Over the past 3 years we have brought out 4 new electric pusher props
that fit around "gaps" in their product line.  I have established a
pretty good rapport with them, basically I take them a request, they ask
me to buy 200 props as a launch order, the ECL community buys them (at
least most of them) from me and all is in balance.  There is NO CHANCE
that I will get rich off this, but thankfully I have not gone broke
either.  That should keep on as long as we get props that people want.

By far the most popular ECL set-up is the 12x6EP with an AXI 2826/12 on 4 cells, turning 8200-8400 RPM (roughly 75% throttle) to deliver about 55mph.  However the new Thick Blade version of the 12x6EP requires more RPM to deliver the same air speed - European Champion Igor Berger reported he needed an additional 800 RPM.  This requires a little too high throttle position (governing suffers) or adding a cell to the pack - obsolescing all the 4S packs you might already have on-hand. No wonder people are starting to "horde" the old thin blade 12x6's.

The simplistic approach to dealing with this would be to go to APC and ask them to crank up the pitch - probably to a 12x7, to make up the RPM.  However, if we are going to get a new prop why not see if we can get a little "greedy" and get something a little better?

I have flown one of the new 13x5.5EP's that was clipped to 12" dia.  I also use a thin blade 13x4.5EP clipped to 12" that really pulls.  The resulting prop profile is a wider blade than the normal 12" prop, but probably falls short of what APC does for the big RC pattern wide blades.  The props I mentioned are also too "flat" for the 2826/12 with 4S, however the wide blade PULLS like a truck and definitely is a good idea. 

I want to see if there is sufficient interest for getting APC to design our next electric pusher prop that:

* Is a Pusher
* Is 12" in diameter
* Is designed with a wide blade shape - at least as wide as the clipped 13"
* Is pitched such that it turns 8300 RPM for 55mph. (likely around 6.5 or 7 pitch)

The above parameters should result in a prop that is a drop-in replacement for the thin blade 12x6EP within one or two clicks on your FM-9.  Battery usage should be comparable because we are asking the same diameter disc to generate the same airspeed.  I expect dynamic (maneuvering) performance should be enhanced by the wide blade design.

Users of the 12x6EP thin: do the above parameters fit your expectations?  Do you have any modifications or additions you would like to see?

Would you be interested in BUYING a prop that fit the above parameters if/when they become available?  The new prop should cost about $6.  This is just a reality check, its easier for me to commit to a 200 prop order if I have confidence that I can actually SELL them!

Need your feedback folks...

If the theoretical new prop performs better with the 2826 series and 4-Cell batteries without overtaxing the system, count me in for a least a few. I use the 12-6EP thin blade (and have several in my stash) with the 2826-10 920KV motor on 3000 mah 4-cells. Do you reckon the higher pitch wider blade 12-incher would work well for those of us using the -10 variant?

Hi Dennis,
I'm very interested. I have an SV-11 with an E-Flight 25. It weighs just over 68 ounces ready to fly, (is  very draggy as we all know )and uses a 4S 3900 TP pack with a Hubin FM-9 and Phoenix 45. The first 10-12 outings  were flown using the APC 13x 4.5 EP. The motor bit the dust( bearings, armature scuff) due to  oscillation and resulting heat.  The plane flew a 5.4 lap on .018 x 63' ( eyelet to eyelet) @ approx. 9,450 RPM. The replacement E-25 has been incremently ( read slowly) advanced along (  Governor Gain & PWM rate reduced).  However, I then had to increase the RPM to nearly 9,900 RPM to a achieve 5.8 lap which was too slow for this ship and me. Yesterday, I tried a 12x6 EP " old style" and was able to get 5.3 at just over 8,200 RPM, so I feel I'm getting closer to my target 5.4-5.5 lap time  with the all important side benefit of  reduced RPM and heat.

Okay, I think a 12x7EP would be about right- I could lower the RPM more , get a lap time to my liking, and  perhaps get more punch for the verticals and overheads.
 For me, it would need to have a hub no thicker than the "old style"12x6 EP because  there isn't much thread left on the shaft  for the nut with a GP E-  plastic Spinner.
Do you think a 13X 4.5 cut to 12 or 12 1/2 might work. I'm afraid that the new 13x 5.5 might be a bit much; even if cut.

Hemen:
Are you using the APC 10X5?  If so I think your best option would be the 11x5.5 Pusher clipped to 10" and turning around 9800 RPM.  This is probably slower than what you are turning now and that might save you some battery drain - per your thread.

Mike:
The prop I describe should be a drop in replacement for the thin 12x6EP that works so well with the /12 motor (kv=760).  However since you are using the /10 motor you could be OK with either the new thick blade 12x6 or a 13x5.5 clipped to 12" and turning around 9300 RPM.

Frank:
Unfortunately we can expect all of the new APC's to have thicker hubs.

Frank & Bob:
I think the wider blade should be right in the wheelhouse for your SV's, along with Bob's T-Rex & Rick's Legacy.

I have to agree with what Bob sez about line tension. I am a small guy, 145lb. soakin' wet, and I have way too much tension as well with my  E-powered SV-11. Flew fast combat and  .60 Carrier in the sixties- neither pulled anywhere like this beast.

Dennis, I would consider a trying a  cutdown 13 x 5.5 ep, but wonder if it'll give me any improvement over the 12x6ep. The other concern would be  the RPM required to get my 5.3-5.5 lap times with that prop.

Too bad about the thick(er) hub, Dennis. I can just imagine APCs product liability concerns...

Has anybody experienced /heard of tossed blades on electrics?

Back in the 60s,  East coast combat pilots loved  the  yellow Tornado small hubbed 8x8s on highly tuned Fox 36XBBs and Supertigre 35 combat engines . Scarinzi advised that we boil 'em( fine way to make a soup),  file groove the drive washer at both sides of the blade base area, and reverse the prop washer to keep them from tossing blades.

That worked, but of course, legal ramifications  back then  aren't what they are today

Don't run me off, no tar and feathers please...

If this is a 3 blade and I can bolt it on a Saito 56/62 I'm in for a couple to try.

I'm afraid we are off your target.  They are 2-blade, with the electric cross section.  While they will be thicker than they used to be they probably would be no match for the Saito.

You might want to check out XOAR (xoarintl.com).  They make nice beechwood IC pushers in 2 blade, and tractors in 3 blades; wouldn't hurt to see if they can make you an IC pusher 3 blade..?

Matin Quartim pointed me to the JFX which I have ordered and received a sample of both the glow and electric versions of the 13-6. Sent HiModels an email and they are going to see about stocking a 13-7.

http://www.himodel.com/plane/JXF_13x6_inch_Beechwood_Propeller_Counter_Rotating.html

This the first prop I'm going to try on a reverse rotation Saito 62 I will be putting the first flights on this weekend. Just checking for other choices.

put me down for 6 of whatever you come up with 

The electric props will most likely not be structurally sufficient for wet-use.
I know that APC mark their product specifically to say that they are not intended for wet use.
take care,
   Dean