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Hartzell CS Prop comparison

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Ottertrack

Member
I am ready to "pull the trigger" on my engine/propeller combo purchase from Vans. I plan to order the (I)O-360-M1B engine with a Hartzell constant speed prop. I am building a 7A and according to Vans I could install the C2YR-72 inch or the 74 inch. They are both the same price of $7300.00. Does anyone know which one would be the best choice, or is the difference negligible?
 
Well, I have the composite 72" because that was the only length recommendation for the taildragger. I asked this question of a Hartzell guy once and he said, use the 74" if you can because the minimum permissible length for that blade is 72" So if damage occurs, you have some margin.

You should verify this yourself with Hartzell and the brain trust here. Good luck, that is a very efficient blade!
 
Hartzell prop

Thanks guys. I'm planning on selling the mags that come with the engine on Craig's List or eBay. I asked Van's if I could order the engine minus the mags and they said no. I am planning on using the Lightspeed Plasma III ignition and I think this combination will be really good. Tomorrow I will call Hartzell and ask them about the 72" vs 74". I appreciate your input!
 
The 74" prop can be trimmed down to 72" if at some point in the future a prop overhaul needs that much metal removed to clean up the blades. Yes it does reduce prop clearance by 1 inch but if you're nosed over that far in a bad landing you're already in more trouble than an extra inch of clearance is likely to help. My opinion only. My Sensenich GA prop is 72" and I have an abundance of clearance on a RV-6.
 
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Ottertrack said:
I am ready to "pull the trigger" on my engine/propeller combo purchase from Vans. I plan to order the (I)O-360-M1B engine with a Hartzell constant speed prop. I am building a 7A and according to Vans I could install the C2YR-72 inch or the 74 inch. They are both the same price of $7300.00. Does anyone know which one would be the best choice, or is the difference negligible?
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I went through the same dilemma. The argument is that the 72" is slightly faster while the 74" improves climb. I think either difference is marginal.

I went with the 72" for the additional ground clearance in my 7A.

Although the 74" gives an additional 1" to trim if the tip is damaged, it was suggested that if the tip was damaged it would normally be more than 1 inch.

No way to make a logical decision
 
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Hartzell 74" Prop

I called Hartzell this morning and Alex, one of the techs, said there is not much difference between the 72" & the 74". He did say the 74" should give a slightly better climb capability. He encouraged me to order the 74" as long as I have adequate ground clearance which I do with the 7A. This I will do. As others pointed out on this thread, in case of a nick at the tip, I would have some extra prop to file off. Thanks again for your thoughts. I live in the wilderness of northern Minnesota, 50 miles from the nearest airport and probably a hundred miles at least from the nearest builder, so I find this forum very valuable for advice.
 
Go for clearance

Prop clearance is like money....you just can't have enough of it.:)

But builders who buy the 74" prop rather than the 72" prop just sort of feel like they're getting something extra for the same price...a bonus of 1" of metal at either tip...something for free....but what they're really getting is the higher likelihood of a prop strike. And possibly lower speed as well.

A prop strike is an insurance claim (if you have hull insurance...which you probably should). So what would you prefer in the event of a prop strike....that the insurance company is forced to replace your 72" prop with a nice new unit or save themselves a few bucks and do a major repair of your mangled 74" prop.

I know what I'd prefer. ;)

Incidentally, anecdotal evidence suggest that the 74" prop will climb a bit better but that the shorter 72" prop will go a bit faster.
 
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If you fly off gravel runways, or even runways that aren't kept clean, then you will be able to dress out a lot of rock damage on a 74" that you won't be able to on a 72".

Although, if you are experienced and use good gravel techniques, shouldn't need to dress the prop much either :D
 
David Z said:
If you fly off gravel runways, or even runways that aren't kept clean, then you will be able to dress out a lot of rock damage on a 74" that you won't be able to on a 72".

Although, if you are experienced and use good gravel techniques, shouldn't need to dress the prop much either :D
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I have 100 hours on my nice new Hartell 72l
" and I already have two stone chips, both 12" from the tip.

I am very carefull on the ground and only fly from maintained airfields. This is with an RV7A. The 72" looks very close to the ground. When I phoned Vans last year about prop length they instantly said 72" even though their web site says 74".
 
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