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MT electric governor?

rdamazio

Well Known Member
I've started reading up a bit more on engines, props, governors and such (I'm still halfway through the fuselage, so just researching).

I noticed that MT has an electric governor option, which technically gets rid of the mechanical prop lever in favor of any electronic controller. I think for the IO-540 that'd be model P-863-5 (vs the usual P-860-5).
As someone who used to fly FADECs, having one less lever on the quadrant sounds appealing, but I'm probably oblivious to the difficulties and downsides of installing and maintaining that.

Any pros and cons of the electric? Has anyone actually used one in their plane?

Thanks!
Rodrigo
 
Hydraulic

I spent a considerable amount of time researching this option. In the end, with the concurrence and recommendation of MT, I decided on the hydraulic. MT did not recommend the electric system for this application.

If you want less levers on the quadrant, go with EFII. No mixture lever needed...
 
I spent a considerable amount of time researching this option. In the end, with the concurrence and recommendation of MT, I decided on the hydraulic. MT did not recommend the electric system for this application.

If you want less levers on the quadrant, go with EFII. No mixture lever needed...

Thanks, that's very useful to know.
Yes, I'm already going with EFII :) I was hoping for single-lever.
 
Thanks, that's very useful to know.
Yes, I'm already going with EFII :) I was hoping for single-lever.

I have an electric CS prop, but not an MT.
Electric props in general are much slower to respond than hydraulic and have a tendency to "hunt". If you have an option to go hydraulic then I don't feel there is any up side to having electric.

I don't know if this applies to the MT electric prop governor, and would be interested to know.
 
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I have an electric MT with the constant speed controller on my Subaru engine, on my RV-7A. For normal flying it works perfectly. I?ve never experienced any hunting and the rpm stays constant during climbs level-offs, and descents.
I don?t do aerobatics which would require quick response from the prop.
If I had the option of hydraulic, I would have gone that way, but I am not disappointed in any way with the electric controller.
 
Yes, according to the Van's engine order form, electric is 6 times slower, but this is a -10 (IO-540), so acro is not a concern.
 
Also...

Also, you need to consider which prop. The MTV12 that Vans recommends is rated for 300HP max. If you are going with a tuned engine, CAI, and EFII, you will likely be right near 300HP.

The MT guys I spoke with recommend going to the MTV9 prop as it is rated for up to 450 HP. They said that the MTV12 is fine for the stock 260HP with a generous margin but running up against the max rating at 300 HP, well, they didn't seem comfortable with the drastically reduced margin...just an FYI.
 
Also, you need to consider which prop. The MTV12 that Vans recommends is rated for 300HP max. If you are going with a tuned engine, CAI, and EFII, you will likely be right near 300HP.

The MT guys I spoke with recommend going to the MTV9 prop as it is rated for up to 450 HP. They said that the MTV12 is fine for the stock 260HP with a generous margin but running up against the max rating at 300 HP, well, they didn't seem comfortable with the drastically reduced margin...just an FYI.

Ah, I just noticed the "290HP Barrett" on your signature :) that's a choice I haven't made yet (I know I want an IO-540 rather than something exotic, but haven't settled on the details).

What do you lose by going with the MTV9 instead of the 12? Weight? Thrust?
 
Loss

Well, the biggest loss is cash...the MTV9 is a little more expensive.

The gain is in weight, about 11 lbs heavier and, according to the techs, reliability of the prop...I am just relaying the message I received, YMMV
 
Well, the biggest loss is cash...the MTV9 is a little more expensive.

The gain is in weight, about 11 lbs heavier and, according to the techs, reliability of the prop...I am just relaying the message I received, YMMV

Thanks. Yeah, 11lb seems significant.
Any sources you can point me to so I can understand a bit more?

I'm mostly thinking that a heavier prop probably takes more power from the engine just to overcome its inertia, so I'm curious to know more about performance.
 
I'm mostly thinking that a heavier prop probably takes more power from the engine just to overcome its inertia, so I'm curious to know more about performance.

Er, no.......

It may take marginally longer to spin up but "take power from the engine" - no.

Electric CS is meant for use where no hydraulics are available (such as an auto conversion). The first choice is hydraulic. Sure, it will work. So, if you are trying to go single lever and the EFII needs an electric drive to interface with (I'm not familiar with the application), then there should be no issue other than extra cost.
 
Er, no.......

It may take marginally longer to spin up but "take power from the engine" - no.

(just in case it wasn't clear, that last question was about the heavier, stronger prop, not about electric governors anymore)

Well, it's additional mass that's being moved (rapidly, in fact), so the force/torque to move it needs to come from somewhere?
 
(just in case it wasn't clear, that last question was about the heavier, stronger prop, not about electric governors anymore)

Well, it's additional mass that's being moved (rapidly, in fact), so the force/torque to move it needs to come from somewhere?

F=MA.

It takes more torque to accelerate it, but it does not take any more force or torque to keep it moving at a fixed RPM.

It does take a little more lift from the wings to support the added weight, so there is a little bit more drag. But no - a heavier prop does not reduce cruise speed significantly just because the engine has to turn a heavier prop at a constant RPM
 
I am running MT electric on RV9a and a O320, It works fine, haven't noticed any hunting. If you are not doing Acro it shouldn't be a problem.
 
I am a little surprised no one has used a linear servo to control the CS prop control, connected to some type of controller. You could use a fairly simple map of MAP vs rpm to control the prop. You could also over-ride the servo manually.

That and EFI of some flavor, and you have most of a FADEC. Real FADECs also have some built in limiting functions, like rpm and overtemp limits. But it would give you single lever control.
 
I am a little surprised no one has used a linear servo to control the CS prop control, connected to some type of controller. You could use a fairly simple map of MAP vs rpm to control the prop. You could also over-ride the servo manually.

That and EFI of some flavor, and you have most of a FADEC. Real FADECs also have some built in limiting functions, like rpm and overtemp limits. But it would give you single lever control.

That's an idea to keep in mind - sounds like something I can experiment with after it's already flying, since it'll need the same cable installation and just adding the servo and controller (I'd probably think of a PID controller to maintain RPM rather than a fixed mapping).
 
look at

Here is an article discussing the Cirrus single lever system. It is mechanical but would lend itself, in concept, to automating the prop function.

The mod you are describing could certainly be accomplished but the question is why?...
 
I don't know anything about Cirrus's system. I think you would need a fairly fast servo, and it needs to be able to be overridden manually, and very easily overridden.

Other than than, I really don't see any problem. A true FADEC isn't mechanical, but basically FBW for the engine. Lots of new cars have been that way for a 10 years or so. You need an electronic throttle as well.

Lots more complicated, lots more testing. And you would still need a mechanical backup on a plane. The benefits would need to pay for the cost. I think the big Continental Lancair uses in the new Evolution automatically chooses to go LOP when it is OK to do so. You can accomplish that with EFI.

A single lever control should be comparatively easy.
 
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