Hartzell 72" or 74"?

[DCalland]

Is your prop the F7496 or the F7497? I'm looking at the F7497 prop even though it is not listed for our engine (as suggested by Hartzell).

[robertahegy]

I have the Van's spec'd Hartzell 74" prop on my 0-360 A1A on my 7A. Great performance (204 mph cruise @ 8000 msl) and climb rate easily exceeds 1800 fpm at gross. It is the HC-C2YR-1BF/F7496. I haven't experienced any problems regarding any restrictions. Actually, never see myself flying in the restricted zone anyway. I believe it is for high MPs and low RPMs. Not likely to encounter those parameters for lengthy times.

Roberta

[Jetj01]

I had the same diameter decision to make too once I had decided on the Hartzel BA....72" 0r 74"......let's see...THE SAME PRICE FOR EITHER the catalog said???? So you mean I get two more inches of expensive Hartzel metalurgy for the same price? (STS) Yes you do, Van's said! Easy decision: Just took delivery of my 74" prop. I feel like I was able to "take it to the man"!



Jj

Building RV-4 Fastback
Flying RV-6 IO-360/Hoffman
Flying YAK 50
...military stuff!
North Texas

[Jekyll]

The 74 inch BF prop still has a restriction on the O-360 (180hp). I emailed Hartzell last week and asked directly. My set up is C2YR-1BF/F7496 prop on a Mattituck TMX-IO-360 parallel valve, dual e-mag, RV-7A. The Hartzell web site (Homebuilt section) doesn't show this prop/engine combination but, the setup is OK but with restrictions.

Their answer:

"There is a placard for your particular setup. It is as follows:

DO NOT OPERATE ABOVE 22 INCHES MP BELOW 2350 RPM. O-360-A1A: OPERATION ABOVE 2600 RPM IS LIMITED TO TAKEOFF, IOF-360-A1A: MAXIMUM ENGINE SPEED LIMITED TO 2650 RPM."

Jekyll

Jekyll

[KirkGrovesRV8]

Originally Posted by 13brv3

In full confession mode, I can explain my 74" choice. My buddy has an O-360 powered RV-8, with a 74" older styl Hartzell. I must be able to meet, or exceed his climb and cruise performance

I figure the blended airfoil prop will exceed his cruise performance, even at the same diameter. I'm guessing it doesn't help as much at climb speeds, so having the same 74" diameter should keep me from losing a climb contest.

Interestingly enough, my old RV-8 had an O-360, and Sensenich 72" aluminum prop. I could outrun him by a few kts in cruise, but of course he killed me in climb.

Just as another footnote.. I ordered a 74" BA prop from vans but I was sent a 72". My climb rate at 120mph is 2150fpm and at 8000' I am seeing 185kts true airspeed at 75% power.
I have been able to verify this numbers so I feel pretty comfortable with them.
All the Best

[Rick6a]

Being mathmatically challenged, I must admit complicated formulas describing prop efficiencies are way out of my depth.

I contacted Hartzell's John Popel and said I'd really like a three bladed prop like a Black Max fitted to a local 180 H.P Comanche. I was told testing has not been done on RV's, and the prop choices offered thru Van's are proven. If I wanted a 3-bladed Hartzell prop I would be on my own and further....would not enjoy its significant OEM pricing.

Back to square one, I too labored over the 74" versus 72" choice. Unless I missed the point if raised in a previous post, days ago I finally ordered the 72" version largely based upon Van's published literature. While I really like the idea that a 74" prop can always be cut down, in the end I heeded Van's semi-cautionary note that 74" is a good choice for an 8A but because of potential ground clearance issues, a 72" dia. is recommended for an -8.

[redhawk]

After reading all the excellent posts regarding which prop length is best, my limited brain capacity has been reached, and my big decision now is to go with a long neck or standard length beer bottle.
Of course the long neck is less clearance between the counter top and my thirsty choppers!

[Capflyer]

Redhawk....LMAO, I like the way you think. Perhaps some additional data points are needed however. Typically at the local brewpub the 16oz draft IPA gives a better quality ride than the light performers in most long necks. While the distance between rim and lips is slightly increased you gain volume and quality by going with the shorter carafe.