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  #1  
Old 09-29-2021, 08:47 AM
FireMedic_2009 FireMedic_2009 is offline
 
Join Date: Nov 2016
Location: Tampa, FL
Posts: 237
Default Prop performance test procedure

Does anyone have a prop test procedure in order to compare two fixed pitch props? I will be testing a 2-blades prop and a ground adjustable 3-bladed prop and would like some ideas or procedure on how to compare.

I know I have to test them at the same density altitude. Not sure if it really matters if itís at 5500ft or 8500ft although I believe the 3-blade is a little better at higher altitudes like 11500ft so I guess I can take some data points at high altitude.

In level flight I can get airspeed at various rpms, 2300, 2400, 2500, 2600, WOT

If the density altitude is similar at the airport elevation than you can obtain true takeoff data which you can get fpm data at various airspeed climb outs, 85kts, 100kts, 115kts. If the density altitude is a 1000ft above the airport elevation from what it from the first prop I guess you could start at 1000ft above the airport and level off at 85kts and than firewall it begin your climb.

Please add any suggestions you may have.

Thanks
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  #2  
Old 09-29-2021, 10:42 AM
drspud drspud is offline
 
Join Date: Sep 2020
Location: Plant City
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This what we use for propeller performance evaluations
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  #3  
Old 10-04-2021, 04:14 PM
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smokyray smokyray is offline
 
Join Date: Jan 2005
Location: TX32
Posts: 1,965
Default Prop me up

I tested nine different FP props on my RV4 over a 10 year period. I always went for the "big 5" first then the finer points that separate the average from the good and excellent. Mission requirements always override perfection and going in a FP will always be a compromise. A lot depends on your requirements and mission.

That said...for my requirements I needed off pavement capabilities, high altitude cruise and rain protection. This is what I found on my short gear RV4, 2 blade test.

1. Ground clearance: 69" optimum.
2. Static RPM: 2200
3. WOT at SL: 2750-2800 5000' 2700 (24"/2400 match), 10K 2600- 2700
4. Smoothness
5. Cost, durability.

Winners: Catto Gen 2 (I helped Craig develop his props for RVs, great guy)
MT 2 blade FP (incredible German engineering and quality)
Gary Hertzler 2 (unbelievable performance and high tech airfoil)

Contender I tested on a 9A for Sensenich, the 2 blade GA composite. Amazing prop.

Testing requires a lot of hours at different altitudes, seasons and aircraft weights.
Bottom line, it depends on what you want, or what you need...there's a lot of info on this site, search threads and you'll see a lot of data.

V/R
Smokey

Last edited by smokyray : 10-04-2021 at 04:20 PM.
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  #4  
Old 10-04-2021, 07:23 PM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
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Default

Quote:
Originally Posted by FireMedic_2009 View Post
Does anyone have a prop test procedure in order to compare two fixed pitch props? I will be testing a 2-blades prop and a ground adjustable 3-bladed prop and would like some ideas or procedure on how to compare.

I know I have to test them at the same density altitude. Not sure if it really matters if itís at 5500ft or 8500ft although I believe the 3-blade is a little better at higher altitudes like 11500ft so I guess I can take some data points at high altitude.

In level flight I can get airspeed at various rpms, 2300, 2400, 2500, 2600, WOT

If the density altitude is similar at the airport elevation than you can obtain true takeoff data which you can get fpm data at various airspeed climb outs, 85kts, 100kts, 115kts. If the density altitude is a 1000ft above the airport elevation from what it from the first prop I guess you could start at 1000ft above the airport and level off at 85kts and than firewall it begin your climb.

Please add any suggestions you may have.

Thanks
I think youíve laid out a good test program for the data you want - the only thing Iíll suggest is that the easiest way to get good data with the least Ned for post-test manipulation is to do your testing first thing in the morning, so the air is velvet-smooth, and to do the tests on consecutive days, so that you get very similar conditions. Donít spread the process out over months, or you will have to account for temperature divergences, etc.

You can see the process I follow for prop testing in the July 2021 issue of Kitplanes.

Paul
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