X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fmailhost01.isp.att.net ([207.115.11.51] verified) by logan.com (CommuniGate Pro SMTP 5.2.11) with ESMTP id 3415947 for flyrotary@lancaironline.net; Wed, 07 Jan 2009 22:22:06 -0500 Received-SPF: pass receiver=logan.com; client-ip=207.115.11.51; envelope-from=bobperk9@bellsouth.net Received: from fwebmail14.isp.att.net ([207.115.9.154]) by isp.att.net (frfwmhc01) with SMTP id <20090108032130H0100fm4c4e>; Thu, 8 Jan 2009 03:21:30 +0000 X-Originating-IP: [207.115.9.154] Received: from [74.249.209.22] by fwebmail14.isp.att.net; Thu, 08 Jan 2009 03:21:28 +0000 From: "Bob Perkinson" To: "Rotary motors in aircraft" Subject: Re: [FlyRotary] Re: Spinner size Date: Thu, 08 Jan 2009 03:21:28 +0000 Message-Id: <010820090321.3655.496571380008DF6000000E4722230650629B0A02D2089B9A019C04040A0DBFC7059D0A9F0D010D@att.net> In-Reply-To: X-Mailer: AT&T Message Center Version 1 (Oct 30 2008) X-Authenticated-Sender: Ym9icGVyazlAYmVsbHNvdXRoLm5ldA== MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="NextPart_Webmail_9m3u9jl4l_3655_1231384888_0" --NextPart_Webmail_9m3u9jl4l_3655_1231384888_0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Chris, You must be the person Ann at Van's was talking about. Ann mentioned to m= e that someone had a Sam James cowl and the spinner was to small, I wast o= rdering my finish kit less the cowl at the time. I have a Sam James cowl t= hat I got from Bernie Kerr. I told her that I would get back with her ab= out the spinner. I immediately went to my storage building and measured th= e face of the cowl, it was 13". The only difference that I see is that yo= u have the cowl that has the one large cooling opening at the bottom. The = cowl I have has two cooling inlets like the vans cowl. I wonder why the .7= 5" Difference in the cowl face? Bob Perkinson -------------- Original message from Charlie England : -------------- > Al Gietzen wrote: > > > > I have the James rotary cowl--front =E2=80=9Cface=E2=80=9D has a 13.75= =E2=80=9D diameter. I=20 > > also have the Vans 13=E2=80=9D spinner that is already cut to fit my CA= TTO=20 > > prop. This leaves about a 3/8 lip of cowl showing all the way around=20 > > the spinner. Take a look at the picture. > > > > I know any amount of lip will cause drag, but is this enough to=20 > > warrant a new spinner? UHS makes a 14=E2=80=9D one that would probably = do the=20 > > trick. > > > > Chris > > > > My opinion is that is more a matter of appearance than function. The=20 > > air flow at that point is very turbulent, and any resultant drag would= =20 > > be less than measurable. > > > > BTW; on the post about the fuel pressure sensor I thought you were the= =20 > > other Chris with the Velocity. > > > > Al G > > >=20 > I can't even spell aerodynamicist (& neither can my spell checker), but= =20 > everything I've read says that it's better to have the cowl face bigger= =20 > than the spinner bigger. My impression is that the air will speed up=20 > slightly but not be greatly disturbed as it continues around the cowl,=20 > but if the spinner is bigger it will cause really bad turbulence as the= =20 > air tries to turn the corner at the edge of the spinner to fill that gap. >=20 > Will James assured me that the stock Van's spinner fits his cowl, so I'm= =20 > going with his assurance. >=20 > FWIW, >=20 > Charlie >=20 > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/Lis= t.html --NextPart_Webmail_9m3u9jl4l_3655_1231384888_0 Content-Type: multipart/related; boundary="NextPart_Webmail_9m3u9jl4l_3655_1231384888_1" --NextPart_Webmail_9m3u9jl4l_3655_1231384888_1 Content-Type: text/html; charset="utf-8" Content-Transfer-Encoding: quoted-printable

=20 Chris,
You must be the person Ann at Van's was talking about. = ; Ann mentioned to me that someone had a Sam James cowl and the spinner was= to small, I wast ordering my finish kit less the cowl at the time.&n= bsp; I have a Sam James cowl that I got from Bernie Kerr. = I told her that I would get back with her about the spinner. I immed= iately went to my storage building and measured the face of the cowl, = it was 13". The only difference that I see is that you have the cowl= that has the one large cooling opening at the bottom. The cowl I hav= e has two cooling inlets like the vans cowl. I wonder why the .75" Di= fference in the cowl face?

Bob Perkinson

-------------- Original message from Charlie England <ceengland@bellsou= th.net>: --------------

> Al Gietzen wrote:
> >
> > I have the James rotary cowl--front =E2=80=9Cface=E2=80=9D ha= s a 13.75=E2=80=9D diameter. I=20
> > also have the Vans 13=E2=80=9D spinner that is already cut to= fit my CATTO=20
> > prop. This leaves about a 3/8 lip of cowl showing all the way= around=20
> > the spinner. Take a look at the picture.
> >
> > I know any amount of lip will cause drag, but is this enough = to=20
> > warrant a new spinner? UHS makes a 14=E2=80=9D one that would= probably do the=20
> > trick.
> >
> > Chris
> >
> > My opinion is that is more a matter of appearance than functi= on. The=20
> > air flow at that point is very turbulent, and any resultant d= rag would=20
> > be less than measurable.
> >
> > BTW; on the post about the fuel pressure sensor I thought you= were the=20
> > other Chris with the Velocity.
> >
> > Al G
> >
>=20
> I can't even spell aerodynamicist (& neither can my spell chec= ker), but=20
> everything I've read says that it's better to have the cowl face b= igger=20
> than the spinner bigger. My impression is that the air will speed = up=20
> slightly but not be greatly disturbed as it continues around the c= owl,=20
> but if the spinner is bigger it will cause really bad turbulence a= s the=20
> air tries to turn the corner at the edge of the spinner to fill th= at gap.
>=20
> Will James assured me that the stock Van's spinner fits his cowl, = so I'm=20
> going with his assurance.
>=20
> FWIW,
>=20
> Charlie
>=20
> --
> Homepage: http://www.flyrotary.com/
> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrot= ary/List.html

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