Guys,

I finally got around to doing some work with the pusher props and long story short I like them. I have been flying my Excitation (600 sq in, 60 oz, AXI 2826/10, 4S1P 3850 mah, 9000 rpm, 65ft C to C, 5.0 lap) ship for about 8 months with a normal APCE 12x5 (repitched from 6)tractor props and have tried different blade widths (cut down 13") and some of the old standard wood "46" size props. In the end I always came back to the 12x5. I have been curious about the pushers and decided that electric is the easyest to try it on (just switch any two motor leads and it reverses the rotation direction). The one challenge was getting the pitch gauge set up to read the reverse pitch. What I do with my pitch gauge is to clamp the swing arm at the pitch I want then check both blades, this eliminates errors for repitching. For me I just set station 9 on the 12" props (around the 70% length) and pitch the whole blade from there by heating the root and tweeking (you get a feel for how much pretty quick). Since the reading are all relative you get a starting point then adjust the swing arm for more or less as needed.

For the pusher what I did was with the swing arm clamped for the pitch that I have been flying, mark a line the full length of the plate on the back side of the gauge indicator plate (the part with the numbers). This sets the pitch point. Then I disassembled the swing arm and gauge plate and installed it flipped backward so that the swing arm and gauge plate are reversed from the normal position (the bolts holes all line up perfect just that the heads will not be flush). Now you can pitch the prop as normal to the same angle as the tractor prop. This worked and I hit the same lap time at the same rpm  as with the tractor prop.

I flew the ship back to back with the tractor then switched to the pusher. The first thing I noticed was that the ship liked to hug the ground a little more on the take off roll. Some of the flap tweak was off a little because the torque reaction is opposite. The inside maneuvers were just fine the big gain was on the outside corners. It just feels very, very solid. For me, I liked the solid fell on the outsides and the top of the vertical and hourglass. This is worth trying but you do need to check the pitch as it may not hit the same mare from the factory as the tractor  prop.

Best, Dennis

Alan,

I have not measured the stock APCE 12x6 prop before I repitched. Once I set the reverse gauge I did have to reduce the pitch on the APCE 12x6P to hit the same pitch I have been flying the tractor prop at.

One way to check this without taking apart the Prather pitch gauge is to build a "Windy" pitch gauge. This is a simple piece of 1/2" sq with a dowel or pin for the hub to fit over. The length is out to the 70% point of the blade. On the end you screw a  (rt triangle shape) triangular piece of 1/8" plywood that fits the angle of the underside of the blade. By making small changes to the angle you can get a relative reference point. Once you get the prop pitched to what you want you can glue it firm. For the pusher gauge just make a mirror image of this (this sounds like more work then is it is).

One other thing about the pusher is the need to revise the spinner cutout. I had an old plastic spinner that I was able to refit and it works fine.

I really like the solid feel of the outsides in the wind. For me I feel more confident having the insides a little losers then the outsides, this is a personnel choice but its easy to try with ECL.

Best,        Dennis

Alan,

I did a couple test flights tonight with the longer 69' lines and the 12x6 APCE P prop and a Zinger 12x6 P cut down to 11.5" x6. All at the same 9000 rpm. The Zinger gave a lap time of 5.3 sec which is pretty close to were I was hoping to be. The only thing I noticed was the prop was quite noisy, which means it was not as efficient as it could be. With the APCE 12x6P from the package (didn't even need balancing) I think you are right it gave a lap time of 5.7 sec. My guess is from the factory it is about 3/4" lower in pitch then the tractor version. With the one that I set to the same pitch as my tractor it hit the same lap time with either setup. I will check against the baseline pusher and see how close the factor pitch is to my depitched one.

At the 5.3 lap time the ship seemed pretty good but will need more time to see if there is any real advantage to the higher pitch longer line length.

Best,             Dennis

Alan.

The way I have been doing it is to first set the prather pitch gauge to match the prop with the desired pitch (at station 9 for 11 - 12" diameter props) and clamp the gauge bar to the indicator plate. Then take a straight edge and marking the back side of the indicator plate angle with a thin pilot marker. Then you can take the gauge apart the reverse the indicator plate and swing arm to now allow pitching the pusher. I then clamp the swing arm to the line that was drawn on the back of the indicator plate. Mount the prop on the prop holder and test to see where the prop is relative to were you want the pitch (this is sometimes only a 1/64" difference but it is all you need). Then just repitch with a heat gun. I set my 12" props at station 9 (I only use a single station and find it works fine). I heat the hub area for about 2" out top side and bottom side (I try to balance heating from top to bottom). I usually heat for about 30 sec then let it sit for another 30 sec or so then heat again for 30 ish sec (you get a feel for it very quick, start slow). I leave the prop on the slide block for the whole time. Then using a thin cotton glove I grab hub in one hand and the blade near the hub in the other and tweak in the direction you want to move the pitch. The APCE's repitch easily very similar to carbon fiber props, just a little twist an it moves. I have not had any blades go out of track do it this way.

The IC APC props take a lot more heat (sometimes 2 min) and a pretty big twist to move them but they will move. Check the pitch and if you need more heat again and tweak. Some have said that the blade will return to molded pitch, to date I have flown the same prop for over 8 month and the pitch has not moved.

Best,            Dennis