|
|
Joe, I know this may sound a bit elementary, but have you assured that your throttle plate in your throttle body is fully open when your "GO KNOB" is all the way in the "GO" position. Sometimes the simplest thing can be a "Got'cha " {:>)
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message ----- From: "Joe Hull" <joeh@pilgrimtech.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, June 02, 2006 2:23 PM
Subject: [FlyRotary] Re: ***SPAM*** [FlyRotary] Prop design speed
My rough calculations, with an estimated 20% slip, says this prop with a
76" pitch, is good for 121 MPH with a 2.85 drive and 160 MPH with a 2.17
drive assuming a 6000 RPM cruise???
Where am I going wrong?
I'm not the prop designer - that would be Craig Catto. He knows his stuff so
I'm trusting his numbers. My guess is that there may be a couple variables
that are missing or need adjusting in the numbers. The slip % may be less
and the 76" may be at the 1/3 distance mark and there may be more twist on
the outer 2/3's. One thing I do know is that at full throttle I can't get
much over 5000RPM at 4000ft and about 140kts IAS (approx 160mph). The design
speed for the prop is 5,800RPM (with my 2.17 PSRU).
Cozy's aren't known for their drag - so it isn't the airframe that's holding
it back. Either the engine is way under-delivering on power or the prop is
way over pitched or both.
Joe Hull
Cozy Mk-IV #991 (In Phase1 Flight Test - 23.8 hrs flown)
Redmond (Seattle), Washington
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/
|
|