Maximum throws?

[Dave Dupre]

I'm setting up a new 42% IMAC plane. This is the first time I have a chance to control every aspect of the plane (brand new). I know I will be running 10-12° elevator, 15-20° aileron, and maybe 15° rudder during normal sequence flying. However, what does this crowd think about the maximum throw you would make available at 100% servo travel? I was thinking 20° elevator, 20-25 aileron, and all I can get (40°) rudder. I like to have a little more throw available for landing/takeoff, but I don't want to give up too much precision. I'm using 1" arms on all the servos except rudder. I have total control of the control arm length. On the elevators, it looks like 1" arms and 1 5/8" horns gets me about 20° elevator using my servo tester. I haven't hooked up a receiver yet.

I will absolutely NEVER be flying any form of freestyle or aggressive maneuvers with this plane - precision only. Advanced for now with a hopeful jump to Unlimited eventually.

Dave

[Rich Whitlow]

I run about 25 deg elevator and 35 deg ailerons for snaps and landings.

[Steve Sides]

I think you're in the ballpark on throws. I like 1/2" servo arms on elev, 5/8" to 3/4" on ail and 1" to 1-1/4" on the rudder. The accompanying surface horns are a minimum of 2x (up to 3x) the servo horn length to maximize mechanical advantage. I put all the servos in front of a homemade protractor with a long (8") rod attached to the servo horn so I can more readily see the deflection. I adjust each servo for a minimum of 55% each way and 0% in the center. Then use that same rod on the servo installed to make sure the arm is parallel to the hinge line.

For snaps I have a logical switch set up to increase ail throw and decrease elev and rudd throw while the condition is met. The condition is triggered when the rudder and aileron are at the max position (max is whatever you say it is). This allows me to show good pitch departure while preventing the aircraft from getting too deep into the snap. I also run what some consider to be LOTS of expo - in the 60-70% range. Very soft in the center without giving up the throw when I need it.

[Dave Dupre]

Thanks. In general, if I have 2x mechanical advantage and 60° servo travel, I should get in the neighborhood of 30° surface travel. With 3x, I should get 20°.

[Steve Sides]

I guess I should be more clear. The 3x mech advantage is on the elev where I use very sort servo arms. Would be really hard to get 3x on a rudder with 1' to 1-1/4" servo arms. The control horn would be sticking way out in the airstream ! Might induce some drag lol !

[Dave Dupre]

A bit, yes. 😀