Ejection Baffles

Old Fart ===> Superannuated Gaseous Excretion

LOL I suppose that's better than calling myself an senior methane development manager.... LOL

Originally posted by Mad Rocketeer
Old Fart ===> Superannuated Gaseous Excretion

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Temporally extended metabolically generated aromatic hydrocarbon by-product projector.

I'm a sighintust. I'm good at making up names.

Man! You both came up with better ones!

But DynaSoar, if you want to impress us with scientific names, you gotta make something Latin sounding outta them.

Originally posted by shockwaveriderz
I think its amazing that in the year 2004, we still don't have any data on how hot the ejection charge gases really are..... or worse, if the gases are funneled through a baffle of X or Y design, how much the gases are cooled......

If some 16-18 yr wants to do an NAR R&D report and win that $1000 cash prize next year at NARAM heres a good idea for you... Use thermocouples at different dstances from the ejection charge to measure the drop in temperatue of the gases with length and diameter...then try baffles....

The old centuri baffle was no mor than what? 1-1.5 in length ? I wonder what the gas temp change was in that 1-1.5" .......perhaps if one was made longer, then it would cool the gases that no wadding at all would be needed....

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I'm 18. I might take you up on that. I use piston ejection on all my rockets. For HPR it's the only way to go IMHO.

You know, this would make a great R&D project (both temp *and* pressure/volume). It would be a very valuable report too

I am finishing up a Fliskits Richter Recker (yeah, Jim, I know, I was "finishing up" two weeks ago) for which I modified a coupler into a baffle.

Too bad I lost the link for the basic plan, but I added four bulkheads separated by X-shaped braces that divide the space between two bulheads into 4 chambers.

Each bulkhead has two pie-shaped sections removed (opposing), so that gases flow up into the chamber above. Then the gases must make a perpendicular turn to flow through holes in the braces and another perpendicular turn to flow up through the next bulkhead.

In all, there are 6 right-angled turns. Not using any "baffle media" as this is a permanent (non-cleanable) baffle

Hopefully, I'll get a chance to test it out at the HGS Launch.

PS: Jim, is the RR stable if you remove the upper "payload" section and just launch the "booster" (with nosecone)? If so, I'm going to want to order another nose, since I didn't think of this until after I'd glued the nose in,

I read a report a while back but can't remember were.
In the report it stated that the gasses from BP ejection charges average about 300 degrees.
That being said the biggest problem for chutes ect.. is the flames and burning chunks.
What is left is nothing but hot air that your chute is exposed to for a fraction of a second.
Try this test, set your oven to say 350 or even 400, make sure the racks are out so you have room to work.
Quickly put your chute into and then remove and see what happens.
I guess according to the report the gasses don't really need to be cooled just the flames and burning particulate need to be arrested.

I know of one person who is planning to replace the upper payload section (3/5ths of the rocket) with a nose cone. I don't have stability info for that configuration but it would be easy enough to rocsim if anyone cares to give it a shot...

With D motors I would venture a guess that she'd be stable. Not so sure with E motors..

Hmm, I have a kitbash of the Quest Commander, where I used the body tubes from 3 Commander kits. So the BT is 30" long with an ID of 0.747".

I wouldn't be especially surprised if it doesn't really need wadding at all. A test flight may be in order, once I repair the broken fin from its one and only flight so far.

Does anyone have any thoughts, suggestions, or experiences to share before I do this and end up losing this rocket? <grin>

Also, does anyone have any idea how far the "hot particles" can travel in a small tube and still be hot enough to melt a parachute? From what I've read in this thread, there are still a LOT of unknowns when it comes to the ejection charges of BP motors.

As a side note, there are flame arrestors used in industry, and they basically stop flames from propagating down piping by cooling the flame front with a steel mesh or another type of "torturous path" steel element, just like the "Chore Boy" elements that DynaSoar and others have been talking about here. Take a look here ( https://www.enardo.com/flamearrestors.asp ) if you're even remotely interested in seeing what I'm talking about.

Originally posted by Derek

PS: Jim, is the RR stable if you remove the upper "payload" section and just launch the "booster" (with nosecone)? If so, I'm going to want to order another nose, since I didn't think of this until after I'd glued the nose in,

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Well, I can give you a qualified "YES" answer to this now

DJ flew his RR in just this configuration a few weeks ago and it was very stable, looked good too. I beleive he flew it on D motors, so the jury is still out on E motors...