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----- Original Message ----- From: "Charlie England" <ceengland@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, May 01, 2005 9:36 PM
Subject: [FlyRotary] Re: Inserts
rijakits wrote:
> snipped
>
>Charlie,
>
>I suggest you look also into exhaust augmentation.
>If you are already "skunk working" on something new and exhaust related,
you
>might as well reap the benefits from that. It should help with cooling
>(pulls air through the radiators/oil cooler), it would provide some kind
of
>fairing (streamlines the cooling exit, exhaust exit and might hide any
>muffler), it also should muffle the exhaust noise (might get away with
out
>any muffler...). As the augmentation implies a mixing with cooler
(...than
>exhaust) air this should muffle the noise as well. If it does not mix, it
>will at least suround the hot exhaust gases with a mantle of cooler air -
>muffling again. It should also increase efficiency as you have the
exhaust
>gases do some work - should also work for a turbo (double duty!)
>Last but not least benefit: Depending on the exhaust routing ( how early
in
>the duct you can introduce the exhaust pipe into the cooling duct), the
>cooler air in the duct will isolate the exhaust heat from the rest of the
>engine compartement.
>
>Just a little info from this site: http://bd-4.org/cooling_nicoson.html
>Dan Nicoson is planning a V8 installation with exhaust augmentation, so
it
>is also liquid cooled and a lot of heat to be removed.......
>
>Anyway, I hope between all on this list the maximum power, lightest
weight,
>most reliable system is found some time, so I can shamelessly copy the
>perfect setup!! - ...sometime when I get to build:))
>
>Cheers,
>Thomas Jakits
>
Thanks for the link; it's good reading. I've thought a lot about exhaust
augmentation. The 2 downsides I've heard (2nd hand info only) is that
they can actually increase drag at high speeds & that they usually
*increase* noise levels. The 2nd is not too hard to understand & pilot
opinions about certified planes using the technique seem universal that
they are louder than similar designs w/o augmentation. The 1st is a
little harder to understand. Maybe the augmenters draw too much air
through the system.
Are you considering a BD-4? I owned one for about a year, between two
RV-4's.
Charlie
I guess one could work with some kind of cowl flaps with the augmentation
idea to reduce drag (or limit the intake with flaps...)
The only airplane I ever got close to that uses augmentation was a
Twin-Bonanza, and you are eright it is failry loud. But it doesn't use any
muffler and the augmenters are not faired either, but are rather open,
pointing downwards at a rather steep angle.
If you look at Dan Nicosons drawing, the exhaust "jet" is very far forward
of from where the fairing seems to end and it points straight back.
I would hope/expect that thiswould muffle/mix the air a lot better that if
the fairing would end right at or shortly after the exhaust pipe.....
To the BD-4, see my private e-mail...
Thomas Jakits.
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