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View Poll Results: What is your combination?
1 13 35.14%
2 24 64.86%
3 0 0%
Voters: 37. You may not vote on this poll

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  #1  
Old 07-11-2018, 06:11 PM
AX-O's Avatar
AX-O AX-O is offline
 
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Default Counterbalanced crank and constant speed prop question.

All,
I am trying to collect data on how many folks are running a constant speed prop with a counterbalanced crank and without a counterbalance crank. depending on the results, I may be working on a project for a constant speed prop (flight test). If you care to provide feedback, reply with one of the answers below. If you care to ellaborate on #3 (if that is your selection), that will deeply appreciated.

1. Counterbalanced crank and constant speed prop.

2. Non-counterbalanced crank and constant speed prop. No prop issues/failure.

3. Non-counterbalanced crank and constant speed prop. Some prop issues/failure.

Thank you for the feedback.
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  #2  
Old 07-11-2018, 06:21 PM
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skylor skylor is offline
 
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Default Engine/Prop Combo

Constant speed (Hartzell) and counter-balanced crank.

Skylor

Last edited by skylor : 07-12-2018 at 04:25 AM.
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  #3  
Old 07-11-2018, 06:21 PM
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Toobuilder Toobuilder is offline
 
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Default

I'm guessing that you are discussing 4 bangers only? If not, it's going to skew your data
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  #4  
Old 07-11-2018, 09:26 PM
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AX-O AX-O is offline
 
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Default

Quote:
Originally Posted by Toobuilder View Post
I'm guessing that you are discussing 4 bangers only? If not, it's going to skew your data
Good point. I am only refering to 4 cylinder engines. Thank you.
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The information that I post is just that; information and my own personal experiences. You need to weight out the pros and cons and make up your own mind/decisions. The pictures posted may not show the final stage or configuration. Build at your own risk.
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  #5  
Old 07-11-2018, 09:31 PM
MConner MConner is offline
 
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Location: Snead Island, Florida
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Take one off then, I voted counterbalanced with c/s...540
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  #6  
Old 07-11-2018, 09:49 PM
Chkaharyer99 Chkaharyer99 is offline
 
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Location: Pilot Hill, CA
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2. Non-counterbalanced crank and constant speed prop. No prop issues/failure.

Titan IO-360 Parallel valve. 9:1 compression.

Hartzell metal blended airfoil with B-hub.

Approximately 800 hours on prop engine combo.
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Last edited by Chkaharyer99 : 07-12-2018 at 10:29 AM.
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  #7  
Old 07-12-2018, 08:00 AM
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Dan Langhout Dan Langhout is offline
 
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2. (Stroked) non-counterbalanced crank and constant speed prop. No prop issues/failure.

Aerosport IO-375/Hartzell.
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  #8  
Old 07-12-2018, 08:22 AM
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airguy airguy is offline
 
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Not a lot of time on it so far, only 260 hours, but non-counterbalanced and Whirlwind C/S here, no problems.
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  #9  
Old 07-12-2018, 09:19 AM
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DanH DanH is offline
 
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The questions are much too superficial.

Blade failure is a function of vibration, i.e. number of cycles and amplitude. The blade is a victim. Whack it at one of its natural frequencies, and it will resonate. If the resonant vibration exists for enough cycles (think operating hours), or has high amplitude (meaning high stress), the blade will fail eventually. If run at a engine RPM which does not result in significant blade vibration, the blade will be fine.

Mere knowledge of the crank type is useless without also knowing the operating condition. That's why prop manufacturers who actually instrument and test their blades using strain gauge arrays may insist on operating restrictions...an RPM range, or RPM/MP combination, at which operation is to be transitory only. The measured stresses were high in those ranges, so they wish to limit the number of cycles.

In general, plain crank engines result in more prop restrictions. However, the presence of pendulum absorbers does not guarantee a happy prop across the entire operating range. The IO360-A3B6D/McCauley is an example.

Nor is the issue restricted to constant speed props.

In addition, the questions say "constant speed" but do not specify a blade material. Aluminum, composite, and wood blades are very different.
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  #10  
Old 07-12-2018, 09:44 AM
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Thanks Dan for the info. I was trying to make a quick poll and a small post so i could actually get data. If someone said “i have had issues”, then i was going to contact the person individually. We have instrumented data for some combos of cranks/props. Just trying to get some feedback from users vice only from a test stand.
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The information that I post is just that; information and my own personal experiences. You need to weight out the pros and cons and make up your own mind/decisions. The pictures posted may not show the final stage or configuration. Build at your own risk.
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