Mailing List flyrotary@lancaironline.net Message #41476
From: Charlie England <ceengland@bellsouth.net>
Subject: Re: [FlyRotary] Re: Fuel burn
Date: Sun, 10 Feb 2008 18:06:34 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Mark,

Isn't 7000/2.85=2456.14 ??

Is the M/T optimized (diameter, pitch, twist) for turning only 2150rpm?

Charlie


Mark Steitle wrote:
Al,

Yes, I'm running one of Tracy's 2.85:1.00 boxes.

Mark 

On Feb 10, 2008 12:20 PM, Al Gietzen <ALVentures@cox.net> wrote:

Subject: [FlyRotary] Re: Fuel burn

 

Thanks, good data Al. I'm sure that some of the differences we're seeing are due to altitude.  So far, I've stayed fairly low (3000-5000').  I may try some higher altitude flight soon just to see how it changes my performance numbers.  Another difference is that I have a M/T electric constant speed prop.  I normally set it to 2150rpm for takeoff.  This allows the engine to turn around 7000 rpm, which will account some for the higher fuel burn I'm seeing.  My airport is at 520' msl, so there's a 1000' difference there from your 1500' msl airport.  Yes, she really accelerates down the runway.   I'm usually airborne in about 900-1000'. 

Mark

I'm not sure I see how these correlate "set it to 2150rpm for takeoff.  This allows the engine to turn around 7000 rpm,"; but the big difference is that you're putting out more horses than I am.  At 7000 you're likely looking at about 300 hp, so 25-26 gph would be expected.  Are you running a 2.85 ratio redrive; or something else?

Al

 


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