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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-900443@logan.com>
Subject: Re: [FlyRotary] Re: Intake plenum  HELP??
Date: Wed, 20 Apr 2005 22:06:07 -0400
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Like many other things in the aircraft hobby, the best you can possibly
obtain is the ultimate compromise between many variables.  I have read
somewhere that a 90deg bend reduces air velocity less than 1% - don't know
how valid that might be, but even if close that would only knock 1/2pV^2
about 2.8% off your perfect pressure recovery of 1" MAP.  So weighing the
complexity or space constraints of going from a 90 deg turn of the air to a
straight in run - the question is "Is it really worth it?".  Perhaps if an
all-out racer.  By the way, Tracy has a 90 deg bend in his ram air system
and at 220+MPH, Id' say he is doing pretty good.  FWIW

Ed A

----- Original Message -----
From: "Jim Sower" <canarder@frontiernet.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Wednesday, April 20, 2005 9:59 PM
Subject: [FlyRotary] Re: Intake plenum HELP??


> By way of perspective, at 160 kias (~174 mph) with perfect recovery -
> all of the dynamic pressure gets transferred to the intake with no
> losses - you will pick up almost exactly 1" MAP.  At 200 kias (230 mph)
> it's just over 1.5" MAP gain.
> It's like having the MAP that was available 1000' below you working for
> you where you are now.
> Jim S.
>
>
> Jerry Hey wrote:
>
> > Randy,  Thanks for your comments. The purpose of the ram air is to
> > pressurize the plenum, at least that is what I am trying to do with
> > it.  Moving the ram air scoop forward is not possible.  As you can see
> > from the drawing room under the cowl goes away quickly as you move
> > forward.  There would not be room for the large air filter I am trying
> > to use.  Of course we are also talking about MY limitations.  I am
> > hoping someone will engineer a better solution.  Space and weight
> > restrictions make designing anything for an airplane a lot of fun.
> > Jerry
> >
> >
> > On Monday, April 18, 2005, at 04:11 PM, randy echtinaw wrote:
> >
> >> Jerry,
> >>    I know very little about this stuff, in fact all I know is what
> >> you guys have taught me but . . . It seems counter productive to me
> >> to be trying to get a boost from using ram air and then making it
> >> turn 180 degrees before entering the combustion chamber. Seems like
> >> more boost is available the straighter the ram air can travel. Would
> >> it be possible to mount your "scoop" on the side of the cowling or
> >> underneath and move it ahead  so you could get some semblance of a
> >> straight shot through the filter then into intake plenum?
> >> Randy
> >>
> >>
> >> On Apr 18, 2005, at 4:43 PM, Jerry Hey wrote:
> >>
> >>> Here is a drawing of an intake for filtered ram air.  It will fit
> >>> inside a Tailwind Cowl.  I have not yet figured out how it goes
> >>> together and I am hoping the considerable brain power on this list
> >>> will come to my rescue. I need to be able to service
> >>> (install/remove) the air filter.  The air filter is hose clamped
> >>> over the flange.     Jerry
> >>> <Plenum 4-18. JPG.JPG> Homepage:  http://www.flyrotary.com/
> >>>
> >>>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >>>>
> >>
> >>
> >>>>  Homepage:  http://www.flyrotary.com/
> >>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >>>
> >>
> >
> >
> >>>  Homepage:  http://www.flyrotary.com/
> >>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
> >>
> >
> >
>
> >>  Homepage:  http://www.flyrotary.com/
> >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>