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Nick,
I've been in 14 races over the years behind
Hartzel. Airventure Cup and Sun 100 mostly.
The Hartzel props do consistently beat the MT props by a
hair. However, most of us agree the 3 blades look better.
Lately, I've gone to a Cato fixed pitch composite prop
68".
You loose takeoff and some landing performance but more
than make up for it in cruise speed , fuel economy, light weight, lower
vibration and low cost.
Mark Ravinski
360 1539 hrs
Sent: Tuesday, June 18, 2013 4:59 PM
Subject: [LML] Re: Propeller choice for Lancair 320 and Back Plate
failures
Thanks Dan,
That’s all useful info. At first, one would be tempted to say that 3-4
knots is not significant, but if it is repeatable....
I remember years ago some of us wondering why one aircraft was faster than
another and swapping supposedly identical props between supposedly identical
aircraft, then flying in formation and finding one prop was always 3 or 4 knots
better.
Nick
Sent: Tuesday, June 18, 2013 6:47 PM
Subject: [LML] Re: Propeller choice for Lancair 320 and Back Plate
failures
Nick,
I’ve got a Lancair 320 with the IO-320-D1B 160hp engine and
the Hartzell 70” prop that Lancair and Hartzell approved for this airframe and
engine. I’m very pleased with the performance. A friend of mine has
the same airframe and engine as I do but has the MT 3-blade prop. When we
fly formation at exactly the same power settings, I am pulling away from him at
about 3-4kts. We haven’t tried a side-by-side climb comparison but the
2-blade Hartzell is definitely a bit faster in cruise than the 3-blade Hartzell,
just as prop theory would suggest.
When I built the plane I was concerned about spinner wobble
and stresses, so I created a little donut inside the spinner that fits snugly
around the prop hub. You can see a photo of it here: http://lancair.net/pix/olsen/olsen-construction.
After 720hrs on the airplane I have had no problems with spinner or
cracking.
Cheers!
Dan Olsen
Fort Collins, CO
N320DK, 320 MKII, 720hrs
N630DK, IV-P, 20% complete
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