Control forces

[Dorsal]

While I am delighted with the nimble feel of my KF7 I have always felt the elevator controls where a little heavy. This has been added to by the fact that I finally installed my autopilot servos and the standard Dynon servo (32 inch pounds) is not up to the task on pitch as it slips trying to do the test pattern. While an easy (and likely) fix to this is to go to the slightly beefier servo I am curious as to what others get for stick forces in a 7 or SS on the ground. I have the spring assist so the elevator will hold a neutral position. My thoughts are that the drag may be coming from the slip bearing on the elevator pushrod halfway down the fuselage (I think this has been changed to a pivot support on the SS). If anyone out there has a similar set up in a 7 or SS and is willing to do a pull test at the stick I would like to know what forces you are getting.

[cap01]

dorsal , while i was completing the model IV i noticed the elavator was pretty stiff . as in if you pulled the stick all the way back , the elevator would stay up . i probably have a smaller elevator but the weight of the elevator alone wouldnt make the stick go forward . a coulpe of times a year i put a paint brush on a rod and reach back and lube the bearing with grease . i would like to be able to get back in there with some lps and see how that works but havent figured out how to do that yet . the grease does help some . never been an issue really since i dont have or intend to have an a/p .

[Newkid]

Dorsal, I just got done flying a Super Sport from Idaho to Phoenix and back. I felt the elevator was way to heavy, compared to the IV or Rans. There is a big gap between the elevator and horizontal, maybe a gap seal would lighten it up.

[ahazi]

After talking to Ty during the Desert Fox 2011 fly in, I became interested in the flying qualities of the KF4 vs the KF7. So as an extension to elevator force differences I was wondering if wing span has something to do with elevator stick forces.

Dorsal (and Ty)- how long are your wings? Do you have the horner (drooped) type ends or just the shorter wing ends.

Is there a relationship between wing length and elevator force? Is the aileron control lighter with the shorter wing? Most people that have shorter wing prefer it this way as the handling is more nimble.

I am just starting to build a KF7 and it seems that I will have to make a decision on the wing configuration or just build the optional extensions to shorten/lengthen the wings until I figure what I want.

Ariel

KSMO
Building KF7
Flying Diamond DA40-180 N469JP

[Newkid]

Ariel, My dad has had two long wing IVs and a IV Speedster. All had Hornier style wing tips. I have only flown the new long wing, but my dad told me they all felt the same in pitch. The Speedster's roll rate was quicker than the long wings and it also rode better through turbulence. I really think that sealing the gap between the horizontal and elevator would help. I know that filling the gap between the vertical and rudder on the IVs made it feel like the rudder had power steering.

[Dorsal]

I can not comment on the gap seal but for the moment I am dealing with the apparent drag on the elevator while on the ground.

[CDE2FLY]

Hi Dorsal - My Series 7 has the manual trim and elevator gap seals built in. The manual trim has a mixer of sorts to assist stick force through the full range of motion. I've always thought the elevator force is nice and light with plenty of authority to flare with flaps (I generally use the 1/2 flap setting on TO and landing). Not sure if you recall the stick force on mine when you flew it but it would be interesting to compare with yours.

Anxious to see your AP setup....the 914 conversion is nearly finiished and can't wait to get back in the air!

[napierm]

cap01,

Both on my KF3 and this 4 project the elevator was stiff due the plastic hinge bushings.

I reamed them out on the 3 in place (hard to do) on both the elevator and rudder and that freed them both up.

On the 4, the rudder has rod end bearings and is very smooth. For the elevator I borrowed a rt-angle drill (threaded bits) and just drilled the bushings in place to 3/16 - easy. Still no slop and not so tight as before.

FWIW,

Mark Napier