Comparing a Prince P Tip to a Senenich

[Onex107]

For your information. I'm not sure what this test means but here are the results. A Sonex friend added a turbo to his Aerovee and let me try the Prince P Tip he removed. My Aerovee is the standard, AeroInjector version that I have flown 65 hours with a Sensenich 54 X 44 wood prop. His Prince is also a 54 X 44 carbon fiber covered, wood base prop.
I warmed up my engine and did a wot run up. As usual it ran up to 2880/2900 rpm and held there. I removed the Sensenich and installed the Prince and did another run up. The engine accelerated rapidly to 3050 and held. I flew with this prop and at the beginning of takeoff it hit 3000 immediately and during climb out I had to reduce the throttle to keep the rpm under 3100. I don't think I got off the ground any sooner nor climbed any faster. The Sensenich turns 2900 at the beginning of take off and accelerates to 3000 wot during climb out at 90 mph and 500 ft/min.
I'm told the Prince is designed to flex to a lower pitch under load and resume 44 pitch at cruise. It definitely reduces under load but I flew some straight and level and at 3000 rpm my air speed/ground speed was 120 mph, the same as the Sensenich. This was a crude test but I didn't see enough difference between the two props to support the higher rpm during take off.

[Bruce593SX]

If you pitch up to reduce rpm to 3000 what does that do to your climb rate/speed with the p-tip?

[vigilant104]

It sounds like a net plus for the Prince prop.
If they are producing the same cruise speed at WOT, but the Prince is allowing you to turn higher RPM on takeoff/climb, then that's good news.
If the Sensenich maxes out at 3000 RPM at WOT during your climb but the Prince lets you go to 3100+ RPM< that's about 3-5 additional HP according to the Aerovee dyno graph (wish we could post images, it would go here). Assuming the props have similar aerodynamic efficiency, that equates to a slightly higher climb rate or higher speed during climb.

Given the error/swings/uncertainties of the instruments involved (airspeed, VVI, RPM) and the likely small differences we are talking about, I'd tend to trust the RPM as the most reliable "quick look" at what is happening, unless some really controlled tests can be done. If, at WOT, the Prince is allowing you 150 additional RPM on TO roll (that's about 6-7 HP at these RPMs) and the same cruise speeds at the same RPMs, that's consistent with what Prince claims for the p-tip, and probably what you want.

Thanks for running the test and providing the info!

[Onex107]

[quote="Onex107"]For your information. I'm not sure what this test means but here are the results. A Sonex friend added a turbo to his Aerovee and let me try the Prince P Tip he removed. My Aerovee is the standard, AeroInjector version that I have flown 65 hours with a Sensenich 54 X 44 wood prop. His Prince is also a 54 X 44 carbon fiber covered, wood base prop.
I warmed up my engine and did a wot run up. As usual it ran up to 2880/2900 rpm and held there. I removed the Sensenich and installed the Prince and did another run up. The engine accelerated rapidly to 3050 and held. I flew with this prop and at the beginning of takeoff it hit 3000 immediately and during climb out I had to reduce the throttle to keep the rpm under 3100. I don't think I got off the ground any sooner nor climbed any faster. The Sensenich turns 2900 at the beginning of take off and accelerates to 3000 wot during climb out at 90 mph and 500 ft/min.
I'm told the Prince is designed to flex to a lower pitch under load and resume 44 pitch at cruise. It definitely reduces under load but I flew some straight and level and at 3000 rpm my air speed/ground speed was 120 mph, the same as the Sensenich. This was a crude test but I didn't see enough difference between the two props to support the higher rpm during take off.

[quote="Bruce593SX"]If you pitch up to reduce rpm to 3000 what does that do to your climb rate/speed with the p-tip?[I don't know how these quotes work. I expect my airspeed would decrease as you hang on the prop, and the climb rate would increase. But that's a position I wouldn't want to be in if I had an engine failure. The extra airspeed gives me more time to react to an emergency and, at my airport, gives me more options for a landing. I'm not after "performance" for the sake of performance. Short take off distance, climb rate, high airspeed are great to brag about but all I want to do is fly safely and enjoy the scenery as long as I can.


ote](I'm not saying that one prop is better than the other. It would take much more data to prove that. I just don't like to run my cht's high to get a few more HP and questionably more performance. These engines are being pushed pretty hard to do what they do. I'm used to my Cessna O-200 running 2400 hours before OH, but I don't expect the Aerovee will go much past 1000.)

[vigilant104]

I'm not after "performance" for the sake of performance. Short take off distance, climb rate, high airspeed are great to brag about but all I want to do is fly safely and enjoy the scenery as long as I can.
. . . I just don't like to run my cht's high to get a few more HP and questionably more performance. These engines are being pushed pretty hard to do what they do. I'm used to my Cessna O-200 running 2400 hours before OH, but I don't expect the Aerovee will go much past 1000.)

I don't worry much about running the VW engine at slightly higher RPM, the VW engines, in cars, have redline RPMs well above 4000K, something that would destroy an O-200 in short order. Keeping the airspeed up during climb does help with cooling, and I think this does contribute to engine longevity. Still, energy "banked" as altitude during the initial climb is there for keeps and to use if an emergency arises, whereas "extra" airspeed just takes me farther away from a good runway and being lower lets me reach fewer possible landing locations and see fewer options. There are probably many techniques that work, and different good approaches based on the location.

[Sonerai13]

I flew with this prop and at the beginning of takeoff it hit 3000 immediately and during climb out I had to reduce the throttle to keep the rpm under 3100. I don't think I got off the ground any sooner nor climbed any faster....

Why would you worry about going over 3100 in the climb? Why reduce throttle to limit RPM, when the net result of that would be poorer climb performance? What's so special about 3100??

The engine is rated at 3400 rpm continuous, and the core engine will turn about 8 grand in a race car installation. A 54 inch diameter prop's tip speed is only 546 mph at 3400 rpm, which is approximately .7 mach. At 3100 the tip speed is only 498 mph, or about .64 mach. You can run a prop up to about .92 mach tip speeds before you start to lose efficiency, so you could turn a 54 inch prop up to about 4400 rpm before starting to worry about tip speed. So again, no worry with turning more RPM than 3100. No sense in giving up performance! Let 'er turn up if it will!

[Sonerai13]

....the VW engines, in cars, have redline RPMs well above 4000K, something that would destroy an O-200 in short order....

The Continental engine part of your statement isn't necessarily true. The O-200 can turn over 4000 rpm without harm, and does so regularly in the Formula 1 racers at Reno. They typically aren't happy unless they're seeing about 4200 rpm with their race props on the F1 racers. Sure, the engine is going to wear out faster at those RPM, but it isn't necessarily going to be hurt mechanically. It's all about prop tip speeds that limit the RPM of most aircraft engines, not necessarily the mechanical ability of the engine itself.