Prop Selection

[Bissetg]

Has anyone done static thrust strain gauge testing with their Bearhawk? I’m interested in what engine prop combos produce.

[jaredyates]

Bob has done quite a bit of this kind of testing. There is one example in the Beartracks.

https://bearhawk.tips/1833

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He has built his own propellers and checks each one. Static thrust isn't a comprehensive test but is a worthwhile datapoint.

It would be cool to have a chart with several airplanes and their results.

Something I learned at Oshkosh is that Michel Roy is running a fixed pitch prop on his 540 Bearhawk. He reaches 2700 RPM at Vne, and his static RPM is around 2100. That spread is indicative of what it takes to cover our speed range.

[Aero_tango]

Just to give more details on my prop/engine combo. O-540, 245 HP, Catto FP (84/58). Static RPM is 2170 RPM. At full power (1500 ft elevation), I reach 2750 RPM at VNE.
Michel Roy
C-FYMR

[MidGenerationAL]

Another prop shopping question. Aka, so many proptions.

When looking for a used prop what specs should I be looking at to ensure fitment and suitability?
For example I found a 3 blade Hartzell used off a Cessna 182. PHC-G3YF-1RF/F84

So it's a similar plane, similar engine... what else do I need to look at to know if it will work for me?
we don't have mission specific performance needs - general all purpose airplane.

[Bcone1381]

Generally, one should be concerned about harmonics of the prop and engine combination. Bad harmonics will result in blade failure. Harmonics are precipitated by the combustion event. Some engines have crankshaft counter weights to help avoid these harmonic, some have an RPM band to avoid continuous operations in.

Selecting a prop that is certified with your engine is a good way to do that. Almumnium blades are not as good at dispating harmonics as wood or composite blades. Hartzell supports experimental builders. McCaully not so much.

https://hartzellprop.com/EXP-AIRCRAFT/Man-193-Vol-02.pdf

https://hartzellprop.com/EXP-AIRCRAFT/Man-193-Vol-01.pdf

[Battson]

Well, at this risk of boring avid readers, I will re-write-up my prop selection process highlights here.

We ended up with a Hartzell Trailblazer 83" carbon fibre two blade prop. We really like it so far.
Following a lot of research, talking to as many people as possible who have composite props, we decided to try the newest offering on the market. I chose this over the major competitors (MT, Whirlwind) for a range of reasons, including Bearhawk relationship with Hartzell.

Combining the research and our subsequent experience operating the prop, we like the:
- testing by Hartzell which shows it produces 18% more thrust than their standard metal prop offering for a Bearhawk,
- sharp price offered through Bearhawk Aircraft,
- reduced vibration compared to a metal prop,
- lighter weight compared to metal,
- reduced inertia compared to a metal prop, meaning it responds a lot faster,
- shape and width of the blade aesthetically,
- reduced risk of engine damage in the event of prop strike.

We felt the biggest risks with a composite prop were largely the same for all manufacturers:
- stone damage to the carbon fibre; although carbon can be repaired unlike metal, a stone does a lot more damage to carbon,
- chips to the nickel leading edge from stones (same for aluminium really),
- higher cost of replacement blades,
- lower knowledge base in the maintenance shops compared to metal.

Overall we are really happy with the prop so far, but we haven't picked up a stone chip yet....

Seeing as this thread is back to life, I would add that we've been totally thrilled with this prop, which is now in it's 7th year of operating (100hrs a year).

It's been through it's 6-yearly service without issue, and continues to operate flawlessly.

We have picked up the odd small pebble with it, but the paint is so thick it's never caused damage any deeper than the paint! We do a lot of off airport and riverbed work and it hasn't presented any problems.

[Nev]

Another prop shopping question. Aka, so many proptions.

When looking for a used prop what specs should I be looking at to ensure fitment and suitability?
For example I found a 3 blade Hartzell used off a Cessna 182. PHC-G3YF-1RF/F84

So it's a similar plane, similar engine... what else do I need to look at to know if it will work for me?
we don't have mission specific performance needs - general all purpose airplane.

The prop advertised on trade-a-plane looks to be aluminum. For another data point, I've got the 3 bladed Hartzell Trailblazer composite prop on my 4-place. It's an extremely smooth running prop, almost turbine smooth and I've been extremely happy with it. My understanding is that counterweights are added to the engine when running a composite prop so that may be something to keep in mind if you go down that track. Mine currently has 460 hours on it, and mostly off-airport. I've got one stone chip - on the back of one blade from one of my early flights onto a rock strewn airstrip - partly par for the course, and partly me learning a few things the hard way. That required a rebalance. I'd generally echo what Battson has said above.