*** Posted by run ***
[---snip---
I had the pleasure of seeing 2 F-16's scream past at about 7000 ft followed by 2 Tornado's about 20 min's later. The Tornado's I could hear much earlier than the F-16's. It was a great site though!

Regards

Rapier]

Hi Rapier

How early you hear the plane is not so much a noise thing, more a speed thing. Maybe the f-16's were just going faster.

How early you hear an airplane going towards you, depends on how close it is flying to the speed of sound. When we really want to impress people we keep the aircraft at .96 and the you first hear it when it passes above you.

run

*** Posted by kim ***
[I am well aware that you are talking about the SUDDEN appearence of the airnoise around the plane. Please tell me why are you facinated by this phenomina?
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Facination is not the right word. Morely: an interrest in the technics behind the suddennes of the airnoise.
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.......That's the loudest plane I've been on but I did not remember any distinct noises around the plane caused by drag too much on take off. Infact I think the noise you are refering to may be caused by the flaps in the take off position, after a short while they are retracted.
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Flaps should be most noisy during use, and in that way it should be more silent when they gets retracted under the climb, wich is opposite to my experiences.

Obviously, the noiselevel caused by air passing the plane, will rise with the speed of the plane, and one could expect to hear the sound of passing air relatively early (a couple of houndred km/t's?), and there after increase more or less quick towards the highest peak at top travelling speed.
However it is my experience that the airnoise do appear relatively late in the acceleration and rises to its toplevel very quick, whereafter it stays for the rest of the acceleration and flight.- Strange to me!

Does it happen in the same way around mach 1 and the "sonic boom" (the boom appears quite sudden and is hard to pass (while it dosnt rise in level thereafter)???

Kim Nielsen.

*** Posted by run ***
[---snip---
Does it happen in the same way around mach 1 and the "sonic boom" (the boom appears quite sudden and is hard to pass (while it dosnt rise in level thereafter)???

Kim Nielsen.]

Most of the noise in an f-16 is engine or ECS (Environmental Control System) related, so you don't hear much of the airnoise. Even though drag rises around mach 1 you don't notice passing mach 1 at all in a modern jet. You only notice a small flicker of the altimeter and the VVI. You can't feel or hear passing mach 1. The sonic boom can only be heard on the ground and not in the jet producing the sonic boom.
It is very easy passing mach 1 in an f-16 and some pilots have even done it by mistake when trying to escape another plane etc (In Denmark we are not allowed to fly faster than mach .97 over land due to the noise)

run