Re: Gap Staging BP Motors

- R
- Randy
  
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posted
19 years ago

Wed, Jul 21, 2004 7:43 PM

I have done gap staging a few times. The main 'trick' is that you have
> to make sure you vent the area between the motors so the pressure of the > booster motor burning through the top of the motor doesn't pop the > stages apart before the hot particles get a chance to ignite the top > stage motor.

Correct. I have successfully ignited gap staged as far as 10.5 inches. Like Rich said make sure you vent and you may want to use a short peice of scotch tape on 2 sides across the stage joints. You want to use enough to hold them together, not bond them. If it hangs up you have a toasted rocket.

How much is good, only comes from trial and error. I'sda piece of tape about .5" wide x 1" long on 2 sides.

Randy

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- Doug Sams
  
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posted
19 years ago

Wed, Jul 21, 2004 11:24 PM

Thanks, Shockie.

Okay, All, what is meal powder? They say it's "finely powdered" BP. I thought that was called FFFF. What's the diff?

Where can I get dextrin? Drug store? Supermarket? Motor dealer :) ?

Instead of hanging it to dry, how 'bout cutting a short length of this fuse, and, while still wet, putting it in the nozzle of the motor it's to light? (Of course I'd let it dry before trying to use it.)

Will the moisture in the dextrin adversely affect the motor?

I've had this sort of idea kicking around in my head for 3+ years. My plan was to use cotton thread and pyrogen, then dip it in the nozzle and let dry, but since I don't have any pyrogen, I thought this method showed merit as an alternative. What do you think?

Doug

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- David Weinshenker
  
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posted
19 years ago

Wed, Jul 21, 2004 11:38 PM

"Meal powder" is dust-fine BP. "FFFF" is a granulated form of BP, which is prepared by wet-pressing it into cakes and allowing it to dry, and then grinding the solid cake (in non-sparking machinery!!) to the desired particle size.

-dave w

- S
- shockwaveriderz
  
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posted
19 years ago

Wed, Jul 21, 2004 11:47 PM

doug: you can get dextrin at unitednuclear.com and at

formatting link

I have had a very hard time finding unbleached small diameter ( 1/8" to

1/4") cotton cord myself.....

anybody got a for sure source?

. meal powder is just super fine black powder usually 4Fg, sorta like talcum powder which becomes a fine dust .... You could ball mill 4Fg I suppose.... don't know about the humidity/moisture and dextrin questions although dextrin + water = a form of glue

I also suppose you could use the cotton cord/pyrogen although it may burn itself up too fast..?

shockie B)

When Black Powder isn't granulated, and is in a super fine powder state (similar to that of Talcum Powder) it is called "Meal Powder When Black Powder isn't granulated, and is in a super fine powder state (similar to that of Talcum Powder) it is called "Meal Powder". When Black Powder isn't granulated, and is in a super fine powder state (similar to that of Talcum Powder) it is called "Meal Powder".