Ok. here is my LTA info.
http://ltaprojects.com/_wsn/page3.html here are some relevant pictures. you can play where is waldo looking for me.
size: 1,000 cubic ft of H will lift 60 lbs, and the cloth it's self is 15 or so Oz a yard.
construction: The cloth we use runs about 35$ a yard. helium is expensive too 30cense a cubic meter.
to cucullate the size and cloth needed. decide how long or tall you want it to be then. ((1/2hight)^2*pi)*length=volume this is just a simple cylinder, but we got the length and hight need for the volume of H needed. The cloth needed will be 40/(hight*pi)*length. use what ever units you want here. of course the blimp will be cigar shaped, but estimates on a cylinder is close enough.
also you are going to have to build the car that attaches to the envelope. this is where people ride and all the mechanical parts are. This is pretty straight foward. the only trick is the keep it as light as you can without cutting into safety.
One should know that ALL blimps have a DO NOT PULL DURING FLIGHT handle on them. this will cut open a large cut on top of the ship letting out the helium. This is because a crashed blimp is very dangerous being blown around on the ground. as well it is less expensive to fix the whole than tumble damage.
Also a blimp requires a large ground, crew 6 * the number of passengers, to handle the blimp during take off and landing. this can be a dangerous job.
Most airships are blimps, meaning they have to ridigide skeleton. Rigid airships are no longer a good design with modern construction materiald and techneque.
Also: as for takeing bullets. The goodyear gets shot ALL THE TIME. were talking about 300,000 cubic ft of H. Even if you cut out a hole the 4' wide it would take hours for it to deflate.
LTA is a misnomer too. An airship is not actualy lighter that air. the goodyear runs at a couple hundred pounds. Since it has such a large surface airea though, the fins and the propellers keep it in the air, becomeing lighter that air is actualy a great fear of poilets, blimps fall up. then the envelope pops due to expanding gas pressure, then you fall WAY down. there are a number of systems that help to controll and prevent this. the only one worth mentioning is the balonet. it is a smaller baloon inside the actual envlope, it is inflater and deflater useing regular air blown in from the atmosphere. to regulate the air pressure withing the main envolope. the rest is all background stuff .