When the jet goes to afterburner, the color of the flame from its engines changes color. It is noteworthy that for different aircraft, the color of the flame may be different. As a rule, it has a blue, red or yellow tint. For example, the American F-22 fighter has red afterburner engine fire, while the Russian Su-35 has blue. What is the reason for this feature and does the color of the flame somehow affect the operational characteristics of the combat vehicle?
1. What is afterburner
Before dealing with the color of the flame, it is worth recalling what the afterburner is. So, afterburner is a special mode of operation of a jet aircraft engine, which is used to radically increase thrust due to a significant increase in fuel consumption. This mode is needed primarily in order to increase the speed of the aircraft for a short period of time. The option is used mainly on military aircraft for takeoff, combat maneuver or transition to supersonic speed. In the entire history of aviation, only two civil aircraft had afterburner - the Concorde and the Tu-144.
The afterburner mode is implemented in modern aircraft due to the installation of an additional combustion chamber, which is located immediately behind the main chamber and the turbine. Afterburner not only consumes a lot of fuel, but also has a significant thermal and physical impact on the design of aircraft. Therefore, it is used (as a rule) for a very short time. Only a few reconnaissance aircraft, created during the Cold War, were adapted for long-term use of this regime. Examples of such machines are the domestic MiG-31 and the American Lockheed SR-71.
2. Why is the color different
It is quite obvious that domestic jet planes have a blue flame, because they are fighting on the side of the Autobots and Optimus Prime, and their American colleagues are fighting on the side of the Disepticons and Megatron, and that is why they have a red flame! A joke, of course. The color of the flame from the engine nozzle may differ from aircraft to aircraft due to the difference in fuel and also due to the flame temperature. For fighters, the latter is mostly relevant. Is it because the exit temperature of an American plane is lower than that of a domestic one? Does it mean that his engines are weaker?
It's actually not that simple. In terms of thrust both in cruise mode and afterburner, the domestic Su-35 loses to the American F-22. Thus, the engines of the Russian aircraft produce 8,800 kgf in normal mode (each) and 14,500 kg in afterburner mode. American engines deliver 15 876 kgf afterburner, which is one of the best indicators in the world. However, once again - not everything is so simple. Despite the great thrust, the American plane loses to the Russian in speed. Su-35 accelerates on afterburner to 2,684 km / h, and the American F-22 to 2,146 km / h. This is due to the difference in weight. Ready for battle, the Sukhoi weighs 25,300 kg, while the Raptor weighs 29,200 kg.
And here is the key question: why does a more powerful engine have a colder flame at the output? In fact, the F-22 engine is significantly hotter than the Su-35 engine and this is a big problem. In order for this nuance not to have a negative effect on the design, American engineers had to implement several technical tricks with the location of the fuel combustion chamber, as a result of which the flame, reaching the nozzle, has time to cool down and ceases to be blue, becoming red. The engine removed from the Raptor and operating under laboratory conditions has the same blue color as the engine of the Sukhoi.
If you want to know even more interesting things, then you should definitely read about how planes managed to land on aircraft carriers during World War IIif there was almost no room.