Mailing List lml@lancaironline.net Message #70323
From: Charles Brown <browncc1@verizon.net>
Sender: <marv@lancaironline.net>
Subject: Re: Two-blade or three-blade prop for I-550
Date: Mon, 30 Jun 2014 07:38:05 -0400
To: <lml@lancaironline.net>
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I've enclosed the spreadsheet provided to me by Les Doud of Hartzell.  In 2009 his phone number was Phone: 937-778-4262 .  He believes that the 3-blade is more effiicient than the two blade even in cruise.  I have a hard time believing that, and my airplane with 3 blades has not lived up to the prototype Legacy's performance with the 2-blade as documented in the CAFE report; and the 3-blade is heavier and more expensive to buy and overhaul.  Of course, my airplane is probably not as clean as the prototype.

But the 3-blade prop sure looks cool. 





Date: June 29, 2014 8:01:58 AM CDT
Subject: Two-blade or three-blade prop for I-550


I have a chart somewhere from Hartzell which shows the theoretical projection of prop efficiency vs speed for two vs three blade, and the three blade is the winner by a small tweak, a per cent or two at the higher speed.   Several years old, but I do not think the part numbers have changed for the recommended Lancair props.
 
Fred Moreno


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