bending the pushrod for my retracts
 

I have a 60 size spitfire that I am putting together and I am having a really hard time putting the bends in the wire and having the landing gear work. I have installed the retract servo, but when I go to put the gear up or down it does not work right, it either not pushing the gear all the way down, or it is only pushing half way. The servo is working correctly, but it seems that the rod is not pushing/pulling like it should, if anyone can help me, I would really appreciate it cause it is driving me crazy

RE: bending the pushrod for my retracts
 

My limited experience with mechanical gear is that it must lock in the up and down position. Travel volume set at the radio is a method to accomplish locking. Spongy linkage or spongy bell cranks often prevent locking. If the gear does not go to lock in the up and down position it will not stay in place. Lock travel on gear that I have is anywhere from 1/8” to 1/4”of pushrod movement.

Bill

RE: bending the pushrod for my retracts
 

I've set up mechanical retracts on a few planes now. First off, BillS is right on about the spongy linkage. Make sure the pushrod is secured with a sleeve of some kind (like golden rods). However, travel cannot be set be the radio, as you use a retract servo, which is either on or off, no travel adjustment. A retract servo travels 180 degrees, and is only using power when it moves. When it is at either end of it's travel, the servo is 'off', so as not to constantly pull down your battery. You are using a retract servo, right? If you aren't, then there is no way you will ever get the mechanical retracts to work. Standard servos only work with air retracts.

Hitec sells a nice retract servo.

RE: bending the pushrod for my retracts
 

It sounds as if you are not getting enough throw on your pushrods. Depending on what servo you have, it should have come with a big wheel type servo arm that is quite a bit larger than all the other arms that came with it. This is the one that you are probally going to need. Bending the wires does not really increase the ammount of travel distance on the push rods. All the bending does it to obtain a bind free movement of the rod and to get the rod around any obstacales in the wing. You do of course want to keep all bends to a minium as each bend is another chance for slop in the pushrod. Most of the mechanical retracts need about 1 inch of travel to lock up and down. What I do is to just worry about getting one side to work correctly and then I know what I need to do for the other side. Good Luck, Dave

RE: bending the pushrod for my retracts
 

I have also only done a few. I used the big solid servo wheel. The I took the retract and measured how much throw it had from all the way in to all the way out. Then using the servo screw as a center point I drilled two holes directly across from each other at the same measurement as the retract throw. I hope this makes sense. Then I used those two holes to attach the pushrods. This way I was sure the servo was giving the retract the correct travel. The servo wheel also needs to on the servo so the two holes are parallel to the wing leading edge at each end of the travel.

David

RE: bending the pushrod for my retracts
 

Deadeye.

I have a set of retracts in a 64” span Chipmunk built by someone else and am far from an expert. The lock travel on the retracts is 1/4” on both ends and after they lock it appears that there is no way the retract could push back at the servo. To avoid bell cranks I am mounting a standard servo for each retract in the wing. Won’t be the first experiment that did not work out.

After tearing into the wing to find the sponge bell cranks I would always use access doors for anything that might need repair.

Bill

RE: bending the pushrod for my retracts
 

I've come across things like that on other people's 'could you fix this or that for me?' planes. I also installed a tail hatch on my scale TF 182 to get at the tail control surface linkage. Was a pain, but you can hardly see that it is a hatch and it is held on with magnets. With my luck, about the time I covered something up, I'd have to get in there to fix something.

RE: bending the pushrod for my retracts
 

Thank you very much for the info, it really helped, my retracts are finally working