I have been in contact with Yuriy Yatsenko and he has expressed an interest in developing
some Pusher wood props with his CAD system, for electric.

The Yatsenko props are very light, have a broadish blade, and very thin at the tips.
I felt they were outstanding in their glow set up .
Works of art, really, if you have ever seen one.
 I think they would be very good in the electric application.

Yuriy has very specific ideas about props and why he designs them the was he does.
I think they would be an interesting addition to the arsenal  we have in electric power systems.

Yuriy said he would work up some prototypes for me to try out. 
They are re-pitch-able, and very efficient, lighter than APC thin blade electric.
and do not flex as much.

I am aiming toward 13 to 13.5 inch, 6 to 7 inch pitch ( to lower noise levels) and , of course Pusher.

He informed me, that he can make them any size, up to 20 ", and any pitch.

I don't imagine they being very expensive. No price has been mentioned yet.

What I would like to know is, would there be any interest among us electric fliers, in these props.

Please let me know.  The more he makes, the less expensive they will become.

Will,
This would be an interesting prop to try. Currently, the only wood pushers I know of are the Zinger prop kits (as Ted F called Zingers) and they are designed for IC applications with thick blades, they work but pull 35% more amps then the APCE's. You indicated the Yatsenko props are re-pitchable, since they are wood how are they repitched - sanding - steaming? I like the 12" x 5 and 13" x 5 as a good starting points for sizes based on the current 46 & 60 size airplane setups.

Best,        DennisT

That's interesting news, Will.
Assuming the desire is to find the size/pitch that says quiet at 13-1/2" of diameter ...
If we assume a 5.0 seconds lap on 70' foot lines and the "rule of 130" that says that prop tip noise will not be an issue if RPM X diameter is less than 130,000 inch-RPM, then ...
The theoretical pictch of the prop will be 6-1/2 inches.
Given that we typically measure the pitch at the flat face, this means a 5-1/2" pitch.
So I'd suggest a 13-1/2 X 5-1/2.
Bass or Beech with carbon veil stiffening might be a killer lightweight setup.

Dean P.

Hi Dean;  What I meant by the comment is, that I find the APC lower pitched electric pusher props noisier than
the higher pitched props I use.  I don't like noise in electric format.  electric needs to be kept quiet -
that is just how I feel, and no consequence to anyone else.  I do not understand completely the technical principles you mention
here - but I can still observe.   My system I am using, which incorporates an Orbit 20-18, with a
RPM/volt rating of 640, seems to like the rpm range the APC thin electric 13/6.5 pusher prop delivers on 5 cells, on 64 foot eye to eye
lines and a lap speed of 5.2 to 5.3 I can judge, with some accuracy, to what I see, what I feel, and what I hear.
 And what I have right now works for me and keeps me and the airplane happy.  

I don't think I will be suggesting anything to the Yatsenko brothers anytime soon with regard to prop design. They seem to know more about
props than I do breathing.  I want to stay on very good terms with these fine men, but there is a bit of a  language
barrier . so I would have to be delicate and very clear with my suggestions so as not to make it all go sour.  They seem to have very specific ideas about props, if you read their website on the subject.

But I agree, a stiff prop may be excellent.   Their Sharks are excellent with wood.
And I agree, a 13" to 13.5" 5.5 pitch prop may still work with my system.  Are you finding
lower pitch props working better in the maneuvers, in electric ?  

Please keep the ideas flowing, and thank you Dean for your suggestions.



  

XOAR will make pusher versions of their wood props, from what I have seen they dont need reinforcement and they are wood

To re pitch most wood props U have to sand that last inch of blade. For me it one of the ways I controlled lap times.
I still have a box of wood props laying around. The pitch of every single one has been modified at one time or another.

Russell,
The heat repitching of the wood prop is very interesting, could you get some details of the method - do they strip the finish and then heat or soak the prop in something (hot water or ammonia) before heating and twisting. It seems this would be one way (we use to warp rudders and wing tips on HL gliders by exhaling on them - like cleaning glasses- then twisting). It seems you would need to get the finish off to get it to take. Let us know.

Best,      DennisT

I asked Yuriy Yatsenko, about re-pitching  props, and this is what he told me:

He uses an air gun ( his words) that can produce 500 deg.F (300C)  .
Heat the prop in the place you wish to affect, up to 150 deg F (60-70 C) slowly,
then twist the blade slowly by hand and keep it in this position until it cools down.
The area will be like warmed plastic and elastic in property.  Elastic part will come back
to half your twist, so you need to twist about twice what you think.
He repeats the process until pitch is where he wants it.  After awhile you get the "feel"
for it, and you become better at it.
If you put too much pitch in blade, sometimes applying just heat
brings it back a bit. I imagine he checks his results with a pitch gauge.
Some people use hot water, but Yuriy uses the heat gun.

He mentioned to me that the area of most thrust is from the tip of the blade
and then down about 30% of the blade length.  Blade area closer to the hub
creates just 10 to 15%. 

Hope this helps.

Guys,

IT FRINKIN WORKED!!!!!!

I just did a heat only re-pitch of a stock Zinger wood 12x6 Pusher to a 5.3. I needed to move the blade by about 1/16" on each blade (that's what my pitch gauge is set at for my current ship), I used a Top Flite heat gun with the flow closed down to get max temperature. It works just like re-pitching a standard IC thick blade APC. You need to heat the first 15% of the blade off the hub, alternating front and back for about 2 - 3 minutes total, then put gloves on, grab the hub in one hand and the blade just short of mid blade and twist in the direction you want the pitch to move. As suggested a few posts up you need to twist about twice what you need (with the stock Zinger the blades are quite thick and strong, you need to really twist). I didn't need to hold the twist to long, only about 10 secs. What surprised me was that the finish didn't bubble or discolor at all, it was hot and soft but stayed in place. I rechecked the pitch after the prop fully cooled and the re-pitch held.

Best,                DennisT

Ha ha, I've seen 47c here where I live!!

Stinking hot!!!!!

I'd still be worried the props would spring back a bit, especially if the plane was left in the car on a hot day.

Guys,
This afternoon I put the repitched Zinger prop in the car were I would have my ship for transport, it was over 92 degrees outside. It sat for five hours. I checked the pitch and it held the repitch. Will try to do some flight test this weekend.

Best,             DennisT

Hi Will. Interesting, we seem to have the same idea allmost simultaneously I talked about this with Yuriy some weeks ago and it seems to be no problem to make a mirror image of his existing cnc program. But I'll have those for IC! It's not only something for electric guys From Moscov, L

47C???   YIKES I'd be worried about my composite prop turning into a noodle!

Yeh, that's like, what, 116 f.   That's hot !