[Spaceships 7] Homebrew: Expanding on Gasbags

[DaltonS]

Originally Posted by ericbsmith

According to this website Helium weighs about twice as much as Hydrogen, however the important factor isn't their relative weights to each other but rather their relative weight to the Air, which primarily consists of Nitrogen and Oxygen. Due to impurities in both gases this the lifting power of Helium is between 88%-93% of the same volume of Hydrogen. This is why airships pretty much switched to Helium - you only get about 10% less lift, but the risk of flammability is drastically reduced and necessity to prevent all leaks means you can even save a little weight on materials.

The problem with the website's figures was that they are centered around the volume of the gasbag rather than the mass of the lifting gas, and Spaceships systems are centered on mass. On a ton-for-ton basis, hydrogen is much superior to helium for lift. One thing I didn't address was the cost; I have no idea what sort of multiplier I should use. The hardware used for each gas would be different, and since the lifting gas isn't expended, it can be considered part of the hardware. Leaks would be replenished as a part of regular maintenance. (Note: if hydrogen is relatively cheap, there might be a venting allowance as gas recovery might be more expensive.)

Dalton “who will be updating the equation to include pressure” Spence