Air-brake cables were used to determine feasibility and length needed
We used the Series 6 air-brake cables to determine feasibility and precise length cable we need.
The air-brake cables can only handle about 4 degrees of deflection in each direction. In other words the ability of the cable to follow other than a perfect in line pull or push.
The Felstar cable we will use has the ability to handle about 8 degrees of deflection in all directions.
This means if we can make the air-brake cable happy, then Felstar cable will be very happy.
We used the longer air-brake cable for the aft attachment and the shorter cable for the front attachment.
When connected to the flap cross tube, I adjusted things to replicate the Felstar cable. The only minor snafu is the air-brake cable only has a 3" travel where we need a 4" travel. We were happy to see things work and route the cable forward. The neat thing was that the aft cable was a bit less than a foot short of what we needed, but the amount needed was a perfectly straight run the the front attachment, so we measured what extra length we needed, then added it to the length of the air-brake cable to arrive at the precise length we need.
We will use bulkhead mounting on both ends.
4" travel rated at 170lbs. push and 400lbs. pull. Since the cable is routed very close to straight, when I asked a representative how much load in push did he think I would need to exert to fail the cable, his thought was it would probably be more than 500 lbs.
Some issues to overcome:
** The back attachment needs more ability to tolerate deflection, so we are using a plastic self aligning pillow block. The pitch tube tunnel will get reinforcement to hold the pillow block bracket in place (Three 3/16" screws, 4130 Chrome Moly bracket). The cable will be inserted from the back towards the front with the pillow block and bracket already installed on the cable.
NOTE: I think on an already built aircraft there is a good chance you could cut out the old push rod and remove it through the gear tunnel and save yourself an engine removal.
** Since the rear attachment can articulate, the cable needs the ability to move fore and aft just below the spars, so we are installing a clamp holder that will allow a little movement (Adel clamp and 2024 Aluminium bracket, Two 3/16" screws will mount the holder just aft of the fuel selector access cover).
** The front attachment is pretty straight forward, it will remain in a fixed position as the front attachment deflects less than the ability of the cable to tolerate. The wheel tunnel will be reinforced to hold the front bracket (Two 1/4-28 screws, 4130 Chrome Moly bracket).
Y13-11-27
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