X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 51 [XX] (65%) RECEIVED: IP not found on home country list (35%) SPAM TRICK: contains gapped text Return-Path: Received: from mail33.syd.optusnet.com.au ([211.29.132.104] verified) by logan.com (CommuniGate Pro SMTP 5.1.5) with ESMTPS id 1800179 for flyrotary@lancaironline.net; Tue, 30 Jan 2007 16:59:31 -0500 Received-SPF: none receiver=logan.com; client-ip=211.29.132.104; envelope-from=lendich@optusnet.com.au Received: from george (d211-31-114-81.dsl.nsw.optusnet.com.au [211.31.114.81]) by mail33.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id l0ULwYpl001987 for ; Wed, 31 Jan 2007 08:58:35 +1100 Message-ID: <00b201c744b9$cabf6d50$51721fd3@george> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: New Cowl Contest Date: Wed, 31 Jan 2007 07:58:34 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00AF_01C7450D.9B521E10" 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-Antivirus: avast! (VPS 0657-0, 12/12/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_00AF_01C7450D.9B521E10 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Jarrett, What sort of CNC is that ? George ( down under) Dave, I'd vote for the smiley, I would still wonder if having the opening = out off the bottom face of the cowl wouldn't be better. Mind you, two = other things come into play. There probably isn't to much [more] = turbulent air or thicker boundry layer that close behind the prop at = that location. No more than the turbulance farther out. Secondly, the = rotational vector up close to the cowl very well could be less than = farther out.[ to exagerate the issue, imagine the rotational vector out = near the prop tip's.] I've designed a few cowls over the last couple years. Attached are a = couple pictures to illustrate. Since you plan to use a lower and upper = ducting, I've attached drawings/pic's showing how I've done both = designs. It would be a simple matter to combine the two, to arrive at = your desired design. Also I've not said much in the past, but my CNC mill has been = installed and is just awaiting final wire-up and commisioning. I plan to = start offering its use to the Rotary crowd in producing components like = cowls, proper diffusion ducting, spinners [which properly fair into the = cowls] etc. Theres many other components I'd like to get into building = but plan to start out with these few and expand from there. The mill is = currently capable of milling parts up to 8 x 18 x 3 [feet] and will be = upgraded in the spring to have a 4ft [instead of 3] Z axis. Later, we = plan to expand its abilities to 5 axis, however this is more in the = neighbourhood of a year or so. I'll have a website up in the next month or so. However the meantime, = if I can be of help, please let me know. Jarrett Johnson ----- Original Message ----- From: David Leonard =20 Date: Tuesday, January 30, 2007 2:22 pm=20 Subject: [FlyRotary] Re: New Cowl Contest=20 > Todd, if it aint broke dont fix it!!!!=20 >=20 > You are right about the boundry layer. But you can make up for=20 > that with a=20 > little extra size or maybe moving closer to the prop (eg P-40).=20 >=20 > Also, Doug dempsy has been telling me how Chuck Dunlap had a real=20 > problemwith a duct that was away from the boundry layer, but fixed=20 > his issue when=20 > he make it bigger and more like the smile.=20 >=20 > The smile votes seem to have it so far...=20 >=20 > Dave Leonard=20 >=20 >=20 > On 1/30/07, Todd Bartrim wrote:=20 > >=20 > > I was thinking that the "oh cowl" would be better at excluding the = > > boundary layer, which would be better for cooling. This is just=20 > based on=20 > > comments I've read on the list during previous ducting=20 > discussions. Based on=20 > > this info, I felt my oil cooler duct was less than optimal (even=20 > though> temps are good), so I figured I could reduce the size of=20 > my inlet if I=20 > > eliminated the boundary air layer. As your "smile" duct is=20 > similar (see=20 > > attached pic) I figured this would be applicable. I hope I'm=20 > wrong and you=20 > > prove it before I change my cowl.=20 > >=20 > > Todd (building Electric Bob's Audio Isolator Amplifier today)=20 > >=20 > > On 1/30/07, Ernest Christley wrote:=20 > > >=20 > > > David Leonard wrote:=20 > > >=20 > > > > I call them the "Oh Cowl" and the "Smiley Cowl..."his=20 > > >=20 > > > Go with the smile, but put a raised ledge on the cowl side=20 > just behind=20 > > > the spinner to accelerate the air and thin the boundary layer.=20 > Reduces=20 > > > the ingestion of turbulent air. Check the CAFE Foundation's = drag=20 > > > reduction report. They have a picture of what it looks like=20 > on a=20 > > > production aircraft. I have a link to it at home, but not here. = > > >=20 > > > --=20 > > > ,|"|"|, Ernest Christley |=20 > > > ----=3D=3D=3D<{{(oQo)}}>=3D=3D=3D---- Dyke Delta Builder = |=20 > > > o| d |o http://ernest.isa-geek.org |=20 > > >=20 > > > --=20 > > > Homepage: http://www.flyrotary.com/=20 > > > Archive and UnSub: =20 > http://mail.lancaironline.net/lists/flyrotary/> >=20 > >=20 > >=20 > > --=20 > > Homepage: http://www.flyrotary.com/=20 > > Archive and UnSub: = http://mail.lancaironline.net/lists/flyrotary/=20 > >=20 > >=20 > >=20 > >=20 >=20 >=20 > --=20 > David Leonard=20 >=20 > Turbo Rotary RV-6 N4VY=20 > My websites at:=20 > http://members.aol.com/_ht_a/rotaryroster/index.html=20 > http://members.aol.com/_ht_a/vp4skydoc/index.html=20 > http://leonardiniraq.blogspot.com=20 >=20 -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: http://mail.lancaironline.net/lists/flyrotary/ ------=_NextPart_000_00AF_01C7450D.9B521E10 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
 
 Jarrett,
What sort of CNC is that ?
George ( down under)

Dave,

I'd vote for the smiley, I would still wonder if having the = opening out off the bottom face of the cowl wouldn't be better. = Mind you,=20 two other things come into play. There probably isn't to much [more] = turbulent=20 air or thicker boundry layer that close behind the prop at that = location. No=20 more than the turbulance farther out. Secondly, the rotational vector = up close=20 to the cowl very well could be less than farther out.[ to exagerate = the issue,=20 imagine the rotational vector out near the prop tip's.]

I've designed a few cowls  over the last couple years. = Attached are a couple pictures to illustrate. Since you plan = to use=20 a lower and upper ducting, I've attached drawings/pic's showing how = I've done=20 both designs. It would be a simple matter to combine the two, to = arrive at=20 your desired design.

Also I've not said much in the past, but my CNC mill has = been=20 installed and is just awaiting final wire-up and commisioning. I plan = to start=20 offering its use to the Rotary crowd in producing components like = cowls,=20 proper diffusion ducting, spinners [which properly fair into the = cowls] etc.=20 Theres many other components I'd like to get into building but plan to = start=20 out with these few and expand from there. The mill is currently capable of milling parts up to 8 x 18 x 3 = [feet] and will=20 be upgraded in the spring to have a 4ft [instead of 3] Z axis. Later, = we plan=20 to expand its abilities to 5 axis, however this is more in the = neighbourhood=20 of a year or so.

I'll have a website up in the next month or = so. However the=20 meantime, if I can be of help, please let me know.

 

Jarrett Johnson

 

 

 

 

----- Original Message -----

From: David Leonard <wdleonard@gmail.com>=20

Date: Tuesday, January 30, 2007 2:22 pm=20

Subject: [FlyRotary] Re: New Cowl Contest=20

> Todd, if it aint broke dont fix it!!!!
>
> = You are=20 right about the boundry layer.  But you can make up for
> = that=20 with a
> little extra size or maybe moving closer to the prop = (eg=20 P-40).
>
> Also, Doug dempsy has been telling me how = Chuck=20 Dunlap had a real
> problemwith a duct that was away from the = boundry=20 layer, but fixed
> his issue when
> he make it bigger = and more=20 like the smile.
>
> The smile votes seem to have it so = far...=20
>
> Dave Leonard
>
>
> On 1/30/07, = Todd=20 Bartrim <bartrim@gmail.com> wrote:
> >
> > I = was=20 thinking that the "oh cowl" would be better at excluding the
> = >=20 boundary layer, which would be better for cooling. This is just =
> based=20 on
> > comments I've read on the list during previous = ducting=20
> discussions. Based on
> > this info, I felt my oil = cooler=20 duct was less than optimal (even
> though> temps are good), = so I=20 figured I could reduce the size of
> my inlet if I
> = >=20 eliminated the boundary air layer. As your "smile" duct is
> = similar=20 (see
> > attached pic) I figured this would be applicable. I = hope=20 I'm
> wrong and you
> > prove it before I change my = cowl.=20
> >
> > Todd    (building Electric = Bob's=20 Audio Isolator Amplifier today)
> >
> > On = 1/30/07, Ernest=20 Christley <echristley@nc.rr.com > wrote:
> > > =
>=20 > > David Leonard wrote:
> > >
> > > = > I=20 call them the "Oh Cowl" and the "Smiley Cowl..."his
> > > =
> > > Go with the smile, but put a raised ledge on the = cowl side=20
> just behind
> > > the spinner to accelerate the = air and=20 thin the boundary layer.
> Reduces
> > > the = ingestion of=20 turbulent air.  Check the CAFE Foundation's drag
> > = >=20 reduction report.  They have a picture of what it looks like =
> on=20 a
> > > production aircraft.  I have a link to it at = home,=20 but not here.
> > >
> > > --
> >=20 >         =20 = ,|"|"|,           =   =20 Ernest Christley       |
> > = >=20 ----=3D=3D=3D<{{(oQo)}}>=3D=3D=3D----    Dyke = Delta=20 Builder      |
> >=20 >         o|  d =20 |o        = http://ernest.isa-geek.org =20 |
> > >
> > > --
> > > = Homepage: =20 http://www.flyrotary.com/
> > > Archive and = UnSub:  =20
> http://mail.lancaironline.net/lists/flyrotary/> > =
> >=20
> >
> > --
> > Homepage: =20 http://www.flyrotary.com/
> > Archive and UnSub:   = http://mail.lancaironline.net/lists/flyrotary/
> >
> = >=20
> >
> >
>
>
> --
> = David=20 Leonard
>
> Turbo Rotary RV-6 N4VY
> My websites = at:=20
> http://members.aol.com/_ht_a/rotaryroster/index.html
> = http://members.aol.com/_ht_a/vp4skydoc/index.html
>=20 http://leonardiniraq.blogspot.com
>=20

--
Homepage:  http://www.flyrotary.com/
Archive and=20 UnSub:  =20 http://mail.lancaironline.net/lists/flyrotary/
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