Question on the "Rudder Trim System"...

noelf · #1 04-15-2010, 06:03 PM

...from M.L. Skunk Works. For the users that have installed this on a flying aircraft, were you able to remove the rudder trim tab / wedge that gets placed and size refined during Phase I testing? Or do you just leave the existing tab in place and just finesse the trim with the "new" trim wheel??

DeltaRomeo · #2 04-15-2010, 08:22 PM

Quote:

Originally Posted by noelf

...from M.L. Skunk Works. For the users that have installed this on a flying aircraft, were you able to remove the rudder trim tab / wedge that gets placed and size refined during Phase I testing? Or do you just leave the existing tab in place and just finesse the trim with the "new" trim wheel??

Left the tab on. I only have one flight on the newly installed system (plane down for some repainting right now), and I figure I'll have to tweek the trim system to get it squared away (didn't test it in flight on that one time it has flown). I only intend to use it on those 90kt hand flown IFR practice approaches - the wedge on the rudder is set for cruise flight (ball is about half out at 90kts).

I should have some more data in a week or so.

Bob Axsom · #3 04-15-2010, 08:55 PM

I installed the system on my short tail six and I left the wedge in place. The airplane is not known for its great rudder sensitivity. I tried several springs and although the system functions as designed it just didn't feel right to me personally so I disconnected it and I still have the wedge in place.

Bob Axsom

Update: I removed the wedge and installed a ground adjustable tab that is removable with screws. That is the best solution I have found at this point. There is a thread with photos in the forum somewhere.

Bob Axsom

David-aviator · #4 04-15-2010, 09:49 PM

The only time I need rudder trim is in cruise. For local low speed sight seeing the ball is about centered.

I usually sit there with my left foot applying a slight amount of pressure to keep the ball centered. Obviously, that gets tiring after a while.

The mechanics have not yet been worked out but a solution could be a left rudder cable brake of some sort for long cross country flight. Something that would clamp and hold the rudder cable until not needed.

If I ever figure it out and it works, I will post it.

L.Adamson · #5 04-15-2010, 10:07 PM

Quote:

Originally Posted by David-aviator

The only time I need rudder trim is in cruise. For local low speed sight seeing the ball is about centered.

I usually sit there with my left foot applying a slight amount of pressure to keep the ball centered. Obviously, that gets tiring after a while.

The mechanics have not yet been worked out but a solution could be a left rudder cable brake of some sort for long cross country flight. Something that would clamp and hold the rudder cable until not needed.

If I ever figure it out and it works, I will post it.

The RV "6's" that I'm familiar with, never had a built in vertical stab offset, as the newer models have. Unless.... it was built in when the sixes went to the taller tail, which I'm not too familiar with.

With out a tab or wedge on the "6", it really does take a fair amount of foot pressure to center the ball. Yet, just that 5" or so of a tab or wedge, makes all the difference.

Therefor, there is going to be quite a difference when it comes to thoughts in regards to the spring assisted rudder setup, due to different models. I don't have the "system", but I could almost guarentee that you wouldn't want to remove the tab/wedge on a short tailed "6". The spring would really have to be strong on one side, to compensate.

I'd still like a rudder trim though. Just for those times when my cruise speeds vary over quite a range.

L.Adamson --- RV6A

gasman · #6 04-15-2010, 10:31 PM

[quote=David-aviator;424316]The only time I need rudder trim is in cruise. For local low speed sight seeing the ball is about centered.

I usually sit there with my left foot applying a slight amount of pressure to keep the ball centered. Obviously, that gets tiring after a while.

The mechanics have not yet been worked out but a solution could be a left rudder cable brake of some sort for long cross country flight. Something that would clamp and hold the rudder cable until not needed.

If I ever figure it out and it works, I will post it.

[/QUOTE

David, try this..... on the center nylon block, remove the washer and tighten down on the nut to increase friction on the cross tubes. Enough to be a pull by hand, but your feet won't notice the difference.
With the friction set, the rudder can be set in position during cruse with just a tap on the pedals. If you can't get enough friction, you might need to do the same to the end blocks also. This has worked great on my 6A for 300 hours.

49clipper · #7 04-23-2011, 10:21 PM

I installed the rudder trim system from Skunks works and it never worked at all. I tried everything I could, heavier springs, tighter cables, loosened up the tail wheel springs, nothing worked at all. It has no effect. I don't know if my rudder bar is too tight, or what but that spring setup willnot move the rudder pedals at all. I gave up on it. Save your money.
Jim

woodmanrog · #8 04-24-2011, 05:33 AM

I have been flying with the Skunkworks rudder system for well over a year now. Here are my thoughts. I thought there would be an advantage as we could adjust trim in cruise during flights. It turns out that anywhere between 2200 and 2600 rpm (fp prop) there is no change to adjust. The ball stays centered all of the time. I had to tighten the adjusting knob so tight so to keep it from moving that I can barely move it by hand at all. If it is looser, the springs and wind pull the rudder system out of trim. I had a tab originally and eliminated it. After all, isn't that the purpose of internal trim? If I had it to do over, I would just leave the small wooden tab on the rudder. Less weight, less trouble, less money. By the way, I still need to put in rudder on takeoff and climb, but that's the only time.
Woodman
RV6A with Counterbalanced Rudder

Bob Axsom · #9 04-24-2011, 10:32 AM

I flew with the plastic wedge for several years and as I modified the plane the performance changed and the trim could not be adjusted to compensate. As I said earlier I tried the spring system and found it unsatisfactory. I developed a removable ground adjustable 0.032 2024 aluminum rudder tab and it works just fine.

Bob Axsom

dbuds2 · #10 09-04-2011, 04:46 AM

Anticipating the need for some rudder trim, I thought of a system to run thin (1/8") bungie aft and attach one end to the left rudder cable and one to the right rudder cable. So the bungie runs along the front of the wing spar, just below the stick, then each end thru the spar/wiring holes, and then each bungie end goes aft along to the cable to attach to the rudder cable in the battery area.

My thought is that I can reach down, slide the bungie left or right to put enough spring tension on the rudder control. The forces from the bungie are easily over powered by foot and rudder operation.