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New E-Prop install


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2 hours ago, FlyingMonkey said:

Cost?  Prop diameter?

Also, I'm a little unsure about the statement: "the ability to achieve higher static and climb RPM (5400-5600)".  It's really hard to get apples-to-apples comparisons on that, and a lot goes into it "prop pitch, aircraft deck angle in the climb, etc).  Not saying you are wrong, I'm just wondering how you tested to see the differences.

I will be in the market for a new prop in the next year or so, I would love to see head-to-head comparisons against the Sensenich.

Andy,

 

My other CTLS has a Sensenich on it and this prop definitely out performs it in takeoff, climb and RPM.  I'm a big fan of the Sensenich and have over 2000hrs behind it but this E-prop pulls hard and runs smoother.  My Sensenich only turns about 4800RPM in climb while achieving 5650 RPM at full throttle cruise at 7500' Density altitude.  The E-prop turns 5450 RPM in climb and 5600 at full throttle cruise at 7500' Density altitude.  I estimate the increased climb rate with the E-prop to be about +300 over the Sensenich at the same weight.    

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3 hours ago, Madhatter said:

The e-prop does not twist in flight.

The only way I can think of for a prop to get a "constant speed effect" is to change pitch in flight.  Since the blades are fixed in the hub, the only way to get a similar effect is for the blade to twist based on loading.  If this is not what is meant, how the heck does it work exactly?

Or is it just a marketing term, meaning "our prop is more efficient than your prop, nyah nyah!" ??

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3 hours ago, Warmi said:

So am I .. I just quoted their marketing spiel  🙂 - I can't complain about the prop not running well and I know quite a few people who had this prop for 1000+ hours ( including Rich of Sting Flight who had his for something like 2000 hours I think ) so I am pretty happy with it ( do I have a choice ? it came with the plane ...)

 

Understood, thanks for the info!

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This is verbatim description from DUC docs - if I read it correctly it claims that twisting and deformation is not what gives it this mythical “constant speed effect” ... it is all about geometry - almost like one of these magical rings for you can get for  $19.95  to make you healthier/faster/thinner etc - I am not an engineer though so who knows ...

The aerodynamic properties of this propeller have been designed to have a "constant speed" effect. The blades that are made from unidirectional layers of carbon fiber prepeg epoxy and their structure has been defined in order to obtain the maximum stresses in torsion and bending. Therefore the effect of "constant speed" is not related to the deformation of the blade but its geometry and its particular profile.

 

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Sensenich has a new prop out and has had for about a year or so. It outperforms the ones you have on your CT's now by quite a bit I was told. The first one listed below is the ones out there on CT's now. The second one is the new one. You can get it in length from 65" -70".
 
prop model:  3B0R5 R68C-0
desc:  the original 3 blade 68" diameter rotax propeller, adjustable pitch, white with red tips, 
includes standard hardware kit and pitch gage system
 
New model: 
prop model:  3Y0R5 C70MY
desc:  latest generation 3 blade 68" diameter rotax propeller, adjustable pitch, white with red tips, includes standard hardware kit and airfoil template for use with protractor (not included). Price is right at $2380.
 
If you want one I can order it and save you a few dollars.
 
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1 hour ago, coppercity said:

Andy,

 

My other CTLS has a Sensenich on it and this prop definitely out performs it in takeoff, climb and RPM.  I'm a big fan of the Sensenich and have over 2000hrs behind it but this E-prop pulls hard and runs smoother.  My Sensenich only turns about 4800RPM in climb while achieving 5650 RPM at full throttle cruise at 7500' Density altitude.  The E-prop turns 5450 RPM in climb and 5600 at full throttle cruise at 7500' Density altitude.  I estimate the increased climb rate with the E-prop to be about +300 over the Sensenich at the same weight.    

I guess maybe my aerodynamic understanding is flawed.  Does it matter what the rpm in climb is?  I know a flatter pitch will turn faster for a given throttle setting, and that generally leads to better climb.  But doesn't RPM in a climb have nothing to do with anything except how hard the engine is loaded at that throttle setting (I assume we're talking WOT here)?  If you are turning 5400rpm in climb vs. 4800rpm,  why not pitch up more to load the engine and produce an even higher climb rate?

It sounds like what we're saying is that the engine has less load on it in a WOT climb, yet still climbs 300fpm more?  And yet the E-prop is loaded MORE in cruise (5600rpm  vs 5650rpm) at WOT?  Not sure how the prop is loaded both more and less than the Sensenich at a fixed pitch setting.  I suppose this is the "constant speed effect", but so far nobody can explain what that means.

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14 minutes ago, Warmi said:

This is verbatim description from DUC docs - if I read it correctly it claims that twisting and deformation is not what gives it this mythical “constant speed effect” ... it is all about geometry - almost like one of these magical rings for you can get for  $19.95  to make you healthier/faster/thinner etc - I am not an engineer though so who knows ...

The aerodynamic properties of this propeller have been designed to have a "constant speed" effect. The blades that are made from unidirectional layers of carbon fiber prepeg epoxy and their structure has been defined in order to obtain the maximum stresses in torsion and bending. Therefore the effect of "constant speed" is not related to the deformation of the blade but its geometry and its particular profile.

 

So are they saying the prop flexes *less* than a normal prop, and thus produces a better thrust profile.  This could make sense -- I don't know how much a "regular" prop loses in efficiency to flexing. 

I just really wish marketers would not use aviation terms that already have very well-understood meanings.  If what I said above is true, a term like "hyper-rigidity" would be way easier to understand.  It's like saying ADS-B has a "TCAS effect", though they are nowhere near the same thing.

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5 minutes ago, FlyingMonkey said:

I guess maybe my aerodynamic understanding is flawed.  Does it matter what the rpm in climb is?  I know a flatter pitch will turn faster for a given throttle setting, and that generally leads to better climb.  But doesn't RPM in a climb have nothing to do with anything except how hard the engine is loaded at that throttle setting (I assume we're talking WOT here)?  If you are turning 5400rpm in climb vs. 4800rpm,  why not pitch up more to load the engine and produce an even higher climb rate?

It sounds like what we're saying is that the engine has less load on it in a WOT climb, yet still climbs 300fpm more?  And yet the E-prop is loaded MORE in cruise (5600rpm  vs 5650rpm) at WOT?  Not sure how the prop is loaded both more and less than the Sensenich at a fixed pitch setting.  I suppose this is the "constant speed effect", but so far nobody can explain what that means.

I hear you Andy, I was surprised as well.  When I took off the first time and saw a momentary 5600 RPM on takeoff roll I thought, this thing is going to way overspeed in cruise, but as I accelerated the RPM's decreased to a steady 5400 on climb and just slightly higher in cruise.  The prop has a pretty unique looking airfoil to it.  RPM in climb does matter, that is the advantage of a constant speed prop, you can set a flat pitch for climb and higher pitch for cruise.  

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All I can say is fly with someone with an e-prop.

The company that makes this prop makes 30,000 blades a year and has been doing it for a long time. As an  aero engineer I am skeptical of many modifications and advertising. However if the data looks reasonable I will spend the money to try it, most fail but some are good and a very few are exceptional. The e-prop is exceptional. I have the data. If anyone is close by come see me. The other prop manufacturers should be worried. It's more than just performance is other things like vibration, no life limit, etc.

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3 hours ago, GrassStripFlyBoy said:

I wonder if they would offer a price break if we cold get 4-5 guys to bundle one order?  If anyone wants to inquire, I might pop on it.  Or wait for a better exchange rate to the Euro.

I would be willing to get in on this, but I hesitate because of the rule changes coming up in the near future. We might be able to get constant speed props in the next couple of years if the FAA gives in to what the community wants, so the experimental guys (and possibly SLSA crew as well, depending on what FDUSA comes up with) could have that option as well.  I would probably take an electrically adjustable constant speed option over this if I had a choice.

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1 hour ago, garrettgee2001 said:

I would be willing to get in on this, but I hesitate because of the rule changes coming up in the near future. We might be able to get constant speed props in the next couple of years if the FAA gives in to what the community wants, so the experimental guys (and possibly SLSA crew as well, depending on what FDUSA comes up with) could have that option as well.  I would probably take an electrically adjustable constant speed option over this if I had a choice.

According to this article , electric constant speed props are not necessarily an automatic win for small LSA planes.

https://foxbatpilot.com/2019/04/04/testing-an-airmaster-constant-speed-propeller-on-the-foxbat/

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3 hours ago, coppercity said:

I hear you Andy, I was surprised as well.  When I took off the first time and saw a momentary 5600 RPM on takeoff roll I thought, this thing is going to way overspeed in cruise, but as I accelerated the RPM's decreased to a steady 5400 on climb and just slightly higher in cruise.  The prop has a pretty unique looking airfoil to it.  RPM in climb does matter, that is the advantage of a constant speed prop, you can set a flat pitch for climb and higher pitch for cruise.  

Sure, but If the engine produces high RPM, it's making less thrust.  Imagine a prop pitched at 1° pitch.  The engine might make 10,000rpm, but the airplane would never get off the ground because the prop isn't making any appreciable thrust, even at that high rpm.

But again, I'm not an aerospace engineer and could have this all wrong.

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3 hours ago, Madhatter said:

All I can say is fly with someone with an e-prop.

The company that makes this prop makes 30,000 blades a year and has been doing it for a long time. As an  aero engineer I am skeptical of many modifications and advertising. However if the data looks reasonable I will spend the money to try it, most fail but some are good and a very few are exceptional. The e-prop is exceptional. I have the data. If anyone is close by come see me. The other prop manufacturers should be worried. It's more than just performance is other things like vibration, no life limit, etc.

Again, I'm not saying anybody here is wrong, lying, or the E-prop is bullshit.  I'm just trying to wrap my head around it.

"Too good to be true usually isn't" and all that.

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14 hours ago, Warmi said:

According to this article , electric constant speed props are not necessarily an automatic win for small LSA planes.

https://foxbatpilot.com/2019/04/04/testing-an-airmaster-constant-speed-propeller-on-the-foxbat/

Interesting article!  Sounds like for that price, the performance gains would be minimal, especially considering with even the neuform prop, airspeeds are close to LSA max, and takeoff performance is already great. Probably not worth the $13,000 price tag!

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