Dana Overall posted a complete list of the parts required to make a pushrod the length required to reach the elevator in the back of his plane, which is only about 6 inches short of my plane. Now I know that Mark L only went part way, but you MUST consider the distance when making the pushrod. A mechanical engineer who built a T-18 put it this way to me, when I explained how I was making my tube from 5/8" 4130 tubing: "it will be fine to pull, but pushing will flex and ultimately bend it". That is when I bought 1 inch thick wall tubing and inserted the 5/8 inside, used AN3 bolts across at 90 degrees (see the site on Dan Heath's link to understand) to stiffen enough for safety. Lose the ailerons, substitute the rudder; lose the rudder, substitute ailerons; lose the elevator - pray!
5/8 tubing is good for short distances, but the farther the run, the larger the diameter of the tubing it needs to be. The RV series use something like 1 1/2 inch thin wall to run between 7 and 8 feet (difference between RV6/7 and RV8 I think). If it were ME changing to a pushtube, I first would NOT follow the path of the cable. I would make my pushrod go to the rear, thru the rear spar and then replace the balance cable as an actuation pushtube on THAT bellcrank. This will ultimately be a shorter run, easier to configure, fewer parts to make, and allow for the adjusting ends to be located inside the plane for ease of tuning and weather protection. One transfer bellcrank next to the stick assembly, slot in the spar, and bellcrank for side to side movement at the rear spar. Attach to the existing bellcrank of the aileron (clearance may need to be made for ends depending on connection type). Just my 2 cents... Colin Rainey brokerpi...@bellsouth.net
