Speed of sound in 1.0

Skalou · July 1, 2015

hello,

I want to share my manually recorded values of the speed of sound in Kerbin athmosphere.

I used the mod aero-GUI and open office for the graphic curve:

[TABLE]
[TR]
[TD][/TD]
[TD]Kerbin[/TD]
[TD]Duna[/TD]
[TD=width: 151]Laythe[/TD]
[/TR]
[TR]
[TD]Altitude asl (m)[/TD]
[TD]Speed of sound (m/s)[/TD]
[TD]Speed of sound (m/s)[/TD]
[TD]Speed of sound (m/s)[/TD]
[/TR]
[TR]
[TD]0[/TD]
[TD]352[/TD]
[TD]437[/TD]
[TD]340[/TD]
[/TR]
[TR]
[TD]1000[/TD]
[TD]347[/TD]
[TD]436[/TD]
[TD]333[/TD]
[/TR]
[TR]
[TD]2000[/TD]
[TD]342[/TD]
[TD]435[/TD]
[TD]322[/TD]
[/TR]
[TR]
[TD]3000[/TD]
[TD]336[/TD]
[TD]434[/TD]
[TD]311[/TD]
[/TR]
[TR]
[TD]4000[/TD]
[TD]330[/TD]
[TD]432[/TD]
[TD]299[/TD]
[/TR]
[TR]
[TD]5000[/TD]
[TD]324[/TD]
[TD]429[/TD]
[TD]290[/TD]
[/TR]
[TR]
[TD]6000[/TD]
[TD]317[/TD]
[TD]426[/TD]
[TD]288[/TD]
[/TR]
[TR]
[TD]7000[/TD]
[TD]311[/TD]
[TD]422[/TD]
[TD]288[/TD]
[/TR]
[TR]
[TD]8000[/TD]
[TD]304[/TD]
[TD]418[/TD]
[TD]288[/TD]
[/TR]
[TR]
[TD]9000[/TD]
[TD]299[/TD]
[TD]413[/TD]
[TD]288[/TD]
[/TR]
[TR]
[TD]10000[/TD]
[TD]298[/TD]
[TD]408[/TD]
[TD]288[/TD]
[/TR]
[TR]
[TD]11000[/TD]
[TD]297[/TD]
[TD]402[/TD]
[TD]289[/TD]
[/TR]
[TR]
[TD]12000[/TD]
[TD]296[/TD]
[TD]397[/TD]
[TD]290[/TD]
[/TR]
[TR]
[TD]13000[/TD]
[TD]296[/TD]
[TD]391[/TD]
[TD]291[/TD]
[/TR]
[TR]
[TD]14000[/TD]
[TD]295[/TD]
[TD]385[/TD]
[TD]293[/TD]
[/TR]
[TR]
[TD]15000[/TD]
[TD]295[/TD]
[TD]379[/TD]
[TD]294[/TD]
[/TR]
[TR]
[TD]16000[/TD]
[TD]295[/TD]
[TD]373[/TD]
[TD]295[/TD]
[/TR]
[TR]
[TD]17000[/TD]
[TD]296[/TD]
[TD]367[/TD]
[TD]296[/TD]
[/TR]
[TR]
[TD]18000[/TD]
[TD]296[/TD]
[TD]361[/TD]
[TD]299[/TD]
[/TR]
[TR]
[TD]19000[/TD]
[TD]297[/TD]
[TD]355[/TD]
[TD]301[/TD]
[/TR]
[TR]
[TD]20000[/TD]
[TD]298[/TD]
[TD]350[/TD]
[TD]303[/TD]
[/TR]
[TR]
[TD]21000[/TD]
[TD]299[/TD]
[TD]345[/TD]
[TD]306[/TD]
[/TR]
[TR]
[TD]22000[/TD]
[TD]300[/TD]
[TD]340[/TD]
[TD]308[/TD]
[/TR]
[TR]
[TD]23000[/TD]
[TD]300[/TD]
[TD]337[/TD]
[TD]307[/TD]
[/TR]
[TR]
[TD]24000[/TD]
[TD]301[/TD]
[TD]331[/TD]
[TD]305[/TD]
[/TR]
[TR]
[TD]25000[/TD]
[TD]303[/TD]
[TD]329[/TD]
[TD]304[/TD]
[/TR]
[TR]
[TD]26000[/TD]
[TD]304[/TD]
[TD]328[/TD]
[TD]302[/TD]
[/TR]
[TR]
[TD]27000[/TD]
[TD]307[/TD]
[TD]327[/TD]
[TD]300[/TD]
[/TR]
[TR]
[TD]28000[/TD]
[TD]308[/TD]
[TD]327[/TD]
[TD]297[/TD]
[/TR]
[TR]
[TD]29000[/TD]
[TD]311[/TD]
[TD]327[/TD]
[TD]294[/TD]
[/TR]
[TR]
[TD]30000[/TD]
[TD]313[/TD]
[TD]327[/TD]
[TD]291[/TD]
[/TR]
[TR]
[TD]31000[/TD]
[TD]316[/TD]
[TD]327[/TD]
[TD]289[/TD]
[/TR]
[TR]
[TD]32000[/TD]
[TD]318[/TD]
[TD]327[/TD]
[TD]289[/TD]
[/TR]
[TR]
[TD]33000[/TD]
[TD]321[/TD]
[TD]327[/TD]
[TD]289[/TD]
[/TR]
[TR]
[TD]34000[/TD]
[TD]324[/TD]
[TD]327[/TD]
[TD]290[/TD]
[/TR]
[TR]
[TD]35000[/TD]
[TD]326[/TD]
[TD]327[/TD]
[TD]290[/TD]
[/TR]
[TR]
[TD]36000[/TD]
[TD]328[/TD]
[TD]327[/TD]
[TD]290[/TD]
[/TR]
[TR]
[TD]37000[/TD]
[TD]330[/TD]
[TD]327[/TD]
[TD]290[/TD]
[/TR]
[TR]
[TD]38000[/TD]
[TD]332[/TD]
[TD]327[/TD]
[TD]291[/TD]
[/TR]
[TR]
[TD]39000[/TD]
[TD]332[/TD]
[TD]327[/TD]
[TD]292[/TD]
[/TR]
[TR]
[TD]40000[/TD]
[TD]332[/TD]
[TD]327[/TD]
[TD]293[/TD]
[/TR]
[TR]
[TD]41000[/TD]
[TD]332[/TD]
[TD]327[/TD]
[TD]295[/TD]
[/TR]
[TR]
[TD]42000[/TD]
[TD]330[/TD]
[TD]327[/TD]
[TD]296[/TD]
[/TR]
[TR]
[TD]43000[/TD]
[TD]328[/TD]
[TD]327[/TD]
[TD]297[/TD]
[/TR]
[TR]
[TD]44000[/TD]
[TD]326[/TD]
[TD]327[/TD]
[TD]298[/TD]
[/TR]
[TR]
[TD]45000[/TD]
[TD]323[/TD]
[TD]327[/TD]
[TD]299[/TD]
[/TR]
[TR]
[TD]46000[/TD]
[TD]321[/TD]
[TD]328[/TD]
[TD]300[/TD]
[/TR]
[TR]
[TD]47000[/TD]
[TD]319[/TD]
[TD]338[/TD]
[TD]301[/TD]
[/TR]
[TR]
[TD]48000[/TD]
[TD]317[/TD]
[TD]360[/TD]
[TD]302[/TD]
[/TR]
[TR]
[TD]49000[/TD]
[TD]315[/TD]
[TD]370[/TD]
[TD]302[/TD]
[/TR]
[TR]
[TD]50000[/TD]
[TD]313[/TD]
[TD]373[/TD]
[TD]302[/TD]
[/TR]
[TR]
[TD]51000[/TD]
[TD]311[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]52000[/TD]
[TD]309[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]53000[/TD]
[TD]307[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]54000[/TD]
[TD]304[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]55000[/TD]
[TD]302[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]56000[/TD]
[TD]299[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]57000[/TD]
[TD]297[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]58000[/TD]
[TD]296[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]59000[/TD]
[TD]295[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]60000[/TD]
[TD]295[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]61000[/TD]
[TD]296[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]62000[/TD]
[TD]296[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]63000[/TD]
[TD]297[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]64000[/TD]
[TD]297[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]65000[/TD]
[TD]297[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]66000[/TD]
[TD]296[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]67000[/TD]
[TD]295[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]68000[/TD]
[TD]293[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]69000[/TD]
[TD]291[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]70000[/TD]
[TD]292[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[/TABLE]

the test has started from the KSC launchpad the Y1days4 at 00:30 with a temperature on it of 309Ã‚Â°K (36Ã‚Â°C, 97Ã‚Â°F) and a pressure of 1002 hPa.

i recorded manually the values of the speed of sound(+/- 1 m/s) each 1000m (+/- 50 m) during a vertical launch at 100m/s.

the speed of sound evolve from 349 to 355m/s on the launchpad during the day because it depends of the temperature, pressure,... that now evolves too with the new amazing aero overhaul!

you can compare with the IRL values here: IRL speed of sound

Good job Squad!

Edit:

upgrade with duna , see post #11

upgrade with Laythe , see post #13

Edited July 8, 2015 by Skalou
upgrade with duna , see post #13

Windspren · July 1, 2015

The speeds of sound and light in KSP are instantaneous. I'm not sure how you got that data...

Fenris · July 1, 2015

Huh? I was always taught and read that the speed of sound is highest at sea level then decreases the higher you go "because gas molecules move more slowly at colder temperatures, which slows the speed of sound; sound moves faster through warmer air. Therefore, the speed required to break the sound barrier decreases higher in the atmosphere, where temperatures are colder."

This is one example of what I'm referring to:

Granted this chart starts with a sea level temperature of 15 celsius which can influence exactly what the speed of sound is.

http://www.fighter-planes.com/jetmach1.htm

NFUN · July 1, 2015

The speeds of sound and light in KSP are instantaneous. I'm not sure how you got that data...

He is referring to the effects of the speed of sound in aerodynamics, not the literal sound. Mach numbers are commonly used for a reason, and KSP simulates some effects of drag and heating as one breaks the sound barrier.

- - - Updated - - -

Huh? I was always taught and read that the speed of sound is highest at sea level then decreases the higher you go "because gas molecules move more slowly at colder temperatures, which slows the speed of sound; sound moves faster through warmer air. Therefore, the speed required to break the sound barrier decreases higher in the atmosphere, where temperatures are colder."
This is one example of what I'm referring to:
Granted this chart starts with a sea level temperature of 15 celsius which can influence exactly what the speed of sound is.
http://www.fighter-planes.com/jetmach1.htm

Pressure also has something to do with it, and some parts of the atmosphere are much hotter than you might expect.

Rhomphaia · July 1, 2015

Huh? I was always taught and read that the speed of sound is highest at sea level then decreases the higher you go "because gas molecules move more slowly at colder temperatures, which slows the speed of sound; sound moves faster through warmer air. Therefore, the speed required to break the sound barrier decreases higher in the atmosphere, where temperatures are colder."
This is one example of what I'm referring to:
Granted this chart starts with a sea level temperature of 15 celsius which can influence exactly what the speed of sound is.
http://www.fighter-planes.com/jetmach1.htm

Note that that chart only shows up to 18km, and the speed of sound plateaus at the end of the range covered.

As you get into the stratosphere temperatures start to rise again.

Fenris · July 1, 2015

Note that that chart only shows up to 18km, and the speed of sound plateaus at the end of the range covered.
As you get into the stratosphere temperatures start to rise again.

Ah dang it, I play KSP too much , I saw the 60,000 feet and my brain read it as 60,000 meters.

EDIT: That's why I love this game and community, I'm always learning stuff.

Chaos_Klaus · July 1, 2015

Take a look at these two forum posts:

http://forum.kerbalspaceprogram.com/threads/117069-Great-New-Physics-Thread%21?p=1894742&viewfull=1#post1894742

http://forum.kerbalspaceprogram.com/threads/117069-Great-New-Physics-Thread%21?p=1940443&viewfull=1#post1940443

They take a close look at Temperature and Pressure on post 1.0 Kerbin.

The model follows some kind of standard atmospheric model that was scaled to fit Kerbin.

The speed of sound changes with these parameters.

Skalou · July 2, 2015

The speeds of sound and light in KSP are instantaneous. I'm not sure how you got that data...

Ahahaha, good one!

As said NFUN, this curve curve don't relate the speed or delay for sound effects you can heard when you are exploding a tank hundreds meters aways (this is instantaneous, works in vaccum ,etc..).

But it defines the speed of the mach 1 number (thank's Chaos_Klaus for details in links above)

this affect the drag of your parts and so can be a really important parameter for your jets, spaceplanes, and also rockets ( is your rocket flipping strangely near 15 000m and you don't know why?).

if you go in the debug-menu/physics/drag profil and click on the multiplier button,

you can see the curve affecting the drag depending of the mach number:

drag multiplier in KSP 1.0.4 after the patch:
* Drag curves modified to lower transonic hump.
old drag multiplier in KSP 1.0.2:

So, i wish my graphic will help us to better designing and piloting our ships.

Also do you know a way to record this values automatically? (the mod graphotron don't display the values i want)

i would like to do it on other planets, but i'm too lazy to do it by hand again

Edited July 2, 2015 by Skalou

KerikBalm · July 2, 2015

Ah dang it, I play KSP too much , I saw the 60,000 feet and my brain read it as 60,000 meters.
EDIT: That's why I love this game and community, I'm always learning stuff.

Yea, I have that problem too... stupid US upbringing...

I'll be flying around thinking, oh, 12k isn't so high.... but thats really ~40,000 feet.

30 km... ~100,000 feet... which is pretty much the limit for level flight for anything we've built.

And if we assume kerbin's atmosphere is about 5/7th scale - as it seemed to be in 0.90... with a scale height of 5km, surface pressure of 1 atm, while earth has a scale height of about 7km (granted its not so simple and it to deviates from that in other atmospheric layers)... then its more like 140,000 feet...

And my knowledge of flying around at ~10k *feet* really only translates to flying at about 3km or less on Kerbin

NathanKell · July 2, 2015

In 1.0 it's an 80% atmosphere (so 12km Kerbin = 15km on Earth).

Skalou · July 3, 2015

I finally done it on Duna.

[TABLE]
[TR]
[/TR]
[TR]
[TD][TABLE]
[TR]
[TD]time[/TD]
[TD]position[/TD]
[TD]altitude asl[/TD]
[TD]Static ambient temperature[/TD]
[TD]static presure[/TD]
[TD]speed of sound[/TD]
[/TR]
[TR]
[TD]Y2D349 1h:48min[/TD]
[TD]0Ã‚Â°N 60Ã‚Â°20'W[/TD]
[TD]450m[/TD]
[TD]268Ã‚Â°K[/TD]
[TD]1929hPa[/TD]
[TD]436m/s[/TD]
[/TR]
[TR]
[TD]sun mid-day[/TD]
[TD]equatorial in canyon[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]min 425m/s[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD]max 439m/s[/TD]
[/TR]
[/TABLE]
[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[/TABLE]
values recorded manually during a vertical launch at 100m/s

What a surprise!

[TABLE]
[TR]
[TD]Kerbin[/TD]
[TD]Duna[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Speed of sound (m/s)[/TD]
[TD]Speed of sound (m/s)[/TD]
[TD]Altitude asl (m)[/TD]
[/TR]
[TR]
[TD]352[/TD]
[TD]437[/TD]
[TD]0[/TD]
[/TR]
[TR]
[TD]347[/TD]
[TD]436[/TD]
[TD]1000[/TD]
[/TR]
[TR]
[TD]342[/TD]
[TD]435[/TD]
[TD]2000[/TD]
[/TR]
[TR]
[TD]336[/TD]
[TD]434[/TD]
[TD]3000[/TD]
[/TR]
[TR]
[TD]330[/TD]
[TD]432[/TD]
[TD]4000[/TD]
[/TR]
[TR]
[TD]324[/TD]
[TD]429[/TD]
[TD]5000[/TD]
[/TR]
[TR]
[TD]317[/TD]
[TD]426[/TD]
[TD]6000[/TD]
[/TR]
[TR]
[TD]311[/TD]
[TD]422[/TD]
[TD]7000[/TD]
[/TR]
[TR]
[TD]304[/TD]
[TD]418[/TD]
[TD]8000[/TD]
[/TR]
[TR]
[TD]299[/TD]
[TD]413[/TD]
[TD]9000[/TD]
[/TR]
[TR]
[TD]298[/TD]
[TD]408[/TD]
[TD]10000[/TD]
[/TR]
[TR]
[TD]297[/TD]
[TD]402[/TD]
[TD]11000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD]397[/TD]
[TD]12000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD]391[/TD]
[TD]13000[/TD]
[/TR]
[TR]
[TD]295[/TD]
[TD]385[/TD]
[TD]14000[/TD]
[/TR]
[TR]
[TD]295[/TD]
[TD]379[/TD]
[TD]15000[/TD]
[/TR]
[TR]
[TD]295[/TD]
[TD]373[/TD]
[TD]16000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD]367[/TD]
[TD]17000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD]361[/TD]
[TD]18000[/TD]
[/TR]
[TR]
[TD]297[/TD]
[TD]355[/TD]
[TD]19000[/TD]
[/TR]
[TR]
[TD]298[/TD]
[TD]350[/TD]
[TD]20000[/TD]
[/TR]
[TR]
[TD]299[/TD]
[TD]345[/TD]
[TD]21000[/TD]
[/TR]
[TR]
[TD]300[/TD]
[TD]340[/TD]
[TD]22000[/TD]
[/TR]
[TR]
[TD]300[/TD]
[TD]337[/TD]
[TD]23000[/TD]
[/TR]
[TR]
[TD]301[/TD]
[TD]331[/TD]
[TD]24000[/TD]
[/TR]
[TR]
[TD]303[/TD]
[TD]329[/TD]
[TD]25000[/TD]
[/TR]
[TR]
[TD]304[/TD]
[TD]328[/TD]
[TD]26000[/TD]
[/TR]
[TR]
[TD]307[/TD]
[TD]327[/TD]
[TD]27000[/TD]
[/TR]
[TR]
[TD]308[/TD]
[TD]327[/TD]
[TD]28000[/TD]
[/TR]
[TR]
[TD]311[/TD]
[TD]327[/TD]
[TD]29000[/TD]
[/TR]
[TR]
[TD]313[/TD]
[TD]327[/TD]
[TD]30000[/TD]
[/TR]
[TR]
[TD]316[/TD]
[TD]327[/TD]
[TD]31000[/TD]
[/TR]
[TR]
[TD]318[/TD]
[TD]327[/TD]
[TD]32000[/TD]
[/TR]
[TR]
[TD]321[/TD]
[TD]327[/TD]
[TD]33000[/TD]
[/TR]
[TR]
[TD]324[/TD]
[TD]327[/TD]
[TD]34000[/TD]
[/TR]
[TR]
[TD]326[/TD]
[TD]327[/TD]
[TD]35000[/TD]
[/TR]
[TR]
[TD]328[/TD]
[TD]327[/TD]
[TD]36000[/TD]
[/TR]
[TR]
[TD]330[/TD]
[TD]327[/TD]
[TD]37000[/TD]
[/TR]
[TR]
[TD]332[/TD]
[TD]327[/TD]
[TD]38000[/TD]
[/TR]
[TR]
[TD]332[/TD]
[TD]327[/TD]
[TD]39000[/TD]
[/TR]
[TR]
[TD]332[/TD]
[TD]327[/TD]
[TD]40000[/TD]
[/TR]
[TR]
[TD]332[/TD]
[TD]327[/TD]
[TD]41000[/TD]
[/TR]
[TR]
[TD]330[/TD]
[TD]327[/TD]
[TD]42000[/TD]
[/TR]
[TR]
[TD]328[/TD]
[TD]327[/TD]
[TD]43000[/TD]
[/TR]
[TR]
[TD]326[/TD]
[TD]327[/TD]
[TD]44000[/TD]
[/TR]
[TR]
[TD]323[/TD]
[TD]327[/TD]
[TD]45000[/TD]
[/TR]
[TR]
[TD]321[/TD]
[TD]328[/TD]
[TD]46000[/TD]
[/TR]
[TR]
[TD]319[/TD]
[TD]338[/TD]
[TD]47000[/TD]
[/TR]
[TR]
[TD]317[/TD]
[TD]360[/TD]
[TD]48000[/TD]
[/TR]
[TR]
[TD]315[/TD]
[TD]370[/TD]
[TD]49000[/TD]
[/TR]
[TR]
[TD]313[/TD]
[TD]373[/TD]
[TD]50000[/TD]
[/TR]
[TR]
[TD]311[/TD]
[TD][/TD]
[TD]51000[/TD]
[/TR]
[TR]
[TD]309[/TD]
[TD][/TD]
[TD]52000[/TD]
[/TR]
[TR]
[TD]307[/TD]
[TD][/TD]
[TD]53000[/TD]
[/TR]
[TR]
[TD]304[/TD]
[TD][/TD]
[TD]54000[/TD]
[/TR]
[TR]
[TD]302[/TD]
[TD][/TD]
[TD]55000[/TD]
[/TR]
[TR]
[TD]299[/TD]
[TD][/TD]
[TD]56000[/TD]
[/TR]
[TR]
[TD]297[/TD]
[TD][/TD]
[TD]57000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD][/TD]
[TD]58000[/TD]
[/TR]
[TR]
[TD]295[/TD]
[TD][/TD]
[TD]59000[/TD]
[/TR]
[TR]
[TD]295[/TD]
[TD][/TD]
[TD]60000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD][/TD]
[TD]61000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD][/TD]
[TD]62000[/TD]
[/TR]
[TR]
[TD]297[/TD]
[TD][/TD]
[TD]63000[/TD]
[/TR]
[TR]
[TD]297[/TD]
[TD][/TD]
[TD]64000[/TD]
[/TR]
[TR]
[TD]297[/TD]
[TD][/TD]
[TD]65000[/TD]
[/TR]
[TR]
[TD]296[/TD]
[TD][/TD]
[TD]66000[/TD]
[/TR]
[TR]
[TD]295[/TD]
[TD][/TD]
[TD]67000[/TD]
[/TR]
[TR]
[TD]293[/TD]
[TD][/TD]
[TD]68000[/TD]
[/TR]
[TR]
[TD]291[/TD]
[TD][/TD]
[TD]69000[/TD]
[/TR]
[TR]
[TD]292[/TD]
[TD][/TD]
[TD]70000[/TD]
[/TR]
[/TABLE]

there is a "flat" part of the curve with mach 1=327 m/s between 33km and 45km.

Strangely the temperature is 150Ã‚Â°K here, but the pressure and density still go lower!

Does it means the speed of sound depend only of the Temperature in KSP?

we can also see the values are higher on Duna than on Kerbin, Game play considerations?

i'll edit the first pic.

NathanKel, i take the opportunity to say thank you for the aero-gui mod.

Edited July 3, 2015 by Skalou
thank's

NathanKell · July 4, 2015

You're very welcome!

Speed of sound depends on only three things: the ratio of specific heats, the gas constant for the gas (which can be gotten by dividing the universal gas constant by the molecular weight of the gas, the latter of which KSP stores), and the temperature. Neither density nor pressure are required.

Skalou · July 8, 2015

You're very welcome!
Speed of sound depends on only three things: the ratio of specific heats, the gas constant for the gas (which can be gotten by dividing the universal gas constant by the molecular weight of the gas, the latter of which KSP stores), and the temperature

thank you, so i've looked a bit more and found the law:

where

a = speed of sound [ft/s or m/s]
ÃŽÂ³ = specific heat ratio [dimensionless]
R = specific gas constant [ft-lb/slug/Ã‚Â°R or J/kg/K]
T = atmospheric temperature [degrees Rankine (Ã‚Â°R) or degrees Kelvin (K)]
an intersting link to learn more on speed of sound for rocket:

https://www.grc.nasa.gov/www/k-12/airplane/sound.html

Also, as Laythe as an atmosphere usable for jet engine with their thrust depenpending hardly of the mach number, it was my next target:

Album of the trip

and then:

min/max speed of sound splashed: 336/340m/s

[TABLE]
[TR]
[TD]time[/TD]
[TD]position[/TD]
[TD]altitude asl[/TD]
[TD]Static ambient temperature[/TD]
[TD=width: 96]static presure[/TD]
[/TR]
[TR]
[TD]Y11D243 1:46[/TD]
[TD]0Ã‚Â°10'S165Ã‚Â°36'W[/TD]
[TD]1160m[/TD]
[TD]273K[/TD]
[TD]54,5Pa[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD]Laythe[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Altitude asl (m)[/TD]
[TD]Speed of sound (m/s)[/TD]
[TD]temperature (K)[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]0[/TD]
[TD]340[/TD]
[TD]288[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]1000[/TD]
[TD]333[/TD]
[TD]276[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]2000[/TD]
[TD]322[/TD]
[TD]259[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]3000[/TD]
[TD]311[/TD]
[TD]241[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]4000[/TD]
[TD]299[/TD]
[TD]223[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]5000[/TD]
[TD]290[/TD]
[TD]209[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]6000[/TD]
[TD]288[/TD]
[TD]207[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]7000[/TD]
[TD]288[/TD]
[TD]206[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]8000[/TD]
[TD]288[/TD]
[TD]206[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]9000[/TD]
[TD]288[/TD]
[TD]206[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]10000[/TD]
[TD]288[/TD]
[TD]206[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]11000[/TD]
[TD]289[/TD]
[TD]208[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]12000[/TD]
[TD]290[/TD]
[TD]209[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]13000[/TD]
[TD]291[/TD]
[TD]211[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]14000[/TD]
[TD]293[/TD]
[TD]213[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]15000[/TD]
[TD]294[/TD]
[TD]215[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]16000[/TD]
[TD]295[/TD]
[TD]216[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]17000[/TD]
[TD]296[/TD]
[TD]218[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]18000[/TD]
[TD]299[/TD]
[TD]222[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]19000[/TD]
[TD]301[/TD]
[TD]225[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]20000[/TD]
[TD]303[/TD]
[TD]228[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]21000[/TD]
[TD]306[/TD]
[TD]232[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]22000[/TD]
[TD]308[/TD]
[TD]236[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]23000[/TD]
[TD]307[/TD]
[TD]235[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]24000[/TD]
[TD]305[/TD]
[TD]232[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]25000[/TD]
[TD]304[/TD]
[TD]230[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]26000[/TD]
[TD]302[/TD]
[TD]228[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]27000[/TD]
[TD]300[/TD]
[TD]226[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]28000[/TD]
[TD]297[/TD]
[TD]226[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]29000[/TD]
[TD]294[/TD]
[TD]227[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]30000[/TD]
[TD]291[/TD]
[TD]228[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]31000[/TD]
[TD]289[/TD]
[TD]230[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]32000[/TD]
[TD]289[/TD]
[TD]234[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]33000[/TD]
[TD]289[/TD]
[TD]238[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]34000[/TD]
[TD]290[/TD]
[TD]243[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]35000[/TD]
[TD]290[/TD]
[TD]249[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]36000[/TD]
[TD]290[/TD]
[TD]255[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]37000[/TD]
[TD]290[/TD]
[TD]262[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]38000[/TD]
[TD]291[/TD]
[TD]269[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]39000[/TD]
[TD]292[/TD]
[TD]263[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]40000[/TD]
[TD]293[/TD]
[TD]254[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]41000[/TD]
[TD]295[/TD]
[TD]245[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]42000[/TD]
[TD]296[/TD]
[TD]236[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]43000[/TD]
[TD]297[/TD]
[TD]228[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]44000[/TD]
[TD]298[/TD]
[TD]222[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]45000[/TD]
[TD]299[/TD]
[TD]223[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]46000[/TD]
[TD]300[/TD]
[TD]224[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]47000[/TD]
[TD]301[/TD]
[TD]226[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]48000[/TD]
[TD]302[/TD]
[TD]226[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]49000[/TD]
[TD]302[/TD]
[TD]227[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]50000[/TD]
[TD]302[/TD]
[TD]227[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[/TABLE]

Edited July 8, 2015 by Skalou

mikegarrison · July 8, 2015

As you get into the stratosphere temperatures start to rise again.

No. As you get ABOVE the stratosphere, temperatures start changing again (up and then down again). In the stratosphere temperatures are invariant with altitude. That's WHY it is the "stratosphere," because with no temperature gradient the air stratifies.

Eventually you reach a point where the air is so thin that temperature becomes more of statistical thermodynamic quantity than a fluid dynamic parameter.

Speed of sound in 1.0

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