Variable pitch prop design for electric

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Vigilant1

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Nice. Hmm...move the servo and a swashplate forward of the engine and the same approach could work for an IC engine. Lots more vibration, though, might rear the blades right out of the hub eventually.
 

kubark42

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Really cool to see more of this in the R/C industry. As you point out, the distance between giant scale and ULM is not far at all.

The one thing I didn't see was any discussion about the propeller. You can't just throw any old propeller into a variable pitch system. Are they manufacturing their own blades, or will they adapt someone else's?
 

TFF

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Late 70s early 80s I think Graupner sold a moving pitch prop for .60/10cc engines. The plastic blades were a problem. Done before serious CAD was available. If they had been able to use better blades, they would have been everywhere. Much easier to do today successfully. The F3A guys will be all over it in time. There was a company that made scale war bird props in the early 2000s. Looked pretty but the blades were fragile. After a few crashes of very expensive models after they threw a blade, they were done. Standard model practices of blades touching grass in a bad landing and being ok is thrown out the window. It is a scaled down prop strike once you think about it. They always make it too fragile.
 

Foundationer

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They've been about for RC electric on a small scale for ages. If you've got a conveniently hollow shaft the mechanism isn't that hard:


I was thinking I might make my own composite prop for what I'm building but why stop at that level of over complication when you can make your own prop AND a variable pitch mechanism. TBH if I want efficiency and to leave grass fields quickly I pretty much have to do that.
 

Vigilant1

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IVO twists a composite blade with an embedded torsion rod and DC motor. Works well, reliable, durable, many thousands in service going back 20 years.
Ross,
Thanks, I've been looking for a report on those IVO in flight adjustable props for a while. I do like that the root of each blade is rigidly bolted to the prop flange. Not only seems very secure, but less likely to have/develop any "slop" due to vibration or torque pulses.
Mark
 

rv6ejguy

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Ross,
Thanks, I've been looking for a report on those IVO in flight adjustable props for a while. I do like that the root of each blade is rigidly bolted to the prop flange. Not only seems very secure, but less likely to have/develop any "slop" due to vibration or torque pulses.
Mark
All true. Lots of props using traditional rotating spigots have wear, lube or even thrown blade issues. The IVO design does away with all those issues.
 

Dan Thomas

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IVO twists a composite blade with an embedded torsion rod and DC motor. Works well, reliable, durable, many thousands in service going back 20 years.
I had one on the Subaru in the Glastar. I hated it. I couldn't keep it balanced chordwise, as the blades would shift somewhat on their bolts even though it had the knurled plates and the bolts were torqued to specs. I couldn't use the neutral position, which was about where the pitch was best. Ivo warned about that, and I tried it on the ground; the prop blades fluttered alarmingly. And at that time (22 years ago) there were reports of blade and rod failures. The airplane's owner bought a Warp Drive and we used that instead. Didn't pull as well as the Ivo but was a lot smoother.
 

Vigilant1

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-it seems,NO composite,but plastic formed in matrics...?
"Plastic formed in matrix" ? The blade looks like it is made of a core material with an outer skin of reinforcing fibers in a matrix (epoxy?). These blades also have a LE metal shield.
Link to Ivoprop page (ground adjustable prop, but blades for in flight adjustable are the samel.2-Blade, LH Medium Quick Adjust Prop

Photo of blade root showing construction: IVOPROP - Propellers
 

Vigilant1

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I had one on the Subaru in the Glastar. I hated it. I couldn't keep it balanced chordwise, as the blades would shift somewhat on their bolts even though it had the knurled plates and the bolts were torqued to specs. I couldn't use the neutral position, which was about where the pitch was best. Ivo warned about that, and I tried it on the ground; the prop blades fluttered alarmingly. And at that time (22 years ago) there were reports of blade and rod failures. The airplane's owner bought a Warp Drive and we used that instead. Didn't pull as well as the Ivo but was a lot smoother.
Do you recall if the blades had metal bushings in holes? IIRC, there was a problem with IVOPROP blades shifting slightly in use many years ago, due to the metal bushings in the prop blades (torque down the prop bolts and the crush plate/hub was clamping down only on the bushings, not the whole root of the composite blade face). I think they eliminated or modified the bushings later to address this. All from my memory, subject to more informed opinion.
 

rv6ejguy

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I had one on the Subaru in the Glastar. I hated it. I couldn't keep it balanced chordwise, as the blades would shift somewhat on their bolts even though it had the knurled plates and the bolts were torqued to specs. I couldn't use the neutral position, which was about where the pitch was best. Ivo warned about that, and I tried it on the ground; the prop blades fluttered alarmingly. And at that time (22 years ago) there were reports of blade and rod failures. The airplane's owner bought a Warp Drive and we used that instead. Didn't pull as well as the Ivo but was a lot smoother.
The early IVOs had issues with non-knurled squash plates and bushings causing blade shifting. Zero problems with mine and I have dozens of customers flying IVOs, also with no issues. Mine has the knurled plates and no bushings.
 

rv6ejguy

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-it seems,NO composite,but plastic formed in matrics...?
Composite means more than one material- which these are. An MT is also composite- wood core, glass skin.

"Ivoprop Corporation, founded in 1984 by Ivo Zdarsky, is an American manufacturer of composite propellers for homebuilt and ultralight aircraft, as well as airboats. The company's headquarters are in Long Beach, California."
 
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