Young Writers Society

I want to fire someone out of a cannon in a capsule. I also want them to survive the ordeal. Question: is there any conventional (i.e. non-magical) way to have them survive the initial acceleration? For instance, filling the capsule with a very dense and viscous fluid that would absorb most of the energy and keep the person inside from being slathered all over the walls?

How fast are we talking here? The Formula Rossa roller coaster goes from 0 - 140kmh (150mph) in five seconds, and I assume its passengers don't get splattered in their seats >.<

If it's not too fast, then giving the person some kind of relaxant or anasthetic would help the body to absorb impact, which is how some people survive unbelievable circumstances because they pass out before impact.

Harnesses tend to work nicely. Elastic stuffs would absorb quite a lot of it. I'm a sci-fi geek not an accredited science nerd, so I can't offer much more help than that I'm afraid.

The muzzle velocity of the device I'm thinking of is a little higher, on the order of ~12,000 km/h in ~2 seconds, enough to send the capsule into suborbital flight.

The human body can survive acceleration from behind (ie- your back is facing the direction you are accelerating in, and you watch things drop away) much easier than from the front. I think it's about 25% more. Unfortunately I don't remember many specifics. It was a guy testing rear-facing airplane seats.

In sci-fi they just call them exactly that, Inertia Dampeners.

A piece of kit that creates artificial gravity within the craft that cancels out the "get pushed into seat" effect.

Yeah, I don't want that. I want something more tangible than "it makes inertia magically go away".

1) Fluids do not absorb energy. They transfer energy. It may not seem like much of a distinction, but it's part of the reason why underwater explosions are so much worse than explosions in air. Here's a fine video to illustrate.

2) Fluids generally don't compress well. This is why they transfer rather than absorb energy. I mention this because people are way, way more compressible than fluids, and at the levels of acceleration you're talking about, fluid = solid mass of human-squishing.

3) While being suspended in fluid will dampen inertia to a point, a person's internal squishies will not be suspended in that fluid are are thus prone to squishing due to acceleration. Aside from the solid mass of human-squishing issue that is.

Basically, I am unaware of any current systems that would be able to compensate for the amount of acceleration in such a short amount of time that you're talking about.

Is it absolutely necessary that the capsule be shot out of a cannon? A more gradual acceleration would be more feasible to compensate for.

I have to agree with Kyllorac that you don't have a whole lot to work with if you aren't willing to have vaguely magical sci-fi tools. There just isn't anything we know of that could make those kind of g-forces survivable for a human.

One possibility you could explore, if it might fit into your story, is modifying the human rather than the capsule. They'd need to be pretty tough, but I think a human whose physical structure is modified to be more resistant to g-forces is more feasible than a capsule that would protect a normal human in those circumstances. As Kyll mentioned, even a fantastic capsule won't prevent internal organs from getting completely destroyed.

The gun idea really isn't too far off though.

Thanks for the replies, Kyll and Nightshade. I'm more willing to modify the cannon idea rather than the human themselves, because the technology in my world does not allow for that.

I was wondering: Kyll, you said fluids do not compress and thus transfer energy rather than absorb it. If we were to make a compressible liquid, would that cause it to absorb energy instead?

Liquids are by definition incompressible. If you make a "compressible" liquid, it's a gas. Solids are only made compressible through gas bubbles. Why packing peanuts and bubblewrap are so light.

And before you go thinking about bubblewrap, the Mythbusters proved that it takes over 10 feet to protect from the impact of a 30 foot fall— which would smother you from the weight of said bubblewrap. You get mild injury at 15 feet, with the absolute max amount of bubblewrap you can hold on yourself. (They had 3 feet of very specially designed padding)

I'm going with Kyll on this: modify the method of launch so there's slower acceleration.