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                           Tailwind-List Digest Archive
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                     Total Messages Posted Mon 02/17/03: 1
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Today's Message Index:
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     1. 05:22 AM - Re: Re: Exhaust Tailpipe Question  (Boud Kuenen)
 
 
 
________________________________  Message 1  _____________________________________


Time: 05:22:39 AM PST US
From: "Boud Kuenen" <bkuenen@horizonaero.com>
Subject: Re: Tailwind-List: RE: Exhaust Tailpipe Question

--> Tailwind-List message posted by: "Boud Kuenen" <bkuenen@horizonaero.com>

Hey Guys,

Earl is right!  Aim it in what looks like a safe direction and get going.  I
have a Vetterman exhaust and the pipes end about an inch inside the air
outlet (Clement cowl), they are aimed pretty much straight back with a touch
of down.  I double skinned the middle third of the belly with .016 aluminum
(unpainted) and 4 layers of dry  4.5 oz fiber glass in between.  When I
first started up the engine, it blew out a bunch of preservative oil out the
back and some of it stuck to the bare aluminum but it was very spread out,
from this I decided that the exhaust was disipating quite well.  I have a
plastic anti-collision light about 3 feet behind the air outlet and this too
got covered with the preservative oil, but none of it has ever shown any
sign of heat.  If I feel the inside of the belly skin after running it a
while, it feels no different than the firewall.

Boud Kuenen
NX888WT
----- Original Message -----
From: "William Bernard" <billbernard@worldnet.att.net>
Subject: Re: Tailwind-List: RE: Exhaust Tailpipe Question


> --> Tailwind-List message posted by: "William Bernard"
<billbernard@worldnet.att.net>
>
> Earl, you probably don't want to hear about the computer controled
variable
> geometry outlet nozzles for the exhaust pipes, do you?  <Grin>
>
> Bill
> ----- Original Message -----
> From: "Earl Luce" <luceair@worldnet.att.net>
> To: <tailwind-list@matronics.com>
> Subject: Re: Tailwind-List: RE: Exhaust Tailpipe Question
>
>
> > --> Tailwind-List message posted by: "Earl Luce"
> <luceair@worldnet.att.net>
> >
> > Hey guys;
> > I think your thinking tooooooooooooo much !!!! The object is to keep it
> > simple and safe , go with what works and get it in the air sometime in
> your
> > lifetime.
> > Earl Luce
> > ----- Original Message -----
> > From: "William Bernard" <billbernard@worldnet.att.net>
> > To: <tailwind-list@matronics.com>
> > Subject: Re: Tailwind-List: RE: Exhaust Tailpipe Question
> >
> >
> > > --> Tailwind-List message posted by: "William Bernard"
> > <billbernard@worldnet.att.net>
> > >
> > > Jim, If my trigonometry is correct, the 'pulse' of exhaust gas should
be
> > > just over 4.5 inches below the belly when it gets to the fabric, using
> the
> > > dimmensions you described. (10 degree angle, 15 inches back, two
inches
> > > below the belly)
> > >
> > > This strikes me as a bit close and assumes that the gasses don't
> dispurse
> > at
> > > all in that distance. Maybe a bit more down angle 20 degrees??? might
be
> > > better.
> > >
> > > Just a guess.
> > >
> > > Bill
> > > ----- Original Message -----
> > > From: <Mcculleyja@aol.com>
> > > To: <Tailwind-list@matronics.com>
> > > Subject: Tailwind-List: RE: Exhaust Tailpipe Question
> > >
> > >
> > > > --> Tailwind-List message posted by: Mcculleyja@aol.com
> > > >
> > > > Thanks, Bill and George for your responses. I have read Paser's book
> and
> > > it
> > > > is indeed very good.  My plan is to angle the pipes ten degrees
> downward
> > > with
> > > > respect to the metal belly surface aft of the firewall and terminate
> the
> > > > pipes about 4 inches aft of the firewall, and with the exit about 2
> > inches
> > > > below the metal surface,  but my concern is with what may be the
> > > temperature
> > > > seen by the fabric that begins approximately 15 inches beyond that
> > point.
> > > I
> > > > suspect the aircraft angle of attack during climb will impose more
hot
> > > flow
> > > > against the fabric than at any other flight condition.
> > > >
> > > > Has anyone already acquired some measured data relative to this on a
> > > Tailwind?
> > > > Unfortunately, I don't have the lower cowl configuration that Jim
> > Clement
> > > > uses.
> > > >
> > > > Jim McCulley
> > > >
> > > >
> > > > >Jim Clement's pipes exit where the engine air exits so they are not
> in
> > > > >the slip stream and they point mostly back and down a little.
> > > > George....Phoenix
> > > >
> > > > > William Bernard <billbernard@worldnet.att.net> wrote: -->
> > Tailwind-List
> > > > message
> > > > >posted by: "William Bernard"
> > > >
> > > > >Jim, A Mustang II builder named Kent Paser has done a lot of
> > > experimentation
> > > > >on going fast and has also written a book about it, "Speed With
> > Ecomony"
> > > >
> > > > >In his chapter on exhaust systems, he says the the exhaust pipes
> > pointing
> > > > >parallel to the bottom of the fuselage give some 'jet thrust'. He
> also
> > > > >relates a story in which, during an experiment, the exhaust tips
> turned
> > > > >upward and melted the aluminum belly.
> > > >
> > > > >Exhaust gasses are in the range of 1400-1600 degrees F and so you
> don't
> > > want
> > > > >them pointed at the airplane, unless perhaps it's made of titanium
or
> > > > >inconel X. Maybe a good compromise might be to have the pipes exit
at
> a
> > > > >slight angle away from the belly.
> > > >
> > > > >BTW Kent's book offers a lot of tips applicable to any aircraft, to
> > > increase
> > > > >performance. I got my copy at buildersbookstore.com, if I remember
> > > > >correctly.
> > > >
> > > > >Bill
> > > > ----- Original Message -----
> > > > >From:
> > > > >Subject: Tailwind-List: Exhaust Tailpipe Question
> > > > > --> Tailwind-List message posted by: Mcculleyja@aol.com
> > > > > Does any measured temperature data or other information exist to
> > > identify
> > > > >how
> > > > > far below the ship's belly the end of the tailpipe must be and how
> far
> > > > >ahead
> > > > > of the start of the fabric it must terminate to avoid overheating
> the
> > > > >fabric?
> > > > > Has anyone successfully (i.e. safely) run their tailpipe(s)
> > essentially
> > > > > parallel to the airflow below the belly to create less turbulence
> and
> > to
> > > > >take
> > > > > advantage of the available jet thrust from the exhaust gases
exiting
> > > > >parallel
> > > > > to the flight path? What are some typical measurements and angles
at
> > the
> > > > > exit end of the pipes that existing installations use?
> > > > >
> > > > > Jim McCulley
> > > > > (Seeing light ahead in the tunnel)
> > > >
> > > >
> > >
> > >
> >
> >
>
>