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Old 25th Apr 2010, 11:47
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Centaurus
 
Join Date: Jun 2000
Location: Australia
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Fascinating subject, Prince and especially the history of fusible plugs as you explained it. The Lancaster bomber and its larger version the Lincoln (which I flew) had expanding strong canvas (I think) bags that pressed against brake drums and inflated by 450psi pneumatic pressure. Every squeeze of the brake lever on the pilots control column dropped the total available pneumatic pressure and one had to be careful of not running out of steam as it it were, after a long taxi in a crosswind.

If the brakes were used excessively and continually such as during an aborted take off or even a flapless landing on a short runway, the canvas brake bag would burn through with friction and look Ma - no hands no brakes. Not too bad on a nosewheel aircraft but no fun on a heavy tail-wheel type such as the Lincoln where it was easy to ground-loop. And talking about a no brakes landing: The long-in-tooth among us will recall the former RAF flight safety magazine called "Air Clues".

A story appeared about a Vampire pilot that had brake failure on landing and was in real trouble of going off the end of the runway. In his incident report the pilot said he decided to wind back the Vampire canopy to create more drag to slow up. It didn't work that well and he finished up in the mud unhurt.

The editor of Air Clues was in fact a former respected Fleet Street journalist or well versed radio play actor (I forget which) and he had a droll way with words. He used the pseudonym of Wing Commander Spry, when commenting on flight safety matters.

Commenting on the pilots action of opening the canopy for drag, he offered the suggestion if the pilot had thought about it at the time, more drag could be attained by the simple process of the pilot tying the four corners of his handkerchief and holding it outside the cockpit in the airstream where it would it would act as a braking parachute.

Now back to the original subject of fusible plugs. Taxiing a 737 at Kai Tak airport Hong Kong, I was appalled to see an Air India 747 at the blocks with huge plumes of white steam rising from a set of wheels as engineers directed stream of cold water from a high pressure water hose upon hot brakes suffered after a long taxi-in after a heavily braked landing. I waited for the inevitable wheel rims explosion but it didn't happen, thank goodness.
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