many many years ago in basic RAF training I sat through yet another of those horrible training films, but this one fascinated me. When the Russians wanted a new trans siberian canal they dug a deep trench, laid in a 12in sausage of HE, lit the blue touchpaper and stood back. The film we watched was taken from a helicopter a few thousand feet up. The sausage detonated at around 5 miles a second and made a canal. It looked like slow motion as it travelled along the ground. That always stuck in my mind. Interestingly (to me anyway) the detonating shockwave has an angle of about 13 degrees which is also the angle of incidence that a wing stalls at. Education is a wonderful thing.