Mailing List flyrotary@lancaironline.net Message #19268
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] fuel injector size, and redrive losses
Date: Tue, 22 Mar 2005 14:25:28 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
RC Engineering's calcs show that you are good to 302 HP at 43 psi fuel pressure, .50 BSFC, and 100% duty cycle.  Of course you can't run the injectors at 100% (except maybe briefly like a drag race, not applicable to aircraft).  So at 80% duty cycle the 38 lb injectors should be good for 242 HP.  Enjoy your idle!!!  Your injectors are big enough unless you P-Port and turn at least 8000 RPM.

Hi Ken,
 
RC Engineering's calc shows the same as the fuel calculator that I posted the other day.  Four 38 lb/hr injectors, at 80% duty cycle, .55 BSFC, should be good for about 220 HP at the flywheel.  I imagine that will be enough for the current engine, but not by a wide margin.  I plan to run this engine as high as 8000 if I can, though I'll be amazed if I can get beyond 7500.  Don't need no stinkin' P-Port for these rpms :-)
 
On the fuel spreadsheet that I posted (stolen) the other day, it gives a HP figure for the flywheel, and rear wheels.  The estimate for the power loss due to a manual trans and diff is 15% on this spreadsheet.  Anyone know what this amounts to for our redrive, and prop?  
 
Cheers,
Rusty (hoping Ed out types me)
 
   
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