4" caliber 'Product Launcher' ABS Cannon
After destroying some RIM pagers by by shooting 1.5" hardwood plugs at them, and by dropping a
heavy steel weight on them, I felt a need to come up with a new and improved method of
destroying some prototypes in 2002. The logical next step, I figured, was to actually
shoot the BlackBerry itself out of a cannon.
Because the prototypes I wanted to shoot were
just over 3 inches wide, I had to go up to a 4-inch (102 mm) caliber,
which is the next largest size of ABS pipe. Of course,
firing a product that is just over 3" out of a 4" cannon presents some problems. No amount
of wadding could make up for this difference in caliber.
The solution was to make some 4-inc wooden plugs. I made these to fit quite precisely in the barrel.
With one end of the barrel sealed, it took a good 20 seconds for the plug to drop to the bottom
because of the air resistance. I then cut a grove around the circumference of the plug
to squish soft material into for an even better seal.
This picture shows two of the plugs that I made for firing the BlackBerries. The plug with
the blue cloth attached has a slot to help hold the device. The blue sling is
intended as a sort of drag chute, and also to make it easier to find. The idea is
to fire the device a long way, but I don't want the plug to fly off into oblivion.
The slot in the plug is for holding the "unit under test".
Behind the plugs is the back end of the cannon, with a spark plug facing the camera, and
a fueling valve on the end. The wooden block around the valive is to catch the recoil.
To the left of that is a bunch of AA batteries wired in series,
which I used to power the ignition coil.
When I first tested this cannon, I used Propane and Oxygen. The shots were loud, but
I was a bit disappointed, because I expected it to be unbelievably loud. To push the
plug out of the barrel takes a 5:1 expansion of the gas, and that
was probably all I was getting with that fuel. For the actual launching event
(with lots of co-workers there), I remembered to bring the 'good stuff' in terms of fuel.
I used "bernzOmatic MPS gas". The bottle says its "Methylacetylene Propadiene, stabilized".
It also says "Burns Hotter than Propane for Welding, Brazing and Soldering".
I mixed it with oxygen, of course. What a difference that made! It made a good bang!
The muzzle flashes were also quite impressive. I have since however seen a documentary
about the Bismark, and the muzzle flash from those 16-inch guns put mine to shame!
We launched some BlackBerries in the air, but we had a hard time retrieving them - all we could
find was a few plastic parts that broke off early. The actual device was way out
in the field somwhere. We couldn't find it. Thanks to the drag chute, we were able
to locate the plug each time and reuse it.
For the sake of targeted shooting, I brought a 1" thick steel plate. We fired the
BlackBery devices at that at close range. The above shot shows the cannon just after firing.
You can see the cannon is hovering in the air. The pieces of wood on the left of it are
there to catch recoil. The mess on the right is the target area. Towards the top of it, you can see
the plug (what's left of it) ricocheting off, while all the dust is probably parts of the
deivce on impact. The device itself folded in several places from the impact.
Behind the green patio table 'blast shield' is Ron Harding, with his camrea (also protected)
taking pictures of the imact zone at close range.
I invited some people from work to the event. Plus, Jack Idsik (who's property we used) had
kids, and there was a kid's birthday party at a neighbours, so it made for lots of spectators.
It was possible to herd all the kids onto the garage (in the background) for the actual
fueling and firing. But between shots, it seemed like there were kids everywhere. Not that
there was anything explosive after a firing, but you never know.
Previous cannons I built had lasted for many firings, but I hadn't used MPS gas
before. I figured this cannon should last a long time, due to it's simple
construction. But the MPS gas appears to be a lot more powerful.
I noticed the 2" plug I had at the breech had somehow come out partway after some of the firings.
On later examination of the videos that were taken, I could see quite a progressively larger
flame coming out from the plug, even though I re-tightened it every time. Somehow,
the pressure was enough to get it to skip threads. The only thing that kept it from coming
all the way out is that was that it hit the wooden bracket that I used to catch the recoil.
On the very last shot, I decided to shoot the empty oxygen cylinder (one cylinder is good
for about ten shots). I also used a somewhat damaged plug, which took a bit of
force to ram down the barrel. The shot itself was very disappointing - the bottle must
have gone no more than 25 meters. But on close examination,
the barrel had a big crack along its length. The pictures shows the crack. The
screw hole is for a screw that I put in to keep the plugs from sliding too far back.
There is still room for improvement with this design. With the leakage out the back plug,
not all of the energy went into shooting the projectile. The next BlackBerry product I
"launched" was just under 3" wide, so my next cannon used a 3" barrel,
with a 4" reinforced combustion chamber.
Still, the imact was enough to completely destroy the device - more effectively than
firing a wooden plug at it. The circuit boards ended
up stripped bare of surface-mount
components, even where nothing hit the PCB. The deceleratoin from the impact was enough
to rip the components off the board.
In addition to firing the cannon, Kent Nickerson also brought some model rockets which he
fired off. After this wanton destruction, we were all feeling more manly and satified.
We subsequently had a nice BBQ courtesy of Jack Idsik's wife. We also reviewed the video
footage just taken. Food and entertainment, who could ask for anything more?
Back to cannon page