Don your anorak and get technical about airplanes.
#743424 by holliefabbabe
17 Apr 2010, 19:22
hi guys one of my girls have just asked me a question that i dont know answer too . it follows and is typed by hollie age 6 1/4


This dust , we have in our house , is it the same as the dust in in the sky from the volcano, and how hot does a big plane like english rose engines get and how hot does the sand have to get to melt please? y)
#743428 by tontybear
17 Apr 2010, 19:54
well hello young Hollie and what sensible questions.

The dust in your house is mainly (and this is a bit yukky) dead skin from you and other members of your family and maybe even from your pets. There maybe some from soil in the garden or pollen from flowers etc.

Volcano dust is more like very finly ground sand and is mainly pumice - mum may have a foot scraper made from it. A tub of it would feel a bit like fine flour (mum may have some in the kitchen she could show you) or talcum powder.

How hot does an engine get? A jet engine can get as hot as 2,000 degrees Centrigrade. If you think sitting next to the fire is hot then the engine is a lot, lot hotter.

It can get so hot that it melts the volcano dust and that is what clogs the engines and stops them working.

The dust is also so fine that it can scratch the windows of the cockpit - its a bit like the dishwasher making a glass cloudy.

Hope this answers your questions
#743432 by Bill S
17 Apr 2010, 20:18
Holliefabbabesbabe:
The critical jet turbine temperature is the Turbine Inlet Temperature (Google the acronym to get actual values for specific engines!) For most modern jets this is in the region of 850C.

Sand melts at about 1300-1400C but the volcanic ash is not sand - it is melting at about 600C!

The turbine blades that run in the hot gases are cooled with small airducts that pass through them - these cause the problems when they get blocked. No cooling air and the blades soon heat up and are destroyed.

Another problem is that the ash is extremely abrasive - it has many very sharp edges - if you can a sample, have a look at it under a microscope. It is so sharp even very small quantities can do damage - which is why people should not be wearing contact lenses where dust may be falling. This can damage many different parts of an aircraft, not just the engines and windscreen - on one occasion an aircraft required $80million to repair after flying through an ash cloud.

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