Re: air speed measurement above mach 1

Raul Ferreira <1@xxxxx> wrote:

> >
> >The speed of sound in air depends on the pressure, temperature, and
> >humidity of the air.
> >
> >An airplane moving at Mach 1 at 5000 feet is not going the same speed
> >as an airplane moving at Mach 1 at 20,000 feet.
> >
> >Airspeed indicators don't measure the speed of sound, they measure the
> >speed of the airplane relative to the air by measuring air impact pressure.
> >
> >Sound has nothing to do with it.
> >
> >The speed of anything is measured directly by measuring how long it takes
> >to go between two fixed points a known distance apart.
> >
> >How do you observe two fixed points if you are moving?


> When you are talking about airspeed you are talking about pressure. A
> "static" pressure against another static and different pressure.

When you are talking about airspeed, you are talking about airspeed.

Airspeed in airplanes is commonly indirectly measured by measuring the
impact pressure of the air as the airplane moves through it.

Sound has nothing to do with it.

> When you talk about sound you talk about vibration. The pressure is
> not static but it is vibrating. There is also sound pressure.

This is babble and not related to anything.

> For instance, the sonic boom, it happens when the plane reaches sound
> speed. I was told that it happens because the pressure of the air
> against the fuselage is "converted" into sound ( correct me if i
> wrong). This sound has a frequency or it is just a sudden change in
> pressure?

You are wrong.

http://science.howstuffworks.com/question73.htm

You might want to spend some time on this site.

> After sonic boom, the plane generates loud noise sounds, so there are
> vibrations everywhere. What kind of sound does a fighter pilot hear
> in the plane above Mach 1 if he could hear it? I suppose that it is
> something so loud that he has to use some protective device.

The pilot doesn't, nor could he possibly, hear a sonic boom.

http://science.howstuffworks.com/question73.htm

You need to spend some time on this site.

> By the way, the fighter pilot hears the sonic boom has we (on the
> ground) do? Does he feel any kind of reaction on the plane at Mach1?

The pilot doesn't, nor could he possibly, hear a sonic boom.

http://science.howstuffworks.com/question73.htm

You desperately need to spend some time on this site.

> When i wrote sound speed barrier i think i mean sound speech barrier.
> Do you agree?

There is no such thing as a "sound speech barrier".

The term "sound barrier" is a left over from before the jet engine was
invented making exceeding Mach 1 trivial.

Because of the aerodynamics of propellers, it is very difficult for a
propeller driven aircraft to achieve Mach 1.


--
Jim Pennino

Remove .spam.sux to reply.
.

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