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

[LoonyBob]

Under static conditions, propellors are running with a very high degree of recirculation, which remains significant up to 20~30kts foward speed (light aircraft). Recirculation gives a weird spanwise inflow velocity distribution on the blades, and so a weird lift (thrust) distribution - not very representative of flying conditions..

A look at fixed pitch props on TC'd aircraft (Cherokees, 172s etc) shows that a maximum static RPM of ~85% of full power RPM, will allow a healthy RoC, and WOT level flight without engine overspeeding; a 65% cruise of 1.5~1.6 Vs1 is typical, but 75% gives not much increase, as the prop is becoming depitched. This can be tweaked by adding a bit of pitch - a "cruise" prop - at the expense of a longer TOD.

Fitting a CS prop to such a beast will give markedly better TO performance, simply because the engine is allowed to develop near full power for the entire TO roll and initial climb. At the top end, the CS prop will not change the airframe's power needs, but should offer 5~8% better cruise.

Whilst Cherokee 172s are somewhat draggy, RAAus machines range from very draggy to very clean; however, a static WOT RPM of ~85% of full power RPM is a good starting point.

Note that most fixed pitch props for TC'd aircraft have "overtwisted" blades (twisted beyond optimal performance for the speed range in question), because (a) tradition [most propellor makers still don't use blade element theory!], and (b) it tends to meet the overspeeding requirements for certification without much difficulty.

Most (all?) composite RA blades are a tad undertwisted, which limits the propellor's efficient speed range.

 

In summary: a CS prop will yield near-optimal TO performance for any aircraft, though not much if Vs1 >= 30kts; and should give optimal cruise, but not huge increases, subject to blade twist. A VP prop is a step in the right direction.

The D18 gets a ground roll of ~110m, a healthy climb, and will cruise at Vno on a fixed pitch prop. The climb and fuel burn can be improved by drag reduction, and reducing the TO roll by ~15m is not worth the weight of a "live" prop...

[LoonyBob]

1 hour ago, skippydiesel said:

Hi Kyle,

 

Three questions:

• Is there a CS (Glorious) E-prop in Australia?
• Why have E-Prop opted for hydraulic pitch change, rather than one of the electric systems?
• Is there an In-Flight-Adjustable variant of the Glorious (or plans to offer one)?

Electric props tend to have slow actuation (the forces can be quite high), and I do know that an early version of a well-known German VP prop on a 503, used to "hunt" when using a CS controller, and sometimes allowed engine overspeed at the end of climbout. Hydraulic actuators give both more force & more damping...

[skippydiesel]

My limited experince is with the Airmaster electric system and way back when I was in GA, hydraulic .

 

So far (about 60 hrs) I can say the Airmaster is not at all slow to move between changes, seems to have no problem adjusting pitch, whatever the situation and neither hunts or allows overspeed.

 

The Airmaster can be used like a traditional CS, with the pilot controlling all pitch changes or in semi automatic ie preset Takeoff , Climb, Cruise.

 

[facthunter]

Adjusting the pitch stops is the only way to be safe with overspeeding.. Nev

[Blueadventures]

Fitted a 175 size 3 blade E-Props to a mates Vixxen A32.  The agent for foxbat is happy with them and said at least a 10 knot speed increase should be seen. The static is set at 5,410 rpm presently so will see what WOT S&L 2,500 feet gives and adjust accordingly.  The owner of the Bristelle at our airfield is totally happy with the E-Props he bought from Mark on the forum.

[BrendAn]

1 hour ago, Blueadventures said:

Fitted a 175 size 3 blade E-Props to a mates Vixxen A32.  The agent for foxbat is happy with them and said at least a 10 knot speed increase should be seen. The static is set at 5,410 rpm presently so will see what WOT S&L 2,500 feet gives and adjust accordingly.  The owner of the Bristelle at our airfield is totally happy with the E-Props he bought from Mark on the forum.

10 knots is a huge increase. What is it that makes e props perform so much better than other brands.

[facthunter]

The SALES Pitch??   Nev

[Blueadventures]

23 minutes ago, BrendAn said:

10 knots is a huge increase. What is it that makes e props perform so much better than other brands.

Best to read their webb site and Mark Kyles posts; from my experience like the company say set RPM for 5,500 at 2,500 ft straight and level and they are at their best, don't waste your time with any other setting.  I tried 5,800 after being at 5,480 rpm thinking that would be good, I instantly learnt that it's a no, no; could not even get to 100 kts.  Reset to 5,500 rpm and now 108 kts plus. I've fitted and adjusted 4 E-props now and many others and would not hesitate to recommend them over other brands around.

Edited May 8 by Blueadventures
spelling

[Blueadventures]

6 minutes ago, facthunter said:

The SALES Pitch??   Nev

Not really a sales pitch, more just stating what to expect speed wise compared to the original propeller sold on the aircraft.  They are sold with a guaranteed refund and like had been posted will loan a prop for a trial so you after fitting you either send prop back if unhappy or send payment; how many aviation or other products do that.  Best if any doubt track down an owner with one and seek answers about how they find them.  Thier a bit like when radial tyres overtook conventional tyres years back.

[Kyle Communications]

Eprops are designed from the ground up by very smart people versed in fluid dynamic and using some very trick software. They just dont copy and remix old designs. You have to remember that the Eprop for Rotax engines was specifically designed for the engine that has a gearbox. NOT a direct drive although later this year they will release their new prop for the Jabiru series of engines which is a 2 blade. You can of course get a 2 blade for a rotax but that is a waste because again it was designed for a gearbox engine. It also helps that it is the lightest propellor you can get with the latest materials. Everyone also notices the vast difference when starting and stopping the engine...no more big clunks..The blades are not wide like all other props..this reduces the drag of the propellor. One thing to remember of course is that reduced drag will affect your landing approach. Every single customer who has bought a Eprop from me has been super happy and every single one has had a dramatic increase in cruise speed. Also they all cant believe how smooth they are..they are a huge level above anything even with the best dynamic balance you can do on a normal prop. I have sold over 70 props now and in fact another 2 are on order this week. If you set them up as per the instructions they tell you then you will get the performance. If you listen to the "old guard" you will NOT get the performace. The designers know what they are doing.

One of the first few props I sold was for a A22 foxbat..he got 8kts increase in cruise..he used to love is Warp Drive props...he sold all 3 he had after using the Eprop. I dont want this to be taken as a sales pitch. It isnt. Its just information to chew on but the best recommendation is from the people that use them. I dont have to have any sales pitch..they sell themselves. 

[Area-51]

What does a blade replacement cost on these units?

[Kyle Communications]

I have never had to replace a blade only for anyone. Not sure on the freight cost but the blade themselves are AU$650 each. I would have to find out the freight.

 

Each part of a Eprop has a embeded chip in it with the parts specs recorded in it when its made. I will require the serial number of the broken part so they can make the replacement to the exact same specs. This is required for balancing of the prop to make sure the blade you require is the same weight.

[Area-51]

36 minutes ago, Kyle Communications said:

I have never had to replace a blade only for anyone. Not sure on the freight cost but the blade themselves are AU$650 each. I would have to find out the freight.

 

Each part of a Eprop has a embeded chip in it with the parts specs recorded in it when its made. I will require the serial number of the broken part so they can make the replacement to the exact same specs. This is required for balancing of the prop to make sure the blade you require is the same weight.

Thanks, just wanting to know for maintenance planning... Aware of the block chain micro chip feature; great idea...

[Blueadventures]

Some real life in service E-Prop experience just for info.  The prop I fitted to a Vixxen  A32 912ULS yesterday is achieving 5,400rpm S&L (This will be adjusted to get the 5,500 rpm in the near future)  The owner is happy and advises that at WOT at 5,400 = 127kts.

 

At 5,200 rpm his preferred cruise he now gets 122 kts (Was 108 kts with the Keiv propeller)  a 14 knot improvement and is totally happy with prop.

Edited May 9 by Blueadventures

[facthunter]

 Sales "pitch" was a play on words. Prop efficiency can be determined  in various ways and there have been plenty of them  of high efficiency  already produced perhaps not so much for what we fly . You can't invent thrust or get over 100% efficiency. Matching it to the Plane is always important. You can certainly play around a lot and get nowhere..  I'm not intending to bag this prop. I thought the Kiev prop was a great performer in a past experience  with a skyranger.  Nev

[Blueadventures]

1 minute ago, facthunter said:

 Sales "pitch" was a play on words. Prop efficiency can be determined  in various ways and there have been plenty of them  of high efficiency  already produced perhaps not so much for what we fly . You can't invent thrust or get over 100% efficiency. Matching it to the Plane is always important. You can certainly play around a lot and get nowhere..  I'm not intending to bag this prop. I thought the Kiev prop was a great performer in a past experience  with a skyranger.  Nev

All good, understand. Kiev are the preferred with Skyranger kits and UK builds historically.  I had a DUC first and very happy with it (my only dislike was the gold coloured anodised alloy boss that gets corrosion and needs attention otherwise the corrosion will get away) and now the E-prop which is the best by far.  Have experience with the heavy Fiti props would not buy one now, Bolly also on a Skyfox good prop and good service, similar to Kiev but in my description both are old style build materials.  DUC are good and a progression towards the lighter designs with better resins etc.  E-Prop are now the bench mark with their design and materials and now have many years in service and props in use plus 4,000 hours so one set should see out 2 Rotax engine lifes.

[Red]

On 09/05/2024 at 1:17 AM, Blueadventures said:

Some real life in service E-Prop experience just for info.  The prop I fitted to a Vixxen  A32 912ULS yesterday is achieving 5,400rpm S&L (This will be adjusted to get the 5,500 rpm in the near future)  The owner is happy and advises that at WOT at 5,400 = 127kts.

 

At 5,200 rpm his preferred cruise he now gets 122 kts (Was 108 kts with the Keiv propeller)  a 14 knot improvement and is totally happy with prop.

Importantly did he get that improvement in the airspeed/RPM ratio with no change in fuel consumption or throttle position?, without knowing that or having a manifold pressure reading for both setups it can't be taken at face value, you can of course change the airspeed/RPM relationship on any prop just by altering pitch but the engine load changes

Edited June 15 by Red