The theory behind the aircraft ALTIMETER

This is another extension of aeronautical science, so that guys we'll have a look about the simple technique behind the ALT or Altimeter. I'm @dulip and I hope to introduce more simple things in aircraft with you, I think you will like that.

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You can see it as a very simple instrument but I like to say that that is one of the, blind flying panelinstrument also. These are called as six key flight instruments those are ALT, ASI, AH, VSI,DI and Turn and slip indicator.. In future articles I like to give you the deep idea about these key instruments. So today's topic is the most essential but simple in construction that's altimeter...

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Now we can go through the instrument by using above clear figure. I put that figure here because it will very useful to get a clear idea about the altimeter principle and its construction.

The principle of the altimeter is Aneroid Barometer principle,For the further studies you can use the links I have given to you. ALT consists of evacuated corrugated capsule, coupling mechanism, pinion, quadrant and a dial... The operation is so simple, as we know when we climb through the atmosphere belt then the static pressure will reduce, due to that reason in high altitudes pressure is low and near to the surface static pressure is high due to the gravity.

Simply I will explain the operation of the altimeter, in aircraft instruments some of them are powered and some of them are not. Altimeter also fall into non powered category but a static air line is fed in to its sealed container. Previously I have told you that capsule is evacuated one but it is pressured to the sea level pressure that means 14.7 psi so that in ground level capsule inside pressure and the fed static pressure both are equal then cancel out therefor the reading will be zero, I think now you can get an idea about the working process.. Suppose aircraft get a climb then as previous capsule pressure remains same but fed static pressure will be reduce and due to the pressure difference capsule will expand.. The coupling mechanism connected to the capsule so that this expansion indicates to the pilot as an altitude gain...

I hope you get some kind of information.. Thanks for your valuable time...
Stay Safe....