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1. 08:05 AM - Re: RV10-List Digest: 4 Msgs - 01/24/05 (LessDragProd@aol.com)
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| Subject: | Re: RV10-List Digest: 4 Msgs - 01/24/05 |
--> RV10-List message posted by: LessDragProd@aol.com
Hi Al,
One of the reasons I like working will MT Propeller is that they seem to
have a better business ethic than our own American propeller manufacturers.
Regards,
Jim Ayers
In a message dated 01/24/2005 11:59:22 PM Pacific Standard Time,
rv10-list-digest@matronics.com writes:
Time: 08:41:35 AM PST US
From: AI Nut <ainut@hiwaay.net>
Subject: Re: RV10-List: Lycoming - tractor engine or turbine smooth?
--> RV10-List message posted by: AI Nut <ainut@hiwaay.net>
It may be smoother, but I'm told by prop manufacturers that one will
lose a few kts in cruise with a 3-blade. I opted for smoother.
David
LessDragProd@aol.com wrote:
>--> RV10-List message posted by: LessDragProd@aol.com
>
>Lycoming - tractor engine or turbine smooth?
>
>This is the real question that needs to be asked when you are considering
>which propeller to buy.
>
>I had an opportunity to test four different constant speed propellers on
one
>aircraft. There were three different 2 blade propellers and one 3 blade
>propeller. This aircraft was owned by a friend who flew the aircraft. I
just
>went along as the observer and data recorder.
>
>The original CS propeller on the aircraft had been dynamically balanced on
>the engine. Since the plan was to leave the original propeller on the
>aircraft when we were finished with the testing, we did not removed the
dynamic
>balance weights from the engine ring gear.
>
>All three of the 2 blade propellers had about the same vibration level
>during their flights.
>
>Then we flew the 3 blade propeller. On the takeoff roll and initial
climb,
>I noticed the pilot was highly stressed about something. About mid field,
as
>we were climbing out, he finally said that something must be wrong with
the
>engine. That the engine wasn't producing power.
>
>We laughed about this later.
>
>We seem to expect a certain vibration level which can be directly related
to
>the engine power. We don't even think about this. And it's not something
>that any instructor I have had has ever talked about. It's just there.
>
>I've been told that a 2 blade propeller has a 2nd order harmonic on the
>Lycoming engine.
>
>And the 3 blade propeller does not have the 2nd order harmonic on the
>Lycoming engine.
>
>What does this really mean?
>
>On another test sequence, I had an opportunity to again ride in a friends
>aircraft. On this friends Harmon Rocket 2 with a stock Lycoming
IO-540-C4B5,
>we removed a 2 blade propeller and installed a 3 blade propeller.
>The 3 blade propeller made the Lycoming run like it was an electric motor,
>it was so vibration free.
>When we install a second 2 blade propeller, the same old vibration came
>right back. At the same level as the first 2 blade propeller.
>
>So the question goes back to you, the builder/flyers. Do you want
"turbine
>smooth" or "tractor engine"?
>
>Regards,
>Jim Ayers
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