Rotating space colonies (Calculated On)

Lets actually do some back of the envelope calculations shall we.

Firstly:

Stress (tension) on a rotating hoop (for simplicity, the place of
maximum stress is a loop at the outer edges).

stress(tension = (material density)x (angular velocity)^2 x (radius)^2

Anyone who questions the above formula can look it up.

Now: radial acceleration (artifical gravity due to rotation) is as
follows:
acc = (tangential velocity)^2 / (radius)

now tangential velocity = angular velocity X radius

Now after we do all the subtitution we get:

stress = density x acc x radius

Now stress for steel is 200MPa
density = 8000 kg/m^3
and the desired acceleration is 9.8 m/s^2 or for this calculation 10.
2x10^8 = 8x10^3 x 10 x radius

rearranging and solving we get
radius = 2500 m.

So a rotating pressure vessel will contain 100KPa of air, and lets
add a safety factor of 100 % so that stress is now 100 MPa.

This gives a radius of 1200 m.

Bill

--- In spacesettlers@yahoogroups.com, "Xenophile"