E-Prop. Still a good choice?

[Jacques]

19 hours ago, Jim Meade said:

Jacques, what is your target RPM and do you vary that between seasons?

 

target is what E-props says .... about 5500 WOT level .... we got 5560 ..close enough  ....now , for our FIRST winter with the E-props, we got 2-3oo rpm less ..but I'll leave it  like this , as the next flight will only be in the spring

[procharger]

I set mine at 25.5 which gave me 5480 RPM level flight it works really

well at that setting for me. When going full throttle from a stand still it

turns about 5400 rpm in a few seconds once its rolling it grabs and drops

back to around 5180 on climb out I see 1350 when climbing out at 80

knots. Works really well CTSW.

[Jacques]

here what I just received from a friend...that owns a CT2K..the very first CT in Canada in 2004.

( the Kaspar is the in-flight ajustable propeller installed on the plane since new.) 

 

[GrassStripFlyBoy]

I've had a few flights with the new E-Prop, overall I'm thrilled.  I noticed when decending out of cruise phase (building or faster airspeed, and powering back RPM), there is a region around 4800 RPM where there is roughness.  If I power back, or power up, maybe 100 rpm it's normal smoothness.  Appears to be a dynamic of increased airspeed around the 4800 RPM mark.  Anyone else notice similar situation?  It's not major but is definitely noticeable.

[procharger]

Mine  does a little bit to.

[Anticept]

I would be surprised if anyone doesn't have a little vibration in certain ranges. You have a spinning fan that has an airplane cowling right behind it, so there's a bit of an air cushion in part of the rotation. Combine that with the complexity of the gearbox system and you have a recipe for resonance.

Just keep your ears open and listen to her, she'll tell you what she likes and what she doesn't.

[FlyingMonkey]

On 1/15/2023 at 3:38 PM, GrassStripFlyBoy said:

I've had a few flights with the new E-Prop, overall I'm thrilled.  I noticed when decending out of cruise phase (building or faster airspeed, and powering back RPM), there is a region around 4800 RPM where there is roughness.  If I power back, or power up, maybe 100 rpm it's normal smoothness.  Appears to be a dynamic of increased airspeed around the 4800 RPM mark.  Anyone else notice similar situation?  It's not major but is definitely noticeable.

Yeah same.  Something like 4700-4800rpm seems a little rougher/more vibey than the rest of the range. Not bad, just a little noticeable.  That might be the range of least aerodynamic efficiency for the "constant speed effect".  I'm used to it now, but there seemed to be a lower range, maybe 3000-3500rpm where the acceleration pull seemed a little weak as you accelerate through it, but it makes up for it with a more steady pull throughout the full RPM range.

Honestly slowing it down is my biggest problem.  It has less residual drag than the Neuform so it you're fast on short final you'll likely stay fast.  I get about 100KIAS at 4800rpm, which is pretty crazy.  If you want to cross the Atlantic and conserve fuel, this is the prop to have.

[GrassStripFlyBoy]

Thanks guys, I don't think this will be any annoyance - good to know it cross checks with others.  In summer flying I tend to power back further, this cold air has me trying to keep the RPM's up.

[SkyrangerRich]

Hi all. 

Minor update. Although the prop arrived in late December, it’s only in the last week that I’ve had the paperwork allowing me to fit it. Prop went on at the weekend.

I’ve run it up on the ground and am getting almost exactly 5500 max static, as I understand it that should also be around 5500 WOT in the air?

I now need to have an inspector look it over and sign it off for a test flight, then I need to do 5 hours of test flying before I can apply to have it officially added to the approved modifications list. 

So getting there, albeit slowly!

[FlyingMonkey]

1 hour ago, SkyrangerRich said:

Hi all. 

Minor update. Although the prop arrived in late December, it’s only in the last week that I’ve had the paperwork allowing me to fit it. Prop went on at the weekend.

I’ve run it up on the ground and am getting almost exactly 5500 max static, as I understand it that should also be around 5500 WOT in the air?

I now need to have an inspector look it over and sign it off for a test flight, then I need to do 5 hours of test flying before I can apply to have it officially added to the approved modifications list. 

So getting there, albeit slowly!

Yeah, 5500rpm WOT in level flight at your normal cruise altitude is ideal according to the factory.  Be aware that the E-prop acts counter to other props on the ground.  Most props on the takeoff roll have a lower rpm, then creep up as you pick up speed.

The e-prop is opposite, it will start off at high rpm on the takeoff roll and then come down a bit as you pick up speed and climb out.  It’s not a big deal, just be aware of it or it will really surprise you and you might assume something’s wrong.
 

When doing your WOT rpm test in flight, let the airplane stay at WOT for 10-15sec before recording the rpm…the prop will load up at first and rpm will come up as the airplane accelerates.

[Anticept]

Small correction, 5500 WOT at 2-3000 feet per the instructions. If someone is installing a prop where they can't test at that altitude, they should contact e-props

[Tom Baker]

The 5500 static will be close. Your in flight RPM may be a touch low. 

I just had a customer forward me a letter saying that E-Props are now EASA type certified. That should make your approval easier.

[SkyrangerRich]

1 hour ago, Tom Baker said:

The 5500 static will be close. Your in flight RPM may be a touch low. 

I just had a customer forward me a letter saying that E-Props are now EASA type certified. That should make your approval easier.

A touch low? Do you think I’ll need to increase the static revs a bit to get near 5500 WOT in the air?

I guess I’ll find out myself sooner rather than later… but the weather is not on my side currently!

Alas I don’t think the EASA certification will help - our regulatory body like to assess and approve all modifications on all airframe types. 

[Tom Baker]

27 minutes ago, SkyrangerRich said:

A touch low? Do you think I’ll need to increase the static revs a bit to get near 5500 WOT in the air?

I guess I’ll find out myself sooner rather than later… but the weather is not on my side currently!

Alas I don’t think the EASA certification will help - our regulatory body like to assess and approve all modifications on all airframe types. 

I suspect that you will be within 100 RPM. You are certainly close enough for a first test flight. It might be close enough that you will want to leave it there.

[FlyingMonkey]

9 hours ago, Anticept said:

Small correction, 5500 WOT at 2-3000 feet per the instructions. If someone is installing a prop where they can't test at that altitude, they should contact e-props

Thanks for that.

[SkyrangerRich]

Anyone else keep losing spinner bolts?

 Mine are all done to 5nm, but I consistently lose one or two in flight. 

I know we aren’t supposed to use thread locker on the blade bolts, but I think I’m going to need to put it on the spinner bolts. 

[Madhatter]

When I had my v12 prop I lost a spinner screw which damaged a blade. I now have the v20 prop but I use Locktite 222 low strength and no longer have an issue. The rivnuts in the spinner backplate have no locking ability. The only other option would be to use a longer screw and a locknut.

[Garrett Gee]

2 hours ago, SkyrangerRich said:

Anyone else keep losing spinner bolts?

 Mine are all done to 5nm, but I consistently lose one or two in flight. 

I know we aren’t supposed to use thread locker on the blade bolts, but I think I’m going to need to put it on the spinner bolts. 

 

1 hour ago, Madhatter said:

When I had my v12 prop I lost a spinner screw which damaged a blade. I now have the v20 prop but I use Locktite 222 low strength and no longer have an issue. The rivnuts in the spinner backplate have no locking ability. The only other option would be to use a longer screw and a locknut.

I haven't used locktite on any of mine and have about 75 hours over the last year and have not lost a single spinner screw.  I do try to put a screw driver on them occassionally just to make sure.  I am also using titanium screws, but I don't know if that will make a difference.

[Madhatter]

The spinner screws are not titanium. It's not worth taking the chance as a screw can take a chip out of a blade. If it exceeds the repairable size, then the blade must be changed or repaired by E-Props. Using Locktite 222 is easy to use and you can still remove the screws easily.

 

[Anticept]

Another option is buy some rubber washers.

[Garrett Gee]

2 hours ago, Madhatter said:

The spinner screws are not titanium. It's not worth taking the chance as a screw can take a chip out of a blade. If it exceeds the repairable size, then the blade must be changed or repaired by E-Props. Using Locktite 222 is easy to use and you can still remove the screws easily.

 

I'll adjust my original statement, I changed them out for titanium.  But either way, Loctite is probably the safest bet.  Also unlike e-props factory design, I use a small nylon washer under the head of the screw.

 

Disclaimer, I take ZERO responsibility, as this is not an e-props approved change.  But our Diamonds and Cessna all use a small nylon washer under the screws on their spinners.

[Madhatter]

The problem with a fiber or nylon washer is that eventually it relaxes due to pressure and the screw loosens. They are OK to use if you use locktite or have a locking rivnut. The E-Props does not.

[Madhatter]

Talked to E-Props today and they are aware of the loose screw issue. The use of a special locking rivnut used on carbon fiber is hugely expensive for now ( over $10 each rivnut ). They agreed that a drop of "low strength" Locktite would be acceptable.

 

[procharger]

teflon tape also works on screws easy to get out.