I have a nice little program, written by a Belgium music professor. it is available on my wanadoo website http://home.wanadoo.nl/pereivers/helmholtz.exe. I put it there for safekeeping, and this is the first time I see others publish their working along the same lines. Thanks guys.
Using the program it is clear how the pipe length and tub volume influence each other, and the longer pipe makes the setup more peaky (high Q-factor) Thus the shorter pipes make it less sensitive to volume mismatch and wrong pipe diameter, like Kris noted.
Like Dick noted, more power is accompanied by higher internal pressure, because this pressure is the spring behind the spring-mass system that it represents. The pressure, being the spring in the spring-mass system, also inreases resonant rpm, and is governed by the tub volume, stinger pipe length and diameter.

Things are shaping up. Dar Zealon, are you reading this?? I wrote you an e-mail on the principles involved

DKjens,
I do not have that much experience with the engine yet. One on my test stand, but little time to do many experiments. It's winter, and my oil burning heating goes berserk, eating at my spare time trying to fix the 40-year old oil pressure regulator. Add to that my venture to combine two MVVS engines into one 1/12 rc-combat monster (.28+.21)=.25 short stroke), to get me going for the new combat season.
Winfried has an engine as well, so we realy are a small circle of users at the moment. Morris keeps his mouth shut as usual. From Krumscheid I heard, that he has systems ready for the engine. From MVVS I have word that they work their asses off to get more engines ready by spring. I still have two on the shelf from my last order.
MVVS also works on a smaller engine in the 40-50cc range, and a watercooled 58cc for cowled-in applications and scale radiators. Do they bite off more than they can chew?? A very dedicated small team they are.
I plan to put my test engine in an Airworld Extra300 which will be about 22 lbs. My KS orderd stuff did not show up yet, so I make no progress whatsoever.
Feeling unhappy??? who,, me?? No way! [>:]