lml@lancaironline.net Mailing List Archive

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

From: Dan & Kari Olsen

Sent: Tuesday, June 18, 2013 6:47 PM

To: lml@lancaironline.net

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