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Sensenich ground adjustable prop

JZet

I'm New Here
I'm considering the engine/prop installation for the RV-8 I am building. I'm looking at an IO-360 (180hp) engine but still unsure of the prop. Constant speed, Catto 3 blade fixed pitch, or Sensenich ground adjustable offered through Van's all under consideration. I'll use the aircraft mainly for short pleasure trips or some aerobatics. Iv'e got a pretty good handle on the constant speed and Catto props, but not too much knowledge on the ground adjustable prop. Any input would be appreciated.
 
Excellent prop for RV-8

Even though i do not have thousands of hours on my plane yet, i think i should say what i experienced so far.

I decided to buy this prop for several reasons:
1.)weight! it is light!! The RV-8 usually tends to be a bit nose heavy. I did not want to put the battery aft and have to add unnecessary weight by using 10 feet of #2 cable to connect it. Therefore i needed a light prop up front.

2.) money:
I hardly hear any fixed pitch RV driver complaining about performance. A constant speed prop has its advantages, but they come at a price. A C/S Prop costs more, is supposed to be overhauled in intervals (even more costs) and is heavier than a fixed pitch prop. (The c.g. Issue is handeled above and i do not repeat it here). Other people may see that different, but for me it is simply not worth it.
If i can not get out of a field fully loaded due to performance, i would just take off with half fuel and make a fuelstop more on my trip.
And i do not live hot&high!

3.) still chooseable performance:
You can set the pitch angle depending on your mission!
You want to go hot&high (e.g. Rockies), set the prop for low pitch and get superb acceleration and climb performance by acceptable cruise numbers.
You want to go long distance without high terrain, set the prop for high pitch and get decent acceleration and climb performance with excellent cruise numbers!

4.) pitch setting procedure
How you set the pitch is dead simple and can be done within 10 minutes of work.
The procedure is straight forward and the whole hub-assembly is very well machined.
To be honest, i think once i found my sweetspot of pitch angle, i will most probably leave it there and deal with upcoming performance issues like a described under 1.). But i still could change the pitch if i wanted to!

5.) factory support
I ordered this prop when ist was just introduced to the market. I did not have any reports from fellow builders, but sensenich is not a newby in the buisness.
I called them up and they answered every questions that i had.
They treated me really well and they were really patient.
Their behavior convinced me about their product.

This were the points that got me sold.

Know, after a couple of hours behind the prop........i do not regret my decision!

The prop runs super-smooth (i actually do not see the necessity for dynamic prob balancing. Smoother would be jet-like) and the performance is exhilarating!
I cannot provide you hard performance numbers as i still adjusting my IAS, CAS, TAS thing in my EFIS, but this prop really has bite!!!

First take off was with 1570 lbs take off weight (230 lbs below max gross), grass runway, no wind, mid 70’s temperature, 500ft pressure altitude.......take of run was approximately 550 feet and she was of the ground, climbing like a homesick angel.

I expect to see the published performance numbers that Van’s publishes for a IO-360 powered RV-8.

I do not see it as a disadvantage, but it is a thing that got my attention.
The airplane does not want to slow down easily.
Especially on landings, power idle, the rest amount of thrust let’s you float down the runway if you were “a little hot” on final (fast that means).
Like said, i do not see it as disadvantage! I see it as aircraft behavior which i, as a pilot, have to deal with. Proper decent-planning, exact pattern speeds and now how to side slip, and this whole thing is a non-issue.

If my prop breaks........i’d buy a new one in a second!!
 
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Just in case you ask....

No, i am not employed or sponsored by them....;)

I am just a very happy customer......
 
Carl is right. For performance in any phase of flight, you can’t beat a blended airfoil Hartzell. It will give you cruise efficiency that you can’t duplicate in most scenarios with a fixed pitch prop, and will at least equal, or almost equal any fixed pitch prop in climb, and will allow you amazing descent angles for tight approaches that a fixed pitch can’t do. This level of performance requires money, as well as loss of payload, compared to most competitive fixed pitch alternatives. For the OP, you’ve said that you are interested in flight mission profiles that for the most part are local in nature. I have the same mission with my RV4. I can’t say enough for keeping the weight off, especially for local fun flying. I could get a little better cruise efficiency with a constant speed prop, but to do so would require spending $10K more than I did with my GA Sensenich, and I would have to remove my O-360 engine from my airplane to modify my firewall to accommodate the required prop governor. You won’t have to do that joyful exercise with your RV8, but the money and loss of payload is for everyone contemplating this option.

My original prop on my 180hp RV4 was a Sensenich metal 72X85 prop. That prop would overspeed my engine at WOT at any altitude - 2900 RPM. In order to respect my engine manufacturers limitations, I couldn’t get more than 60-65% power without over-speeding my engine, unless I was at a relatively high altitude, >8K’. My new GA Sensenich will now not exceed 2700 RPM at WOT and I am able to run my engine at a more comfortable 65-70% power at any altitude - up to a point - without exceeding my 2700 RPM limit, and at a higher MP (% power) than I could before. I have my pitch set to not exceed 2700 RPM, and that setting has resulted in a degradation of enroute climb performance by a little, but it is still pretty good - 1300- 1400 fpm at 125-135 KIAS normally, so I’m quite happy with that. What has surprised me is the takeoff runway performance with my new GA prop. My runway performance has improved by about 20-25%. Even though my pitch setting is more aggressive, my static RPM is about 200-250 RPM higher at the beginning of my takeoff roll than with the metal prop, and I get off the ground about 100-150’ shorter. The carbon fiber, scimitar shaped blades of this prop flex forward slightly (so I am told) at takeoff power - high torque/low or no speed - and because of the scimitar shape there is a change in pitch in the curved section of the prop, and results in a slightly higher RPM (about 2270) - sort of a quasi constant speed. This phenomenon (if true) is born out in RPM indications during takeoff. I notice a reduction in WOT takeoff power RPM after accelerating through approximately 70K+ to about 2150, where it stays until I accelerate above about 100K.

My original metal Sensenich prop would outclimb every Hartzell propped RV8 that I fly formation with - at a noticeable margin, but I was climbing at WOT and 2600 RPM/130 KIAS. My pitch attitude determined my RPM at WOT (still does), and if I wanted to climb at 2500 RPM instead, I would see 2500+ fpm. That prop is for sale, BTW, if you’re interested. I would recommend the Sensenich GA carbon fiber prop for your RV8, if your mission profile is mostly local flying and acro. If you are planning a lot of cross-country, especially long distance, then you might be able to justify a constant speed, but don’t expect to pay for the difference with fuel savings. That Hartzell, or Whirlwind will give you a comfortable cruise, no question, and it will increase your resale value too. I have owned 5 RV’s, 3 of which I built and had CS props on all 3 - 2 Whirlwind 200Rv’s, and a Hartzell on the third. My first RV4 (purchased) had a Catto 2-blade and it was a beauty, but it turned the engine at 3000RPM at WOT, even at 11,000’. I had Mr. Catto adjust it, and he was able to reduce the max RPM to 2900, but I was still leaving performance on the table if I respected the Lycoming limit. On this, my hopefully last RV, I decided to go with the Sensenich GA. For lighter weight fun local flying, you can’t beat a carbon fiber Sensenich.
 
Scott,

Good information, thank you. Money is always a consideration and the extra cost of the constant speed prop probably can't be justified by lower fuel burn if the GA prop gives good performance at a lower cost. Maybe by increased resale value in the future, but that's not always a certain thing. I did see on the Sensenich website that they have a three blade version of the GA prop available for the RV-8. Looks like the same blades as the two blade prop. Another thing to think over.

Joe
 
Whirl Wind GA 200

After 500 hours on my RV-8 with a Catto prop, I switched it out with a Whirl Wind 200 GA. In high DA environments, the GA 200 has given me a modest performance improvement. I found that just .5 degree pitch change can make a difference in finding the sweet spot of good climb and great top end. The near infinite pitch angle adjustability of the GA 200 is a plus.
 
Check the periodic inspection requirements

Before choosing, I recommend you fully investigate each propeller manufacturers periodic inspection requirements.
 
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