I couldn't find anything really mentioned in a search so I am looking for some info. I am going to add an elevator trim tab to my Model 3 and I am wondering if anyone has good info on required deflection and size that has worked for them? I was thinking 3 or 4 inches chord and 10 or 12 inches span on one elevator. If anyone has any experience with a trim tab on an early model I would love to hear about it. I also wouldn't mind any info for the later models as it gives a ballpark to at least start with.
That looks like what Ive been sketching in my head, though I was thinking of adding another spar and not have quite that much span. Do you know how much deflection you use? I am planning to use a 30mm Actuonix servo so I need to figure out horn placement.
For cruise flight, very little trim change is needed with my Kitfox. The Ray Allen electric trim I have is pretty slow, and so I rigged up something else for landing trim. Basicly it is a lever that tightens a bungee that goes from the joystick to the seat truss. JImChuk
Wait, what? So you welded a trim tab and a bay into the elevator but it was slow so you use a bungee system on the stick for landing? The servo I am using will be about 3 seconds for full travel and I am expecting to use about +- 10 degrees. Hopefully it all works out.
Hopefully your servo will be faster than mine was. In retrospect, I wouldn't tear off the fabric on an elevator to install a trim tab. I was rebuilding the entire plane though, so I thought the trim tab was the way to go. Live and learn they say. JImChuk
Giday, Lads. I'm in the same boat right now trying to figure out how to do an electric trim so I bought an Actuonix P16-50-64-12-P unit. I just told them I needed one that would travel about 50 mm in about 4 seconds each way with a 5lb push and they came up with that part number. I'm not sure how big the trim tab should be so I'll likely eyeball it after looking at some examples on the net unless one / some of you on this thread have figured it out....please let me know. I'm upgrading a not previously built KF 1 which has a smallish elevator so I'll make it's chord larger while incorporating the trim tab. I built a Christavia years ago but have lost the plans but that trim tab was perfect. I've decided to build wider main gear too so while I'm here asking questions, could you please advise what would be a suitable width to go to? I think some of you have done that. The stock KF 1 gear width is just 64 1/2" wide. I lucked out with my need for wheels and brakes too. I found a guy up in Labrador who can only fly on floats or skis. He sold me lightly used Matco brakes, wheels and tires for $100 !
Thanks, Dave
The tab I did is about the same size, it works great for cruise trim, but it does not have a
enough authority for low power and flap application needs.
Last edited by Av8r3400; 03-14-2022 at 03:31 PM.
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