MACH Numbers at Various Altitudes

[cool_t]

Questions..... 1. The Air gets thinner as ones altitude get higher right? If not my Weather and Climate classes were fake.. 2. As the Air gets thinner at higher altitudes there is less drag there for Mach-1 should be hit at a slower speed? If im wrong please hit me in the head with a beer. 3. Whats up with the F-15c True/Ground speed indicator not matching the "Sound" when hitting Mach-1 at higher altitudes? 4. Programming issues? Ect? Ect? Any one know or can you guys fix this with a simple patch?

[Exorcet]

Mach speed changes with air temperature. It's not about drag, but the molecules interacting with one another. Colder air slows the speed of sound, so at high altitude, the speed of sound is slower than at sea level.

 

I don't know about the rest, I don't have the game yet.

[A.S]

MACH NUMBER and AIRSPEED vs ALTITUDE

 

MACH NUMBER is defined as a speed ratio, referenced to the speed of sound, i.e.

 

Mach Number = Velocity of Interest / Velocity of Sound (at given atmoshperic conditions)

 

Since the temperature and density of air decreases with altitude, so does the speed of sound, hence a

given true velocity results in a higher MACH number at higher altitudes.

 

 

AIRSPEED is a term that can be easily confused. The unqualified term airspeed can mean any of the following:

 

a. Indicated airspeed (IAS) - the airspeed shown by an airspeed indicator in an aircraft. Indicated airspeed is expressed in knots and is abbreviated KIAS.

 

b. Calibrated airspeed (CAS) - indicated airspeed corrected for static source error due to location of pickup sensor on aircraft. Calibrated airspeed is expressed in knots and is abbreviated KCAS. Normally it doesn't differ much from IAS.

 

c. True airspeed (TAS) - IAS corrected for instrument installation error, compressibility error, and errors due to variations from standard air density. TAS is expressed in knots and is abbreviated KTAS. TAS is approximately equal to CAS at sea level but increases relative to CAS as altitude increases. At 35,000 ft, 250 KIAS (or KCAS) is approximately 430 KTAS.

 

IAS (or CAS) is important in that aircraft dynamics (such as stall speed) responds largely to this quantity. TAS is important for use in navigation (True airspeed ± windspeed = groundspeed).

 

Figures 1 and 2 depict relations between CAS and TAS for various altitudes and non-standard temperature conditions. The first graph depicts lower speed conditions, the second depicts higher speeds.

 

As an example of use, consider the chart on the next page. Assume we are in the cockpit, have read

our IAS from the airspeed indicator, and have applied the aircraft specific airspeed correction to obtain

370 KCAS. We start at point "A" and go horizontally to our flight altitude at point "B" (25,000 ft in this

case). To find our Mach, we go down vertically to point "C" to obtain 0.86 Mach. To get our TAS at our

actual environmental conditions, we go from point "B" vertically until we hit the Sea Level (S.L.)

reference line at point "D", then travel horizontally until we reach our actual outside air

temperature (-20EC at altitude) at point "E", then go up vertically to read our actual TAS from the

scale at point "F" (535KTAS). If we wanted our TAS at "standard" temperature and pressure

conditions, we would follow the dashed lines slanting upward from point "B" to point "G" and read 515

KTAS from the scale. Naturally, we could go into the graph at any point and go "backwards" to find

CAS from true Mach or TAS.

 

Figure 3 shows a much wider range of Mach numbers. It contains only TAS and Mach, since aircraft

generally do not fly above Mach 2, but missiles (which don't have airspeed indicators) do. The data on

this graph can be obtained directly from the following formula for use at altitudes of 36,000 ft and

below:

 

Speed of Sound (KTAS)’ 29.06 RADIACAL/of( 518.7-3.57 A) Where A’altitude (K ft)

 

The speed of sound calculated from this formula can be used with the equation on the first page to

obtain Machnumber. This equation uses the standard sea level temperature of 59E F and a lapse rate

of -3.57E/1000 ft altitude.

Temperature stabilizes at -69.7E F at 36,000 ft so the speed of sound stabilizes there at 573 knots.

See the last page of this section for a derivation of equation [2].

 

 

 

 

 

 

 

..hope that helps a bit...i saved this while back, cause it is pretty good explained...

(PS: i do use also MacH in Lockon in order to know my best "turnperformance" at different altitutes)

 

[digitalJE5U5]

Wow man. I was reading your post like "Oh this is interesting..." then I got to the graphs and all the formulas and my brain locked up. :noexpression:

 

Good info though!

[Kuky]

AS is correct, Mach speed is ratio of aircraft speed over speed of sound for given altitude. In simpler terms, sound travels as pressure wave and the denser the medium the faster air molecule pressure is tranferred, hence the speed of sound is greater (in space there are no air molecules hence there is no sound). At higher altitudes air density is lesser hence the travel medium is less dense also and actual speed of sound is lower. This is why for same aircraft speed (ground speed) you are doing higher Mach number at higher altitude.

[th3flyboy]

AS is correct, Mach speed is ratio of aircraft speed over speed of sound for given altitude. In simpler terms, sound travels as pressure wave and the denser the medium the faster air molecule pressure is tranferred, hence the speed of sound is greater (in space there are no air molecules hence there is no sound). At higher altitudes air density is lesser hence the travel medium is less dense also and actual speed of sound is lower. This is why for same aircraft speed (ground speed) you are doing higher Mach number at higher altitude.

 

Incorrect, ever hear the recordings of Jupiter from the probes that flew by?

[Kuky]

Yeah I hear them every day... geees... do you even know what sound is? It's pressure transfer due to vibration of air molecules... actually its vibration of any particle as sound travels through water, steel etc (any physical medium). Vacuum has no air or any oarticles so no sound can be transferred as there in no travel medium. Are you just trolling or have you been smoking something... what do they use to listen to these probes? Microphones? :D Maybe satellite dishes? If you knew any better then when they say they are using satellite dishes to "listen" to something they are not listening to sound from space but all kinds of EM wavelengths and sound is not one of them.

Edited July 3, 2009 by Kuky

[A.S]

I think flyBoy made a joke:huh: not sure though :music_whistling:

[th3flyboy]

I think flyBoy made a joke:huh: not sure though :music_whistling:

 

you are correct sir...

[Kuky]

Well then your joke did not succeed... I did not laugh :music_whistling:

[GGTharos]

Actually, while you are correct about a true vacuum, you are not correct about the vacuum of space.

 

Sound always has and always will propagate in the vacuum of space, since it is not a true vacuum, but the scale on which things happen is much ... much different ;)

 

As a hint, I shall point to 'solar storms', 'shock waves in the gas surrounding supernovae', 'earth's bow shock', 'solar system bow shock', etc etc. :)

 

Vacuum has no air or any oarticles so no sound can be transferred as there in no travel medium.

[Kuky]

Sorry GG but there is no sound in space ;) The shockwave can and does travell but there is no sound. I would have thought you knew better :)

Edited July 6, 2009 by Kuky

[GGTharos]

There's is a shockwave. Where there is a shockwave, there is moving matter.

Where there is moving matter there is sound. You might not be able to hear it, but it's there.

 

I do know better. ;)

[Kuky]

Looks like not to be the case this time ;)

 

Sound needs molecules to tranferr the pressure/vibrations, in space there are no molecules ;) Space is true vacuum ;)

[GGTharos]

... are your really, really, absolutely, ready to argue this with me, and are you prepared to eat your hat after losing?

 

I'll let you get out of it right now by telling you to go check out the density of matter in 'the vacuum of space' ... it is greater than zero ;)

 

And it isn't molecules - it's reasonably heavy particles. Just about anything will do, but we'll stick with let's say, hydrogen? Yeah, that sounds good. ;)

[Kuky]

If I'm ready? I studied Physics so yes I am, are you?

 

The space is of course not completely empty, as we all know, there are stars, planets, comets and other hard matter in it. However, they are no spready out like air molecules in Earth's atmosphere that occupy it as a whole.

 

Sound requires molecules to transferr it's vibrations from one molecule to another, and if you knew any better you should know huge percentage of space is vacuum, the only parts that are not are those that contain plannets, stars, space dust (left overs from stars that have exploded, supernova etc and accordign to space creation, some of the matter that did not gather and formed planets etc).

 

What scientics do argue is that most mass in the space is unaccounted for and they are currently counting this unknown mass to dark matter, something no one has yet found what it is. But when it comes to sound travel you need molecules of any kind as a medium and those unfortunately fo your argument right now, there aren't any in space ;)

 

And if you think I'm pulling your leg right now there are explanations from NASA about sound in space, or should I say, the lack of, which just proves what Physics already explains in theory.

Edited July 7, 2009 by Kuky

[GGTharos]

Look above, I already have you beat. ;)

[Kuky]

Beat me what? Your saying heavy particles? You're joking right? Tell you one thing, you can think what ever you want, not gonna argue with you here any more about this, don't need to prove to you anything. You've just shown you're not so knowledgebale about everything you so claim to be :)

[GGTharos]

I'm saying 'any particle that's heavy enough'.

 

How else would you like me to put it? 'particles that have a reasonable probability of interacting with each other'?

 

Since you studied physics Kuky, do you know what the probability of a hydrogen atom interacting with another hydrogen atom is inside say, a cubic light-year?

 

Like I said, there is sound, but the scale is on an another level ... on an extremely different level. We're taking about wavelengths light-years in length here.

 

But you don't have to believe me, here's a link for ya, you're welcome to find more.

 

http://blog.chungyc.org/2008/10/sound-in-space/

[Kuky]

Since you studied physics Kuky, do you know what the probability of a hydrogen atom interacting with another hydrogen atom is inside say, a cubic light-year?

 

This from your Mathematics, Statistics course? Not something I've come accross in Physics classes I've had.

 

But argument here is wether we can hear sound in space and we can't. What you're talking about is huge pressure waves that do exist in space (say after supernova)

[GGTharos]

That's right, you can't hear sound that is generated in space because it is beyond your hearing range. Much like you can't hear certain sounds but dogs can.

 

Sound isn't defined as something you can hear, it is defined an oscillating pressure wave - and yes, those huge rippling pressure waves in space are sound.

 

If a tree falls in a forest and you aren't there to hear it, that sound is still generated. Sound is a very pervasive mechanism that functions just about anywhere where you have matter, and it has nothing to do with you being able to hear it, much like light has little to do with whether you can see it or not - audible sound is just like visible light - a particular form of energy of which we can only sense a narrow little sliver of a spectrum.

 

This from your Mathematics, Statistics course? Not something I've come accross in Physics classes I've had.

 

But argument here is wether we can hear sound in space and we can't. What you're talking about is huge pressure waves that do exist in space (say after supernova)

[RvEYoda]

This from your Mathematics, Statistics course? Not something I've come accross in Physics classes I've had.

 

But argument here is wether we can hear sound in space and we can't. What you're talking about is huge pressure waves that do exist in space (say after supernova)

 

Over her studying physics implies stastical mechanics and QM,

but that is if we are talking university studies of physics.

 

This includes for example studying the probabilities of two atoms

coming close to each other in a limited volume ( After you have

defined your limit of what is "interaction", how much movement

do you need to call it "interaction"?).

 

Sound propagation in any medium is a result of probabilities of

the definition of a particle (point parameters) being close enough

to another particle to affect each other (for example changing

movement direction, waves being a part of this group). But like all

physics it is just a matter of defining the correct description for a

subject, and we can probably make it do almost anything ;).

For example it is often modelled on a macroscopic level as spring

interactions between close particles with avg position = 0 in some

reference frame. (oscillations). But it might as well be a repetitive

shock wave causing oscillations on the target (meaning your ear drum

vibrates). Even though such vibrations on human sound scale

(roughly 20Hz-20kHz) would not be heard by these space shockwaves

(which do exist, albeit, they are probably quite a lot smaller than they

would be in what we would define as dense matter/earth system),

they still are vibrations of molecules detectable by target. (

target can for example be a gas mass that starts to oscillate).

 

There are many applications on infra/ultra sound (sound wavelengths

outside human audible band) in use today.

 

I'm sure there are people better than me on this subject in this forum,

that could explain this in more detail (or correct me if I made a mistake)

Edited July 7, 2009 by =RvE=Yoda

[golfsierra2]

If a tree falls in a forest and you aren't there to hear it, that sound is still generated.

 

Now we are very close to Schroedingers's cat..... :music_whistling:

[golfsierra2]

http://www.nasa.gov/vision/universe/features/halloween_sounds.html

 

My favorite:

http://www.nasa.gov/mission_pages/cassini/multimedia/pia07966.html

 

 

Thought you might want to listen to this....

[A.S]

Scientists Make Radio Waves Travel Faster Than Light

 

aaaaa liiiiiittle bit offtopic, ..but hey... :smartass: ... :huh: .. :book: ... :helpsmilie:

 

Scientist John Singleton insists that Albert Einstein wouldn't be mad at him, even though at first blush Singleton appears to have twisted the famous physicist's theories about light into a pretzel.

 

Most people think Einstein said that nothing can travel faster than the speed of light, but that's not really the case, Singleton said.

 

Einstein predicted that particles and information can't travel faster than the speed of light — but phenomenon like radio waves? That's a different story, said Singleton, a Los Alamos National Laboratory Fellow.

 

Singleton has created a gadget that abuses radio waves so severely that they finally give in and travel faster than light.

 

The polarization synchrotron combines the waves with a rapidly spinning magnetic field, and the result could explain why pulsars — which are super-dense spinning stars that are a subclass of neutron stars — emit such powerful signals, a phenomenon that has baffled many scientists, Singleton said.

 

"Pulsars are rapidly rotating neutron stars that emit radio waves in pulses, but what we don't know is why these pulses are so bright or why they travel such long distances," Singleton said. "What we think is these are transmitting the same way our machine does."

 

And beyond explaining what has been a bit of a mystery to the astronomical community, Singleton's discovery could have wide-ranging technological impacts in areas such as medicine and communications, he said.

 

"Because nobody's really thought about things that travel faster than light before, this is a wide-open technological field," Singleton said.

 

One possible use for the resulting speedy radio waves — which are packed into a very powerful wave the size of a pencil point — could be the creation of a new generation of cell phones that communicate directly to satellites, rather than transmitting through relay towers as they now do.

 

Those phones would have more reliable service and would also be more difficult for hackers to intercept, Singleton said.

 

Another application could be in very targeted chemotherapy, where a patient takes the drugs, and the radio waves are used to activate them very specifically in the area around a tumor, he said.

 

If Einstein were still alive, he probably wouldn't be all that surprised by the discovery, Perez said, even if it does seem on the surface to conflict with some of his theories.

 

"He might have thought, 'why did this take so long,' " Perez said.

 

 

http://current.com/items/90301786_scientists-make-radio-waves-travel-faster-than-light.htm

 

the next thing to come could be "you cant waste/create energy, just convert" to be approved wrong too.....or the theories of gravity (the master-riddle)...hehe

 

Oh, btw, germans "tunneled" information (not only signal, nope, whole package) with over lightspeed long time ago....how come? look up google!

Edited July 7, 2009 by A.S