Classic British Flight Sim

Posted: **19 May 2006, 17:47**

TobyVickers wrote:Speed of sound is given by:

C=SQR(gamma*R*T)

Where gamma is the ratio of specific heats (which is about 1.4 for air), R is the gas constant (0.286 kJ/kg/K for air) and T is the absolute temperature in Kelvin.

Mach number is of course:

Ma = v/c where v is the velocity of the gas or object we are concerned with and c is the local speed of sound.

I think that's what I said...The only variables being T and c, which will both change for a given Flight Level on a day to day basis...But not enough to worry about when planning...Your scanned table above is based on ISA.

Posted: **19 May 2006, 17:49**

Wasnt posted for your benefit so much as those who were arguing the t*ss on the earlier pages.

Posted: **19 May 2006, 23:24**

In practice, in my day no one bothered to work out the TAS. You just multiplied the mach by 600 to get a notional TAS. The indicated mach no does , of course, vary with temperature, as does TAS, and thus this approximation was perfectly acceptable and accurate to about 1.5%

Chris

Posted: **20 May 2006, 00:13**

I like that Chris. It has holes but it's simple and simple generally works

ATB

DaveB :tab:

Classic British Flight Sim

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