E-Props ...who has first hand experience with these

[Kyle Communications]

Durandal is a tractor prop   Excalibur is a pusher prop and the Glorious is the new IFA constant speed one

 

[facthunter]

One measure of a prop's efficiency would be thrust/Shaft horsepower.  Nev

[RFguy]

cant compare unless airspeed /efficiency is in the picture.

I went four blade for rotax because of superior takeoff performance- more blades, less blade loading per blade and not as far into 'stall' if you like , IE AoA per blade lower , ---at low airspeeds much less than the screw speed.  Exact performance will depend a bit at what drag you end up with and IE what RPM your end up with.  Little / no penalty for 4 versus 2 blades with the Eprop at cruise speed. That's the advantage I like. AND Eprop will get you all this data...

[facthunter]

You tend to have a fascination with the complex. Our planes don't cruise that fast. There used t5o be rules of thumb that covered all the prop angle settings and Jabiru don't like  being overpropped.  Nev

[Kyle Communications]

Hot off the press from Eprop

 

This is a great video for how to set it up for any aircraft

 

 

 

 

 

[mhcrowder]

Ok,  We're finally flying with our Just Aircraft Highlander with a Rotax 912is Sport engine and the 3 blade ground adjustable Durandal eProp.  We're currently seeing  5450-5500 RPM at WOT level cruise (Alt 3000ft and MAP is 26.5 inHg) and 5000-5050 RPM in sustained climbs.  This seems to be where eProps wants the WOT level flight RPM.  Should we decrease the prop to get our climb RPM up a little higher?  We realize we'll hurt our top end cruise speed and improve our climb performance.  We're also trying to balance the 912is engine with it's Power/ECO modes.  

 

What is everyone's thoughts here?

 

==

Michael Crowder

[meglin]

We supply a 2-blade propeller with a diameter of 2 m (78.7") on this airplane and motor. With more powerful motors, 3 and 4 blade versions of the same diameter. Would be curious to compare :).

[RFguy]

For something like the rotax , for a prop pitched for max rpm at best climb, we  control climb RPM at WOT by pitching up the aircraft and slowing the aircraft down and prop RPM falls  to within limits.      Generally we do not fly at WOT  when S&L , this would mean an overspeed.

 

If you operate out of restricted ALAs, I would be pitching it for MAX RPM (5800) at  best climb . That is what matters most when you need to clear the trees.   You could also pitch for 5800 at  best angle (usually slower) but  might mean you overspeed at 75% cruise in S&L but that will depend on the airframe (drag behaviour)  and the prop . IE how much faster cruise is. 

If you pitch for 5500 RPM at 75% S&L, you might be leaving some climb performance on the table , that depends on  the difference between best climb and your 75% cruise speed. If there is not much of a difference, then pitching for best angle might still mean you dont overspeed at 75% S&L. 

 

BUT Different props will have different airspeed behaviour.

 

Edited September 18 by RFguy

[RFguy]

And also consider an airplane pitched for a student might be different to for a seasoned pilot. That is to say, maybe do not pitch the prop too fine such that the student is having to continuously be concerned with the engine overspeeding when the primary objective is to learn to fly the aircraft. IE might be pitched for 5500 WOT best climb to give the student some breathing space (but leaves some performance on the table) 

[Kyle Communications]

Read the instructions for Eprop..they are the designers and manufacturers..they say pitch for 5500 WOT in level flight. This is where the prop is most efficient

Setting it anywhere else you will obviously compromise the original design critieria. That drop off seems to be pretty large from my experience here with over 50 Eprop propellors fitted you must have a very high AOA on takeoff. most will climb at around 5200 to 5300 rpm when set to 5500 at WOT

 

[BrendAn]

15 hours ago, meglin said:

We supply a 2-blade propeller with a diameter of 2 m (78.7") on this airplane and motor. With more powerful motors, 3 and 4 blade versions of the same diameter. Would be curious to compare :).

what would you supply for an xair standard with a 582 and 2.62 -1 gearbox.

i got a quote on an e prop but that was far too expensive with our poor exchange rate.

[meglin]

Of course, the 3-blade propeller is 1700 mm (67") in diameter. It can be saber blades (quieter) or classic blades (cheaper).

If clearance allows, you can also go with 2 blades of 68,9". There can be saber, classic and ellipse-shaped blades.

There is no point in talking about price - it is always lower than quality. 

[Kyle Communications]

EXC-3-185-C4-T (X-AIR Rotax 582 gear ratio 2.62)

 

This is what you would require for your Xair

 

[BrendAn]

2 hours ago, meglin said:

Of course, the 3-blade propeller is 1700 mm (67") in diameter. It can be saber blades (quieter) or classic blades (cheaper).

If clearance allows, you can also go with 2 blades of 68,9". There can be saber, classic and ellipse-shaped blades.

There is no point in talking about price - it is always lower than quality. 

Nice looking prop 

[BrendAn]

1 hour ago, Kyle Communications said:

EXC-3-185-C4-T (X-AIR Rotax 582 gear ratio 2.62)

 

This is what you would require for your Xair

 

Yes. I had the model number from e props website which is excellent by the way.  But $4500 with spinner compared to $1900 for a bolly. I think we're below 60 cents exchange rate the day I got the quote.

[mhcrowder]

Got a response from Anne LAVRAND President / Sales Manager at eProps.  They think the prop is tuned where's it needs to be.  She even indicated that the WT9 with 912iS only gets 4800 on climb out and has been blessed by Rotax.

 

Thanks everyone for the advice.

 

Michael