Economics of Project Orion

[SirNitram]

Takeoff weight was 10k tons. The nuclear devices are included in that weight. And also, I believe the plan is to use fission devices. Fusion isn't much use at the yields we're using. You need to get significantly larger the 20kt devices for it to make sense. 20kt isn't much larger than the two devices we used in war, which were notoriously inefficent.

The main design was 10k tons spaceship, same amount fuel, as I've read it. And it proposed pure fusion devices; or they took the math from it, one of two, as that's the only way you get the contamination figures they had.

[Gil Hamilton]

[ Air resistance simply isn't an issue--yes, it would be bad for an object of that size, but already by the 1960s the simple fact is that we were launching rockets which accelerated at 400gs. The rather mild acceleration of the Orion, never exceeding 8gs, is nothing compared to that in terms of the friction it would generate, even with a much large surface being presented into the airflow.

Actually, air resistance was basically it. The 400g rockets would have much less air resistance because they are rocket shaped and designed with that in mind. Orion was not rocket shaped, it was basically a small office building stuck on top of a enormous metal disk. Even back in the 50s and 60s they knew it would only work if you neglected air resistance, otherwise air resistance would strip too much energy off of it. It's the difference between firing an arrow and a frisbee straight up.