sizing/performance questions

[Cheebs]

I have done alot of research since a buddy of mine turned me onto making a pulse jet, I have found info on exhaust/intake length ratios, but i have not been able to find much on combustion chamber sizing or how the size affects your intake/exhaust diameter. is there a ratio between the volume of my combustion chamber and the volume of my exhaust/intake that i should be considering?

I have built a lockwood style with a 5 inch diam CC, its 7 inches in length, I originally had alot of fuel problems which i thought to be an intake/exhaust ratio problem which lead to alot of modification that got me nowhere. after reading other posts i fixed my fuel mixture problem but before then I had shortened the combustion chamber and lengthened the intake/ exhaust as well as adding a proper cone to the exhaust. It runs well when i get the fuel just right, but i have little control over throttle, it has a sweet spot and if i try to alter it at all it stops pulsing or it flames out.

the original sizes of my engine were a 5 inch diam by 9 inch long CC, 7 inch long by 2 inch diam intake, and a 49inch long by 1 7/16 inch diam exhaust. I never had a cone on the exhaust. it started easily and i had some throttle control, and it had a very strong concussion to it, but it would flame out due to bad fuel mixture, but before i figured that out (thanks to Becks post on another lockwood with a similar problem) i modified the engine to a 5inch diam by 7 inch long CC, 9 inch long by 2 inch intake , and a 63 inch long by 1 7/16 inch diam exhaust, and i put a proper cone on it, it runs but no control on throttle and it doesn't have the same concussion that it did before.

Is this how its supposed to be? Was it the 'big fart' sound before that was causing the concussion? any input would be much appreciated. Thanks.

[Mike Everman]

Hey, cheebs.
So big fart and runs well at right throttle, huh? Ok, so where to begin is getting on the same page, because we get some folks that think it's running when it's not, so no offense meant if I ask. At any level, is your motor running with no added air?
Is it generating thrust?

Check pyro joe's sticky topic above for your initial questions.

[Cheebs]

well since the post i have done more tinkering with my fuel system and found that liquid propane works better than vapour. i have added a preheat to the fuel intake, 9 wraps on the exhaust and 5 wraps on the intake with dual injectors, its running great now. im not running a regulator so when the tank would get cold it was causing pressure issues (amature mistake) . thanks for the help. im sure ill have more questions when i make my big engine... im thinkin about a 9 inch CC