X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from misav06.sasknet.sk.ca ([142.165.20.170] verified) by logan.com (CommuniGate Pro SMTP 5.0.4) with ESMTP id 892112 for flyrotary@lancaironline.net; Wed, 21 Dec 2005 22:32:46 -0500 Received-SPF: none receiver=logan.com; client-ip=142.165.20.170; envelope-from=hjjohnson@sasktel.net Received: from bgmpomr1.sasknet.sk.ca ([142.165.72.22]) by misav06 with InterScan Messaging Security Suite; Wed, 21 Dec 2005 21:31:58 -0600 Received: from home ([206.163.241.108]) by bgmpomr1.sasknet.sk.ca (SaskTel eMessaging Service) with ESMTPA id <0IRV008QPR59DM80@bgmpomr1.sasknet.sk.ca> for flyrotary@lancaironline.net; Wed, 21 Dec 2005 21:31:58 -0600 (CST) Date: Wed, 21 Dec 2005 21:31:57 -0600 From: Jarrett & Heidi Johnson Subject: Re: [FlyRotary] Re: Props To: Rotary motors in aircraft Message-id: <00e301c606a8$432b2050$6501a8c0@home> MIME-version: 1.0 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Mailer: Microsoft Outlook Express 6.00.2900.2180 Content-type: multipart/alternative; boundary="Boundary_(ID_YFLXs+3bAoXh+Ggu5eAlwg)" X-Priority: 3 X-MSMail-priority: Normal References: This is a multi-part message in MIME format. --Boundary_(ID_YFLXs+3bAoXh+Ggu5eAlwg) Content-type: text/plain; charset=iso-8859-1 Content-transfer-encoding: 7BIT I'm wondering if there isn't a way to also figure in the forward speed into all of this? These formula's so far will show the tip speed at zero forward speed [ if I've been following this correctly]?? The addition of forward speed may not have a very large impact but it should have some effect shouldn't it? Jarrett Johnson ----- Original Message ----- From: Bulent Aliev To: Rotary motors in aircraft Sent: Wednesday, December 21, 2005 4:14 PM Subject: [FlyRotary] Re: Props Thanks George. my mistake was that i did not convert it to MPH. I was also given the formula for cruise speed: Pitch" x RPM x 60 = MPH 12 x 5280 Buly On Dec 21, 2005, at 4:39 PM, george lendich wrote: Buly, Looking at the formula given by members on this list, 2 out of 3 were spot on with Hoverhawk and the third was close. Examples: 1. Prop Dia x 3.1416x RPM/ 720 - Correct! 2. Prop RPM x Dia x .00436 - Correct ( 3.14/ 720 =.00436) 3. 3.14 x 64 {given prop dia} ( 5500/2.17 {given RPM})= 508346/707 - slightly incorrect ( as compared to the other 3 examples, which include Hoverhawk) i.e 3.14/ 707 = .004809 whereas all the others are 3.14/ 720 = .00436. Now that I have that sorted - can someone tell me how to calculate pitch, easily!! George ( down under) Thanks Perry. This makes me feel much better. Looks like the formulas given to me were not good. Buly On Dec 19, 2005, at 2:00 PM, Perry Casson wrote: I think your math is off a bit - Here's a online calculator http:// www.hoverhawk.com/propspd.html I think 6900 puts a 72" prop close to mach 0.9 but I've never ran mine above 6500 Perry Casson -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ Buly atlasyts@bellsouth.net -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ Bulent "Buly" Aliev http://home.bellsouth.net/p/s/community.dll?ep=16&ext=1&groupid=164323&ck= ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.371 / Virus Database: 267.14.2/208 - Release Date: 12/20/2005 --Boundary_(ID_YFLXs+3bAoXh+Ggu5eAlwg) Content-type: text/html; charset=iso-8859-1 Content-transfer-encoding: 7BIT
I'm wondering if there isn't a way to also figure in the forward speed into all of this? These formula's so far will show the tip speed at zero forward speed [ if I've been following this correctly]??  The addition of forward speed may not have a very large impact but it should have some effect shouldn't it?
 
Jarrett Johnson
----- Original Message -----
Sent: Wednesday, December 21, 2005 4:14 PM
Subject: [FlyRotary] Re: Props

Thanks George. my mistake was that i did not convert it to MPH.
I was also given the formula for cruise speed:

Pitch" x RPM x 60  = MPH
       12 x 5280

Buly
On Dec 21, 2005, at 4:39 PM, george lendich wrote:

Buly,
Looking at the formula given by members on this list, 2 out of 3 were spot
on with Hoverhawk and the third was close.

Examples:
1. Prop Dia x 3.1416x RPM/ 720 - Correct!

2. Prop RPM x Dia x .00436 - Correct ( 3.14/ 720 =.00436)

3. 3.14 x 64 {given prop dia} ( 5500/2.17 {given RPM})= 508346/707 -
slightly incorrect ( as compared to the other 3 examples, which include
Hoverhawk)

i.e 3.14/ 707 = .004809 whereas all the others are 3.14/ 720 = .00436.

Now that I have that sorted - can someone tell me how to calculate pitch,
easily!!
George ( down under)


Thanks Perry. This makes me feel much better. Looks like the formulas
given to me were not good.
Buly
On Dec 19, 2005, at 2:00 PM, Perry Casson wrote:

I think your math is off a bit - Here's a online calculator http://
www.hoverhawk.com/propspd.html

I think 6900 puts a 72" prop close to  mach 0.9 but I've never ran
mine above 6500

Perry Casson



--

Buly




--




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