# Low-tech inertial dampeners

Inspired by the movie “Event Horizon”:

In order to absorb the extreme Gs of starship acceleration the Event Horizon housed the occupants within a tank of fluid in a state of neutral bouyancy.

Can a human body take high Gs and sudden bursts of acceleration using this method?

I propose a test for the SDSAB…Mythbusters style.

Engineer a tank full of water…say, about the size of a refrigerator…and place a test article inside…the size of a football.

The test article should be made neutrally bouyant.

Attach some kind of sensor/recorder to the TA that measures the rate of change in pressure, as well as G forces.

Would that work? It seems as though any method would only help with sudden changes in acceleration for a short time period. Any constant acceleration would simply pin you to the surrounding container once the limits of the spring, foam, liquid are exhausted.

A neutral buoyancy object would experience the same acceleration as the tank of fluid containing it. When you accelerate in a car with the windows up, do you feel air rushing to the back seat? All that air is neutrally buoyant in air.

Only if the object is NOT buoyant would the acceleration be damped.

For real fun, tape the string of a helium balloon to the center console in your car. Because the balloon has positive buoyancy, it will experience exaggerated acceleration. It will move forward as you accelerate, rearward as you brake, and toward the inside of curves. The effect is not subtle.

Hasn’t something like this been tested somewhere in all of those Engineering Week egg drop tests? I know I read somewhere about an entrant who suspended the egg in a container of jello. I can’t remember whether the egg lived or not.

You don’t need a refrigerator sized tester to check for G forces. In fact, you’d have a harder time finding a way to apply G forces to a larger apparatus. With a smaller apparatus, you can rig up a centrifuge or drop it from a calculated height, depending on what kind of acceleration you want.

Yes. As early as 1939, Dr. Wilbur Franks noted (here - warning pdf):

This segues immediately into practical accleration protection for pilots of high-performance aircraft. The benefits of a fluid-filled g-suit didn’t outweigh the costs to pilot maneuverability, suit weight, or complexity - that’s why g-suits today are air-filled. Another thing that was tested was prone pilot positions, but this also wasn’t desirable (although the seat on an F-16, for example, is reclined).

I think the effect being sought is not so much the damping of the acceleration as the mitigation of its harmful effects. A relatively incompressible fluid will ensure approximately equal pressure on all parts of the body, which sounds as if it should be helpful.

Ah, well then just have your space travelers lie on a water bed.

You don’t feel it, but it happens. Put a balloon in a car and accelerate, the balloon will move to the front of the car indicating that the air is being “pushed” to the back.

I can’t see how a fluid filled container can work for anything other than very brief periods of high g-forces.

From a relativistic perspective, wouldn’t an “inertial dampener” that manages to counteract a constant acceleration effectively be an “anti gravity” device?

If you’re at neutral buoyancy, and have the same compressibility as the surrounding fluid, you’ll remain stationary with respect to the fluid no matter what the acceleration. This effect will hold whether you’re under 50 G’s for 1 second, or one hour.
What’s more, the pressure of the surrounding fluid will prevent bodily fluids from pooling at your lower extremities. Such pooling would require displacement of internal or external fluid by an internal fluid of equal density, and no matter what the acceleration, there’s no force to drive such a process.
Since the human body is not of uniform density throughout, you’d still notice things like your bones trying to come out your backside, or mitochondria compacting against one side of all your cells, but that’s nothing compared to the effect of having all the blood within you trying to get as intimate with an acceleration couch as possible.