Hi all,
Please pardon me to jump in. My present project is not a Europa but a Dyn
Aero MCR 4S four seater, with a Rotax 914.
However we share many common concerns and maybe sonebody could ben
interested by our experience with trim tab servos.
The factory provided us with a system not unlike the one described in this
thread : a Futaba S 9001 RC model servo and a command box, to be connected
to the Ray allen stick grips. The command box is said to be derived from a
servo tester.
After installation, we found several shorcomings in the setup :
- The servo only holds position when the ship's power is on.
- When switching the Master on, the servo quickly goes to full travel before
going back to the assigned position.
- Several builders reported erratic uncommanded trim tab movements in flight
at altitude.
- Others reported interference problems with the strobe wires.
- No provision was made for end-of-travel switching.
Our opinion was there's more to the system than just a small servo tester.
On a fairly fast light plane, the trims must behave in flight , and
uncommanded movements are unacceptable. Besides, in case of power failure
the tabs MUST stay put. Besides the Rotax alternator really lacks in output,
and we'd rather not to tax it permanently for a sedom used system.
So we trashed the whole system and bought a RAC T4-5 servo and a tiny double
NAIS relay big as a sugar lump. Although the travel is rather short, the
tests proved satisfactory :
- No power, no movement possible
- No stick grip input, no movement.
- Limit switches are included
- No pulse signal to be interfered with.
- Away with the printed cuircuit and 70 gram box.
Flight tests are still ahead, for we still have the Rotax 914 to install and
rads and intercooler ducts to design.
For what it's worth,
Regards
Gilles
Grenoble, France
Wirng and systems 95% complete and smoke tested
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