Tweet
What you see here is conceptual but I have the motor in hand and have been tuning that to see if this is even feasible, I recently got it to work well so I thought I'd post this design. Not wanting to weld or otherwise modify the structure on my kit this is what I'm thinking for a bolt-on solution. Travel is limited to +-25 degrees per the RAC design guide. With the horn 1" from the hinge pivot I get 0.85" of travel stop to stop. I haven't worked out whether I'll attach a larger tab and right now you can see it's just the hinge leg, but this is an easy enough part to swap out and find what works. I'd rather have too small a tab to start and sneak up on the ideal size. I'm using an extension rod to minimize the cutout I'll need in the rudder skin as connecting it directly to the actuator made for too large a cross section intersecting the skin. The aluminum extension rod will thread onto the end of the actuator then pass through the bracket and nylon bushing. I'm thinking about the RAC threaded rod and clevis kit for the jump from the extension to the horn.
You can see I've put a housing around the actuator to prevent drumming of the fabric against the actuator body and to provide a mount for an access plate. There will need to be a pass-through for the rod going to the rudder trim horn, the standard one I've seen around is the plan there.
The actuator is an Actuonix P16-P, 50mm stroke, 256:1 gearing, coming in at a hefty 0.21lbs (95g). I'm using their control board to limit the stroke and speed, ~.85" and 20% respectively. I'm also using a 10-turn pot as the control which I think will work well, it seems to give very fine adjustment and will emulate the manual rudder trim knob I'm use to in the PA-28s I fly. Currently it takes 4 full turns of the pot to move the actuator .85", or stop to stop in this system, so it's a little more sensitive but still feels like enough throw on the adjustment. I'll have a position indicator on the panel above the control knob. Unfortunately the indicator isn't adjustable in relation to the stroke so at full deflection the indicator will only show 1/2 or so, but I think that will be ok so long as it's centered about the neutral point.
Weight wise the components shown add up to 0.52 lbs, though there are a few other brackets to account for. Using a conservative 0.75 lbs and a moment arm of 192" (estimated, I've yet to measure) I get an aft CG penalty of 0.09", or 0.75%. This doesn't seem too bad given the functionality.
I will need to wire into the rudder now, so another hole in the skin and possible weather ingress. The rudder also swings around so much these components are going to get knocked about quite a bit, I'm striving to make everything as tight as I can to reduce vibration and wear. The actuator itself is close to the rudder pivot so it won't see too much of this. With just the hinge leg as a tab this sticks out 1.25" from the rudder end and will be prone to damage easily, but it will also be easy (and cheap) to replace so that's not too much of a worry.
Rudder 1.png
Rudder 2.png
Rudder 3.png
You can see I've put a housing around the actuator to prevent drumming of the fabric against the actuator body and to provide a mount for an access plate. There will need to be a pass-through for the rod going to the rudder trim horn, the standard one I've seen around is the plan there.
The actuator is an Actuonix P16-P, 50mm stroke, 256:1 gearing, coming in at a hefty 0.21lbs (95g). I'm using their control board to limit the stroke and speed, ~.85" and 20% respectively. I'm also using a 10-turn pot as the control which I think will work well, it seems to give very fine adjustment and will emulate the manual rudder trim knob I'm use to in the PA-28s I fly. Currently it takes 4 full turns of the pot to move the actuator .85", or stop to stop in this system, so it's a little more sensitive but still feels like enough throw on the adjustment. I'll have a position indicator on the panel above the control knob. Unfortunately the indicator isn't adjustable in relation to the stroke so at full deflection the indicator will only show 1/2 or so, but I think that will be ok so long as it's centered about the neutral point.
Weight wise the components shown add up to 0.52 lbs, though there are a few other brackets to account for. Using a conservative 0.75 lbs and a moment arm of 192" (estimated, I've yet to measure) I get an aft CG penalty of 0.09", or 0.75%. This doesn't seem too bad given the functionality.
I will need to wire into the rudder now, so another hole in the skin and possible weather ingress. The rudder also swings around so much these components are going to get knocked about quite a bit, I'm striving to make everything as tight as I can to reduce vibration and wear. The actuator itself is close to the rudder pivot so it won't see too much of this. With just the hinge leg as a tab this sticks out 1.25" from the rudder end and will be prone to damage easily, but it will also be easy (and cheap) to replace so that's not too much of a worry.
Rudder 1.png
Rudder 2.png
Rudder 3.png
Comment