On Mon, Jun 22, 2015 at 8:53 PM, Johannes Trimmel <[email protected]> wrote:
> For ordinary loading yes, but if you unload just one item (a basket with one > or 2 hardy ranchers and some equipment)? You put down a rope on a whinch, > and if you unload, the blimp goes up, but that is not really a problem if it > wants to go now anyway. Yes, it is. This is not like a ship at sea, where it just floats a little higher as you unload, or deeper as you load. That works because the ship is on the boundary between a high-density medium - sea - and low-density - air. When you drop weight from an airship it will not rise a little and then stop. It will rise quite a long way - far enough that its mass is equal to the volume of less dense air at altitude that it displaces. And in an earth-like atmosphere, that can be a long way, because the density of the atmosphere decreases quite slowly with altitude. For TL6 airships, the problem with that was that their gasbags could not hold much pressure, and would thus rip open if the ship rose too far. That was why they were always controlling their altitude very carefully, and stayed fairly low, compared to aircraft: they needed a substantial safety margin of altitude below the point the gasbags were in danger. For higher-tech airships, what you do is pump some of the gas into cylinders at reasonably high pressure, so that the gasbags shrink a little and you displace less air. But you still need careful positive control all the time, and this all adds weight and cost. John _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
