Cannon over Pusher Plate

Any cannon (hollow tube plus pusher plate) will weigh a lot more than just a "pusher plate". It is time to discuss a rather obvious ancient device, the gunpowder cannon. The scientists on the original Orion Project were at the very beginning of the satellite age. The ability to proposing constructing a cannon in pieces in space, using astronauts and space stations, was not feasible. They discarded the logical walls of the cannon to leave just a pusher-plate! For me in this decade a ground launch option does not seem practical, kind of ever.

However this extra weight of the craft (500 to 5000 tonnes and keep going up if you need to envision successful physical containment) is not a problem but almost an essential factor for a space crew using this fuel as an accelerant. Again no test has been done so there is a lot of theory. However obviously if immense force is unleashed with each detonation, if the craft is too light then acceleration will knock out the crew. Acceleration of the craft when actually already in space (as it will be when built there) is going to be determined by dividing that force by the mass (excluding relativity secondary considerations). This extra mass may be very much needed and indeed one might argue that some ballast may be required. If of course you start to diverge into speculative smaller blasts, I'm afraid I have no inside knowledge and must stick to the original historical observations of the Los Alamos project. I advise others to do the same.

Cannon over Pusher Plate continued

The most important issue to me does however seem to be the technicality of building a 500 tonne space cannon in space from the smaller parts we can actually get up there using existing rocket technology! I would as a historian encourage study of the lessons of the early European cannon makers in the 14th century, forced to make cannons out of separate pieces. The technological limits of iron foundry at that time could not cast them in one piece large enough to do the job of being large enough to penetrate European castle walls. Our equivalent today is that we cannot build rockets powerful enough to put in one shot 500 tonnes of mass and more into orbit.