Thought I’d share my experience with fitting one of the new DFC heads onto my 550E.
My only real concern with this style of head, compared to my original V1 with the one-piece blade grips, was the reduced distance between the centre line of the feathering shaft and the blade grip control ball. Having seen the newer V2 two-piece grips, I knew this distance was reduced changing the head geometry fpr the worse, which would in turn mean I have to alter the Vbar’s collective and cyclic travel values below the recommended 80% mark. As I didn’t want to do the latter, I looked into reducing the mechanical travel range, to bring it more inline with the old grips. Ideally I’d have liked to extend the blade grip arms outwards to match the original distance (I still might in time with machined spacers, anyone got CNC access?) but for the time being I fitted the shortest 3G control balls to the swashplate. This helped the cyclic travel range nicely, collective range is still a little higher than I’d like at 80%, but it works ok.
Like some others have found, it seems the solid control links are perhaps a little too long, meaning you have to wind in the servo to swash links quite a bit. To reduce this amount I shaved 1mm off the bottom of the plastic control links, so they could be screwed on some more.
This, coupled with 4~5 full turns on the servo links had mid stick back to 0 degree’s pitch.
My final worry was that of an easier to achieve blade strike in aggressive manouvers, although highly unlikely. My feelings are that out the box the stock Align dampers will be fine, but put a good few hard flights on them and they will loosen up and the feathering spindle will be able to flap. This could lead to a boom strike and if left unchanged put undue stress on the control rod fixing bolts, possibly leading to a fatigue failure over time. With this in mind I fitted the hardest dampers I could find, I went with the KBDD Extreme Edition For Hard 3d – Blue – Trex 600 (http://www.modelhelicopters.co.uk/extreme-edition-for-hard-3d-blue-trex-600.html) With these fitted the Vbar gain had to drop from 100% set previously using the KBDD Orange dampers, down to the 60% mark. However this could also be made worse by the geometry change with the new head design.
With the above done and setup it was off to the field for a test fly. Took a few lift off’s to remove some gain wobbles, but the model was soon whizzing around nicely. I can’t say I’ve seen a major improvement, as the model was already very well behaved with the Vbar dialled in, but boy does it look good! With more stick time I should be able to better feel the benefits this type of head can offer.