines with a spring system on its elevator, it stays well balanced and very easy to control all the way thru the landing. I'd like to have that on my LS. The MC does not have roll springs but the aerodynamic forces on them are nice thru out the speed range. Everyone comments on how heavy the rudder feels in the CT, but I think that heaviness is needed since the rudder is so effective, maybe a dual spring type system with a lighter spring to start and a heavy spring toward max travel would get rid of that detent feeling.

[Roger Lee]

We have 3 axis trim.

If you use it the controls are always balanced for the most part. Mine can fly hands off at anytime and coming from helicopters I prefer a soft touch on the stick. It's all in what you get used to.

[Ed Cesnalis]

Roger,

 

I'm not sure that trimming has anything to do with balanced controls. While in trim and flying hands off if the ailerons require more force and travel then the stabilator then the stick forces are not balanced yet you can fly hands off.

 

I do agree it is all what you get used to. As you know I didn't fly for a couple years and when I got back in my CTSW I had lost the feel for the stabilator, when I'm not used to it it is pretty touchy, not so with ailerons or rudder.

[Roger Lee]

Howdy Ed,,

 

The stab is mechanically balanced outside the aircraft before install. Stabs are inherently more responsive than an elevator. You more or less have the entire tail surface flying and an elevator only partial. Stabilator type aircraft if short coupled will always be more sensitive.

As you just stated the more flying you do the less sensitive it feels because you acclimate to it. For those that have a hard time with a sensitive control, low over all hours in a CT or only sporadic flying time then more frequent flying would help. I fly twice a week and wouldn't want my controls any stiffer like a 182 station wagon. I prefer the Ferrari.