> I'm not sure comparing things to close-to-wartime tech from 90 years ago is a valid approach.

You might be surprised how good WW2-era scientists were at chemistry and science.

The earlier poster has a point. Gasoline, Diesel, and Kerosene have all been studied extensively (especially in the 1930s and 1940s BECAUSE of preparations for WW2). The safety of soldiers was paramount even to the Nazis.

War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points.

That means that kerosene __literally__ can't catch on fire at room temperature. You need to warm up kerosene before its appropriate to burn (Of course, once its burning it will warm up the rest of the kerosene and keep burning. But this isn't some super-explosive volatile chemical we're talking about here)

Gasoline is still safe, but not as safe as the other two (-40C Flash Point). Gasoline was safer than a lot of the other petroleum products that were investigated back then, and was still chosen as a fuel for war machines.

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The same is not necessarily true for H2. H2 will explode at any temperature (even near absolute zero).

> You might be surprised how good WW2-era scientists were at chemistry and science.

I'm well aware of chemical prowess in that period, especially on the German part. They had a bunch of Nobel prize winners.

However, that's why I said "close-to-wartime". First of all, in case you weren't aware, the Hindenburg was supposed to use helium but due to a lack of helium in Germany (I think it was primarily due to American export restrictions), they had to use hydrogen.

I don't know of other limitations for the Hindenburg, per se, but knowing the overall German shortages of the period, I wouldn't be surprised if they had other structural issues with the Hindenburg itself, especially since it wasn't designed to be used with hydrogen.

On top of this, the Hindenburg design was from the late 20s, 1929, I believe.

If materials science, modeling, etc haven't advanced since 1929, I'll eat a shoe. If we're somehow worse at managing hydrogen after almost 100 years, I'll eat the other shoe.

A comparison with the Hindenburg isn't useful in any case. To put enough hydrogen in a car to get a reasonable number of miles, you need to compress it to 10,000psi. The Hindenburg is basically atmospheric pressure.

10k psi actually makes hydrogen safer (chemically). Consider it a form of positive pressure - there is much less risk of air getting into the tank.

The Hindenburg crew had to regularly test the hydrogen cells for oxygen content.

> War machines: be they airplanes, tanks, or battleships, were all going to be exposed to enemy fire and explosions. These fuels (Kerosene and Diesel in particular) were chosen because they're extremely safe: high flash points and even higher auto-ignition points.

I'm not sure those were really the reasons for the choices that were made in most cases. Airplanes of the era used gasoline engines because Otto engines provided much better power/weight than the diesel engines of that time. For submarines, I'm not sure safety was a bigger factor than being able to use the same(?) fuel oil that the predominantly steam powered surface fleets were using, and that diesel engines provided better fuel economy than gasoline ones.

One place where safety might(?) have been a factor was that the USSR decided to power its tanks with diesel, whereas the other major combatants used gasoline engines in their tanks. I'm sure this prevented a lot of fiery demises for Soviet tank crews.

> The safety of soldiers was paramount even to the Nazis.

I wouldn't say paramount: https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet

(the Komet had a tendency to blow itself and its pilots up due to the hypergolic fuel)