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  #1  
Old 05-05-2022, 09:00 AM
DHoover DHoover is offline
 
Join Date: Aug 2018
Location: San Antonio, TX
Posts: 13
Default Prop Swap: Catto to Hartzell - What test data do you want?

As the title says I'm swapping from a 3B Catto to a Hartzell in my RV-7. Thanks @Walt!

I'm waiting on my prop gov and cables to show up for the swap so I've got a little time yet and wondered if there's any specific test data folks would be interested in for this particular permutation of propellers?

Here's what I've considered so far:
- Measured change to CG (I'm too tail heavy currently)
- Takeoff performance
- Cruise performance by fuel flow, % Power, MP and RPM (I'd like to be able to judge blade efficiency knowing the Catto is really good)
- Measured Sound Level (my wife is an audiologist and I promised her it'd be quieter in cruise - hope I'm right)

I'll take any advice on testing these but what else would help folks choose props?
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N24726 RV-7 Flying
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  #2  
Old 05-05-2022, 09:07 AM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest
Posts: 2,446
Default Looks

Quote:
Originally Posted by DHoover View Post
As the title says I'm swapping from a 3B Catto to a Hartzell in my RV-7. Thanks @Walt!

I'm waiting on my prop gov and cables to show up for the swap so I've got a little time yet and wondered if there's any specific test data folks would be interested in for this particular permutation of propellers?

Here's what I've considered so far:
- Measured change to CG (I'm too tail heavy currently)
- Takeoff performance
- Cruise performance by fuel flow, % Power, MP and RPM (I'd like to be able to judge blade efficiency knowing the Catto is really good)
- Measured Sound Level (my wife is an audiologist and I promised her it'd be quieter in cruise - hope I'm right)

I'll take any advice on testing these but what else would help folks choose props?
Which prop looks better. after all one only sees the plane and the prop when things are stationary on the ground.

(I am joking of course, sort of)
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WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

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  #3  
Old 05-05-2022, 09:20 AM
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grjtucson grjtucson is online now
 
Join Date: Oct 2005
Location: Tucson, AZ
Posts: 197
Default Good (or Bad) Vibrations

Quote:
Originally Posted by DHoover View Post
I'll take any advice on testing these but what else would help folks choose props?
Suspect measuring this would be difficult/involved/expensive but I'd certainly be interested in your subjective comparison of vibration levels / "smoothness".

Thanks,

George
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Tucson, AZ - N567AJ RV-7 Standard Build
Empennage 1/06, Wings 11/06, Fuselage 9/08, Panel Wiring 7/19, to airport 10/20, first engine run 2/21. AWC 11/11/21. First flights 11/17/21. My first flight 12/17/21, my first solo 12/20/21.
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  #4  
Old 05-05-2022, 09:55 AM
Mikeyb Mikeyb is offline
 
Join Date: Nov 2018
Location: Pasadena ca
Posts: 176
Default

Good Test!
There doesn’t seem to be a lot of quantitative data on the effect of engine braking. For instance the flight profile from cruise to pattern speed with both props.

More of a stunt than a measurement but I’d love to see the time required to do a circuit of the pattern at your airport takeoff to landing with both props.
Mike
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  #5  
Old 05-05-2022, 10:31 AM
DHoover DHoover is offline
 
Join Date: Aug 2018
Location: San Antonio, TX
Posts: 13
Default

John,
Hard to argue - the Catto wins the looks, hands down!

George,
Great idea, I'll think about a way to measure but certainly will provide the subjective assessment.

Mike,
I was considering using some kind of breaking test on approaches. Maybe 3nm final, 3 deg glide slope entered at a specific speed (120kts). I know the catto struggles to slow me to flap speed in with those parameters so maybe recording the speed at 1nm final would give the data we're looking for. I'll keep scratching my head on this one.
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N24726 RV-7 Flying
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  #6  
Old 05-05-2022, 10:53 AM
Steve Watkins Steve Watkins is offline
 
Join Date: May 2020
Location: Upland,CA
Posts: 27
Default Stabilized descent rate?

How about descent rate at idle power @ 80 or 100kts? Flaps up, fine pitch vs Fixed Catto. What are the specs on the engine, the Catto and the Hartzell? I have a catto 3 blade 68x76 on my 180 hp M1B powered RV-8 and have been debating switching to CS for a while. I'm interested in your findings. Thanks!
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  #7  
Old 06-07-2022, 04:43 PM
Steve Watkins Steve Watkins is offline
 
Join Date: May 2020
Location: Upland,CA
Posts: 27
Default Update

Any update on your prop swap?
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