Props...aerobatic vs. non.

[miyu1975]

I have been looking at props on barnstormers getting ready to purchase one this summer sometime. It will go on my RV7 with IO 360 200hp... I plan to eventually enjoy basic aerobatics in the RV. My question is which prop are people installing? I assumed all props were aerobatic but after a few calls I learned different..

After pricing it looks may best to go with Vans hartzer BA prop.

*Is vans hartzell BA aerobatic?...C2YR-1BF/F74972 $6800.00

*This one from Doug Works in Tulsa, OK HC-C2YK-1BF/F7666A-2 (non-aerobatic) with A suffix hub....he is asking $5,000 for these. anyone have a dealings with Doug Works?

*This one from propellerpartsmarket.com....HC-C2YR-4CF/FC7666A-2 (aerobatic) for $7500.00...

[Andy Hill]

Is vans hartzell BA aerobatic?

In "prop" terms no...

F74972 / F7666A-2 refer to the blades which are not relevant to "aerobatic" or not.

Hartzell Manual

The last one you list is "aerobatic" since it is a -4 - see Manual p2-1 for index. These use counterweights such that when Oil Pressure is lost, the prop coarsens, and does not overspeed. Counterweights come at a weight, and presumably cost, implication, and need different governor type/setup.

To put a -4 in an RV is rare, but not unknown. There is one horror story of someone doing a detailed test profile who did seriously overspeed his prop / engine, and unsurprisingly now has a -4 Details somewhere here on VAF.

To require the -4, you would probably want to do serious aerobatics, with extended -ve 'g', and RVs are not good in this area. I use a standard -1, tend to aerobat using ~2400RPM, and if -ve 'g' is ongoing, listen carefully - you will hear the engine beginning to increase in speed, and can throttle back. OTOH if you have 2600+ RPM set, and are distracted / unlucky, you might get well beyond 2700RPM [NB you are allowed without inspection +10% for 3s = 2970RPM on a Lyc, 10% for nearly 30s on a Hartzell].

From your post, I would go for the F7497 -1 - whether 72" or 74" see elsewhere for the debate

HTH?

Andy
RV-8 G-HILZ
RV-8tors

[Mike Redd]

I have the Hartzell aerobattic on a 7 with IO360 200HP, The only thing I remember doing different is the counter weights will hit if you use Van's spinner so you 'll need to cut a hole and create a bump on each side of the spinner for the weights to travel. Then be prepared for all the questions about the bumps. I have 700+ hrs, no problems. Don't notice the extra weight either. I didn't choose the prop it came with the engine, off a British Bulldog trainer plane.

[Toobuilder]

Originally Posted by miyu1975

I have been looking at props on barnstormers getting ready to purchase one this summer sometime. It will go on my RV7 with IO 360 200hp... I plan to eventually enjoy basic aerobatics in the RV. My question is which prop are people installing...

My Hiperbipe has the counterwieghted "aerobatic" Hartzell, and at my level of skill it is really only needed during knife edge flight or flat turns when the oil pressure drops to zero. The -8 I fly has a standard Hartzel BA and it works fine for about anything you are going to do in a "sport" airplane like an RV. Rolls, loops, snaps, hammerhead turns - no problem with the "standard" BA Hartzel. So in a word, I'd go with the BA over the counterwighted model. It's lighter, and will deliver a faster cruise speed with no noticable difference in aerobatic capability (in an RV).