This episode marks the return of Major, now Colonel, Dick Strawbridge and the Bothers In Arms taking on the Chemical Brothers in a race to build a cannon. A win is determined by whichever team hits a target (about 7 feet across) closest to the bullseye. Should both teams hit the bullseye, the speed of their projectile will reveal the winner.

In essence, a cannon is a strong tube (called the barrel) that is sealed off at one end (the breach). An explosion at the sealed end forces the hot gasses up and out of the muzzle, pushing whatever is in front of it out at a tremendous (we hope) velocity. There are few design choices and explosives you can use, effectively, but we'll discover those as the episode progresses.

The Chemical Brothers
l to r: Pat, Captain Paul and Rob
David Rainer is their expert on the bottom
The (mustachioed) Brothers in Arms
David, Dick and team captain Bobby Strawbridge
inset; Dr Derek Allsop
As you can see, the explosion at the back
of the cannon will cause the steel to bulge
momentarily before expunging the projectile
This monsterous cannon was used by the
Germans during WWII. It's mounted on
a train!
The Chemical Brothers will be using
age-old black powder.
The Brothers In Arms will be using
cordite, a modern explosive.
Our judge today is Major Dave Reid
who is a weapons tester.
Derek? Did you remember to carry
the four?
While the Chemical Brothers are
readying a sight for their cannon...
...Brothers In Arms expert Derek is being
quite lathe-y.
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