E-Props Initial Impressions

[FlyingMonkey]

I finished installing and testing an E-Props 3-blade V20 "Durandal" series prop to replace my Neuform.  There was not really anything wrong with my Neuform, but it does have some cosmetic gel coat cracking (which Arian from FD-USA says is only cosmetic) and a few non-structural nicks in the plastic edge protector.  I was initially going to go with a Sensenich replacement., but after reading the positive comments here and doing some research, I decided on the E-Props.  The claimed performance is higher, price is lower (about $800-1000 less with spinner than Sensenich), and weight is FAR lower (4.4lb complete versus about 10lb for Sensenich).

Before I get into the prop itself, I want to give a shout out to Al Downs.  I bought this from him as an unopened NIB prop that he intended to to install but didn't get the chance.  The real problem came when the USPS *destroyed* the box with the spinner in it, and then delivered it with the spinner tip poking through the box and scraped up and damaged.  I had visions of getting screwed on this transactions, but Al was super cool about the whole thing and immediately ordered a new spinner from France and shipped it to me.  He's still working on a claim with USPS on the damaged spinner, but I was very appreciative that he took care of me and didn't wait for the damage claim to go through.  Thanks Al!

The install of the prop was straightforward, but I had a comedy of unlucky events trying to get the pitch adjusted.  First, I'll say I'm not really a fan of the hub design.  There are 15 bolts around the hub (which is carbon fiber), and you have to basically loosen all of them to adjust a blade.  Then you have to re-torque them all back incrementally, first to 6nm (~55in/lb), then 9nm (~80in/lb), and finally to 11nm (~97in/lb).  This makes it pretty time consuming to make a change.  I'm sure there are engineering reasons for this setup, but still a PITA.

Secondly, do NOT buy the E-Props electronic protractor tool.  Al has bought it and so it was included, but if I had bought it I'd be furious.  It is 50 Euro, and is literally this exact tool you can buy on Amazon for ten bucks:

https://www.amazon.com/dp/B08PYQ498P?psc=1&ref=ppx_yo2_dt_b_product_details

with the following 3d-printed object attached (print yourself if you have a 3d printer):  https://aircraft.e-props.fr/DOCS/HEPHOOK.stl

The unit requires calibration against a flat surface (like the face for the prop hub).  Then, if it stops moving more than a minute or so, it shuts itself off and loses the calibration!  So you are playing beat the clock and constantly fiddling with the protractor.  To add insult to injury, the protractor takes a long time to "settle" on a pitch number and loses calibration from even minor bumps.  So I ended up chasing numbers that would change seemingly on a whim.  Just don't.

I went to my trusty Warpdrive protractor, and I still could not get it to keep a pitch.  Then I realized, the pitch lock on my protractor had failed, and the protractor was wandering all over the place!  I ordered a new WD protractor and was interested to find they had changed to an all-metal lock.  Apparently I was not the only one this has happened to!  So a day wasted chasing the pitch, half E-Prop's fault (for offering a truly awful pitch device), and half mine (for being a dumb ass and not realizing my Warp protractor could not lock in a pitch).  Sigh.  Once that got sorted out I was able to pitch all three blades to the recommended 24.5° angle and go fly. 

At this point I will say that E-props recommends pitching to achieve level WOT at 5500rpm.  That seems pretty coarse to me, since my Neuform was pitched for around 5650rpm WOT which has worked great.  But I wanted to give the factory the benefit of the doubt on performance so their recommendation is what I was aiming for. 

The factory recommended 24.5° was way, way, way too flat.  On initial rollout I was expecting the RPM to be higher than I'm used to, since others have said that the prop seems a little "backward" that way.  But it immediately went to 5800rpm, so I knew it was too flat.  The RPM came down a little as speed built up and the prop loaded up, and it was accelerating okay so I did not about the takeoff.  I went around the pattern a couple of times and did a little cruise flight.  It did not act like a "too flat" prop.  Performance seemed roughly the same as my Neuform, maybe a tad slower in cruise.

Long story short (and a few adjustments later) I landed at about 27.1° to get the recommended 5500rpm WOT numbers.  I will say it does seem both a bit faster and better climbing than the Neuform factory prop.  Climb solo seems about 1150fpm, which is about 150-200fpm better than I usually see, and that number has been consistent.  I took a friend for a ride Saturday and with both of us loaded and ~26g fuel I still hit 1000fpm.  Impressive.

For cruise speed tests I climbed to 5500ft and got the following numbers at that altitude on a dead wind day:

5000rpm 117kt TAS

5200rpm  124kt TAS

5400rpm  131kt TAS  (126kt GPS ground speed)

5500rpm  132kt TAS  (WOT)

These numbers are better than with the previous prop, which at 5500ft and 5400rpm hit about 126-127kt TAS.  I glanced at the GPS speed at 5400rpm and saw 126kt GPS ground speed, so the TAS number looks pretty accurate to me.  I have the small, non-tundra wheels on my CTSW.

I will say that at lower RPM the E-Props seems about the same as the Neuform, maybe even a hair slower.  But above 5200rpm it seems to overtake the Neuform and by 5400rpm the difference is noticeable.  Couple that with the increased climb and it's a pretty good performance upgrade.  And I'm very happy to have titanium edges instead of the cheap Neuform plastic edges.  Lastly the weight is amazing, I'm saving 8lb useful load over the old prop.  I am still working on my W&B with the new setup, but I don't expect any bad surprises in CG...it flies the same as it always did both sol and with two up. 

The engine starts faster and stops more gently, but I didn't notice significantly better smoothness over the Neuform in flight.  It was fine, just not "better" in normal flying.  It does seem smoother the higher you go in RPM, so I guess the lower weight is paying smoothness dividends the faster it turns.  Again, this prop seems to like turning fast.

I still have more flying to do to get a full handle on it, but my 5hrs in FAA jail are done so I can wring it out a bit and I'll let ya'll know if I see anything else noteworthy.  The big test for me will come when I fly alongside my buddy's Waiex (Y-tailed Sonex) over a longer trip and see if I can keep up with him any better. 

Oh, and here's the beauty shot...I like the bigger and more aggressive spinner:
 

[mbenoit02]

Thanks Andy: you guys know how to make a full story short! The good news after owing few CTs with epro(CTSW, CTSLi UL, and today a brand new 2021 jetgrey CTLSi ) is that CT is back on track with excellent cruise speed.

in other words, I pick exactly the same speed numbers that you have displayed, with the same prop pitch, but with a CTLS weighting  333 kg. New fairing design helps as well.

https://photos.app.goo.gl/NMKxdyyJZERxKKdLA

Remember that the beautiful spinner can be order already prepared for future painting…