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NeilsenRM(at)comcast.net
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 Posted: Tue Sep 09, 2008 11:48 am Post subject: Wood Props |
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Lets ALL keep it nice.
I would personally not have a wood prop on my MKIIIC. My experience has
proven to me that composite props are much better on our airplanes. On my
first plane I lost a wood prop in flight (it sheared the prop bolts and
literally flew off) due to seasonal changes in temperature and humidity. I
didn't know I needed to retorque the prop bolts at least twice a year
because of the shrinking and swelling of a wood prop. This may not be
necessary in all climates but it is in Michigan. I was also told that I
should always leave wood props in a horizontal position so that oils in the
wood would not migrate to one tip causing prop imbalance. I don't know for
sure about this information but that is what I was told.
My direct drive VW had a wood prop because wood props were the only props
that didn't cause crank shaft problems. During taxi testing I got a bit too
close to a tree and clipped a twig. I wasn't much over idle and the branch
where I clipped it was only about a 1/8 inch dia. but the prop split from
the tip almost to the hub.
Since switching to a redrive VW and a PowerFin Prop I lost a 5/16 bolt X 3
inches long from a starter mount. The bolt went thru the prop at cruise
RPMs. It got my attention and I subsequently landed to check things out. The
prop was damaged but serviceable enough to fly almost 400 miles home.
You do what you feel is best but I prefer a composite prop.
Rick Neilsen
Redrive VW powered MKIIIC
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JetPilot
Joined: 10 Jan 2006
Posts: 1246
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| Posted: Tue Sep 09, 2008 5:38 pm Post subject: Re: Wood Props |
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Rick,
I SAW the same experience with a wooden prop on a 447 on a trike that I fly. One day a nylon strap came down and bounced off the tip of the wooden prop... Not catch, but just bounce off the tip... I signaled the pilot to cut the engine so that we could secure the strap. When the engine stopped, the result of this very light strike was a large split from the tip to the hub. The nylon strap did not have a mark on it...
The wooden prop was beyond repair, so we replaced it with a Powerfin. The Powerfin is quieter, smoother, and gives us better performance on the 447. Given what I have seen first hand, and many reports like Ricks of wooden props taking major damage due to the slightest nick, there is no way I would ever put a wooden prop on a pusher plane. The balance and hub torque problems just make a bad situation worse.
Wooden props have been around since the very beginning of flight, for many years they were the only propeller option people had. There is a very good reason that wooden props are almost never used on certified aircraft anymore. The almost total and complete switch from wood to aluminum and composite propellers did not happen for no reason. From small Cessnas and Light Sport airplanes, to larger piston airplanes, almost no one is using wood anymore. Aside from the few Nostalgic and antique repleca airplanes, wooden props are a thing of the past. The vast majority of aircraft engineers and designers recognize that wood propellers are inferior, and would never consider using them on modern aircraft.
Mike
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