Replies to post #47586 on World Surveillance Group Inc (fka WSGI)

[risk_it_us]

Wrong dude:

Due to gas expansion factors, any high altitude airship must be launched only 6% full of lifting gas. For a cigar-shaped airship, this results in severe flight control and structural integrity issues due to the difficulty of maintaining a stable center of gravity. This is one of many problem areas where suggested solutions for elongated airships are extremely complicated.

At 60,000 – 70,000 ft. there is often light wind or sometimes none at all. As previously stated, a cigar-shaped airship requires sufficient airflow over its control surfaces to maneuver. In the low density air of high altitude, maneuvering speed needs to be proportionately higher, making it questionable whether or not traditional airship designs can remain stationary within a designated "box” in a low or no wind situation.

[Squirt]

Vern

"....... but has increased in size to where its volume is greater than the water it contains and thusly floats......."

Don't you mean the weight of the water it displaces is greater than it's own weight?

[trunkmonk]

pV = nRT (pressure * volume = the number of molecules * gas constant * temperature)
very predictable pressure-temperature relationship, very linear, no tricks and not hard to figure out because its the law and you dont have to do anything the balance the 2. when one changes the other changes, period.
atmospheric pressure, gravity(changes with altitude), and temperature figure into the bouyancy of an object, differntial pressure is what needs to be maintained.
helium has a boiling point of 4x that temp (-268), at -67 its well into gas state.
here is everything you need to know plus more:

http://www.omsi.edu/visit/physics/air/science/glossary.html#fluid