DIY clutched servo?

BruceMe · #1 06-15-2016, 03:41 PM

I flew behind the GSA 28 and now I can't go back to an un-clutched servo.

Have there been any attempts to build something like a clutch or anything like it?

The idea is that if the AP isn't engaged, it just slides with almost no friction.

Just wonder...

BobTurner · #2 06-15-2016, 03:43 PM

Trio uses a clutch in their servos - but I don't think it is compatible with a TruTrak driver.

BruceMe · #3 06-15-2016, 03:50 PM

Quote:

Originally Posted by BobTurner

Trio uses a clutch in their servos - but I don't think it is compatible with a TruTrak driver.

Per Trio literature
, It's a slip clutch. Which means if you really crank on the stick, it will allow the control to slip past the servo input.

What I'm asking is a clutch that only engages when the AP is on, so if it's not on, the control has no servo motor/gear resistance.

BruceMe · #4 06-15-2016, 03:52 PM

As a side note... I opened the TruTrak DSB-B servo. Internally the arm is connected to a really big gear that connects to the servo stepper motor. There's a IR sensor which appears to be measuring the servo shaft teeth for position.

It's actually really well made, just no room for a clutch.

BobTurner · #5 06-15-2016, 04:02 PM

Quote:

Originally Posted by BruceMe

Per Trio literature
, It's a slip clutch. Which means if you really crank on the stick, it will allow the control to slip past the servo input.

What I'm asking is a clutch that only engages when the AP is on, so if it's not on, the control has no servo motor/gear resistance.

I've had mine apart and played with it. I can assure you that when off the clutch physically disengages, and the external arm is very easy to turn. The 'slip' part is fail-safe #1; if for some reason it won't disengage, you can overpower it. (Fail-safe #2 is a nylon gear that will strip with sufficient applied force.)

As you can tell, I'm very happy with the Trio. Flies approaches a whole lot better than I do!

Weasel · #6 06-15-2016, 04:08 PM

Like Bob says. Trio has exactly what you are asking for. When disengaged, you cant tell it is in the system. I had one on the RV-4.

BruceMe · #7 06-15-2016, 04:11 PM

Quote:

Originally Posted by BobTurner

I've had mine apart and played with it. I can assure you that when off the clutch physically disengages, and the external arm is very easy to turn. The 'slip' part is fail-safe #1; if for some reason it won't disengage, you can overpower it. (Fail-safe #2 is a nylon gear that will strip with sufficient applied force.)

As you can tell, I'm very happy with the Trio. Flies approaches a whole lot better than I do!

Nice! Can they be found used?

BobTurner · #8 06-15-2016, 04:51 PM

Quote:

Originally Posted by BruceMe

Nice! Can they be found used?

I see the previous generation for sale here, from time to time. Take a look at the Trio web page to see what options you're looking for. Personally, with a -10, I really like the auto trim. On an ILS or LPV approach, I can reduce throttle, autopilot will hold GS and re-trim, and when I disconnect with airport in sight the plane is in trim. Also you can use the trim even when the autopilot is off. It's speed sensitive so it gives you fine trim in cruise, faster when slow. Requires electric trim, obviously.

Kevin Horton · #9 06-15-2016, 05:34 PM

Quote:

Originally Posted by BruceMe

Nice! Can they be found used?

The servo for the Navaid Devices wing leveller is similar, and you may find a used one if you look hard enough. If you do find a Navaid servo, it is compatible with the Trio control head.

BruceMe · #10 06-16-2016, 06:26 AM

Quote:

Originally Posted by Kevin Horton

The servo for the Navaid Devices wing leveller is similar, and you may find a used one if you look hard enough. If you do find a Navaid servo, it is compatible with the Trio control head.

First, tell your brother Timmy to work his way down to Kansas!

I actually own an old NavAid head I never installed. I'll try to find a servo. What the heck.