Here it is:

Fuel, 30% heli, Wildcat Youngblood Mix
Temp: around 80ºF

APC 14x6 @ 10300 rpm = 9.5 lb
MA K-series 14x6 2nd gen. @ 10600 rpm = 9.25 lb
APC 15x4W @ 9700 rpm = 9 lb
Pro Zinger 15x4 @ 10300 rpm = 8.75 lb

Tachometer: Royal Tachometer
Thrust measurement is done by attaching a digital force gauge with an extension bar, hooking to the Sullivan tail gear brass collar on a Funtana 40.

All measurements are sustained reading, not the initial peak reading.

This confirmed what I found in the air, that APC 15x4W does not pull as well as APC 14x6.

If anybody has different thrust finding, please post. Thanks[8D]

Thanks seanychen! What was the size of the MA K series? Also do you have an APC 14x4W to try?

That's interesting. I wonder if the spool up is comparable between the two APCs. I would also like to see the thrust for both at 5,000 rpm &6,000 rpm and so on. I'm not asking you to do it. I was just wondering how it would pan out. I need to get a 14x6aAPC and try it.


David

MA is 14x6.

I did try an APC 14x4W last year, and I recall it peaking at 10700 rpm. I think it pulls about 9.5 lb. ~ 10 lb. I no longer have a 14x4W to verify though.

I agree that mid-throttle thrust should be higher with the low-pitch wide prop. I find that while using higher pitch prop, I end up doing a lot of yo-yo-ing during hover, as I need to change throttle more for incremental increase of pull.

would you normally run your .82 at 10300? I've tached my .82 at 10400 with 15% coolpower but i run it around at 9400-9600. I was thinking about using 30% and i wasn't sure about how to prop it but if the 15wx4 gets 9lb at 9700 i think i'll be happy. I wonder what kind of thrust you would get from the 14x6 if you dropped the rpm to 9700..i'm not asking you to do that but with a 600 rpm difference it only makes sense that 14x6 would pull more considering how close they are in pitch and diameter

My point exactly. My .82 is on a 3-D plane. It runs wide open maybe 15% of the time.


David

Prop it to your liking. Sometimes having a lower pitch is more useful than having maximum thrust.

How on earth did you get 10300 RPM from an APC 14x6 with your Saito .82? With 25% Omega I peak my .82 at 9600 (with spinner, but I don't think it makes that much difference) on that prop. I'm at sea-level too.

Also, I get 8800 RPM from a Pro Zinger 15x4, which seems to put more load on the engine than the APC 15x4w. I once got the APC 15x4 to peak at 9660, but the best peak I've gotten since is about 9450, and that was on a bench. On the plane it's never been higher than 9200 RPM.

Either I've got a really crummy engine or you've got a really good one.

What 25% fuel are you using? I think I tried it once and didn't really like it. Heli fuel w/ 23% low viscosity lube work great on Saito & YS.

If you get APC 15x4 to peak at 9660 on bench, then it's pretty much the same I got on that prop. APC 14x6 is indeed lighter load than APC 15x4W.

Pro Zinger 15x4 is narrower than APC 15x4W, and should get a few hundred rpms more than APC 15x4W, but not as high as APC 14x6. Maybe your setup on the plane is causing some variance. There is a quick fix though. Put on an APC 14x4W and rev it high. This engine seems to be more concsistent when it full-throttles above 10k.

Omega 25%.

I got that 15x4 to peak there once, but haven't been able to get it up there since. Odd that a 14x6 is a lighter load. I tried again and it still wouldn't go past about 9650. I'll try the Pro Zinger once more and see what happens.

Hey seanychen, I got the same APC 14x6 I referred to in the earlier post to peak at around 9900RPM on my new (Horizon replaced the other .82 that I was having problems with) .82. This is with about 1.5 gallons through it. I'm using 25% Omega fuel so with a bit more runtime on it and adjusting for the difference in nitro we're using I think I'm about the same as you are. Also, I got the APC 15x4w to peak around 9700RPM. The 14x6 spools a lot faster, and is actually easier to tune than the 15x4w.

I still haven't been able to get the Pro Zinger to rev real well. I am using a modified one that spins around 9400RPM peak. It might go higher, dunno, the engine was running very inconsistently today. I think it is because on my bench the tank is about 2" lower than the carb, and it was moving around a lot.

Pe Reviers thrust calculator predicts almost exactly the same thrust numbers you obtained in actual testing.

How does this compare with "aero design propeller selector" program you can download on google? It would be interesting to see the theory versus the real thing.

[quote]ORIGINAL: seanychen




MA K-series 14x6 2nd gen. @ 10600 rpm = 9.25 lb

i impulse bought a pro zinger 14x5 for my 82 on a 3d plane. has anyone used this prop or compared it to others?

I would think it would work fine. It must push about the same amout of air as a 14x4W and spool up faster than the heavy APC. Try it and let us know.