From: whos@ddsw1.MCS.COM (Ben Feen)
Subject: Re: Help with "bomb"
Organization: ddsw1.MCS.COM Contributor, Chicago, IL
Date: Wed, 8 Apr 1992 23:14:57 GMT

In article <1992Mar31.095055.23133@ncrcae.ColumbiaSC.NCR.COM> jdg@devine.ColumbiaSC.NCR.COM (Jim Griggers) writes:
>I am new to this newsgroup, apologies if this is common knowledge.
>
>I have been elected to help with special effects on a theatrical set.  One
>of my assignments is to create an explosion on stage, the force of which
>"kills" someone.  The description of the effect is below:
>
>	A flash powder "bomb" is contained in a 20 gal. can and located
>	under the stair landing.  A heating register mounted in the
>	floor of the landing permits smoke to escape.  Clive stands
>	on this register when he announces, `Dinner is served.'  The
>	explosion is triggered by the electrician.  Containing the
>	bomb in the can focuses the smoke up through the register
>	in a column.  The sound of the explosion should be loud
>	enough to startle the audience.

Here's how I would OPTIMALLY do it:  Use a PyroPac (commercially available 
theatrical explosion effect equipment and powder) OFFSTAGE (way off) for a
concussion effect.  At the same time, a fog machine is triggered to feed fog
through the register. This way, you have NO sparks near the set, and the smoke
won't choke anyone. (I've inhaled clouds of pure fog from a fog machine and it
was only mildly annoying.) 

>As much as I have played with fireworks as a kid, I have never had to 
>electrically set off an explosion.  A lot of things I have thought about
>are probably not reliable enough for this application.  I need to *accurately*
>and *reliably* be able to trigger the explosion.  This seems to eliminate
>fuses that have unpredictable burn times.

Ummm... I really hate to burst your bubble, but theatrical pyrotechnics 
is a field for people with experience, or at least knowledge of safety codes.
Most of the stuff you want to do violates fire and safety codes. Remember that
if something goes wrong, YOU are PERSONALLY responsible for hundreds of people,
and maybe a building.

1)  Use commercially available supplies for pyrotechnics.  Unless you have
a chemistry degree and experience in the field, mix-it-yourself is a bad idea.
PyroPac, a  reliable system, supplies you with doofusproof (almost) bottles of
effect powder.  You mix them according to the effect you want.  

2)  NEVER use explosives near people.  Actors are very accident-prone, and will
walk in the way of ANYTHING. 

3)  Your set will have to be flameproofed with ROSCOFLAMEX or something if you
use anything which burns.

4)  Your best bet is to use a sound effect (played over BIG speakers!) of an
explosion (you can get these from sound effects LPs or CDs)  and a fog machine.
Heavy-duty foggers will load an area with non-smelly smoke FAST (I recently 
worked a jazz concert, and filled a 70' stage with fog in about 4 seconds.
That's with a hand-held unit) I doubt it'll take a 2 second blast from a good
unit for your needs.

>PS. There are no theatrical supply stores in Columbia,SC.  I may need to
>    mail order supplies or make my own.

Get a Charleston phone book.  Look for Disc Jockeys too;  You may be able to
rent a fog machine from someone.


Crossposting to the brand-new alt.stagecraft group 'cause they can use the 
discussion...
-- 
Mail whos@ddsw1.mcs.com. | Whos at ddsw1? | Yes! | What? | No, whos! | Huh? |
Who? | Who what? | No, whos@ddsw1.mcs.com!  | Where? | DDSW1! | Who's there?|
Right! | Right? | Yes! | Oh, right@ddsw1.mcs.com? | No, WHOS@ddsw1.mcs.com! |
That's what I wanna find out! | What? | Who! | He's at ddsw1! | AAAAAAAAAGH!|