A Flap Push-Rod is not going to work post Mod 78
We spent several days studying how to modify the flap push-rod to work with both short and long wings (post Mod 78).
We were using the wood spar template supplied with Mod 78 since we didn't yet modify our spars.
We weren't able to come up with a modified shape of the push-rod that would allow clearance of the glider wing spars, air-brake cable and pitch cross tube in both the gear retracted and gear lowered position on our XS Monowheel. I know the Classic tunnel is different, so can't say for certain if same issues will be encountered.
As the push-rod is shaped now (pretty close to factory, just a tweak here and there), it clears short wing spar and air-brake cable, but contacts the post Mod 78 glider spar.
If the push-rod is reshaped to clear the post Mod 78 glider spar, it contacts the air-brake cable in the gear retracted position.
If the push-rod is reshaped to clear the air-brake cable in the retracted position, it contacts the pitch cross tube in the gear lowered position.
I am proficient at TIG welding and was prepared to bent, miter, create fish-eye joints and weld to create a push-rod of shape needed. If I could make it work with cardboard (Cap'n Crunch breakfast cereal box to be exact), I could make it work with metal.
It's not going to happen. Different components are trying to occupy the same space during different gear positions.
That said, I can reshape for a given fixed position. A push-pull cable can remain in a fixed position. Thx. Nev for the heads up that the first prototype Europa used a push-pull cable for flap deployment.
OPTIONS:
** Install an electric actuator. Could have the flaps chase the gear with switches (only two positions for flaps, up and down). Concern even with the faster motor is getting the outriggers to lock in the down position, but Andy thinks it should be OK. Of course could lock the outriggers in the down position, not kool and according to Justin (he has retracting in the wing outriggers) less than a knot at 130 knot difference.
Ivan thinks it's a bad idea to unlink flaps with gear for fear that chance of a gear up landing is very much increased (even though it will allow cross wind take off with less than full flaps).
** Try and shoot way high with the starboard air-brake cable. Things would be incredibly tight, but probably doable. Now you somehow have to get the air-brake cable to attach to the wing. The Series 6 cables supplied have very little ability to tolerate any deflection (probably less than 4 degrees in each direction), where Teleflex or similar can tolerate 8 degrees. So if you use some sort of bell-crank behind the seat, you would need to address that issue. Also would probably need a different length cable. Host of other issues would need to be ironed out, including making a reshaped push-rod.
**** The option we chose is to use a Series 6 push-pull cable. The mfg. is Felstar (dimensions almost identical to Teleflex), has a little less backlash. It comes with 5/16-24 male threaded ends, so the aft Heims fitting and front clevis screws right on.
Y13-11-27
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