X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from email2k3.itlnet.net ([64.19.112.15] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1138275 for flyrotary@lancaironline.net; Fri, 02 Jun 2006 19:08:14 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.19.112.15; envelope-from=jwvoto@itlnet.net Received: from rav.itlnet.net (unverified [192.168.10.149]) by itlnet.net (Rockliffe SMTPRA 6.1.22) with SMTP id for ; Fri, 2 Jun 2006 18:07:30 -0500 X-Spam-Checker-Version: SpamAssassin 3.1.1 (2006-03-10) on rav.itlnet.net X-Spam-Level: X-Spam-Status: No, score=-1.4 required=5.0 tests=ALL_TRUSTED,HTML_MESSAGE autolearn=failed version=3.1.1 Received: from JWVOTO (unverified [64.19.116.38]) by itlnet.net (Rockliffe SMTPRA 6.1.22) with ESMTP id for ; Fri, 2 Jun 2006 18:07:29 -0500 Message-ID: <002101c6869a$f57af740$26741340@JWVOTO> From: "Wendell Voto" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: ***SPAM*** [FlyRotary] Prop design speed Date: Fri, 2 Jun 2006 18:18:26 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C68670.F16931A0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C68670.F16931A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable ----- Original Message -----=20 From: Ernest Christley=20 To: Rotary motors in aircraft=20 Sent: Friday, June 02, 2006 2:16 PM Subject: [FlyRotary] Re: ***SPAM*** [FlyRotary] Prop design speed Joe Hull wrote: >>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? >> =20 >> > >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.=20 > >Joe Hull >> > The 80% figure may be Craig being conservative. Tony Bingelis says = the=20 slip may increase to 85%-90% under favorable conditions. Which I'm = sure=20 you're doing at WOT. Mathematically, that would take you up to around = 150mph. But still, you're getting the speed without the prop RPMs. = It=20 sounds like there is more pitch in this prop than what is advertised. --=20 Joe, Do you have wheel pants installed? Wendell (Cozy builder - hoping to need a prop some day) ------=_NextPart_000_001E_01C68670.F16931A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
----- Original Message -----
From:=20 Ernest=20 Christley
Sent: Friday, June 02, 2006 = 2:16 PM
Subject: [FlyRotary] Re: = ***SPAM***=20 [FlyRotary] Prop design speed

Joe Hull wrote:

>>My rough calculations, with an = estimated=20 20% slip, says this prop with a
>>76" pitch, is good for 121 = MPH with=20 a 2.85 drive and 160 MPH with a 2.17
>>drive assuming a 6000 = RPM=20 cruise???
>>Where am I going = wrong?
>>   =20
>>
>
>I'm not the prop designer - that would be = Craig=20 Catto. He knows his stuff so
>I'm trusting his numbers. My guess = is that=20 there may be a couple variables
>that are missing or need = adjusting in=20 the numbers. The slip % may be less
>and the 76" may be at the = 1/3=20 distance mark and there may be more twist on
>the outer 2/3's. = One thing=20 I do know is that at full throttle I can't get
>much over = 5000RPM at=20 4000ft and about 140kts IAS (approx 160mph). The design
>speed = for the=20 prop is 5,800RPM (with my 2.17 PSRU).
>
>Cozy's aren't = known for=20 their drag - so it isn't the airframe that's holding
>it back. = Either=20 the engine is way under-delivering on power or the prop is
>way = over=20 pitched or both.
>
>Joe Hull
>>
>
The = 80%=20 figure may be Craig being conservative.  Tony Bingelis says the =
slip=20 may increase to 85%-90% under favorable conditions. Which I'm sure =
you're=20 doing at WOT.  Mathematically, that would take you up to around=20
150mph.  But still, you're getting the speed without the prop = RPMs.  It
sounds like there is more pitch in this prop than = what is=20 advertised.
--
Joe,
Do you have wheel pants = installed?
Wendell (Cozy builder - hoping to need a = prop some=20 day)
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