Monday 13 April 2009

High flight

Here's a bit of cutting edge technology from yesteryear - the Bristol 138 high altitude research aircraft. In 1936, Squadron Leader F.R.D. Swain of the Royal Air Force took one of these to a record-breaking height of 49,967 ft (15,230 m). When the Italians broke Swain's altitude record, Flight Lieutenant M.J. Adam took a Bristol 138 to 53,937 feet (16,440 m) on 30th June 1937, regaining the record. Pretty impressive for the late 1930s, considering that modern passenger jets cruise around the 40,000 feet (12,000m) mark.

Unlike modern passenger jets, the Bristol 138 didn't have a pressurised cabin, so the pilot had to use an early pressure suit, based on the Haldane-Davis design. The suit is a pretty impressive piece of kit - a bit like the sort of gear that spacemen wore in vintage pulp science fiction. There are pictures of Flight Lieutenant Adam kitted out in his Dan Dare suit here and here (part of a gallery of photos of Bristol 138 flights here).

The Haldane-Davis type pressure suit was based on a design by the physiologist Professor John Scott Haldane, famous for his research into what happens to the human body under extreme conditions (Haldane died in 1936, before Swain's record-breaking flight). Haldane's researches into the medical effects of gasses and extremes of atmospheric pressure led to the use of canaries in mines to provide early warning of dangerous carbon monoxide levels, respirators for mine rescue workers, decompression tables and decompression equipment for deep sea divers, gas masks for soldiers to combat poison gas used during the First World War and the use of oxygen to treat the victims of gas attacks, as well as setting out a design for pressure suits used by high-altitude pilots. A hands-on sort of boffin, Haldane thought nothing of experimenting on himself and his family, as this review of his biography notes:

Born into a Scottish aristocratic family whose motto was “suffer”, Haldane certainly suffered for his science. His life was, writes Goodman, “the greatest sustained physiological experiment in the history of the human lung”.
In his lifelong quest to understand the secrets of respiration, he became a connoisseur of rare gases, an authority on their detection and effects. After 29 minutes breathing carbon monoxide, Haldane calmly noted that he felt “distinctly abnormal”: he was panting, breathing 18 times a minute, his limbs shook and his pulse was racing. Soon, he began to feel unsteady on his feet.
Once, on his way home from his laboratory after such an experiment, he was stopped by an Oxford policeman who had observed the scientist’s stumbling progress. Haldane explained that it was not due to alcohol but gas. His housekeeper offered her sympathies to his wife, Kathleen: “I knows how you feel, ma’am. My husband’s just the same on a Friday night.”
In his report on the Tylorstown disaster, “Haldane delivered, for the first time, an accurate diagnosis of the greatest cause of death among miners”. It was Haldane who taught miners how to protect themselves using canaries or mice in specially designed cages. Such creatures are affected by gas 20 times faster than a man. According to Goodman, Haldane was “himself such a canary, putting his own health and life on the line to protect others”. He also invented breathing equipment that allowed rescue teams to operate safely. Thousands of men owe their lives to his work.
As a young researcher, he studied the air in overcrowded Dundee slums, turning up without warning in the middle of the night to collect air in bedrooms where eight people were sleeping. When a Select Committee called upon him to “delve inside the lower depths of government and analyse the stink that flowed beneath”, he ventured into the sewers below Westminster Palace. A born iconoclast, he successfully challenged the idea that “sewer air” was a cause of typhoid and other diseases.
Haldane liked nothing better than to explore dangerous mine shafts and sewers. But it was in the specially constructed, air-tight chamber in his lab that the effects of gases on people were revealed. In an age before risk assessments and ethics committees, Haldane was a serial self-experimenter. He also thought nothing of exposing his own son – the geneticist J. B. S. Haldane – to dangerous doses of chlorine and other noxious gases. His young daughter Naomi (later the writer Naomi Mitchison) once told a 6-year-old friend outside their house: “You come in. My father wants your blood.” Her friend screamed and ran away.
Haldane had a profound sense of public service and he believed passionately that the world could be made a better place through the appliance of science. From miners dying of carbon monoxide poisoning and soldiers being gassed like rats in the trenches, to mountaineers and aviators coping with high altitudes, Haldane showed that science could bring light into the darkness.

The full review can be seen here. If dad had used you as a human guinea pig, you could perhaps be forgiven for having "issues", but, Haldane's son, the immensely quotable J.B.S. Haldane, seems to have been made of sterner stuff, going on to continue the family tradition of self-experimentation, suffering crushed vertebrae when an experiment involving high levels of oxygen saturation triggered a fit, and a burst eardrum after a session in a decompression chamber, (he later wrote "the drum generally heals up; and if a hole remains in it, although one is somewhat deaf, one can blow tobacco smoke out of the ear in question, which is a social accomplishment"). It was an attitude which he retained to the end of his life - in his will, he left his body to medical science with the words: "whether I continue to exist or not, I shall have no further use for it [my body], and desire that it shall be used by others. Its refrigeration, if this is possible, should be a first charge on my estate."
Retuning to the record-breaking plane itself, it seems to have owed some of its performance to the design of its supercharged Pegasus radial engine which, like the airframe, was manufactured by the Bristol Aeroplane Company (there's a cheekily-titled article about the company's history here). Lightweight plywood construction also played a part, but one of the main features was the plane's immense size. I remember as a small kid having a plastic model of the Bristol 138 in my bedroom (it was manufactured by Frog, a company that will be remembered by former little boys, now of a certain age, as the runner-up to Airfix in the plastic model aeroplane world). For a single-engined aircraft, the model 138 was huge - next to it, an Airfix Spitfire in the same scale appeared like a herring gull flying in formation with an albatross. This impression is confirmed by an article in Flight magazine in October 1936, which observed that "with its large span it seems likely that the machine is the largest single-seater aeroplane ever built."
Looking at the 138 today, one of the things that strikes me is that the wings, although long, don't seem to have a very high aspect ratio (i.e. they don't have the long, narrow shape of the wings of a modern glider or the U2, which are the optimum shape to generate lots of lift). Come to think of it, comparing the 138 to an albatross is rather misleading, as the albatross also has very high aspect ratio wings, evolved for long duration flights as opposed to maneuverability (coincidentally, all this talk of size, scale and dimensions brings J.B.S. Haldane's essay On Being the Right Size to mind). In contrast the general appearance of the Bristol 138 is more like a scaled-up version of a smaller aircraft than a modern high-altitude design. I suspect that this is due to the limitations of manufacturing in the 30's - presumably the techniques and materials available then dictated that a wing of sufficient strength needed to be wider and thicker than one manufactured with more up-to date technology. And that's not the only example of how far and how fast technology has developed since then - just consider that only 31 years after Flight Lieutenant Adam, in his proto-space suit, established a world record by taking the Bristol 138 to 53,937 feet, the crew of Apollo 8 were taking their craft to the far side of the moon.

2 comments:

Geoff said...

Update...
http://en.wikipedia.org/wiki/Caproni_Ca.161

Andrew King said...

Fair cop, Geoff. I wondered how long it would take for somebody to point out that, after snatching the record back from the Italians, Adam and the Bristol 138 retained the world record for less than four months.

There are some pictures of another 1930's pressure suit, this time modelled by the Italian, Lieutenant Colonel Mario Pezzi, who pipped Adam's height by another 890 metres here.