Review: The Hartzell Composite Propellor on my RV-7A

[dreed]

ah... sorry I thought you wanted it for the 4 bangers

[BlackhawkSP]

Originally Posted by ebridges

Did you deal with Hartzell directly for this prop setup? I cannot find anyone else that has on like it and Vans only offers a 2 blade aluminum or 3 blade composite from Hartzell. I really like the idea of it. I want the lightest, smoothest prop I can get and I'm wondering if this fits the bill!

Even though they didn't list it, I called Van's and was told I could order through them what I wanted from Hartzell. I had consulted with the engineers at Hartzell and was told that this prop could handle high compression pistons and E.I. (LSE) with no problems. There would also be no worries about RPM avoid ranges:-). Make sure that you check the clearances from the trailing edges of the blades and the inlet of the lower cowl. I got the numbers from Hartzell and made sure that I put the Rod Bower inlet on accordingly. Things worked out great. I love this setup still on the RV-10.

[KGT]

I swapped my Catto 3 blade for the Hartzell composite and also swapped my 0-360 180hp for a BPE XIO-360 200hp angle valve engine in my RV8.
I must say I?m thrilled with the results. For me this is a perfect engine/prop combo! Before the change I cruised 170knts at 6-8000 feet at 2500 rpm and now at 2400rpm at 190knts rich of peak till I?m sure it?s broken in. Take off roll is stunning in my opinion.
I know this is not a very scientific report of my results but this combo works great for me!

Kevin

[Hartstoc]

Originally Posted by KGT

I swapped my Catto 3 blade for the Hartzell composite and also swapped my 0-360 180hp for a BPE XIO-360 200hp angle valve engine in my RV8.
I must say I’m thrilled with the results. For me this is a perfect engine/prop combo! Before the change I cruised 170knts at 6-8000 feet at 2500 rpm and now at 2400rpm at 190knts rich of peak till I’m sure it’s broken in. Take off roll is stunning in my opinion.
I know this is not a very scientific report of my results but this combo works great for me!

Kevin

I would agree that you have hit on an ideal powerplant for this propellor, it will soak up everything your engine can throw at it! If I ever need a major on my 180HP Lyclone, I’ll be very tempted. It would be a tough decision on my 7A, though, as the lightweight prop and lighter weight engine results in spectacular handling, and adding that much polar mass would significantly diminish the nimbleness factor, but what a climber it would become!- Otis

[Kip]

Originally Posted by Hartstoc

To put it in a nutshell, if I opened my hangar one day to find that someone had put the FP Sensenich back on my airplane(and of course deposited about $15K back into my bank account!), I?d be ordering another Hartzell Composite without the slightest hesitation, but I appreciate that it is not the prop for everyone. I?d be happy to respond to any questions or comments.- Otis

Hi Otis, what a great post! This is my first post on VAF, and even though I have been around RVs since the beginning (used to work with Dick at Hyster Co.), I have not and am not building an RV, but a Rans S-21. It will have an IOX-340, 180 hp Titan engine with 9.0:1 CR. Props up to 80" diameter will work on the taildragger I'm building. I've been looking at this prop as a possibility and wondering what your thoughts are about it's suitability for the S-21. Excellent T/O and climb ability are important but so is cruise speed for this quasi-STOL aircraft. There doesn't seem to be many options for this niche market. I guess I need to talk to some engineering/tech people at Hartzell and wondering if you can suggest anyone in particular?

[scsmith]

The OP mentioned that Jack Norris had commented about the Hartzell prop not being optimum based on classical propeller theory. In case anyone is interested, I can expand on that a little bit.

Classical theory with some nice refinements leads to propeller blades that are shaped more like the Whirl Wind 200RV prop. However, there is a noteable shortcoming to that classical theory as generally applied, in that it does not include transonic effects.

Including transonic effects in the propeller blade design tends to shift the blade shape toward wider chords that operate at lower lift coefficients to produce the same ideal circulation and lift distribution, and also allows thinner blade sections (at least as a percentage of blade chord if not outright thickness). Thinner thickness to chord ratio and lower lift coefficient both tend to delay transonic drag rise.

So the interesting design challenge here is to optimize the blades for the trade-off of adding more wetted area which is skin friction drag but reduces transonic drag effects.

The fact that the 2-blade Hartzell "Blended Airfoil" prop and the Whirl Wind 200RV prop both provide almost identical cruise speed suggests that, at least at 2400 rpm on a 72" prop (A helical tip Mach number of about 0.7), the design space is rather flat - that is, multiple design points can have very similar performance.
If you are going to race fast, you might find that the Hartzell starts to have an edge.

I might point out that the guys at Hartzell have been designing propellers for a long time, and they know their stuff. You can bet they have modern computational design methods that do a good job of accounting for both transonic and viscous effects.

[Hartstoc]

Originally Posted by Kip

Hi Otis, what a great post! This is my first post on VAF, and even though I have been around RVs since the beginning (used to work with Dick at Hyster Co.), I have not and am not building an RV, but a Rans S-21. It will have an IOX-340, 180 hp Titan engine with 9.0:1 CR. Props up to 80" diameter will work on the taildragger I'm building. I've been looking at this prop as a possibility and wondering what your thoughts are about it's suitability for the S-21. Excellent T/O and climb ability are important but so is cruise speed for this quasi-STOL aircraft. There doesn't seem to be many options for this niche market. I guess I need to talk to some engineering/tech people at Hartzell and wondering if you can suggest anyone in particular?

Hello Kip, thanks for the kind words and welcome to posting on VAF- I get the impression that you have a lot of company in the ?non-RV but paying attention to VAF? crowd. I cannot help but imagine that this prop would be an excellent candidate for your bird. You might pick up some valuable insight reading the post following yours, as you would be taking advantage of the low lift coefficient/high RPM condition during high performance climbouts. The relevance of my RV-only experience with it is purely anecdotal, but I certainly get the impression that the slower I go the harder it pulls during climbouts. In cruise, you will have a ton of margin for extracting everything your engine can produce at lower RPM?s. Sorry I cannot recommend anyonein particular at Hartzell, but the support staff there is quite knowledgable. Good luck- Otis

[Hartstoc]

Originally Posted by scsmith

The OP mentioned that Jack Norris had commented about the Hartzell prop not being optimum based on classical propeller theory. In case anyone is interested, I can expand on that a little bit.

Classical theory with some nice refinements leads to propeller blades that are shaped more like the Whirl Wind 200RV prop. However, there is a noteable shortcoming to that classical theory as generally applied, in that it does not include transonic effects.

Including transonic effects in the propeller blade design tends to shift the blade shape toward wider chords that operate at lower lift coefficients to produce the same ideal circulation and lift distribution, and also allows thinner blade sections (at least as a percentage of blade chord if not outright thickness). Thinner thickness to chord ratio and lower lift coefficient both tend to delay transonic drag rise.

So the interesting design challenge here is to optimize the blades for the trade-off of adding more wetted area which is skin friction drag but reduces transonic drag effects.

The fact that the 2-blade Hartzell "Blended Airfoil" prop and the Whirl Wind 200RV prop both provide almost identical cruise speed suggests that, at least at 2400 rpm on a 72" prop (A helical tip Mach number of about 0.7), the design space is rather flat - that is, multiple design points can have very similar performance.
If you are going to race fast, you might find that the Hartzell starts to have an edge.

I might point out that the guys at Hartzell have been designing propellers for a long time, and they know their stuff. You can bet they have modern computational design methods that do a good job of accounting for both transonic and viscous effects.

Steve- Thank you for this valuable post. Anything that sheds light on the “black magic” of propellor design for we neophytes is much appreciated! I’ve intuitively felt that the high “thinness ratio” of this prop was key to its incredible performance. Given that the “twist” of a blade on a CS installation can only be optimized for a particular RPM/speed ratio, it stands to reason that low thinness ratio blades operating at higher lift coefficients might have some very draggy sections with possible flow separation in many scenarios near the limits of pitch travel. I also wonder about the effect, if any, of the oddly slippery surface finish of the carbon fibre blades. It feels “lubricated” when you run your hand over it, not “grabby” like a glossy painted blade. I’m not even trying to disguise my general ignorance here, so no laughing please! -Otis

[fl-mike]

Originally Posted by scsmith

snip>>
Including transonic effects in the propeller blade design tends to shift the blade shape toward wider chords that operate at lower lift coefficients to produce the same ideal circulation and lift distribution, and also allows thinner blade sections (at least as a percentage of blade chord if not outright thickness). Thinner thickness to chord ratio and lower lift coefficient both tend to delay transonic drag rise.

and my understanding is that the advent of carbon fiber materials allowed the prop designers to finally get to that thin ratio in our size props.

[scsmith]

Originally Posted by fl-mike

and my understanding is that the advent of carbon fiber materials allowed the prop designers to finally get to that thin ratio in our size props.

Yes, that is likely true. Although, even the aluminum BA blades are fairly thin.