flyrotary@lancaironline.net Mailing List Archive

Hi Todd,

Actually, No - not anything significant. Although I now cruise at 5600 rpm vice 5200 rpm with the 2.17 the fuel burn is identical. I think the 2.85 puts less load on the engine permitting it to turn faster at the same fuel burn. Just a theory.

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

From: Todd Bartrim

To: Rotary motors in aircraft

Sent: Sunday, December 11, 2005 3:06 AM

Subject: [FlyRotary] Re: Elippse Propeller

Hi Ed;

I know that it has been stated in the past, but refresh my memory. Have you observed any fuel consumption change from the 2.17 to the 2.85????

Todd (tough game tonight, so too tired to check the archives)

Also looking at the power difference at the two different rpms, I calculate 160 at 5200 and 180HP at 6000, whether that is accurate absolute power it shows a possible 12.5% increase. The disc area carved out by the 74" prop is approx 18% more although its speed is approx 13% less. So I think more area, more HP and more pitch appears to add up in my case to considerably better low speed performance. The top speed appears not to have changed, still a shade under 200 MPH around 197MPH for both props.