----- Original Message -----

From: Charles Brown

Sent: Monday, June 30, 2014 7:38 AM

Subject: Re: Two-blade or three-blade prop for I-550

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. 

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From: "frederickemoreno@gmail.com" <frederickemoreno@gmail.com>

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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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.






From: "frederickemoreno@gmail.com" <frederickemoreno@gmail.com>
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