I was wondering how powerful the engines of the MIG 29 are. On Wikipedia I found some specifications for it.

  1. How is the mass flow rate calculated? I know mass flow rate = density * area * velocity.
    Is this the mass flow rate for max thrust?

  2. Is it possible to determine the thrust / mass flow rate in the operating point (so I mean where you normally fly with, for which the engine is designed for high life cycle)?

  • $\begingroup$ It's not stated in the figures listed but I think it's safe to assume the mass flow rate is for maximum thrust at sea level, when the engine/aircraft is stationary. This removes most variables with engine installation/inlet geometry. Mass flow rate widely varies with airspeed, Mach and altitude, so your second point will be quite hard to answer. $\endgroup$
    – Efe Ballı
    Aug 2 at 21:45

1 Answer 1


Generally, data found is sea level static take-off power unless stated otherwise.

Mass flow cannot be measured easily, so indeed, mass flow is calculated, but not how you expressed.

Dealing with gas turbine performance data, the best tool to calculate the mass flow is using a gas turbine simulation tool (the mass flow is usually not given). If there is more data available (e.g. thrust, specific fuel consumption, turbine entry temperature), these can be used to calculate the mass flow. Gas turbine performance engineers furthermore take into account the technology level, the overall compression ratio to forecast turbine cooling flows and apply turbo machinery (fan, compressor and turbines) off-design characteristics maps so that they can make calculations of other performance points than the take-off power.

The flow in the design/reference point (the point where you have the most data available, usually take-off power) is found iteratively when tuning the model. The mass flow for any other operating point is calculated by the model based on the input parameters (ambient/flight and conditions power setting).


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