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

From: H & J Johnson

To: Rotary motors in aircraft

Sent: Wednesday, January 31, 2007 8:09 AM

Subject: [FlyRotary] Re: New Cowl Contest

George, its a Gantry Mill, the parts sit almost right on the floor and the gantry runs on two long side rails which are bolted into the floor. Attached is a picture showing a similar type of machine. This particular unit is from Scaled in So-cal. Mine is smaller than this unit, but then I didn't have the budget that they do :-)

I'll have pictures/vid's up on my website, which should be in about a month.

Jarrett

 

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

From: George Lendich <lendich@optusnet.com.au>

Date: Tuesday, January 30, 2007 3:58 pm

Subject: [FlyRotary] Re: New Cowl Contest

>
>   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 <wdleonard@gmail.com>
>
>  Date: Tuesday, January 30, 2007 2:22 pm
>
>  Subject: [FlyRotary] Re: New Cowl Contest
>
>
>  > Todd, if it aint broke dont fix it!!!!
>  >
>  > You are right about the boundry layer.  But you can make up
> for
>  > that with a
>  > little extra size or maybe moving closer to the prop (eg P-
> 40).
>  >
>  > Also, Doug dempsy has been telling me how Chuck Dunlap had a
> real
>  > problemwith a duct that was away from the boundry layer, but
> fixed
>  > his issue when
>  > he make it bigger and more like the smile.
>  >
>  > The smile votes seem to have it so far...
>  >
>  > Dave Leonard
>  >
>  >
>  > On 1/30/07, Todd Bartrim <bartrim@gmail.com> wrote:
>  > >
>  > > I was thinking that the "oh cowl" would be better at
> excluding the
>  > > boundary layer, which would be better for cooling. This is
> just
>  > based on
>  > > comments I've read on the list during previous ducting
>  > discussions. Based on
>  > > this info, I felt my oil cooler duct was less than optimal
> (even
>  > though> temps are good), so I figured I could reduce the size
> of
>  > my inlet if I
>  > > eliminated the boundary air layer. As your "smile" duct is
>  > similar (see
>  > > attached pic) I figured this would be applicable. I hope I'm
>  > wrong and you
>  > > prove it before I change my cowl.
>  > >
>  > > Todd    (building Electric Bob's Audio Isolator Amplifier
> today)
>  > >
>  > > On 1/30/07, Ernest Christley <echristley@nc.rr.com > wrote:
>  > > >
>  > > > David Leonard wrote:
>  > > >
>  > > > > I call them the "Oh Cowl" and the "Smiley Cowl..."his
>  > > >
>  > > > Go with the smile, but put a raised ledge on the cowl side
>  > just behind
>  > > > the spinner to accelerate the air and thin the boundary
> layer.
>  > Reduces
>  > > > the ingestion of turbulent air.  Check the CAFE
> Foundation's drag
>  > > > reduction report.  They have a picture of what it looks
> like
>  > on a
>  > > > production aircraft.  I have a link to it at home, but not
> here.
>  > > >
>  > > > --
>  > > >          ,|"|"|,              Ernest Christley       |
>  > > > ----===<{{(oQo)}}>===----    Dyke Delta Builder      |
>  > > >         o|  d  |o        http://ernest.isa-geek.org  |
>  > > >
>  > > > --
>  > > > 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/
>  > >
>  > >
>  > >
>  > >
>  >
>  >
>  > --
>  > David Leonard
>  >
>  > Turbo Rotary RV-6 N4VY
>  > My websites at:
>  > http://members.aol.com/_ht_a/rotaryroster/index.html
>  > http://members.aol.com/_ht_a/vp4skydoc/index.html
>  > http://leonardiniraq.blogspot.com
>  >
>
>
> -------------------------------------------------------------------
> -----------
>
>
>  --
>  Homepage:  http://www.flyrotary.com/
>  Archive and UnSub:   http://mail.lancaironline.net/lists/flyrotary/
>

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