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Old 7th Dec 2014, 14:11
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keith williams
 
Join Date: Jan 2011
Location: England
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For readers who have difficulty with the idea that changing temperature at any given combination of flight level and CAS will not change the Mach number the link below illustrates this effect well.

Just insert a pressure altitude and temperature then select CAS and insert a CAS value. Click on the "Submit" button and read off the TAS, LSS and Mach number. Then change the temperature and click the "Submit" button. The TAS and LSS will change, but the Mach number will remain unchanged.

For 230 knots CAS at 10000 ft the App gives Mach 0.417 ish. The difference between this and the nav computer result of 0.445 is caused by slightly different approximations used in the two methods.


https://www.google.co.uk/url?sa=t&rc...TNrM_Z5ikZzt2Q


And the link below includes a CAS/TAS/MACH/EAS converter which illustrates the ECTM/ERTM graphs well.

To test the effects of climbing or descending with one speed (CAS, EAS, TAS or Mach) constant, just input a pressure altitude and a value for whatever speed is to be constant. Click "compute" and read of the other speeds. Repeat this for several pressure altitudes and trends will become obvious.


https://www.google.co.uk/url?sa=t&rc...80642063,d.d2s

Last edited by keith williams; 7th Dec 2014 at 14:34.
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