REFLECTOR: Exhaust systems - Supertrapp

[Rodney Brim]

I used a supertrapp for approximately 6 months on a 540.  It does reduce the
sound very well, and does not impact the prop with heat.  It does create
quite a bit of turbulence that impacts the prop and is most noticeable in a
climb.  I can't remember specifically, but I believe it resulted in a loss
of more than 200/fpm of climb.  It's draggy in cruise as well.

I've tested various configurations of rear-facing exhausts within the
cowling on a 3 bladed prop.  I also tried simply chopping the factory
forward facing exhausts, and reversing them to flow directly back.  I've
never had any charring.  When exiting from within the cowl exit holes it did
raise bubbles on the skin of the MT prop, indicating the existence of heat,
and I did get the grey haze or dust which could be wiped away.

Directing the exhaust down and back at a 45 (sideways and back would work as
well) so the sound foot print gets broken up by the prop, and having enough
air space (as the factory or Custom Aircraft Parts design provides) to
defuse the heat seems to work best.

Rodney Brim,

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Alexander Balic
Sent: Friday, July 11, 2003 8:44 PM
To: reflector@tvbf.org
Subject: RE: REFLECTOR: Exhaust systems


How about installing a 2 or 3 element supertrapp muffler there at the end of
each pipe.  My experience with them is that there is very little restriction
created, and the exhaust would not be flowing directly against the prop.....

-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Scott Derrick
Sent: Friday, July 11, 2003 9:22 PM
To: reflector@tvbf.org
Subject: Re: REFLECTOR: Exhaust systems


Tom,

You should take a look at the 3-into-1 by Custom Aircraft Parts.
Pictures and drawings are on the web site.

I'd at lesat do some measuring before throwing in the towel.

Scott


Tom Martino wrote:
> My custom cowling was expensive and I would have to do way more than just
a new exhaust.  The cowling would basically have to be custom made because I
am using a non-standard engine for this airframe (IO-540 on a 173RG)
>
> -----Original Message-----
> From: Scott Derrick [mailto:scott@tnstaafl.net]
> Sent: Friday, July 11, 2003 9:33 AM
> To: reflector@tvbf.org
> Subject: Re: REFLECTOR: Exhaust systems
>
>
> You can always use the forward facing exhaust system sold by the factory.
>
> or:
>
> Custom Arcraft Parts sells a cool 3-into-1 downward facing exhaust for
> 6cyl velocity.
>
> Both are burn proof for a big 6 with a 3 bladed prop on a pusher.
>
> Scott
>
> Tom Martino wrote:
>
>>So, can the three bladed prop be mounted on an IO-540 to avoid burning?
>>(Sorry if I seem dense)  If so, how?
>>
>>
>>
>>-----Original Message-----
>>From: Simon Aegerter [mailto:simon@aegerter.net]
>>Sent: Friday, July 11, 2003 8:17 AM
>>To: reflector@tvbf.org
>>Subject: Re: REFLECTOR: Exhaust systems
>>
>>
>>
>>>After all, 3 does divide evenly into 6.
>>
>>
>>You are absolutely right, Dale.
>>
>>A 6-cylinder engine fires 6 times during 2 full turns, that is 720
>>degrees. 720/6 = 120. That means, the blasts are seperated by 120
>>deg. That happens to be the spacing of the blades of a 3-blade prop.
>>So. with a 6 cyl. engine and a three bladed prop you can have the
>>blast in one of two places: onto the blades or between them,
>>depending on how you mount the prop. Presto!
>>
>>I have not flown a whole lot of hours since I turned my exhausts
>>(3-in-1) backwards but I see no charring, just some soot.
>>
>>Somebody asked about a 4-bladed prop. Same argument, different
>>result: a 4-cyl fires 4 times in two turns - so 180 deg apart. unless
>>you have 8 ways to mount your prop, you are making sure that at least
>>two blades are hit every two turns.
>>
>>Best
>>Simon
>
>
>
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