I don't know jack about slippage, but I think it is the percentage difference between actual distance traveled and theoretical distance traveled if your propeller corkscrewed through the air with no thrust. I found a prop slip calculator online and for 86 inch pitch, 2.85 gear ratio, 7000 rpm, 180 mph, I get 10% slip. Granted the calculator was for boat propellers, but I don't think it matters as long as the units are correct. There has to be some slip because there would be no thrust otherwise. So what is considered a reasonable or good amount of slip? Using Bill's numbers 86 inch pitch, 2.85 gear ratio, 7000 rpm, 200 mph, I get 0% slip. That can't be right! On Fri, Jul 4, 2014 at 7:19 AM, Bill Bradburry <flyrotary@lancaironline.net> wrote: Christian, It seems that you have a lot of prop slippage at cruise. I think that at that prop rpm you should be getting 200mph if you had no slippage. Bill -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] Sent: Thursday, July 03, 2014 4:01 PM To: Rotary motors in aircraft Subject: [FlyRotary] Rv7 renises p port Well hi all Just thought I'd throw out there the mods I,ve done to the renises in an rv7'. Well the p ported engine is now back in the plane and running well, over the standard short manifold that was originally in the plane I have gained around 400 static rpm, same prop and gearbox combo, 2.85 ratio, this equates to allot more hp at takeoff, just shy of 2300 prop rpm, I'm running a prince p tip prop at 68" x 86" pitch, At 8000 ft it is turning 7000 at 180 mph tas which is an improvement of 25 mph on previous tests, . So next plan is bigger prop and less pitch to let it rev to 7500 in strait and level. Cheers Christian Rv7 renises Aus Sent from my iPad -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
Christian, It seems that you have a lot of prop slippage at cruise. I think that at that prop rpm you should be getting 200mph if you had no slippage. Bill -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] Sent: Thursday, July 03, 2014 4:01 PM To: Rotary motors in aircraft Subject: [FlyRotary] Rv7 renises p port Well hi all Just thought I'd throw out there the mods I,ve done to the renises in an rv7'. Well the p ported engine is now back in the plane and running well, over the standard short manifold that was originally in the plane I have gained around 400 static rpm, same prop and gearbox combo, 2.85 ratio, this equates to allot more hp at takeoff, just shy of 2300 prop rpm, I'm running a prince p tip prop at 68" x 86" pitch, At 8000 ft it is turning 7000 at 180 mph tas which is an improvement of 25 mph on previous tests, . So next plan is bigger prop and less pitch to let it rev to 7500 in strait and level. Cheers Christian Rv7 renises Aus Sent from my iPad -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html