Spreadsheet - Emulating CAS/TAS whizz wheel

[one25six]

Thanks to John Tullamarine who is already looking at this for me, but I thought I would put it out to the wider audience for help.

I am doing some engine tests on my plane after tweaking some things, and would like a quick way of crunching a whole series numbers to work out my TAS without using the Jepp Whizz wheel each time.

Already I have done a crude worksheet using interpolation figures but they are rough - here is what I want to put in:

1.CAS
2.MSL OAT or OAT at Indicated Altitude (either is good - apply STD ISA deviation where neccessary)
3.QnH

The only result I want is TAS.

At my ferocious speeds there is no further consideration of TAT neccessary!

Has anybody already got a spreadhseet for this? I am having trouble applying the atmospheric equation and density heights to the wonders of Excel.

Thanks,

125.6