<VV> Kamm Back and Exhaust Fumes

Mel Francis mfrancis at wi.rr.com
Sat Mar 15 15:00:48 EDT 2008


Just one additional correction, James

The LM Corvair may not have a Kamm back, but it does have a Kamm TAIL, which 
generates a negative pressure all across the rear fascia,
due to the aerodynamic effect of this type of tail.

Evidence of this can be seen when an LM car has leaky pushrod seals and the 
dirty oil droplets completely cover the  cove area,
due to the upward swirl of oil fumes in this area. You may not have seen a 
Corvair like this recently, but during the late '60s, this was a fairly 
common sight in traffic.
Owners who were negligent in complete servicing after a fan-belt break that 
caused the pushrod seals to cook, would find the tail dirtying itself 
constantly.

If your rear decklid has a bad condition or non-existent seal, exhaust fumes 
and any other oil-contaminated air in this cove area will be continually
drawn into the engine compartment by the cooling fan, due to the engine 
cover overhanging the cove area. This is why GM installed a seal in
the first place. Can you think of any other GM car with a rubber seal all 
around the hood? It was needed on the Corvair to separate the two air 
currents.

So, yes, under these extreme conditions, exhaust fumes may be drawn forward 
and mixed with the engine cooling air.
But any Corvair that has been fairly well maintained and has a suitable 
seal, will more likely contaminate its direct-air heater
system with exhaust fume leakage inside the lower shrouds.

Mel Francis
'65 110 Convertible


----- Original Message ----- 
From: "james rice" <ricebugg at mtco.com>
To: <virtualvairs at corvair.org>
Sent: Saturday, March 15, 2008 12:10 PM
Subject: Re: <VV> Kamm Back and Exhaust Fumes


> ALL:
>
> Bob Hall said:  "Exhausts that exit straight back will be sucked back into
> the engine
> compartment and then the heater due to the Kamm effect at the squared off
> back  of
> the car.  That's why all stock Corvairs had exhausts that exit at the
> side."
>
> The Corvair does not have a "Kamm back".  I'm not about to get excessively
> historical and aerodynamically technical, because I don't want to take the
> time to consult my books or files on the subject.  So briefly, the Kamm 
> back
> affect was discovered by the German professor Wunibal Kamm in the late 
> '40's
> or very early '50's.  He was researching aero questions, and discovered if
> the slope of roof was maintained at about 15 degrees or less toward the 
> rear
> and then  "chopped off", the car would have the same drag coefficient as 
> if
> it had a really long tail normally associated with "stream-lines cars".
>



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