X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [24.25.9.103] (HELO ms-smtp-04-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 5.0.4) with ESMTP id 891958 for flyrotary@lancaironline.net; Wed, 21 Dec 2005 19:55:14 -0500 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-025-165.carolina.res.rr.com [24.74.25.165]) by ms-smtp-04-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id jBM0sR1u009939 for ; Wed, 21 Dec 2005 19:54:27 -0500 (EST) Message-ID: <000d01c60692$457671e0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Props Date: Wed, 21 Dec 2005 19:54:32 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01C60668.5C600580" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_000A_01C60668.5C600580 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Yes, George. If we assumed no slip in the prop then theoretically the = formula will give you the pitch of the prop you would need to screw = through the air and achieve your MPH at your RPM input. This is based = simply on the screw principal. I am certainly not a prop expert, but I = also believe that since the prop is a spinning wing (airfoil), that = there is a lift component in the direction of flight which may result = in more speed than the formula could account for. =20 Your second equation can be reduced further from (Inches/Minute)/(RPM) = =3D (Inches/Minute)/(Revs/Minute) =3D inches/Rev Ed A ----- Original Message -----=20 From: Bulent Aliev=20 To: Rotary motors in aircraft=20 Sent: Wednesday, December 21, 2005 7:08 PM Subject: [FlyRotary] Re: Props Don't ask me George. I'm not an engineer or good with mathematics. Ed = A will know better. Buly On Dec 21, 2005, at 6:20 PM, george lendich wrote: Thanks Buly, So, Pitch" =3D MPH x12 x 5280 RPM x 60 I figure 12 (inches in a foot) and 5280 ( feet in a mile) and 60 ( = minute in an hour). So the top line is converted into inches per minute and the bottom = line RPM. So, Pitch " =3D inches per minute RPM Does that look right to you ? George ( down under) 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 =3D 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 =3D.00436) 3. 3.14 x 64 {given prop dia} ( 5500/2.17 {given RPM})=3D = 508346/707 - slightly incorrect ( as compared to the other 3 examples, which = include Hoverhawk) i.e 3.14/ 707 =3D .004809 whereas all the others are 3.14/ 720 = =3D .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=3D16&ext=3D1&groupid=3D164= 323&ck=3D Bulent "Buly" Aliev = http://home.bellsouth.net/p/s/community.dll?ep=3D16&ext=3D1&groupid=3D164= 323&ck=3D ------=_NextPart_000_000A_01C60668.5C600580 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Yes, George.  If we assumed no slip in the = prop then=20 theoretically the formula will give you the pitch of the prop you would = need to=20 screw through the air and achieve your MPH at your RPM input.  This = is=20 based simply on the screw principal.  I am certainly not a prop = expert, but=20 I also believe that since the prop is  a spinning wing (airfoil), = that=20 there is a lift component  in the direction of flight which may = result in=20 more speed than the formula could account for.  
 
Your second equation can be reduced further from =  =20 (Inches/Minute)/(RPM) =3D (Inches/Minute)/(Revs/Minute) =3D = inches/Rev
 
Ed A
 
 
----- Original Message -----
From:=20 Bulent=20 Aliev
Sent: Wednesday, December 21, = 2005 7:08=20 PM
Subject: [FlyRotary] Re: = Props

Don't ask me George. I'm not an engineer or good with=20 mathematics. Ed A will know better.
Buly
On Dec 21, 2005, at 6:20 PM, george lendich wrote:
Thanks = Buly,
So, Pitch"  =3D = MPH=20 x12 x 5280
           =       =20  RPM x 60
I figure 12 (inches in = a foot)=20 and 5280 ( feet in a mile) and 60 ( minute in an=20 hour).
So the top line is = converted=20 into inches per minute and the bottom line RPM.
 
So, Pitch " =3D = inches=20 per minute
           =         =20 RPM
 
Does that = look right to you=20 ?
George ( down=20 under)
 
 
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=20 60  =3D MPH
       12 x 5280

Buly
On Dec 21, 2005, at 4:39 PM, george lendich wrote:
Buly,
Looking = at the=20 formula given by members on this list, 2 out of 3 were = spot
on with = Hoverhawk and=20 the third was close.
Examples:
1. Prop = Dia x 3.1416x=20 RPM/ 720 - Correct!
2. Prop = RPM x Dia x=20 .00436 - Correct ( 3.14/ 720 =3D.00436)
3. 3.14 x = 64 {given=20 prop dia} ( 5500/2.17 {given RPM})=3D 508346/707 -
slightly = incorrect (=20 as compared to the other 3 examples, which include
Hoverhawk)
i.e 3.14/ = 707 =3D=20 .004809 whereas all the others are 3.14/ 720 =3D = .00436.
Now that = I have that=20 sorted - can someone tell me how to calculate = pitch,
easily!!
George ( = down=20 under)
Thanks = Perry. This=20 makes me feel much better. Looks like the = formulas
given = to me were=20 not good.
Buly
On Dec = 19, 2005, at=20 2:00 PM, Perry Casson wrote:
I = think your math=20 is off a bit - Here's a online calculator = http://
www.hoverhawk.com/propspd.html
I = think 6900 puts=20 a 72" prop close to  = mach 0.9 but I've never = ran
mine = above=20 6500
Perry=20 Casson
--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:=20   = http://mail.lancaironline.net/lists/flyrotary/
Buly
atlasyts@bellsouth.net
--
Homepage:  http://www.flyrotary.com/
Archive = and UnSub:=20   http://mail.lancaironline.net/lists/flyrotary/
--
Homepage:  http://www.flyrotary.com/
Archive = and UnSub:=20   http://mail.lancaironline.net/lists/flyrotary/

Bulent "Buly" Aliev

http://home.bellsouth.net/p/s/community.dll?ep=3D16&ext=3D= 1&groupid=3D164323&ck=3D


Bulent "Buly" Aliev

http://home.bellsouth.net/p/s/community.dl= l?ep=3D16&ext=3D1&groupid=3D164323&ck=3D

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