I split the difference. On my Corsair which has a 9.25'' cord the bellcrank pivot point is 5 3/8'' behind the leading edge/2.5'' behind the wing spar. The BC is located in the outside wing panel behind the fuel tank and engine, and the carb. push rod travels through a copper tube soldered inside of the fuel tank. I once bought a class 1 plane that had the BC slanted to the low speed angle and the BC soon developed a worn spot where the pivot point came in contact with the throttle groove of the BC and when you tried to throttle back after the HS run it(the throttle) was locked in the wide open position. Oh boy was that fun. Anyway if its split you end up flying the HS portion with a little up elevator and the LS portion with a little down elevator. A little practice and its no big deal. eric

My concern is that, when installed per the 1955 directions, the slider-slot is pointed directly at the leadout guide, thereby precluding frioction on the slot.  Logical !

My origianl gut feeling was that line pull is highest at high speed, so the slot should be lined up proper at high.

Then, with the leadouts kicked back, the slot will be subjected to a 15-20 degree side load.  Not good, but maybe better than a side load at top speed.

The opposite logic might be that at low speed you need all the smoothness you can get to work the controls, so it needs to be proper at low speed and just live with the problem for the first 16 seconds of the flight.  It only needs to slide ONCE at an angle....

hummmmmmm....

Something that I've found is once the engine starts most if not all of the binding goes away. I think it has something to do with those 18,000 impulses per minute. Bob, I didn't know that you used the helper wire on the down line. Did Pete put you on to that? Your Vampires have the lines on the bottom of the wing as I recall so must have missed it. John Donaldson here in Reno equipped his Seahog with the same feature and now swears by how good it works. My planes don't have lead outs so never gave it much thought because I felt it might damage the flying lines. John uses the same set up I do and has had no trouble at all with his flying lines. The only time there is any contact is during LS and the line load is probably down at 8 pounds or less so it has work just fine. Your right that you have to see to understand how it works and how simple it is to install. I hope to see you next Sunday in Woodland and I can look at the Vampires. eric

Picture number two, the lines with the slider in the rearward position. The wire tether that the down line goes through limits the down line from going straight back through the lead out guide in the slider. This prevents the down line from "shorting up" due to the geometry change. I had to adjust it by trial and error to get it just right but that was easy.

It works well and does not seem to add enough friction to prevent good control.

Let me know if you have further questions.

Bob