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Maverick
10-21-2020, 07:58 AM
I have a 912 ULS on a KF5 with a 72" IvoProp and cockpit adjustable propeller. I've been told I should run the engine up to 5,800 rpm and set the prop to 5,600 to fly. I tried this and could only get the engine rpms up to 4,800. I've flattened the prop as much as I can. I've read other threads that suggest that this might be a prop length issue. Does anyone have any experience with this problem? What was your solution?

Maverick

avidflyer
10-21-2020, 09:06 AM
I'm running a 72" IVO ultralight prop on my 912 80 HP engine, and have it set for about 5000 static rpm. Seems to be working good for me. With 20 more HP, you should be able to spin that prop pretty good... JImChuk

PapuaPilot
10-24-2020, 08:54 AM
Are you 100% sure you tachometer is correct?

Maverick
10-24-2020, 01:50 PM
Turns out that the circuit breaker for the adjustable prop was popped and I wasn't flattening the prop. Once I figured that out I was able to get up to over 5800 rpm. All is good.
Thanks.

Slyfox
10-24-2020, 04:10 PM
Turns out that the circuit breaker for the adjustable prop was popped and I wasn't flattening the prop. Once I figured that out I was able to get up to over 5800 rpm. All is good.
Thanks.
now that's funny. not always do I flatten until the circuit breaker pops, but that's how the system was designed. you flatten the prop, the breaker pops and your ready to land. at least that's what I do, flatten until no more rpm change and stop. well a couple flights ago I checked my prop before getting in the plane, works all the time even with the main off, and I didn't hear the prop. I thought crap, motor problems, than I looked on the panel and saw the breaker was popped. reset and all was ok.

Slyfox
10-24-2020, 04:13 PM
one more thing on the prop breaker, there is a bunch of wire that gets wound up and put under the panel. that wound up wire is actually the resistor for the breaker to work right. if you cut that extra wire out, ends up being a super amount of wire, the breaker will blow with the slightest use of the prop motor.

Eric Page
10-25-2020, 11:00 AM
Some time ago there was a lengthy discussion of the Ivoprop circuit breaker issues on the AeroElectric-List forum, and the forum moderator, Bob Nuckolls, designed a circuit that gently stops the motor without tripping a circuit breaker or requiring manual reset by the pilot. It was reported by at least a couple of forum members to work well. You'll find a link to the circuit schematic and Bob's description of how it works, here (http://forum.matronics.com/viewtopic.php?t=70658).

If you want to read the discussion that led to this design, you can, but it's a bit of a mission:


Start at this search link (http://forum.matronics.com/search.php).
Enter "IVO" in the [Search for Keywords:] box
Select 'AeroElectric-List' from the [Forum:] dropdown menu
Click the [Search] button

Because of the way the Matronics forums work (as a hybrid of online forum and email list server), the results are a disorganized mess, but it's all there.

There was a later design that I was briefly involved in developing that used a PIC microcontroller. I don't believe that it went any further than a prototype, and I don't recall that it was ever installed in an aircraft. Anyway, getting ahold of the firmware to run it could be difficult.