'Ignition! An Informal History of Rocket Propellants' - Book Review

Ignition! An Informal History of Rocket Propellants
by John Drury Clark

John Clark was a rocket scientist. The book has leapt on to my very short list of non-fiction books that are genuinely entertaining to read, the other two entries being The Ghost Map by Steven Johnson and A Short History of Nearly Everything by Bill Bryson. A basic understanding of Chemistry and Physics (high school level) is required to understand the chemical reactions detailed and the thrust calculations he eventually gets to. Like Bryson, he makes otherwise dry material fascinating by explaining the details of problems. A text book might explain that a particular propellant was sensitive to explosion and leave it at that - it's an important detail, but doesn't leave much impression. But Clark does:

I used to take advantage of this property [the exceptional reactivity of
mixed acid] when somebody came into my lab looking for a job. At an
inconspicuous signal, one of my henchmen would drop the finger of an old
rubber glove into a flask containing about 100 cc of mixed acid — and then
stand back. The rubber would swell and squirm a moment, and then a
magnificent rocket-like jet of flame would rise from the flask, with
appropriate hissing noises. I could usually tell from the candidate’s
demeanor whether he had the sort of nervous system desirable in a
propellant chemist.

Johnson fills you in on which propellants smell truly horrible - and even which smell good:

One of the oddest combinations to be investigated was tried by RMI, who
burned d-limonene with WFNA. d-limonene is a terpene which can be extracted
from the skins of citrus fruits, and all during the runs the test area was
blanketed with a delightful odor of lemon oil. The contrast with the odors
of most other rocket propellants makes the event worth recording.

His writing is quite eloquent and generally a pleasure to read. I've already put his marvelous explanation of the "hard start" into this blog: I'll now include a few more quotes. He didn't like peroxide much as an oxidizer:

[A] splash of peroxide on a wool suit can turn the wearer into a flaming
torch, suitable for decorating Nero’s gardens.
The only thing to do was to keep the peroxide in a tank made of something
that didn’t catalyze its decomposition (very pure aluminum was best) and to
keep it clean. The cleanliness required was not merely surgical — it was
levitical. Merely preparing an aluminum tank to hold peroxide was a
project, a diverting ceremonial that could take days. Scrubbing, alkaline
washes, acid washes, flushing, passivation with dilute peroxide — it went
on and on. And even when it was successfully completed, the peroxide would
still decompose slowly; not enough to start a runaway chain reaction, but
enough to build up an oxygen pressure in a sealed tank, and make packaging
And there was always the problem of gross pollution. Say that somebody
dropped (accidentally or otherwise) a greasy wrench into 10,000 gallons of
90 percent peroxide in the hold of the ship. What would happen — and would
the ship survive? This question so worried people that one functionary in
the Rocket Branch (safely in Washington) who had apparently been reading
Captain Horatio Horn-blower, wanted us at NARTS to build ourselves a
10,000-gallon tank, fill it up with 90 percent peroxide, and then drop into
it — so help me God — one rat.

In reference to chlorine trifluoride aka "CTF:"

All this sounds fairly academic and innocuous, but when it is translated
into the problem of handling the stuff, the results are horrendous. It is,
of course, extremely toxic, but that’s the least of the problem. It is
hypergolic with every known fuel, and so rapidly hypergolic that no
ignition delay has ever been measured. It is also hypergolic with such
things as cloth, wood, and test engineers, not to mention asbestos, sand,
and water — with which it reacts explosively.  It can be kept in some of
the ordinary structural metals — steel, copper, aluminum, etc. — because of
the formation of a thin film of insoluble metal fluoride which protects the
bulk of the metal, just as the invisible coat of oxide on aluminum keeps it
from burning up in the atmosphere. If, however, this coat is melted or
scrubbed off, and has no chance to reform, the operator is confronted with
the problem of coping with a metal-fluorine fire. For dealing with this
situation, I have always recommended a good pair of running shoes.

He found quite a few new expressions for what most of us would have called an "explosion:"

And when you have a turbine spinning at some 4000 rpm, and the clearance
between the blades is a few thousandths of an inch, and this sticky,
viscous liquid deposits on the blades, the engine is likely to undergo what
the British, with precision, call “catastrophic self-disassembly.”

He held strong opinions on a lot of things, including the use of a monopropellant made of liquid oxygen and liquid methane:

How he avoided suicide (the first rule in handling liquid oxygen is that
you never, never let it come in contact with a potential fuel) is an
interesting question, particularly as JPL later demonstrated that you could
make the mixture detonate merely by shining a bright light on it.

"Isolde" was a monopropellant his crew worked with, made from diisopropyl amine:

If you have a monopropellant blow in your motor, that’s one thing. But if
that detonation propagates back (at some 7000 meters per second, usually)
through the propellant line to the propellant tank, and that blows, then
you can be in real trouble. If the diameter of the propellant line is small
enough, the detonation will not propagate and dies out — the limiting
diameter being called the “critical diameter.” It varies with the nature of
the propellant, the material of which the line is made (steel, aluminum,
glass, etc.) with the temperature, and maybe with a few more things. (When
we found that a detonation in Isolde would propagate nicely through
hypodermic-needle tubing, our hair stood on end, and we perspired gently.)

A mixture of dinitrogen tetroxide and the IsoButylene Adduct of tetrafluorohydrazine:

So there was a large audience for the subsequent events. The old destroyer
gun turret which housed our card-gap setup had become a bit frayed and
tattered from the shrapnel it had contained (The plating on a destroyer is
usually thick enough to keep out the water and the smaller fish). So we had
installed an inner layer of armor plate, standing off about an inch and a
half from the original plating And, as the setup hadn’t been used for
several months, a large colony of bats ... had moved into the gap to spend
the winter And when the first shot went off, they all came boiling out with
their sonar gear fouled up, shaking their heads and pounding their ears.
They chose one rocket mechanic — as it happens, a remarkably goosy
character anyway — and decided that it was all his fault. And if you,
gentle reader, have never seen a nervous rocket mechanic, complete with
monkey suit, being buzzed by nine thousand demented bats and trying to beat
them off with a shovel, there is something missing from your experience.

He leaves you with a knowledge of where liquid rocket propellant technology stood in 1972. If anyone ever manages to write a history from then until today that's half as entertaining, I'll read it immediately.