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havoc821

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How exactly do flashbulbs work? Do they explode or just create a lot of heat? Thanks!
 

Micromeister

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Heat to ignite thermalite inserted in the motors and taped to the bulb.
 

Ryan S.

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flashbulbs flash very brightly and creat alot of heat, there is enough heat to ignite black powder charges for example. I would use ematches, they are simpler and smaller
 

powderburner

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Since quick-fuse-stuff (like thermalite) is relatively hard to get, and you never know how the rules change from day to day regarding LEUPs for this stuff, I have used a different approach

I stand the motor (I use BP motors) bottom-up on a workbench, fill the nozzle with loose blackpowder or aluminized flash powder (one firecracker's worth is just about perfect) and place the flashbulb directly on that. Then I cover the whole bottom of the motor with masking tape, leaving the leads to the flashbulb sticking out. Reliability, for me, has been 100% in several dozen tries----works well to get clusters triggered simultaneously, especially if the launcher's ignition system does not have an auto battery to ensure lots of amps. Biggest problem is finding usable flashbulbs.
 

Stymye

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powder,,,,just remember don't rub your feet on the carpet before you get to the launch pad with it! lol
 

Ray Dunakin

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Originally posted by powderburner
I stand the motor (I use BP motors) bottom-up on a workbench, fill the nozzle with loose blackpowder or aluminized flash powder (one firecracker's worth is just about perfect) and place the flashbulb directly on that. Then I cover the whole bottom of the motor with masking tape, leaving the leads to the flashbulb sticking out. Reliability, for me, has been 100% in several dozen tries----works well to get clusters triggered simultaneously, especially if the launcher's ignition system does not have an auto battery to ensure lots of amps. Biggest problem is finding usable flashbulbs.
Just don't try this with composite motors.

I love flashbulbs but they're getting hard to find these days. And Thermalite is even more useful but also hard to obtain. Which is really a shame because it's one of the best rocketry items ever invented (though it was not created specifically for rocketry).
 

powderburner

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Originally posted by Ray Dunakin
Just don't try this with composite motors.
Absolutely.

In fact, I would not recommend anyone try this even with BP motors with a 'core-burn' propellant grain. I only use this on the basic Estes-type end-burn A, B, and C motors. Otherwise, with composites or with a long core through a BP grain, you will fill up the motor with an excessive amount of starter/primer. You will get a bang instead of a whoosh.
 

Elapid

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probably one of the coolest things available commercially
:D

i have piles of flashbulbs, i assume you break away the plastic covering the Magnesium?
 

powderburner

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Originally posted by Elapid
i assume you break away the plastic covering the Magnesium?
If you mean removing the bulb from the plastic cube/packaging, it's OK to remove the reflector from behind the bulb.

If you mean opening the bulb itself, that is not necessary and could well mess up the operation of the flash bulb. I have never heard of anyone opening the actual bulb.

If you put one of these flash bulbs in contact with a pyro fuse, or a dose of BP, the intense flash will ignite the adjoining materials. The flash will heat up the pyro material to/beyond ignition temperatures, right through the bulb's glass capsule.
 

havoc821

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Reason I was asking was for large motor clusters or for airstarts, I was going to use the flashbuld to ignite the thermalite. Ya'll kept saying thermAlite when you meant thermOlite. ThermOlite is the hard to get stuff that requires LEUP, thermAlite is sold by PyroteK and is not regulated. Just to clear things up.:D I was thinking for my Saturn V cluster, core 29mm surrounded by 4x 18mm Cs, since the AP lights slower than BP, I decided to light the AP and the fuses to the BP at the same time (like cut the fuses for 2 secs) so that the BP motors would light if not at the same time or shortly after the AP motor lights. It should be pretty cool! Thanks guys, you helped out a lot. One last question. Whre can I get flashbulbs? Are they cheap? Thanks!
 

Stewart32

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but, are we talkintg the instamatic style flashcube flashbulbs here (ie Bluedot)

As I recall, this variety flashed by shorting the terminals. No electrical charge was necessary. (I found this out the hard way by dismantaling a "cube".) I also recall the the glass bulb had some sort of plastic overcoat, presumably as a safegaurd against glass shrapnel? Is this the variety used in flashbulb detonation?
 

Rick Lindsey

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Originally posted by Stewart32
but, are we talkintg the instamatic style flashcube flashbulbs here (ie Bluedot)
"Back in the Day" (8-12 years ago when I was active in HPR) we used flashbulbs extensively to ignite ejection charges, though I never used them for ignitors. They were definately not the "cube" type flashbulbs, but looked alot like a small flashlight bulb.

-Rick
 

Fore Check

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I was gonna start a new thread for this, but thought I'd try here first.

I recently acquired a bunch of Robby's Rocket pre-wired flash-bulb deployment cases. Having never used them (I got them in anticipation of starting dual-deploy flying this summer) it sure would have been nice if they came with some basic instructions.

Also, are they re-usable or are they a one-time deal?

Here's a link to the eBay page where I got them. I've exchanged emails with the seller, and he basically said ask someone else.

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWN:IT&viewitem=&item=170071681070&rd=1&rd=1
 

PopRocket

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Fore Check, they are single use ejection charge canisters. To use them you simply pour the appropriate amount of black powder (based upon tube volume) into the cardboard tube and then push one of the sticky paper discs down on top of the powder using the little wooden rod that should be included with the kit. The idea is to seal the tube and keep the black powder in contact with the flash bulb which is installed in the bottom of the tube.

I have used these extensively in the past with a 100% success rate.
 

Fore Check

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Originally posted by PopRocket
Fore Check, they are single use ejection charge canisters. To use them you simply pour the appropriate amount of black powder (based upon tube volume) into the cardboard tube and then push one of the sticky paper discs down on top of the powder using the little wooden rod that should be included with the kit. The idea is to seal the tube and keep the black powder in contact with the flash bulb which is installed in the bottom of the tube.

I have used these extensively in the past with a 100% success rate.
That's what I thought - but I wanted someone to re-assure that. Thanks!!!!!!!
 
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