Gas bag construction..

The actual construction of the gas bag is going to be difficult, as there's little to no info about such things on the internet.. The best I could find was this thread on an RC forum, talking about gluing together mylar film for small blimps. Since my project is substantially bigger, it shouldn't be as sensitive to variables like the thickness/weight of the mylar, so I can make a tougher envelope and not have to worry so much about it tearing, however I haven't decided what glue would be best for this, and how to do the ends of the envelope....

The mylar is available from Ebay down to 1 mil, which is thicker then the RC forum was using but I might even go for 2 mil just because having these things leak/tear sounds like a nightmare and a half. The mylar on ebay is reflective, and is apparently intended to conserve light in indoor marijuana growing operations.... As much as I'd like it to be un-coated (which would probably clear), this mylar should suffice. I will probably by a 4'x100' roll so I have extra to experiment with, perhaps I'll make a bigger/smaller zeppelin when I'm done with this one...

Leaks should not be as much of an issue because I will not have very high pressure gas, unlike regular latex balloons, the mylar balloon is exactly the size I want it, and doesn't need to be stretched when inflated, so that's a plus.

In order to really get the zeppelin look, I'm going to make it rigid bodied, which is silly for an airship of this minute size, but I really love the framework look of zeppelins, so I'm going to do it no matter how difficult.

These posts aren't very structured... Excuse my excitement.

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.

Introduction

Ok, so this is probably crazy, but I'm a 17 year old guy, absolutely adore airships (like most a lot of people) and not this goodyear mushy blimp stuff either, the good ol' rigid ones, to such an extent I desperately want my own, since it'll at least be awhile until I can afford to build a real one, I'm going to build it in miniature.

I've had a copy of the original Hindenburg blueprints on my wall for as long as I can remember, and have had this fascination since I was maybe 8, I first got a book explaining the basics and had my mom read it over and over.

As of now I haven't decided much about it's designs, but I'm thinking balsa frame, mylar film balloons, electric control system (possibly a camera, so you could fly out of sight!), and I'm going to fill it with home-made hydrogen for lift, as opposed to using up precious non-renewable helium (I've always wanted to make hydrogen anyway..).

I'll post here whenever I have good info/designs/anything interesting, hopefully I can make this dream a reality in not terribly long (I'm thinking maybe 6 months, possibly longer/shorter). I'm not going to bother looking too professional with my pictures, as this really is just screwing around, but I hope I can help anyone else who wants to make one, and I'll post any valuable data I might come up with.

While I work out the details, you can enjoy some zeppelin videos (and 1930's culture) from Youtube!