Ed Huntress wrote:


I read the article on two-stroke expansion chambers because I have a
particular family interest. I see that the author repeats the version
usually told, that Walter Kaaden discovered the principle in the 1950s. If I
can ever find the photo, or the guy who has it, there is one of a 35cc
2-stroke model boat engine, built in 1933, that won some championship model
races that year -- with the aid of a tapered expansion-chamber exhaust with
a short reverse cone on the exit end. My uncle designed and built it.

Yeah, that version is repeated so often it must be true by now..;-)

My understanding is that Kaaden was the guy developed an empirical
model that worked, and allowed the development of the modern chamber.
There are lots of pre-Kaaden examples, some with no return cone (i.e.
megaphone) But Kaaden was the guy who built them to suit the engine
characteristics and understood how the wave action worked. Just look at
the WW2 buzzbombs (pulsejet) for an example of a expansion chamber used
AS an engine. This well preceded Kaaden's chambers.


But he never patented it. The same is true of the star-drag revolving-spool
fishing reel, in which (then) Ocean City reels expressed an interest, but
declined to buy it. A year later it appeared on the market and it was the
basis for the Penn Reel drag that's still sold today. I have the prototype
reel itself in that case -- but no patent. g

Ahhh, missed opportunities. Hopefully he got his enjoyment in the
process of building it.

As for Octane and Cetane and everything in between. At a certain
point comparisons between different fuels and processes are nearly
meaningless. It's best to bear in mind that these numbers are just aids
to understanding parts of a complex process, nothing more. Comparing
diesel, gasoline, propane, methanol, J fuels, coal slurry, et al might
be fun, but unless you have a specific context, it's hard to hold it all
together in a meaningful way.

Pete
--
Pete Snell
Department of Physics
Royal Military College

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