What's your prop, pitch, and HP?

[RobO]

I tied my Dominator down yesterday and I set the pitch on my prop for the first time. I don't know my engine's HP and I'm curious to know what others think of the results. Ideally, I would be getting ~90HP at std conditions. Unfortunately, I didn't have standard conditions. It was a hot day (for me) and my field altitude is on the higher side.

Conditions & equipment:
Prop: 60-inch, four-blade Powerfin
Engine: Suzuki 1.3L four-cylinder
Redrive: Raven belt 2.11
Ship: Dominator

OAT: 95F
Field Altitude: 5050ft
Humidity: 20-30%

For now, I've set my red line at 6500rpm. I started at 12 degrees and pitched down to 10 degrees with these results:

12 degrees – 5350 rpm
11 degrees – 5540 rpm
10 degrees – 5930 rpm

So the question is to those who've done this a lot, does it look like my engine doing what it should? I realize there is much speculation in answering a question like this. I'm just looking for people's gut comparative feelings.

Thanks

Rob

[GyroRon]

With a 3 blade warp drive on my Dominator, with 65 hp Rotax 582 I had 18-19 degree of pitch measured at the tips and around 325 pounds of thrust. This was with a 3 to 1 ratio and 6450 as the static redline.

I then changed the gearbox ratio to a 2.67 to 1 and had to depitch to about 12 degrees of pitch and netted slightly more thrust at the same rpms.

[Aussie_Paul]

With a 3 blade warp drive on my Dominator, with 65 hp Rotax 582 I had 18-19 degree of pitch measured at the tips and around 325 pounds of thrust. This was with a 3 to 1 ratio and 6450 as the static redline.

I then changed the gearbox ratio to a 2.67 to 1 and had to depitch to about 12 degrees of pitch and netted slightly more thrust at the same rpms.

But I bet it is noisier.;)

Aussie Paul.:)

[PW_Plack]

Rob, it might help if you could put a scale in line and measure static thrust. That's a number you can measure with reasonable accuracy, and which would allow meaningful direct comparisons.

[Rick Whittridge]

Super Mac 90+ turning a 52X26 Tennessee prop. Thrust ? You Bet!

[CLS447]

Rob, My EA81 with 68" 3 blade Warp with Souza 2.18 : 1 redrive .

HP = ?

12 degrees at tip = 5350 rpm's at full throttle .

I think this is where I am at right now. I will verify this soon & post results. I need to have exhaust finished & jet carb properly.

[RobO]

We’ll see how it all plays out. I wasn’t expecting anything definitive; my question was more of a sanity check. The true test will be when the aircraft is moving. And, I plan to do a static test when one of my hangar neighbors is around with his scale. There is still a little engine tuning for me to do too. Thanks for the response. I'll post the static results when I get them.

Rob

[Brent_Brown]

Rob where did you get 6500 as a redline for that motor? I think that is high for it.

[RobO]

I got that red line number from Jeron at Raven. I think he said I could even wind it up higher, but I don't think I need/want to. I believe red line on the auto is 6000, but I may be incorrect.

Rob