X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-03.southeast.rr.com ([24.25.9.102] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1138037 for flyrotary@lancaironline.net; Fri, 02 Jun 2006 14:32:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-111-186.carolina.res.rr.com [24.74.111.186]) by ms-smtp-03.southeast.rr.com (8.13.6/8.13.6) with SMTP id k52IVHCu018975 for ; Fri, 2 Jun 2006 14:31:19 -0400 (EDT) Message-ID: <000501c68672$df75f080$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: ***SPAM*** [FlyRotary] Prop design speed Date: Fri, 2 Jun 2006 14:32:15 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2869 X-Virus-Scanned: Symantec AntiVirus Scan Engine 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" To: "Rotary motors in aircraft" 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/