Monday, 10 December 2012

Ice and snow

Double whammy!

Our excellent results in the school exams is all very well, but the real victory came last Thursday when we finally won the local pub quiz. In fact there were so many of us from the class that we had to split into three teams, and dominated the event with a first, second and third place.

Unfortunately, for us, the only way is down.

Back to work...

Our studies have shifted up another gear, with new material coming at us thick and fast. There is a great deal still to cover before the end of phase one in five teaching weeks, and we will need to continue accelerate to fit it all in. At the same time, the studying has settled into a habitual pattern and the only worry really is whether the information is actually sticking in our heads.

I have noticed that as we progress, the subjects are starting to come together and re-enforce each other. For example, last week we looked at the details of flying controls in both principles of flight and in aircraft systems, and the different perspectives really help to understand the subjects.

The pilot of this aircraft looks to have been fortunate -
it's still in one piece.
Another area that has recently come up in no less than four classes – aircraft systems, meteorology, engines and principles of flight – is icing.

This rather innocuous-sounding problem of super-cooled water droplets freezing onto your plane is described academically as 'increasing drag, reducing lift and increasing weight,' but that rather conceals the true magnitude of the problem. Remember Col Kurtz uttering "The horror. The horror."? That's more like it.

You could equally well describe icing as like having half the wing sawn off, an anvil hung off the bottom and a parachute streaming out the back, all at once. Added to that your instruments may well stop working and in extremis engines can be damaged and may fail and flight controls can freeze solid.

I'm not necessarily talking about lots of ice here, just the sort of stuff you scrape off the windscreen of your car in the morning could be enough to turn a routine take-off into an accident.

With significant airframe icing you might not exactly plummet earth, but maintaining height could become impossible. The aircraft will stall at a higher – but unknown – speed so landing with ice on the wing becomes a fast and risky manoeuvre.

So as you would expect, aircraft designers go to enormous lengths to provide systems to prevent and remove ice. Airlines spend a fortune on de-icing and anti-icing planes on the ground and the weather people do their best to help pilots avoid icing conditions.

All of which adds up to another couple of hundred facts for us to store away in our crowded brains. Facts totally useless for the pub quiz; facts very handy for a few extra marks in the exams; and facts that might, just possibly, prevent an accident one day. A sobering thought as we scrape away at our frozen car windscreens at 7.30am each morning.

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