Need Advice on Prop Pitch RV-9A, 160HP

[Ed_Wischmeyer]

I had a Sensenich for 200+ hours and it was basically fine, no rain problems. However, as with any fixed pitch prop, going cross country in up- and downdrafts, you're always adjusting the power, adding power in the downdrafts and pulling it back in the updrafts (with the autopilot flying). 2600 RPM limit was for me a so-what, as I never flew that high or wanted to burn more gas.

That said, I now have a Hartzell constant speed and the plane can climb more steeply than I like, so I climb at higher airspeeds. The big advantage of the /cs prop is that it has more drag, power off, so you can slow down more easily, especially on landing rollout.

The RV-9A has a huge c.g. range, so that's basically a non-issue. But go run some numbers on a spreadsheet and see for yourself.

[Dbro172]

Can?t go wrong with a whirlwind GA, Sensenich GA, or Catto two or three blade. With those options, all available with Nickel leading edges, I would not bother with a metal prop.

[MS19087]

Hi Tom. You may recall I had 3 different props on my -9A. When you flew with me I had a WW ground adjustable. I really liked that prop. Great performance and no issues with rain, CG, etc. I started with the metal sensenich and I felt I never got the performance I expected out of that. The WW was much better in my option. I ended up with a WW 151 which was a real game changer but $$. So given a choice id definitely consider the WW GA prop. I only hear great things about Catto but have no experience. Ask Vlad. He put 4000 hrs on his😮

[Av8torTom]

Thanks all. I?m leaning strongly towards the WW ground adjustable now

[agirard7a]

Originally Posted by Av8torTom

Another reason for a ground adjustable???

Maybe give you some versatility to find your sweet spot. The more aggressive cruise prop is good for what it is but lacks when the engine has to work harder, creating more heat on climb. Just remember your climbing the hill in 5th gear.

[Christopher Murphy]

Originally Posted by Steve Melton

why would you consider a prop limited to 2600 RPM?

Because its a very good performing propellor even with the rpm restriction

Because Its vitually maintenance free

Because it might provide a CG that make the airplane more useful

Because it might be less expensive than other options

Because even as a cruise prop it will give excellent climb performance if you climb at correct speed.

I had one on my 160hp RV4 for 600 hours and it was a very good choice for me.

Cm

[Steve Melton]

Originally Posted by Christopher Murphy

Because its a very good performing propellor even with the rpm restriction

Because Its vitually maintenance free

Because it might provide a CG that make the airplane more useful

Because it might be less expensive than other options

Because even as a cruise prop it will give excellent climb performance if you climb at correct speed.

I had one on my 160hp RV4 for 600 hours and it was a very good choice for me.

Cm

got it. thx

[Scott Hersha]

Not all metal Sensenich propellers recommended for use on Vans airplanes have that 2600 RPM limit. For instance, my O-360 powered RV4 has a Sensenich 72FM prop and doesn?t have that restriction.. In fact none of the 72? metal props have that restriction.

http://www.sensenich.com/wp-content/...1349891787.pdf

They call the 72FM props 72 inch props, but they are actually 71?. Mine is actually a 72FMS9-1-85, which is 85? pitch. My RV4 climbs very well, but at 2700 RPM in level flight, I?m not at full throttle yet - at any breathable altitude. At full throttle in level flight I?ll see about 2900 RPM. I?ve only run it this way to gather data for Nicole at Catto. A new Catto, or Sensenich repitch is in the plans.

[Av8torTom]

Originally Posted by Scott Hersha

Not all metal Sensenich propellers recommended for use on Vans airplanes have that 2600 RPM limit. For instance, my O-360 powered RV4 has a Sensenich 72FM prop and doesn?t have that restriction.. In fact none of the 72? metal props have that restriction.

http://www.sensenich.com/wp-content/...1349891787.pdf.

Thanks for that info

[pa38112]

Here is the issue with a 2,600 rpm limited prop: RV9's are intended to be cross country machines. Generally this means higher altitudes to take advantage of fuel efficiencies. Above 8,000 ft you can not get to 75% power and you cant hurt your engine running it at 2,700 rpm, so if you have a prop that can not exceed 2,600 rpm you are giving up almost 4% of your speed.
Secondly, if your prop i pitched so that you can not exceed 2,600 it is putting a tremendous strain on your engine on take-off. You are going to have higher peak pressures VS the same operation with a plane pitched for 2,7000.