CL help

[jhurditch]

I am trying to find the Coefficient of Lift for a Dash 8 Q400 for my A/C engineering studies at Uni. I am pretty new to the world of aircraft engineering so need some clarification in what I am doing exactly. If Cl = W/(1/2PV^2S) and I have a mid cruise weight, cruise altitude and cruise velocity should I sub into the V a value of true or indicated airspeed in m/s? How do I find my true airspeed at altitude?

Any help is much appreciated,

Cheers

[sycamore]

Try `www.luizmonteiro.com`,and use imperial units.,IE feet/ft/sec etc

[Genghis the Engineer]

You'll get the same answer if you use CAS and standard sea-level air density (1.225kg/m^3), or TAS and actual air density at altitude, and both will be correct.

If you are given IAS instead of CAS, there should be a small difference but don't worry about it for this level of academic work, just assume that IAS=CAS (just don't ever do that if you start working in a flight test department.)

You should also get the same answer whether you use SI or Imperial units, so long as you use the proper engineering form of the units and don't go near unwanted bastard units such as inches, centimetres or (worst of all) kilogrammes-weight.

G

[jhurditch]

Thanks G, much appreciated