Just tossing this out there but a change of 5 KTAS with a 40% change in weight seems like it might be attributable to uncorrected pitot/static installation error. At 50.000 lbs the AOA would be significantly higher than at 30,000 lbs at the same indicated mach number at a constant altitude and temperature, So maybe any uncorrected installation error could result in a small inaccuracy in IAS and therefore indicated mach number and computed TAS. If the indicated mach number and the computed TAS are both reliant upon the IAS value and the IAS accuracy varies somewhat with AOA, then the different AOA associated with the different weight may account for the difference in computed TAS at various weights. Just a thought...
westhawk
Last edited by westhawk; 24th Oct 2012 at 05:08.
Reason: completing the thought...