500ESP DFC binding at low pitch and extreme cyclic

[Steve Evans]

I've just upgraded my 500ESP to a DFC head and also updated the CGY750 to 1.31. I'm finding that the servo arms are fouling at low pitch and the extremes of cyclic now called for by the CGY750 setup. To get the suggested 10 deg cyclic my AIL/ELE rates in the CGY750 are both 75%. Has anybody with a 500 had to move to the next ball out on the servo arms? How has this flown?

Steve

[marc8090]

I don't have a 500 but sounds like you could either move the ball farther out on the servo arms which will give more cyclic and collective for the same servo travel, or, you could use longer balls on the inner ring of the swashplate to give only more cyclic for a given servo throw without affecting collective.

[Steve Evans]

The bit of info I missed there was that the PIT rate is +50% for ±12 deg of collective.

As I'm using a DFC swash I can't put longer balls on the upper swash to make cyclic more responsive, but leave collective alone. I have no option, I think, but to move the balls out one hole on each CCPM servo and hope they're man enough to handle the increase in load.

Moving the balls out from 13mm to 16mm should reduce the AIL/ELE rates to ~61 which falls smack bang in the middle of the recommended 50-70 range. Unfortunately it'll also drop the PIT rate down to ~41, but low as that is, I think I should be OK.

I'll give this a try and see how it goes!

Steve

[Steve Evans]

43% PIT rate with 63% AIL/ELE rate was much better, but I needed to set the cyclic ring to 110% to prevent the ELE servo arm hitting the AR bracket on full down elevator at min pitch. Hopefully I'll get a test flight in tomorrow.

Steve

[marc8090]

Those numbers sound excellent to me. Cyclics in the 60's and collective in the 40's is how my 700's are and it works just fine.

[Dr.Ben]

Having the PIT swash AFR % turned down to where you do will not cause a problem.

Ben Minor

[Nitroninjarr]

Awesome tip! My collective is good but could use a little less servo throw on the cyclic to eliminate binding. I did know this but didn't click until i just read this and i re-remembered. So much to know in this hobby i forget faster than i learn sometimes.