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  #46  
Old 01-17-2006, 10:10 AM
deuskid deuskid is offline
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Default prop primer 101

John - thx for the follow-up. I'll be following your findings with interest. I got questions tho ....

How is it the IVO is so much less expensive than other adjustable props?

How does it compare performance wise?

This is a recent post on a yahoo experimental group: <snip>
The Sensenich prop performes at least as good as the MT <snip>

writer is flying an H6 soobie.

Why is the MT the 'recomended' prop from Eggfelder [sp?].

Is there some resource that compares these 3 [and other c-s props]?

Thanks,

John
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  #47  
Old 01-17-2006, 10:39 AM
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Quote:
How is it the IVO is so much less expensive than other adjustable props?
I suppose it's because the IVO is much less complex to build. Most of the CS props are hydraulically controlled which requires various precision parts. The IVO is very simple in comparison. Just a torque tube embedded in each molded blade and an electric motor.
Quote:
How does it compare performance wise?
I haven't seen any comparison numbers. With the constant speed box the IVO might be similar in performance. One big difference, of course, is that IVO is not available for Lycoming engines. (IVO supplies aluminum tapes to show any relative movement of the blades. My tapes haven't budged.)
Quote:
The Sensenich prop performes at least as good as the MT <snip>
You'd need context to evaluate this statement. At least as good in what flight regime? Take off, climb, cruise, high speed, altitude? From what I've seen I'd be suprised if a fixed pitch could behave as well as a CS in more than one of these situations at a time.
Quote:
Why is the MT the 'recomended' prop from Eggfelder [sp?].
Maybe they haven't tried the IVO.
Quote:
Is there some resource that compares these 3 [and other c-s props]?
Not that I'm aware of.
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  #48  
Old 01-17-2006, 11:39 AM
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blanket statements

in flight adjustable and constant speed props have better climb, shorter takeoff, shorter landing, cost more money
fixed pitch props have better_________ - what they were optimized for and for us that is usually cruise

in flight adjustable and constant speed props available for pushers

MT = 9000
Aero composites = 13000
IVO = 3500 (not for lycoming or continental)
McCauley = $$$ Currently being tested by Velocity

Choice of control Electric for all, oil for lycoming and continental

Difference between CS and Adjustable - an automatic control based on RPM, you set the RPM, the controller sets the prop pitch for automatic, for in flight adjustable - pilot controls pitch
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  #49  
Old 01-17-2006, 12:10 PM
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Quote:
blanket statements

Actually - incorrect blanket statements

Quote:
in flight adjustable and constant speed props have better climb, shorter takeoff, shorter landing, cost more money
The IVO costs $2140. About $300 LESS than the 3 blade fixed pitch from performance.

Quote:
for in flight adjustable - pilot controls pitch
Not if you buy the $300 constant speed mod from IVO.
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  #50  
Old 01-17-2006, 12:14 PM
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Quote:
Originally Posted by John Slade

Not if you buy the $300 constant speed mod from IVO.
. . .

well then it is no longer an inflight adjustable - itsa constant speed prop
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  #51  
Old 01-17-2006, 01:37 PM
deuskid deuskid is offline
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I'd love to hear from others as well but it seems that unless some major surprise springs up the IVO seems 'THE' most logical choice.

Are there any negatives to using it [except for cost]? Is it less efficient at cruise? Will it 'cost' in fuel consumption or speed?

Thanks
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  #52  
Old 01-17-2006, 01:53 PM
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It will cost in cruise - for the same fuel burn - you will go 5 or so knots slower.

If you are gonna supercharge (turbo or not) and wish to fly high - the in flight adjustable (constant speed or pilot controlled) is the way to go - it will give you the bite you need at higher altitudes to take advantage of the hp you keep with a supercharger.

If you are going auto conversion - it is (in flight or constant speed) almost required as it will fit the HP curve to the performance waaaaay better.

If you are going airplane engine - then you have to go franklin as they will not sell you an ivo with a lycoming or a continental
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  #53  
Old 01-17-2006, 02:02 PM
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Quote:
Originally Posted by deuskid
I'd love to hear from others as well but it seems that unless some major surprise springs up the IVO seems 'THE' most logical choice.

Are there any negatives to using it [except for cost]? Is it less efficient at cruise? Will it 'cost' in fuel consumption or speed?

Thanks
Reported down-sides..
Some guys flying Tractor type aircraft (RV in this instance) have reported decreased performance at high speeds. The suspected reason is the inner portion of the prop blade remains "flat" while the outer portion of the blade flexes/twists. This flat area can be quite draggy. Our canard/pusher aircraft likely blanket this flat plate area so that its not as pertinent.

Requires meticulous attention to torque on the bolts. At some point, it DOES settle down, as John has experienced, but the blades are compressible. The practical result of this is: CARRY A TORQUE WRENCH IN THE PLANE. If you have a spinner, make sure you ahve the tools to remove the spinner and check torque, as needed.

Cant be used on certain A/C engines due to the nature of the torque pulses encountered. Lycoming 4 cyl and Continental 4 cyl are the primary culprits.

Dont consider me to be against the IVO.. to the contrary.. I've got one sitting at the hangar and its part of our plan. You asked for downsides, and I am providing the ones I know of so that you can make an informed decision. If you search this forum, you likely will find other discussion about the IVO when i was not in favor of its use, and my comments about it. Most of my decision about appropriateness for its use was based on the "drag" experience that some tractor guys had in high speed apps. Once some pusher guys spoke up about their experiences I changed my thinking.

Dave
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  #54  
Old 01-17-2006, 02:32 PM
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Sensenich is testing an electric C/S carbon fiber prop right now for the 180-260hp range, 2,3 and 4 blade it seems. Not many details available at this time.

Eggenfellner used to supply the Quinti electric C/S props but they are limited to 160hp. Seemed to work quite well. Light and inexpensive. Once the MT was introduced, most Egg buyers went with it despite the high cost and it just caught on from there.

The IVO has a bit of a stigma attached to it not being a "real prop" due to it's ultralight roots and twisting mechanism. There were some failures many years ago before the knurled capture plates were introduced. However you can't dispute it's low cost and good overall performance.

No need to carry a torque wrench in the plane. After the first 4 runs and 2 hours, mine took no more torque. After 6 hours, I only check it on annuals now. Never takes any, never breaks tapes. Brush life is over 50 hours now too.

My RV has trued 182 knots with the IVO at altitude. I don't really believe the flat plate root theory. At least the IVO has an airfoil here. Most FP props are club shaped at the root so there is no way that they produce any measurable thrust there although there may be less drag. I'd give IVO some credit in knowing what they are doing. Fine for us armchair experts to theorize what may or may not be true. Most of us don't know SH** about props or we'd be making our own.

Whirlwind has been bought by Titan Aircraft and plan some time in the future to offer an electric C/S version of their current composite/ hydraulic props but they are the same price as an MT.

American Propeller offers beautiful composite props for aerobatic aircraft currently. I saw these at Reno. No plans to produce for the rest of us at this time their tech said but that could change I suppose. The first company to offer a quality, electric C/S prop for the 180-260 hp engines at a better price than MT will do lots of business. Let me tell you, that is a hard check to write for the MT!
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  #55  
Old 01-17-2006, 02:46 PM
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Quote:
Originally Posted by rv6ejguy
My RV has trued 182 knots with the IVO at altitude.

Let me tell you, that is a hard check to write for the MT!
182 knots - great stuff - but that is also taking advantage of the turbo supercharger and the increased bite that that takes at altitude.

yeh - the check will be harder for me as i have heard 1 good story and 4 BAD stories on the MT - i'll probably go aero composit.
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  #56  
Old 01-17-2006, 06:37 PM
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StRaNgEdAyS StRaNgEdAyS is offline
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Quote:
Originally Posted by Dust
i have heard 1 good story and 4 BAD stories on the MT
Please share, I'm seriously considering the MT for my plane, I've not heard any bad and I'd like to hear about it if there is.
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  #57  
Old 01-17-2006, 10:36 PM
argoldman argoldman is offline
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Quote:
Originally Posted by rv6ejguy
Sensenich is testing an electric C/S carbon fiber prop right now for the 180-260hp range, 2,3 and 4 blade it seems. Not many details available at this time.

Eggenfellner used to supply the Quinti electric C/S props but they are limited to 160hp. Seemed to work quite well. Light and inexpensive. Once the MT was introduced, most Egg buyers went with it despite the high cost and it just caught on from there.
I believe that Egg is looking at the sensenich for use with the 6 cylinder with his new PRSU. He says that he will start publishing data around Feb 15 so hold on
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  #58  
Old 01-18-2006, 09:20 AM
deuskid deuskid is offline
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Quote:
Originally Posted by rv6ejguy
....<snip>

Eggenfellner used to supply the Quinti electric C/S props but they are limited to 160hp. Seemed to work quite well. Light and inexpensive. Once the MT was introduced, most Egg buyers went with it despite the high cost and it just caught on from there.

<snip> .... <snip>

My RV has trued 182 knots with the IVO at altitude. I don't really believe the flat plate root theory. At least the IVO has an airfoil here.
Ross - it sounds to me that you've made the IVO a sucess with a rotary tractor and John has on a pusher. Are there any others flying this combo? I wonder, would you and John make the same decision today?

Thanks

John
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  #59  
Old 01-18-2006, 09:44 AM
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Quote:
would you and John make the same decision today?
So far, yes. I'll know for sure when I see how it behaves at high speed / high altitude, then switch props and compare this data with the fixed pitch Performance.
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  #60  
Old 01-18-2006, 09:51 AM
deuskid deuskid is offline
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Quote:
Originally Posted by John Slade
So far, yes. I'll know for sure when I see how it behaves at high speed / high altitude, then switch props and compare this data with the fixed pitch Performance.
Thanks for the feedback... this and the new MT thread are just 2 of all the excellent examples where forums are at their best. I am acquiring knowledge and application experience that would take years in more convential venues.

Thank you - to all who make this such a kwel, valuable site.

John
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