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Re: re: A New Friend and a New Lady

Posted: Fri Dec 09, 2005 10:01 am
by Stuart
serverlan wrote:Hi Ed,

I can offer just one piece of info.

The colour of the flame indicates its temperature.
I can't remember the exact figure now, but lets say its about 2100K
If the intake temperature is 300K, then the combustion raises the temperature by a factore of 7:1.
If it burns fast enough to achieve this temperature before the pressure disperses, we could expect a similar increase in pressure above atmospheric.
Thus the initial burn pressure could be up to 700000 whatever-the-metric-units-are.

If the gas were to expand as it is burning (i.e. a slower burn) then that temperature would not be reached (expansion produces cooling) and the temperature would be lower and the colour different. So, at the moment I think that is a reasonable pressure estimate. Most people tell me I'm dreaming, that the measured pressure peaks are much less than that.

700,000 whatevers would be 700,000 Pascals or 700,000 Pa. Or in friendlier terms, 7 atmospheres. Except, no Pjet engine gets the full charge to that temperature. Published figures for the Argus only show a total cycle fluction of around two atmospheres, and part of that is in the negative inflow region (below 1 atmosphere).

Pulse detonation, on the other hand, gets local shock temperatures that are to the moon, but those aren't the same as average temps.

Re: re: A New Friend and a New Lady

Posted: Mon Dec 12, 2005 1:23 pm
by Carl Litzkow
Larry Cottrill wrote:Carl -

Make sure what you present is really applicable in some way to propulsion theory, and doesn't come across as encouraging amateur explosives experimentation. That goes down pretty badly here (even in the Off Topics Forum). I'm sure you'll use good sense; this is just a "word to the wise".

L Cottrill
Trust me on this one my friend, I am very conscience of NOT encouraging the "crazy's" or giving the Forum a negative "personality". I should have said I was trying to provide another design tool, and not emphasized his credentials. He knows it is for PJ propulsion. Most of this thread seemed to be in finding an alternative to UFLOW since no code or upgrades are available. I will censor @ my end and always intended for you to screen before you post. I will e-mail my latest construction jpegs for FWE ver. V today.

The Lady Has a Flamboyant Flare

Posted: Tue Dec 13, 2005 3:02 pm
by larry cottrill
Carl sent this along last night. The new intake, with socket for replaceable end sections. He is also considering making the intake as a whole adjustable in terms of its position along the chamber cone, and I told him I'm in no hurry, if he wants to add that kind of flexibility.

This first attempt at a flare has a certain stylishness, and is reminiscent of the discussion Eric posted on his "suction pulsejet", though his big flare was at the tail, of course.

L Cottrill

re: A New Friend and a New Lady

Posted: Tue Dec 13, 2005 5:05 pm
by Eric
Wow.... Maybe he should make a linear engine. Would be a bit easier to try out really huge flares and adjust intake length.


re: A New Friend and a New Lady

Posted: Thu Jan 05, 2006 2:58 am
by larry cottrill
Here's Carl's first shot at the FWE V front end. With my blessing, he's decided on removable nose plates as well. This one is a sort of Durante shnozzola, all set to bolt right on.

Obviously, Carl takes a back seat to no one when it comes to craftsmanship! He also sent me a few shots of some nice art pieces he has done.

Also note his laboratory grade spark coil in the background (that varnished maple box with black screw terminals, upper left). Carl should be arm-twisted into making us a closeup shot of that, especially showing off the nifty buzzer assembly at the front end that makes it cook.

Thanks, Carl!

L Cottrill

"Yes, we are Cottrill Cyclodyne -
Our wheels grind slow, but exceeding fine."

Materials & Methods: Cylinder Head

Posted: Fri Jan 06, 2006 4:24 pm
by larry cottrill
Making the "cylinder head" (removable chamber dome) - cleverly crafted from a protective cap as featured on standard high-pressure gas cylinders. Should be sufficiently heavy duty for pulsejet work.

L Cottrill

Materials & Methods: Intake and Cones

Posted: Fri Jan 06, 2006 4:35 pm
by larry cottrill
A few more shots: making the intake and drilling the port in the chamber to fit it; the tail cone; all parts together on workbench.

L Cottrill

re: A New Friend and a New Lady

Posted: Fri Jan 06, 2006 8:34 pm
by El-Kablooey
Wow, I hope that runs as good as it looks!

Fuel Stinger Details

Posted: Wed Jan 18, 2006 2:34 pm
by larry cottrill
Well, Carl just sent me four more shots, this time of the fuel stinger setup. He didn't say whether he settled on 1/4-inch or 3/16-inch OD brake line for the stinger, but it's one or the other of those, with a flattened nozzle on the business end, as shown below. The depth of the stinger in the straight upper part of the intake is fully adjustable (possibly even while running, it seems to me).

I sent him an email suggesting that he complicate things a little more by providing a parallel tube connected to a manometer, so we can get pressure / suction values in the intake as the stinger is adjusted to different positions. We'll see if he takes me up on this. I think that would be interesting data to collect once he gets her running.

L Cottrill

re: A New Friend and a New Lady

Posted: Wed Jan 18, 2006 3:41 pm
by hagent
Nice looking shop Larry!

It's nice to have all the tools.

I like the PJ too.

Nice gold touch.