Mailing List flyrotary@lancaironline.net Message #4546
From: Russell Duffy <13brv3@bellsouth.net>
Subject: RE: [FlyRotary] Re: Brief flight report
Date: Sat, 29 Nov 2003 19:55:38 -0600
To: 'Rotary motors in aircraft' <flyrotary@lancaironline.net>
Message
 What maximum power are you willing to run continuously?  7-8 gph  
 
 Do you want to optimize the prop for cruise, or climb? Cruise 
 
 
If this were a Lycoming, and we were trying to find the best cruise speed, we'd go to 8000 ft, and apply full throttle.  Since we know that's about 75% power for a NA engine, the goal would be to pitch the prop for the redline RPM at that altitude.  Simple.
 
Unfortunately, we don't have book numbers to look up, and we can't even go by the 75% rule, since we aren't all making the same 100% power.  For example, Tracy is making 190+, but others are below 150, so 75% power for Tracy, may be more than someone else can make at 100%.  I'm willing to run my engine at 150 HP continuous, which makes it the equivalent of a 200 HP Lycoming in cruise.  I can't say what that is in gph though.  
 
Like everyone has said, it's a balance between climb and cruise, and since we can't look up numbers in a book, we have to figure this out experimentally.  Now that you've defined your limits, you can experiment with pitch until you can satisfy your needs.  Or you can just buy the in-flight adjustable option and save us all a bunch of typing :-)
 
Have fun,
Rusty (flying tomorrow for sure)     

 

 

 

 

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