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Exotic Chemicals in Traveller: Hydrazine

This article originally appeared in the May/June 2017 issue.

This article is on a chemical called hydrazine, an extremely toxic and dangerously unstable liquid that smells a bit like ammonia—probably because it’s made from two ammonia molecules joined together (with the loss of H2). Its formula is N2H4 and its structure somewhat resembles the skewed structure of hydrogen peroxide.

The following is an extract that’s found on multiple web sites about car racing, and kicked off my thoughts on how to use this chemical in my Traveller adventures. Here is hydrazine, the fuel enhancer:

It’s the liquid so potent, so deadly, so illegal that those in Drag Racing who have unleashed its wrath dare not speak its name in public. In the pits, even to this day, it’s known simply as H. Hydrazine has been around, and used as an “exciter” for nitromethane for as long as we’ve had Drag Racing. Actually, its use as a racing fuel predates even the Dry Lakes. Hydrazine is rumoured to have been used by the Nazis as an additive in the Mercedes Formula 1 cars of the pre-war era.

Here’s the basics of how it works. Nitromethane is a mono-propellant that carries its own oxygen supply. Hydrazine is an oxygen scavenging agent. When you combine the two…even with just a tiny percent of H in the mixture, you get an unstable fuel that is at war with itself. Insanely dangerous, yes…but internal combustion nirvana of the highest order is a guaranteed result.

Lakes-era racers who experimented with H found that a stock 90 horsepower flathead would pump out better than 300 horsepower simply by sucking this stuff through its Stromberg. These same racers also discovered Hydrazine’s major drawback for practical use. After running it through an engine, the carbs would start to cake up with a substance that resembled soap flakes. This nasty little by-product was a shock-sensitive explosive called the Methazodic Salt of Hydrazinium Acid, and was the result of allowing vapours from the Nitro/Hydrazine mixture to condense in a closed environment. Right, never mind this stuff will throw your crank on the ground after just a couple of runs, but if you happen to tap the carb with a wrench, it’ll blow your face off. Let’s go racing!

Hydrazine had its big moment in the sun back in 1960, during the height of the NHRA fuel ban. Barnstorming Top Fuel racers were all clustered together in the 180-mph range, when out of the blue, at a small track in Alton Illinois, the Greek shoved a big gulp of H down the throat of his Chrysler and ripped off an unheard of 204 MPH pass, boiling the hides and wheel standing right through the lights.

The Ramchargers were known for experimenting with all sorts of fuel, including hydrazine.

Several years later, during the dawn of the Funny Car era, many injected cars were known to brew up a batch in order to keep up with blown Fuelers. Shotgun-like exhaust notes, bright green header flames and crewmen frantically draining fuel tanks in the shutdown area were tell-tale signs that H was in the house.

Even though Hydrazine has been on perma-ban by every sanctioning body that has ever existed, its use in times of extremely tight competition, or when a barrier is on the verge of being broken has continued right up to the modern era. We can remember one night-time qualifying session back when the 300 mph barrier was about to fall in Funny Car, when one of the cars in contention for the honour made a lap with those freakish header flames dancing up over its roof. It was so obvious that a sudden buzz amongst educated onlookers erupted. Even the announcer that night took note of the unusual site. Officially, it was played off as burning copper from a failed head gasket…but then, the very next pair of cars, there it was again. Eight bright green candles lighting up the night time sky, and yet another barrier crushed. Was it really hydrazine at work? Only the guys mixing the fuel that night know for sure.

Yeah, it’s dangerous stuff. Handled improperly hydrazine will kill you in ways you can’t even spell, but it’s a glorious part of the history and heritage of the thing we call Fuel racing.

So, I can’t really use hydrazine as a fuel additive without messing up how space travel works in Traveller (or can I? maybe in a future article), so how is hydrazine used in space travel today? Well, as it turns out it’s actually used quite a lot.

Hydrazine’s use comes about due to the other important property it has: it burns very exothermically in the presence of oxygen (or oxygen-containing compounds) generating a lot of hot gases, which can be used to produce the exhaust thrust for a rocket. This was first exploited in WW2, when the German Me163B Komet became the world’s first rocket-powered fighter plane. Various fuels were used including a 1:1 mixture of hydrazine and water (known as hydrazine monohydrate), “C Stoff” (57% methanol, 30% hydrazine, 13% water) and “T Stoff” (80% H2O2, 20% water), which were kept in separate tankers at opposite ends of the airfield and were always at least half a mile apart. These were highly explosive mixtures, so it’s no surprise that more German pilots were killed in this plane by fuel leakages and/or explosions than were shot down by the Allies.

To lower (slightly) the risk of unwanted explosion, other variants of hydrazine have been used as rocket fuels, such as monomethylhydrazine (MMH), (CH3)NH(NH2) and unsymmetrical dimethylhydrazine (UDMH), (CH3)2N(NH2). These are often mixed with dinitrogen tetroxide (N2O4) with the advantage being that no ignition source is needed—the two compounds spontaneously combust on contact. These mixtures are normally used in military, orbital, and deep-space rockets because both liquids are storable for long periods at reasonable temperatures and pressures, but not generally for civilian spacecraft due to the toxicity and explosion risks.

More often nowadays, hydrazine is used for manoeuvring thrusters or for slowing spacecraft down on re-entry. Hydrazine-fuelled thrusters were used to land spacecraft on Mars, including the Viking spacecraft in the 1970s, the Phoenix lander (May 2008) and the Curiosity rover (August 2012). In these thrusters, an iridium catalyst, supported on an inert alumina matrix, decomposes the hydrazine to produce large quantities of ammonia, nitrogen, and hydrogen gases from a small amount of liquid hydrazine, and the pressurised hot gas is expelled from the spacecraft producing thrust.

In the movie The Martian, Mark Watney (played by Matt Damon) explains how to make water using hydrazine fuel from the lander’s fuel cells. For a rocket engine, hydrazine is passed through a catalyst which causes it to decompose into ammonia, nitrogen gas, and hydrogen gas according to the following reaction: N2H4 → N2 + 2 H2

In the movie, Mark Watney used that same reaction to produce the hydrogen gas and then, in combination with the oxygen in the habitat, he burned the hydrogen and made water. OK, I’ve read the articles and I know the scientific issues with this. First, hydrazine is incredibly toxic. In reality, technicians who handle hydrazine wear full-body safety suits. That’s OK, as most Traveller PCs takes risks getting out of bed every day. Second, decomposing the hydrazine into nitrogen and hydrogen is highly exothermic. It gives off a lot of heat, 800C in a matter of milliseconds. But hey, this is Traveller and we handwave away heat anyway.

So far so good, we have a highly explosive fuel additive, as amply shown in the movie by Watney’s first attempt that nearly blows him through the side of the habitat. So how do we use hydrazine to make a game of Traveller more interesting? I think the key statement from the original drag racing story is Hydrazine is an oxygen scavenging agent.

Where do we want to scavenge oxygen in Traveller? Why, fuel processing, of course! I give you the poor starship engineer’s fuel purification plant.

Hydrazine, when mixed with a few other ingredients, makes an ideal “quick and dirty” fuel purification additive for starships with fuel scoops and either no fuel purification plant or a faulty one. Just add the inline injector between your fuel scoops and your fuel tanks and the additive removes all those pesky contaminates from the water or gas giant gases you’re sucking up for mis-jump free fuel.

Cost of Hydrazine Injector “Purifier”

One litre of hydrazine additive is enough to purify 1000 tons of fuel. After the litre of additive has been put through the injector the waste cartridge must be emptied. This can be done safely at any class C or better star port.

Using the Hydrazine Injector “Purifier”

Roll 2D6, DM+1 for each 200 tons of fuel processed (cumulative), additional DM+5 if the waste cartridge has been used past one litre. Do not apply any other DMs. On a natural 12 (only), raw hydrazine is sucked into the power plant or jump drive, causing an explosion or misjump; damage is at the referee’s discretion. If the modified roll is 11-, there are no untoward effects. Otherwise consult the Hydrazine Injector Use Table.

Hydrazine Injector Use
Roll Result
2—11 Injector works as intended, no damage
12—14 Injector explodes; 2D6 damage to anyone within 6 meters
15—17 Injector explodes; 4D6 damage to anyone within 6 meters
18—19 Injector explodes; 6D6 damage to anyone within 6 meters; fuel scoops damaged
20—21 Injector explodes; 8D6 damage to anyone within 6 meters; fuel scoops destroyed.
22+ Injector explodes; 10D6 damage to anyone within 6 meters; fuel scoops destroyed; fuel vented and dumped to space.


Hydrazine Waste Cartridge Disposal
Roll Result
2—3 Waste Cartridge explodes, causing 6D6 damage
4—5 Waste Cartridge explodes, causing 4D6 damage
6—7 Waste Cartridge explodes, causing 2D6 damage
8+ Waste Cartridge successfully changed and disposed of