Some Early Notes on Project Scope
The engine is constructed of say 4 cylinders, firing in a sequence, rapidly one after another so as to create the effect and feel of constant acceleration of 1 gravity. Passengers are thus not weightless but stand and move around the vessel in a normal earth gravity. The space drive is thus not behind them but directly beneath them as in a rocket. However rocket is a bit of a misnomer for this form of propulsion because RNE (rapid nuclear explosion) is more equivalent to the small gasoline explosions that cause the cylinders to move in a normal automobile. Of course the size of the nuclear explosion because of critical mass is a minimum force which is used to determine an exact total mass for the vessel, assuming F=MA and the A (acceleration) wanted is the 1G simulated gravity threshold.
How rapid is rapid? If gravity were a pulse, how infrequently would it have to oscillate in order for a human to notice the deviation from a constant normal gravitational pull on the earth's surface? Perhaps 50 times per second or less. For this rapidity to work, as a car has 4 cylinders, there is not just one cannon casting or rocket but 4, rotating in sequence so as to give a chance for the cannon casting to cool down. To build just one of these rockets, open ended cylinders with enough strength to withstand a critical mass nuclear explosion without breach or fracture will require the testing of special materials and astronaut handicrafts. Forgetting that one hundred trial explosions may be needed before a rocket design is good enough to withstand RNE for the duration of a trip to a nearby solar system and back, a closed environment in space such as the space station may be essential for the construction of the cannons - if steel casting of the whole cannon was required in one piece as was required in the middle ages to be discovered before regular cannon breach on the battlefield became extinct. Joining segments did not work, but perhaps rather than steel, titanium and ceramics might be the possible combination.
Some Early Notes on Project Scope continued
In interstellar travel asteroids at high speeds are dangerous and it may be worth constructing several inner hulls and compartments out of the metal to insure that the passenger quarters are fully protected. Chinese payload boosters could put materials cheaply into orbit and stored in nets awaiting astronauts to assemble a large hull. Is hot metal riveting possible or are there other handicrafts?
Apart from crew and passengers an adapted space shuttle would have to be carried with the vessel. It would have to be adapted to enter the planet's surface of another star, survive and be re-launchable irrespective of the level of technological advancement of the alien species encountered. To this effect the shuttle could drag down from orbit the large booster rockets, towing them to a safe altitude and location whereby parachutes would be used. The launch pad could also be dropped this way, or held inside the cargo hold. To re-launch and return to the orbiting vessel, the large booster rockets etc would have to be cranked erect and attached to the shuttle.