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  #151  
Old 07-29-2017, 09:09 PM
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czechsix czechsix is offline
 
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Originally Posted by Carl Froehlich View Post
Considering the Whirlwind 650 hour/5 year teardown and cost, I offer the Hartzell is the better value. I have a lot of hours behind this prop in the RV8A and RV-10, and my third Hartzell BA prop just arrived for the new RV-8 project. I've never had any issues with hub seals or anything else.
If I recall correctly Hartzell has a TBO of something like 6 years but I've never met anyone in either the experimental or certified world who actually does that, and neither do the Whirlwind owners. As for the issues with slinging grease on the Hartzell, it's well documented by many owners, I think Tim Olson has written about it in his blog and plenty of instances in the VAF and Matronics forums. I suspect you are getting your airplanes flying more quickly than the average homebuilder if you've had three of them and no problems so far...
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  #152  
Old 07-29-2017, 09:22 PM
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czechsix czechsix is offline
 
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Originally Posted by rwtalbot View Post
Whirlwind have significantly higher overhaul requirements. Depending upon the model the Whirlwind gives you 3-5 years and between 400-650 hours. There are quite a few reports of premature failures - loose blades, grease leakage, etc
Are those failures on recent 200RV and 74RV models? I know there were some issues like that with the earlier WW 151s about a decade ago but thought those problems had been resolved. If not it looks like I'll have to pick my poison when it comes time to buy a CS prop for my -14...
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RV-14A #140017 - wings complete, empacone in progress...
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  #153  
Old 07-29-2017, 09:35 PM
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Av8rRob Av8rRob is offline
 
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Default Mt 3 blade

Since this thread is turning into a prop discussion, what are the thoughts about using a MT 3 bladed prop. I think I remember the weight is 55lbs so it is more inline with the Hartzell. That should help with cg issues. Besides the 12,500 price any other issues?
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  #154  
Old 07-29-2017, 10:20 PM
redbaron redbaron is offline
 
Join Date: Aug 2013
Location: Lucerne,Ca
Posts: 178
Cool Viking aircraft engines

Take a serious look At the new Viking engines they have been upgraded and include some with turbo charging.
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  #155  
Old 07-30-2017, 10:53 AM
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czechsix czechsix is offline
 
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Quote:
Originally Posted by Av8rRob View Post
Since this thread is turning into a prop discussion, what are the thoughts about using a MT 3 bladed prop. I think I remember the weight is 55lbs so it is more inline with the Hartzell. That should help with cg issues. Besides the 12,500 price any other issues?
My fault for getting the thread off topic, but since you asked....Vans did a bunch of comparative performance testing on various props over a decade ago and published results in the RVator. As I recall Hartzell blended airfoil and Whirlwind provided the best cruise performance and the MT was several knots slower. After that report very few people put MT props on their RVs....Way more cost for less performance doesn't sell too well. That said, it's possible MT has since developed a newer blade design better suited for the RV series, you'd have to research to find out. Also FWIW three blade props from any manufacturer tend to have reduced cruise performance compared to two blades (hence the old saying "two for the go, three for the show"). Three blades also make removal of the lower cowl more difficult and shipping the prop for repair or overhaul a lot more difficult & expensive. So...thats why you see so few 3-blade props on RVs.
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  #156  
Old 07-30-2017, 11:23 AM
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RV6_flyer RV6_flyer is offline
 
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Quote:
Originally Posted by redbaron View Post
Take a serious look At the new Viking engines they have been upgraded and include some with turbo charging.
Not sure why anyone would not follow Van's Aircraft recommendation on engines for an aircraft as expensive as the RV-14(A) kit. They designed the aircraft around two engines. An overweight under powered Honda engine conversion is something that I would not walk away from, I would RUN as fast as I could to get away from it.
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  #157  
Old 07-30-2017, 11:40 AM
David Paule David Paule is offline
 
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Quote:
Originally Posted by czechsix View Post
....Hartzell... ...transmits lots of vibration back into the airframe (typical of any metal prop)....
A good dynamic balance will fix that.

Dave
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  #158  
Old 07-30-2017, 12:33 PM
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czechsix czechsix is offline
 
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Quote:
Originally Posted by David Paule View Post
A good dynamic balance will fix that.
The Hartzell on my -8A was dynamically balanced, but the metal blades don't absorb the engine power pulses, so they get transmitted back into the airframe. Not as noticeable at higher RPMs as it is at lower RPMs and especially during shutdown. The first time I got in a friend's -7A with a Whirlwind prop, it felt more like a car when he started the engine. Much smoother...those carbon fiber blades absorb a lot more of the power pulses than metal.

If you were flying a turboprop, metal vs composite blades wouldn't make any difference as long as the prop is balanced, but not so on piston engines.
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  #159  
Old 07-30-2017, 05:49 PM
MED MED is offline
 
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I spoke with several people at Oshkosh about the differences between the Hartzel aluminum prop and the composite. A couple of discussions helped me to decide to spend the extra $ and buy the composite. Specifically, composite props are "smoother" with less vibration transmitted to the airframe and engine environment, leading to fewer engine baffle cracks, etc. The second advantage, according to Hartzel, is that the composite prop leading edge is nickel, which is much harder than aluminum, leading to a reduced chance of prop nicks. Plus, they said if a nick occurred, leading to a crack in the leading edge, it was a simple job to replace the leading edge. Hartzel said by replacing the leading edge at overhaul, you would essentially have new blades. Unfortunately, the difference in cost is non-trivial.
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  #160  
Old 07-30-2017, 05:54 PM
rwtalbot rwtalbot is offline
 
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Quote:
Originally Posted by MED View Post
The second advantage, according to Hartzel, is that the composite prop leading edge is nickel, which is much harder than aluminum, leading to a reduced chance of prop nicks.
When you hit something soft it takes a dent. If you hit a harder material it cracks. That has been the experience on MT blades for years. Perhaps the Harzell doesn't suffer as much. If it were me I would call my local prop shop and ask their advice.
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