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Saturday, March 1, 2014
Reading List: The Green Flame
- 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.
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