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Why does Tejas have red afterburner flame, and the Su-30MKI has blue?


Lots of users often ask why the color of the afterburner in the SU-30mki engine is different from the Tejas aircraft . What is the reason?

LCA Tejas full afterburn (credit : deb rana)

Engine

Here we have to understand both aircraft use different engine , su use russian engine Lyulka-Saturn AL-31FP where Tejas use American engine General Electric F404-GE-IN20

The Su-30MKI is powered by two Lyulka-Saturn AL-31FP turbofans, each rated at 12,500 kgf (27,550 lbf) of full after-burning thrust, which enable speeds of up to Mach 2 in horizontal flight and a rate of climb of 230 m/s. The mean time between overhaul is reportedly 1,000 hours with a full-life span of 3,000 hours; the titanium nozzle has a mean time between overhaul of 500 hours.

Where Tejas use The General Electric F404 aare a family of afterburning turbofan engines in the 10,500–19,000 lbf (47–85 kN) class (static thrust). The series are produced by GE Aviation. Partners include Volvo Aero, which builds the RM12 variant. The F404 was developed into the larger F414 turbofan, as well as the experimental GE36 civil propfan.

Performance

  • Maximum thrust:
  • 11,000 lbf (48.9 kN) military thrust
  • 17,700 lbf (78.7 kN) with afterburner
  • Overall pressure ratio: 26:1
  • Bypass ratio: 0.34:1
  • Specific fuel consumption:
  • Military thrust: 0.81 lb/lbf/h (83 kg/kN/h)
  • Full afterburner: 1.74 lb/lbf/h (177 kg/kN/h)
  • Thrust-to-weight ratio: 4.8 (dry), 7.8 (afterburning)
Tejas full afterburn (credit : Livefist)
Su-30mki full afterburn (credit on the pic )

Which gamma is better?

American as well as Russian aircraft are refueling with different fuels. Therefore, at a certain temperature, the refraction of light rays, the color of the flame begins to differ greatly. The main reason is the temperature difference, as well as the type of fuel.

During combustion, each material burns in a specific color. For example, from copper the flame will be green, and from sodium yellow. Type of fuel is specially selected for fighters. For modern devices, it has the properties of interchangeability. Su-30mki can be seasoned with a mixture of F-35.

In other words, the color of the flame also depends on other parameters. One of the parameters is the temperature:

  • 600 – dark red;
  • 1300 – yellow;
  • 2500 is blue.

The aircraft thrust depends on the temperature. The bigger it is, the stronger. The color of the flame largely depends on its value.

It would seem that this is not possible. After all, this color appears at a temperature of about 600 degrees. But what about traction? The reason is completely different. It is associated with the design of the aircraft.


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