"Pete Snell" wrote in message
...
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.

No doubt Kaaden deserves credit for doing it in a scientific way. I only
discussed it a couple of times with my uncle, and my recollection is that it
was all trial-and-error at that time. Open megaphones were already in
limited use; the reverse cone on the end probably resulted from random
fooling around.



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.

And using it. He was still using the reel in the '50s. I used it a couple of
times myself. It's quite a piece of work, all German silver and copper.

This was a guy who made everything himself. He built a full-blown fighting
chair for fighting bluefins, right down to making the molds for
vacuum-forming the PVC arm rest covers, and welded all the stainless parts
together. He was a well-known...uh, unusual character. g And he was the
head of the NJ Industrial Arts Teacher's Association. If he were alive
today, he'd be a source of endless fascination on this NG.


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

No doubt. But the interesting thing now is that the research on HCCI and
related "hybrid" engines has produced a flurry of investigations into mixed
fuels, additives for boosting cetane, and so on. If you haven't done so
already you'd probably enjoy seeing the vast research being reported by SAE.
Just go to their site...

http://automobile.sae.org/

....and enter a search term in the box in the upper right of the page.
"Cetane HCCI," without the quotes, produces 8138 hits, and you'll see fuels
you probably hadn't thought of listed right in the headlines.

--
Ed Huntress