need recommendation on repitching Sensenich

[IowaRV9Dreamer]

I own aS ensenich 70CM prop that is supposed to have 79" pitch. I'm planning on using it on my RV-9A, with an O-320 engine.

The prop is currently at Sensenich, getting inspected. They found that it is slightly off in pitch, more like a 78" prop at some stations. I think it was originally made this way in 2001. Neither I nor Senenich think that it has been repitched. It has about 250 hours on it.

My dilemma is should I pay them $175 to repitch the prop to 79" while it is there?

To add to my confusion, I don't know if my engine will be 150 HP or 160 HP. It is an -E2A, so I can go either way.

So, VAF experts, especially RV-9A flying ones with O-320's and metal props... should I:

• A) Plan for 160 HP and repitch to 79" (the standard prop according to Vans)
• 2) Plan for 160HP and leave the pitch as is at 78" (which would make it a "climb" prop)
• III) Plan for 150HP and leave as is (78" is standard for 150 HP)

My random thoughts: I think the key question is what horsepower to plan for.... And that kind of gets into future fuel types.... ack! I know if I leave it flat I'll have about 40 rpm of unusable power down low to stay below 2600 rpm... I'm more interested in cruise than climb... I don't fly in mountains or from short fields....

Help - I've got analysis paralysis... What would you do?

 

[647jc]

I'm currently in phase I flight testing a 9A with a new O320 160 hp & Sensenich 79" prop. At 8500 msl I can easily exceed 2600 rpm with a TAS of about 187 mph. Takeoff performance (1100' above sea level, solo) is about 300 - 400 feet and climb out at 120 mph is between 1500 and 1700 fpm. So, given these data points, I would opt for a slightly higher pitched prop, perhaps 80". My assumption was that an O320 160 hp and a recommended 79" prop at 7800 msl (75% max power) would not be able to red-line the prop, I was wrong.

 

[Steve]

another data point

I have 151 hours on my 160HP ECI/Sensenich combo. The main gear leg fairings are not installed and the nose fairing and pant are still on the workbench, (all in-work, tho).
I have never reached higher than 2500 rpm as indicated by Vans tach with the a/c in the above configuration.

N345SF
Steve

 

[Sam Buchanan]

I own aS ensenich 70CM prop that is supposed to have 79" pitch. I'm planning on using it on my RV-9A, with an O-320 engine.

The prop is currently at Sensenich, getting inspected. They found that it is slightly off in pitch, more like a 78" prop at some stations. I think it was originally made this way in 2001. Neither I nor Senenich think that it has been repitched. It has about 250 hours on it.

My dilemma is should I pay them $175 to repitch the prop to 79" while it is there?

To add to my confusion, I don't know if my engine will be 150 HP or 160 HP. It is an -E2A, so I can go either way.

So, VAF experts, especially RV-9A flying ones with O-320's and metal props... should I:

• A) Plan for 160 HP and repitch to 79" (the standard prop according to Vans)
• 2) Plan for 160HP and leave the pitch as is at 78" (which would make it a "climb" prop)
• III) Plan for 150HP and leave as is (78" is standard for 150 HP)

My random thoughts: I think the key question is what horsepower to plan for.... And that kind of gets into future fuel types.... ack! I know if I leave it flat I'll have about 40 rpm of unusable power down low to stay below 2600 rpm... I'm more interested in cruise than climb... I don't fly in mountains or from short fields....

Help - I've got analysis paralysis... What would you do?

I went through nearly the same process with my O-320 E2D that was originally 150hp then later became 160hp. The prop was originally 77" per Vans recommendation but eventually ended up at 80".

You can read details here:

http://thervjournal.com/fairings.htm#repitch

I find 80" on my well-faired RV-6 is a great compromise between climb and cruise, with a slight edge toward cruise.

I have 151 hours on my 160HP ECI/Sensenich combo. The main gear leg fairings are not installed and the nose fairing and pant are still on the workbench, (all in-work, tho).
I have never reached higher than 2500 rpm as indicated by Vans tach with the a/c in the above configuration.

N345SF
Steve

With no fairings in place any numbers you see now are pretty much meaningless in regard to the original post.

 

[Greg Arehart]

Dave,

I'm flying a different engine and prop, but my take on this is if you are planning mostly cruise flight, pitch the prop for that. I doubt that you will ever have an issue with getting off the ground and climbing in the 9 unless your prop is pitched way beyond 80" (FYI, I am flying behing a 180 hp IO360 with 85" of pitch. I never come close to redline - typically get to 2500 or maybe 2550, but I am also starting at 5000 feet elevation)

greg

 

[carguy614]

every plane a little different....

as you might expect. I have a 9A 160 hp O320 and a 79 pitch 70CM prop. I find that the pitch is perfect for my plane. At 8000 feet density and full throttle I get 2600 exactly. The climb is great. That being said, there are a lot of variables that can affect each individual ship. FWIW, if I had to choose a pitch for MY aircraft, it would be 79. The truth is, you just might not be able to pick the perfect pitch for YOUR ship until it flies.


Regards,
Chris

 

[cleve_thompson]

I have an O-320 (160hp) on my 9A and have a Sensenich fixed prop pitched to 81" and I still must throttle back until I reach about 9,000 ft. to keep below the prop red line of 2600RPM's. I find that climb and take off performance are still great! I have my fairings on.
I am glad that I used the *1" pitch. BTW, this pitch was suggested by an engineer at Sensenich that I talked to at the time of my order.

 

[647jc]

Cleve,

Do you recall what TAS you are seeing just below redline at those altitudes?