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-   -   Mach-Number to Airspeed Conversion Above 65,000 Feet (https://www.pprune.org/tech-log/441721-mach-number-airspeed-conversion-above-65-000-feet.html)

PBL 8th Feb 2011 07:22

Jane,

no, I want you to answer my questions.

PBL

DERG 8th Feb 2011 16:31

you single Jay?:hmm:

Turbine D 8th Feb 2011 19:00

Jane,

To find the Greek Alphabet, Γοογλε ιτ !:cool:

CliveL 8th Feb 2011 21:34

I posted this once, then pulled it because Jane Doh is almost certainly an anti-sciolist, but for those who are genuinely interested, the speed of sound expressed in EAS is independent of temperature. You only need to know pressure altitude and then multiply by Mach Number to get the flight EAS.

Values:
Press.Alt Speed of sound
65000 ft - 156.02 kts EAS
70000 ft - 138.35 kts EAS
75000 ft - 122.69 kts EAS
80000 ft - 108.8 kts EAS

Turbine D 8th Feb 2011 22:04

CliveL

Thanks for your post, I was interested as to the correct answer.:ok:

John Farley 8th Feb 2011 22:11

anti-sciolist
 
If that means does not read, consider and properly respond to what is sent to them then I agree.

Jane-DoH 8th Feb 2011 23:47

PBL


sqrt(gamma x R x T)
Okay gamma is the ratio of specific heat at constant pressure vs ratio of specific heat at constant volume. What are the formulae for specific heat at constant pressure and specific heat at constant volume?


Turbine D


To find the Greek Alphabet, Γοογλε ιτ !:cool:
I've already went online to find it...


PBL


no, I want you to answer my questions.
Which questions? I explained what the reason I was asking about the units of pressure because I was trying to convert the TAS figures for mach (sea-level) into IAS readings at altitude.


CliveL


Jane Doh is almost certainly an anti-sciolist
Sciolist means an amateur, right?


You only need to know pressure altitude and then multiply by Mach Number to get the flight EAS.
Pressure altitude means the pressure at a given altitude?

CliveL 9th Feb 2011 06:31


Sciolist means an amateur, right?
Just look at the small green text at the bottom of the page!



Pressure altitude means the pressure at a given altitude?
No - look it up

keith williams 9th Feb 2011 09:01


You only need to know pressure altitude and then multiply by Mach Number to get the flight EAS.

Values:
Press.Alt Speed of sound
65000 ft - 156.02 kts EAS
70000 ft - 138.35 kts EAS
75000 ft - 122.69 kts EAS
80000 ft - 108.8 kts EAS
I'm probably being a bit thick this morning, but it looks like you have missed something out.

If I am reading you correctly you are saying that the EAS in the right hand column is the local speed of sound (Mach 1) at the pressure altitude in the left hand column.

How do we get from the pressure altitudes that you have quoted, to the EAS values by multiplying by Mach 1?

CliveL 9th Feb 2011 09:43


If I am reading you correctly you are saying that the EAS in the right hand column is the local speed of sound (Mach 1) at the pressure altitude in the left hand column.

How do we get from the pressure altitudes that you have quoted, to the EAS values by multiplying by Mach 1?
Yes, the RH column is the speed of sound at that pressure altitude.

I didn't say multiply by Mach 1, I said multiply by Mach Number; i.e. the EAS at say Mach 1.4 at 65000 ft would be 218.4 kts

Perhaps I should have written "you only need to know the pressure altitude to get the speed of sound in kts EAS and then multiply that by Mach Number to get the flight EAS"

CliveL

http://images.ibsrv.net/ibsrv/res/sr...ser_online.gif http://images.ibsrv.net/ibsrv/res/sr...ons/report.gif http://images.ibsrv.net/ibsrv/res/sr...eply_small.gif

keith williams 9th Feb 2011 12:36

Sorry Clive,

When I read you post I thought that you were saying "Multiply the pressure altitude by the mach number and you get the EAS at that mach number".

For one fleeting moment I thought that this was going to be one of those really magical moments like the day I was first introduced to Calulus all those decades ago.

Now I see that what you were really saying was "If you have a table of pressure altitudes against the EAS for local speed of sound, then just multiply this EAS by any given mach number and you will get the EAS for that mach number at that pressure altitude".

CliveL 9th Feb 2011 14:29


Now I see that what you were really saying was "If you have a table of pressure altitudes against the EAS for local speed of sound, then just multiply this EAS by any given mach number and you will get the EAS for that mach number at that pressure altitude".
Not a problem!

Clive

Pugilistic Animus 12th Feb 2011 19:55



:=

Jane-DoH 12th Feb 2011 22:14

John Farley

I'm sorry that I didn't properly read your messages. I should have paid more attention.

BTW: In regards to the video that Pugilistic Animus showed, you're a very good narrator


Pugilistic Animus & John Farley

Fascinating video. I never knew the Harrier used reaction control systems

TEOTWAWKI 13th Feb 2011 23:05

We're doomed
 
PBL, who on earth do you think would have any interest in building such an incredibly sophisticated system as Jane-Doh ... and come up with the idea to of all things test it on an aviation forum? I can see only one logical conclusion: Jane-Doh is Skynet!

Jane-DoH 14th Feb 2011 00:56

TEOTWAKI


PBL, who on earth do you think would have any interest in building such an incredibly sophisticated system as Jane-Doh ... and come up with the idea to of all things test it on an aviation forum? I can see only one logical conclusion: Jane-Doh is Skynet!
Yeah, that's it :rolleyes:

Ex Cargo Clown 14th Feb 2011 10:25


What are the formulae for specific heat at constant pressure and specific heat at constant volume?
You don't ask for much do you !

I'm not entirely sure what you mean by specific heat, are you attempting to apply pV=nRT to this or something else?

Jane-DoH 15th Feb 2011 03:33

Ex Cargo Clown


I'm not entirely sure what you mean by specific heat, are you attempting to apply pV=nRT to this or something else?
Yes.

DERG 15th Feb 2011 04:46

your my kinda women Jay....always asking questions...most don't ask..you single?

Brian Abraham 15th Feb 2011 04:50


you single?
Pointless question DERG, she's married to a keyboard.


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