Originally Posted by larrykin
Mr May ---
thanks for info on sheet travel for a servo arm.
I'm no maths wizard but... a 3" arm with 90° rotation will produce 3" of line travel. At 180° will travel 6". How can it travel 6.28" with 120° rotation?
I was talking about my new Hitec drum winch and sheet travel with a Spektrum DX5e radio which has no travel limit adjustments. Winch specs say it turns 3½ times BUT may turn between 4 and 6 times with some brand receivers.
Winch travel = drum diameter (D) x Pi (3.1428) x number of drum rotations.
Hence - Hitec drum winch = 40mm D x Pi x 3.5 = 440mm or 17.3" of sheet travel
That seems like a large amount of travel........
does the above sound right re sheet travel?
17.3" is righ even if it is excessive for your boat.
Apologies about the mix up on the servo, I confused your post with the later post which is an arm servo. The diameter is 6" and if allowed to the sheet would/ could travel only 6" but you also get non linear sheeting, which then has to be dialed out using Exponential function on your transmitter. If the sheet is tracked around the circumferance of the circle you end up with 9" of linear or proportional travel.
The cheapest solution is to make a smaller drum for the 3.5 turn winch.