Whilst on the Concorde conversion course at Bristol, occasionally crews would have the privilege of meeting some of the original design engineers and draughtsmen who had worked on the Concorde project.
They were always fascinating to listen to, and provided an intriguing insight into a design world, now long gone, inhabited by engineers and draughtsmen armed with slide rules, drawing boards and blueprints. As ever, with people of real ability, they tended to talk more about their few failures rather than their many successes, often in the most amusing and self deprecating terms. It is their stories which really ought to be preserved, although it is not for us, even now, to relate some of their tales, told to us with a chuckle, but in strict confidence!
Suffice to say that the senior fire officer who misread litres-per-minute as gallons-per-minute during an Olympus water ingestion test probably would not want any further publicity, likewise the apprentice who didn’t defrost the chicken before firing it into an engine running at full power in the bird ingestion test. My favourite was the supersonic hailstone story, fired as part of a hailstone ingestion test, but with uncertain results, the final resting place of said hailstone still being slightly obscure to this day. If anyone in the greater Bristol area got hit by a particularly hard snowball in the early sixties, the Filton test engineers are very sorry, and would like to apologise!
However, it is often the little insights into the past that amuse one the most and stick in one’s mind. During one such conversation, with a couple of thermodynamicists, I ventured to ask how they had settled on the (rather difficult to memorise) various temperature limits associated with Concorde.
For instance, why a nose temperature limit of +127°C, why not +130°C, much easier for a pilot to remember?
“Isn’t it obvious?” one replied politely, genuinely puzzled by my question.
“Computer generation” replied his colleague to him, pointing his pipe stem at me.
“Ah yes” said the first,
“that would be it”.
They then went on to explain, in ever such a kindly manner, that, in thermodynamics, apparently the square, and the square root, of the absolute temperature of a material are terms used in many equations. Being armed mostly only with slide rules (and as they were in the vicinity of 120°C to 130°C as a limit anyway) it had been decided to make life easy and settle on +127°C as the limit, a temperature for which they could easily calculate the square and square root in their heads.
Noticing my bewilderment at the thought that anyone might be able to calculate the square or the square root of 127 in their heads, they proceeded to explain it to me still further, very slowly; in the manner that one would speak to an aged and rather deaf great aunt!
• Absolute zero = -273°C = Zero Kelvin = 0K
• Max Nose temp = +127°C equal to 400K
• √400 = 20
• 400˛ = 160,000.
These are the people with the amusing stories to tell!
Best Regards
Bellerophon