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DIY clutched servo?

BruceMe

BruceMe

Well Known Member
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...
 
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BobTurner said:
Trio uses a clutch in their servos - but I don't think it is compatible with a TruTrak driver.
Click to expand...


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.
 
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.

HgvjXg


It's actually really well made, just no room for a clutch.
 
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BruceMe said:
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.
Click to expand...

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!
 
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.
 
BobTurner said:
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!
Click to expand...

Nice! Can they be found used?
 
BruceMe said:
Nice! Can they be found used?
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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 said:
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.
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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.
 
BruceMe said:
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...
Click to expand...

If you can tell the difference in flight between a modern stepper motor servo with no clutch and the GSA 28 as it relates to feedback on the controls when disengaged, you have some super senses :)
 
Brantel said:
If you can tell the difference in flight between a modern stepper motor servo with no clutch and the GSA 28 as it relates to feedback on the controls when disengaged, you have some super senses :)
Click to expand...

I didn't type that as well as I could have... TruTrak is always driving the gears, even off. And that's not cool to me. That's all I was trying to say. The GSA 28 has a clutch and when it's off... feels just like an RV should.
 
I have trutrak servos and they are not detectable when hand flying. But then, maybe there are some that can feel a pea under a pile of blankets......
 
I like the idea a lot and was planning to do this also, but was waiting to get in the air first. I hope you move ahead with it and good luck.
 
BruceMe said:
Nice! Can they be found used?
Click to expand...

The Trio was a copy of the Navaid servo and you should be able to find those inexpensively. However, Trio made some mods to better support the pitch axis and they only support their servo for the pitch axis.

Larry
 
Veetail88 said:
I have trutrak servos and they are not detectable when hand flying. But then, maybe there are some that can feel a pea under a pile of blankets......
Click to expand...

I agree. I have the Dynon servos (similar to TT) and while I can notice the servo if I think about it in the hanger, I cannot notice it in the air. Completely smooth. If you have the bias springs for ail trim, it has WAY less impact than that.


Larry
 
If you like the GSA 28 servos, why not just buy those? It looks like you can drive them with a G5. G5 ($1199) + 2xGSA 28 ($1500) + install kits ($150?) = $2849. Then sell your TruTrak gear...

Edit: You might need a GMC 305/307... not sure if that's really required with the G5....
 
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