# Order of calculation for turbojet engine parameters? [closed]

As I see it, if you're going to calculate a twin-spool turbojet engine, you

• Determine expected max aircraft speed, and engine thrust at that speed and when stationary.
• Calculate peak mass of air flow
• Calculate energy needed to propel this mass of air
• Calculate bypass ratio
• Calculate compressor properties

And from here I have no idea where to move on. Some books I've read just go through the engine from compressor to exhaust nozzle, but none explains which parameter of the engine is primary and where do calculations start and how they're performed.

Would you give me a clue? Thank you!

• Which propulsion text do you have? I would recommend "Elements of Propulsion: Gas Turbines and Rockets" by Jack Mattingly. The solution procedure to your question is very well explained in this text.
– TRF
Commented Dec 14, 2016 at 0:44
• @CountTo10 It really is better suited for an engineering SE. But I figured I would help out the OP before it gets closed.
– TRF
Commented Dec 14, 2016 at 1:23
• @CountTo10 I see it as an applied physict. Am I wrong? Commented Dec 14, 2016 at 14:02
• Hi Eugene, I am facinated by jet turbine engines, and associated serious tech Ramjet and High Bypass Turbines, it takes 5 votes to close and so it's not up to me. But the questions I answered had more physics, I honestly think you would get a better answer than here. Hey, would you rather fly in an aircraft built by physicists, rather than by engineers :)
– user108787
Commented Dec 14, 2016 at 14:26
• You are correct of course, but I read a detailed book on the Wright brothers recently, Wilbur Wright was an often overlooked genius, a very, very clever self taught man in both the physical and engineering aspects of aerodynamics. And the first man on the moon, Neil Armstrong, always insisted he was an engineer first, before all else. BTW, your question is which parameter of the engine is primary and my guess is its performance / efficiency at the speed regime at which it will spend most time. I retract my close vote, best of luck.
– user108787
Commented Dec 14, 2016 at 19:51