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FADEC/Prop Control for APEX

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Volzalum

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Nov 22, 2019
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Has anyone come up with a FADEC single lever solution for the APEX similar to the Rotax 915is yet?
In other words:
1) Full Digital control of the engine with redundancy, and
2) Variable pitch control (i.e., set it and forget it prop settings with TO, Climb, Cruise, Hold, and Feather)

I get that many folks like the separate lever for constant speed propeller, but a single lever system would be great and might play into the FAA changes for E-LSA coming in the next few years.
 

Volzalum

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Nov 22, 2019
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Thanks. As for the point, for me and possibly others, if building a plane, it would be nice to simplify the workload. Even though the prop lever on a constant speed and manifold pressure and throttle (standard 3 lever) is not difficult to use, it is most definitely easier to turn a dial to a preset setting and then let the Engine control the manifold pressure with a single lever. To each their own though.

The Apex engine looks like it is showing lots of potential to be used instead of the Rotax system for similar or less money. If someone can add 25 or 60 or 160 more horsepower vs the 915is without impacting the weight (maybe even for lighter weight), why wouldn't they want to do that?
 

slociviccoupe

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Palm Bay Fl.
You can do it with motec, haltech, maybe possibly speeduino or arduino.
Thoughtsxare snd not by aircraft standards by any means but how i would attempt it.
Throttle by wire throttle body controlled by ecu. This would allow your throttle lever to be the tps. Would be a where you want throttle held. The ecu will keep the rpm there based on rpm and load.
Ecu controlled boost controll. That way your not fumbling around and worried about map pressures.
Pilot selectable modes on a multi position rotary switch. Takeoff, cruise, and cruise lean.
Let the ecu control the prop pitch with a dual h bridge. Would use something similar to the idle air control chart. Ecu could hold engine rpm and adjust prop pitch and adjust boost.
At least this is how im going to try. And of course there will be ways to manually override
 

Volzalum

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Nov 22, 2019
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Yes. Something very similar in control the 915is but with the power of the APEX line of engines.
 

rbarnes

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I would write RS Flight. Their system is just an ECU that is made to run a fuel injected water cooled 4 cylinder. The prop control is the problem since they use a hydraulic governor that works with the Rotax engine.

I would also reach out to Airmaster and see if they have anything in the works for SLPC system for their electric constant speed props.
The Airmaster system almost does what you want already, but requires the turn of a knob from takeoff./climb/cruise settings that are preset.
 

Volzalum

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Nov 22, 2019
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Doesn't the Airmaster only cover the PropPitch Settings though? Or does it also interface with ECUs to control the Manifold Pressure/Turbo, etc.?
 

rbarnes

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Doesn't the Airmaster only cover the PropPitch Settings though? Or does it also interface with ECUs to control the Manifold Pressure/Turbo, etc.?
It adjust prop pitch to maintain a certain rpm, so it is watching engine RPM. Typically with a system like this and like what Cirrus did is you pick what your climb/cruise rpm is going to be and your more or less stuck with either that rpm or full power rpm. It limits the flexibility of how you operate the engine and propeller but cuts down on work load. Just like the difference between a manual transmission and an automatic. Once you come out of take off power with a SLPC you're going to reduce to a set rpm and then increase or decrease manifold pressure for that rpm. Dont lose sight that what you're doing with a C/S prop is like changing gears in a car and the power lever is your foot on the gas.

What you would need to do is set some kind of proximity sensor on the throttle that sees when you are full throttle for take off and sends a signal to the Airmaster controller that you want to pitch the prop for "take off" and then when you pull it back you go back to "climb" rpm as the prox sensor is activated and then to "cruise" when you pull power a little more to a cruise setting and activate another prox sensor
 

pwood66889

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Quoting the above: "It limits the flexibility of how you operate the engine and propeller but cuts down on work load. Just like the difference between a manual transmission and an automatic. "
To me, the unfulfilled promise of FADEC is one lever. Push for more power, pull back for less.
One must grant, however, the manual vs. automatic business. In my day, most all the race cars were stick shifted, while the daily drivers were auto. Makes perfect sense. If you're looking for max performance without adding anything mechanical that might keep you out of the class you are racing in, you go with manual and a good man (just speaking, ladies).
On the other hand (ladies, especially), if you are trying to keep a load of groceries from sloshing around, and a kid (or 2!) from rattling around, and all 4 fenders on your ride, not having to dedicate a hand to moving the shift lever is a blessing!
So we ask "What have you done for GA lately?" One good thing would be to lighten that work load! When it was the pilot and a single engine, flying out of an air field (large field, with wind sock in the middle. Contrast with air strip where one has a runway for take offs, landings, taxi tests, et al.) it was not that much.
but that just didn't scale well! Up the engines to 4, add other planes, a control tower, and so on - then is slipped into "Pilot Training." No problem when the pilot's other option was marching with a rifle on his (no her's at that time) shoulder.
Hope rant did not offend, but it seems that we have yet to do away with the flight engineer.
 

Volzalum

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OK. I guess I was envisioning how it worked differently. I thought the Rotes 915is FADEC system had a dial on the dash with Takeoff, Climb, Cruise, Hold, and Feather (i.e., basically the gears the prop is in from above discussion) and that the lever control lever (not the dial) was pushed forward and maintained the set RPM for each of the dial settings and the FADEC evaluated all of the engineer parameters to set the turbo, manifold, throttle, fuel flow, etc to the desired RPM and that the FADEC found the best fuel flow. So you could only reduce the RPM with the single lever.
 

rbarnes

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Yep, I have to catch myself thinking about it wrong too. Remember prop pitch sets rpm for a given air speed. Throttle sets how much power you're asking the engine to try push through the prop at that rpm. On non-boosted engines it doesn't matter since you're always running at WOT at altitude anyway and you're using prop pitch to choose what "overdrive gear" you want to run the engine in.

The dial you see on the dash selecting T/O, Climb, Cruise, Hold, Feather are Rotax 915's using an Airmaster prop and controller. RS Flight system controller is a true single lever system and it decides what rpm it will try and hold for a set power level. Probably using a logic similar to what I laid out above, but not sure since I've only seen a handful of installs. Try reaching out to Trent Palmer STOL on YouTube. He has the RS Flight system on his 915 powered KitFox.
 

slociviccoupe

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Are there controllers for electric constant speed props that have a position sensor. Or are they all dumb dual h bridges with limit switches? My spg-5 gearbox has through prop shaft ability but not means or provision for hydraulic govenor.

I can either run electric motor like a stepper or like a servo. If run like a servo ill need position feedback. If ran like a stepper it will cycle max both directions and controller will determine min and max values based on load from each point.
 

rv7charlie

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There are several electric props that have *rpm* sensors; they operate as constant speed props.

If your gearbox allows a through-shaft, then the servo can be behind the gearbox and your position sensor can be there. Keeping the electrical stuff behind the gearbox makes a much simpler and likely, more reliable installation. Some of the VW derivatives in motor-gliders used a manual (mechanical) pitch control, so it obviously can work.
 

cblink.007

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There are several electric props that have *rpm* sensors; they operate as constant speed props.

If your gearbox allows a through-shaft, then the servo can be behind the gearbox and your position sensor can be there. Keeping the electrical stuff behind the gearbox makes a much simpler and likely, more reliable installation. Some of the VW derivatives in motor-gliders used a manual (mechanical) pitch control, so it obviously can work.
So I am inclined to think the SkyTrax box cannot do this. Can the Rotax-C box accomodate?
 

rv7charlie

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No idea on either one. I was just offering ideas to sloci since he said he has through-hub ability. The 912 has through-hub; the RV12 puts its pitot tube through it. (The only reason I know about the 912...)

I may have inadvertently been misleading with my post. I was working on the assumption that he was attempting to 'roll his own'.

The commonly available electric props all use slip rings on the back of the spinner and put the pitch motor on the front of the prop. I haven't tried to keep up with the European stuff made for their light aircraft classes, but I have seen controllable props on many Euro models. Maybe that would be a good place to look.
 

slociviccoupe

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Palm Bay Fl.
My spg-5 from air trikes allows through shaft. Havent recieved it yet. But will be exploring this option when i get it. Would be nice to have the servo behind the box and not deal with slip rings. They offer a prop suited for this but its rorax hub size and i excede the hp limit for rotax sized prop. Have to see if airmaster will do a draw screw through the hub.
If so im planning on using a dual h bridge motor controller hooked to ecu haltech ecu or use an arduino to control prop pitch. Will have to be tested but vary pitch much in same way a cvt transmission would.
 
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