- Dequasie, Andrew.
The Green Flame.
Washington: American Chemical Society, 1991.
ISBN 978-0-8412-1857-4.
-
The 1950s were a time of things which seem, to our
present day safety-obsessed viewpoint, the purest
insanity: exploding multi-megaton thermonuclear bombs
in the atmosphere, keeping bombers with nuclear
weapons constantly in the air waiting for the order
to go to war, planning for
nuclear
powered aircraft, and building up stockpiles of
chemical weapons. Amidst all of this madness, motivated
by fears that the almost completely opaque Soviet Union
might be doing even more crazy things, one of the most
remarkable episodes was the boron fuels project,
chronicled here from the perspective of a young
chemical engineer who, in 1953, joined the effort at Olin
Mathieson Chemical Corporation, a contractor developing
a pilot plant to furnish boron fuels to the Air Force.
Jet aircraft in the 1950s were notoriously thirsty and,
before in-flight refuelling became commonplace, had
limited range.
Boron-based fuels,
which the Air Force called High Energy Fuel (HEF) and the Navy
called “zip fuel”, based upon compounds of
boron and hydrogen called
boranes,
were believed to permit planes to deliver range and
performance around 40% greater than conventional jet fuel.
This bright promise, as is so often the case in
engineering, was marred by several catches.
First of all, boranes are extremely dangerous chemicals.
Many are
pyrophoric:
they burst into flame on contact with the air. They are
also prone to forming shock-sensitive explosive compounds
with any impurities they interact with during processing or
storage. Further, they are neurotoxins, easily absorbed by
inhalation or contact with the skin, with some having
toxicities as great as chemical weapon nerve agents.
The instability of the boranes rules them out as fuels,
but molecules containing a borane group bonded to a hydrocarbon
such as an ethyl, methyl, or propyl group were believed
to be sufficiently well-behaved to be usable.
But first, you had to make the stuff, and just about every
step in the process involved something which wanted to kill
you in one way or another. Not only were the inputs and
outputs of the factory highly toxic, the by-products of
the process were prone to burst into flames or explode at
the slightest provocation, and this gunk regularly needed
to be cleaned out from the tanks and pipes. This task fell
to the junior staff. As the author notes, “The younger
generation has always been the cat's paw of humanity…”.
This book chronicles the harrowing history of the boron
fuels project as seen from ground level. Over the seven
years the author worked on the project, eight people died in
five accidents (however, three of these were workers at
another chemical company who tried, on a lark, to make a
boron-fuelled rocket which blew up in their faces; this
was completely unauthorised by their employer and the
government, so it's stretching things to call this
an industrial accident). But, the author observes,
in the epoch fatal accidents at chemical plants, even those
working with substances less hazardous than boranes, were
far from uncommon.
The boron fuels program was cancelled in 1959, and in 1960
the author moved on to other things. In the end, it was the
physical characteristics of the fuels and their cost which
did in the project. It's one thing for a small group of
qualified engineers and researchers to work with a
dangerous substance, but another entirely to contemplate
airmen in squadron service handling tanker truck loads of
fuel which was as toxic as nerve gas. When burned, one of the
combustion products was boric oxide, a solid which would
coat and corrode the turbine blades in the hot section of
a jet engine. In practice, the boron fuel could be used
only in the afterburner section of engines, which meant a
plane using it would have to have separate fuel tanks and
plumbing for turbine and afterburner fuel, adding weight
and complexity. The solid products in the exhaust reduced
the exhaust velocity, resulting in lower performance than
expected from energy considerations, and caused the
exhaust to be smoky, rendering the plane more easily spotted.
It was calculated, based upon the cost of fuel produced by
the pilot plant, if the
XB-70
were to burn boron fuel continuously, the fuel cost would amount to
around US$ 4.5 million 2010 dollars per hour. Even by
the standards of extravagant cold war defence spending, this was hard
to justify for what proved to be a small improvement in performance.
While the chemistry and engineering is covered in detail,
this book is also a personal narrative which immerses the
reader in the 1950s, where a newly-minted engineer, just
out of his hitch in the army, could land a job, buy a car,
be entrusted with great responsibility on a secret project
considered important to national security, and set out on
a career full of confidence in the future. Perhaps we don't do
such crazy things today (or maybe we do—just different
ones), but it's also apparent from opening this time capsule
how much we've lost.
I have linked the Kindle edition to the title above, since it
is the only edition still in print. You can find the original
hardcover and paperback editions from the ISBN, but they are scarce
and expensive. The index in the Kindle edition is completely useless:
it cites page numbers from the print edition, but no page
numbers are included in the Kindle edition.
March 2014 