Hi All --

My son used to set off 2-liter soda bottles by putting some dry ice in them
and then screwing on the cap.  It takes about 5 minutes for it to build up
enough pressure to burst the bottle, but less if the bottle is in contact
with the ground.  I would try doing this by augering a hole in the ground
(or use a post-hole shovel) just large enough to fit the soda bottle, then
covering the hole with something solid (concrete blocks) just after the cap
has been screwed onto the bottle.  This may be the least expensive method
and should produce a relatively high-frequency content.  The report from
the bottle exploding in air can be heard for over a mile and I can attest
that it annoys neighbors and attracts police attention.  Examining a bottle
after the explosion, it appears the explosion happens quite quickly.  The
bottle is opened starting from the bottom like petals of a flower, with the
cap at the center.

I have tried blowing out an acetylene torch then feeding the gas into an
empty container, then igniting it with a spark plug.  Have gotten mixed
results.  Not sure why.

I have done the "potato cannon" using ether, available at auto-parts stores
in aerosol cans as engine-starting fluid.  After setting them off dozens of
times though, the results are far from uniform.  Probably due to
poorly-controlled fuel-to-air ratio.

Regards,
Karl Cunningham


--On Friday, July 22, 2005 1:46 PM -0400 ChrisAtUpw@....... wrote:

> In a message dated 22/07/2005, royb1@........... writes:
> 
> The carbide idea has some charm (I have a carbide cannon)  but careful 
> control of the acetylene-air ratio would be necessary to  achieve a 
> detonation.  Electrolysis of water automatically insures  stoichiometry.
> Hi Bob,
>  
>     Agreed, but have you worked out how long it would  take to get
> sufficient  H2 and O2 by electrolysis and the number of amp hours
> required?     You would need inert electrodes in the water + lime  soda? 
>  
>     You know the volume of the bottle and hence the  volume of oxygen.
> You  now need to weigh out the right amount of CaC2, tip it in  the
> bottle and wait  till it stops fizzling. It would probably be good
> enough?  
> 
>>    Alternatively, equip your self with some  balloons, fill them with 
>> acetylene + oxygen and apply a glowing fuse or  cigarette? I 
>> suggest setting the gas torch burning with the correct  flame shape,
>> wipe  out the flame and then fill the  balloon? 
> 
> Again, stoichiometry would require careful  control of gas-air ratio. 
> Also, balloons are harder to bury than  bottles.
> 
> 
> 
> The way my mind works, I was thinking of  using sausage shaped balloons
> blown  up inside a thin cardboard tube. If you  light the acetylene flame
> and adjust  the O2 to get a cylindrical  blue centre, you have the
> correct gas ratio. You  then push the flame onto  a cold flat surface to
> snuff it out and use the  nozzle to fill the  balloon? 
>  
>     This should work OK. It gets around having to have  a license to
> handle  explosives.
>  
>     Regards,
>  
>     Chris Chapman


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