Density/Buoyancy

Ok, so in order to estimate a size of the airship alone with the weight of the airship, I need to figure out how much hydrogen I need to lift a certain weight. In this case I'm more concerned with how big it is when it's done, I know I can make some pretty small electronics, so I'm going to worry about that a bit later. A start size for the basic gas bag I'm going to say is about 38cm (it'll be 40 including the framework) by 2 meters (It'll be about 270 long including nose/tail, which I might put smaller cone gas bags in for ballast purposes). To find the area of this basic cylinder, I find the area of one circular end, and multiply by the length. In this case I'm after cubic centimeters, so I'll be doing everything with cm.

The area of a circle is pi times the radius, squared, so for a 38cm circle, the radius is 19cm, which means the equation will pi 19^2, which comes out to 1134.1, so that's in square cm, now multiply that by the length, 2m=200cm, and you get 226822.8 cm^3.

A liter (A liter is 1000 cm^3)of air weights about 1.225g, where as a liter of hydrogen weighs 0.08688g, so the difference between them is how much lift a liter of hydrogen makes, which comes out to about 1.136g/liter. Since a liter is 1000 cm^3, that's 0.0013g/cm^3, so the amount of lift for our gas bag is now easily calculable to about 250 grams. That's over half pound, which should easily cover electronics, and will probably cover framework too, so we're in luck!

Here's the design so far:

And the REAL plan for an R23 zeppelin:

Mine will get better, I promise.