Don Orrick's Rudder Trim
Don Orrick, owner of RV-10 N401JA has this example of what he did for his flying RV-10 for Rudder Trim.Here's his note he sent me to post along with these photos:
"I had been working on a rudder trim system and thought I would share my version of a simple, straight forward manual rudder trim that I feel accomplishes all of the goals mentioned on the matronics list. First off, this is a PROOF OF CONCEPT system NOT the finished product. However it is a tested concept in that I flew with it to Talledega Ala. for the NASCAR race and back(1000 nautical miles) or more last month along with some local flying and it worked flawlessly. Isn't experimental great! Here's what I did. I purchased a cheap venier cable from McMasterCarr (6059K4), made a rudimentary bracket and attached it to the four bolts at the front.I ran the cable down the side of the tunnel and secured it with cable clamps. I cut off the cable to a workable length, remember to pull the center core of the cable out BEFORE you cut the cable casing. The pulley was made from a spare bearing that Van's sent in the tail kit for the elevators (I had it machined down and mounted it between two of the door mounts for the gas shocks I didn't use.) Anything similiar will work, also worth noting is the shield I placed around the pulley wheel this was added to keep the cable from getting tangled up when the cable has slack in it. the key here is the SPRING. It must have enough strength to pull the right rudder pedal down without running the venier out of adjustment before the plane is in trim, but also have enough spring travel remaining to overcome it IF left rudder would need to be applied in any emergency. This system allows both. I repeat the pilot has FULL use of the rudder at all times.The good news is that this is a common spring that was/is used for clutch throwout forks and can be cut to length and bought at any NAPA store. The system is used by applying enough rudder pressure with your foot to center the ball, pull up on the cable to hold the pedal and fine tune things with the venier. I found it easier to over center the ball to the left slighly and then screw the cable down to center,That's it. As you get set up for arrival at your destination simply push the center button of the venier and push down completely disengaging the cable. (this would be part of the arrival checklist just as flaps, etc. would be.) For those concerned about the rudder flopping while parked a lighter spring could be mounted on the left rudder pedal to soften and slow the movement of the rudder. I haven't done this to mine but will play with it down the road. The beautiful carpet from Flightline Interiors covers up the cable so it isn't obtrusive to look at. The final version would be done with a nicer mounting bracket and a real venier cable typical of a mixture control and wouldn't require the crimping together of the solid cable to the wire rope as I have now also a more secure/neater way of attaching the spring to the rudder pedal would be in order. Thanks, Don Orrick N410JA Flying"
Tim's note: Since nearly everyone requires RIGHT rudder to trim the rudder, this system is only installed on one pedal and is used to overcome most or all of that Right rudder trim force. It won't trim an out of trim requiring Left trim, but that should be a rare thing....only perhaps in high-speed smooth-air descents.
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