Effect of temperature on TAS of piston aircraft

[mm_flynn]

I hope some one can help with this question (or refer to a source).

I am trying to work out the effect of temperature on the achievable TAS in piston powered aircraft (I am fully aware of how temperature effects the IAS vs. TAS relationship).

I believe there are two general scenarios

1 - LOP - engine set a constant fuel flow (hence constant power). I think (assuming an airspeed such that parasitic drag is dominate and absolute temperatures) TAS should be -

TAS = Book TAS * (ISA Temp/Actual Temp) ^0.33

IAS = Book IAS *(ISA Temp/Actual temp)^0.33 * (ISA Temp/ Actual temp)*0.5

2 - ROP - engine set at constant RPM/MP/fuelflow (so should have reduced power in above standard temps due to low density air enriching mixture)

TAS = Book TAS * ((standard temp/actual temp) * %loss in power) ^ 0.33

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The questions

1 - Is my logic right on both of these cases?

2 - Is there a standard method of estimating the loss in power as the mixture is enriched?

[NutLoose]

may help

Key Reprints - Lycoming, try the operations section...............