The Fighter Mafia headed by Boyd put forward a key parameter called "Residual Power per Unit Gravity" (SEP for short). The calculation formula of this parameter is: the aircraft thrust is multiplied by the corresponding speed to get the residual power, and the aircraft gravity is divided by the residual power to get the "unit gravity residual power". According to the flight mechanics of the aircraft, the longitudinal acceleration and climb rate are directly proportional to SEP, and other performance parameters of the aircraft, such as stable hovering performance and ceiling, are also related to SEP. Only the instantaneous hovering performance is only related to the maximum available lift coefficient and wing load, and has nothing to do with SEP. Therefore, SEP curves in the flight envelope can be drawn according to the SEP of the aircraft at different altitudes and m numbers. By comparing the SEP curves of different aircraft, the combat performance of the fighter can be determined. This method has become popular all over the world. It is worth mentioning that the absolute value of SEP is equal to the climb rate of aircraft under the same conditions, and the calculation unit is also m/s, but the physical concept is different. Some people also call SEP "energy climb rate". The theoretical formula of fighter's energy maneuverability ratio residual power (sep) is = (thrust-drag) * speed/weight at any point in the flight envelope, and the higher SEP is dominant. The significance of energy maneuver theory lies in:
1, and quantitatively compare the maneuverability of two fighters in the whole flight envelope.
2. Quantitatively optimize air combat tactics according to the mobility difference between the enemy and the enemy.
3. Quantitatively analyze and evaluate the weak links in the flight envelope of future fighters.
The part outside the formula: a fighter that can change its energy faster will gain the initiative in air combat better. The main points of the formula,
1。 Fighters with large thrust-to-weight ratio can get larger sep better.
2。 Larger wing loading can get better results on the flight envelope.
3。 Smaller drag can improve the maneuverability of fighter more than increasing thrust.
4。 The process of energy transformation affects the result of air combat. Such as the conversion of kinetic energy and potential energy.
5。 The fighter with better energy change rate has better maneuverability under the same flight envelope.
The reason why a fighter takes the dominant position in air combat is not the speed and thrust, but the energy level of the fighter. Speed corresponds to kinetic energy, height corresponds to potential energy, and climbing and diving are all conversions between kinetic energy and potential energy. Whoever can change the energy level faster wins. So Boyd began to study the mathematical description of the energy level of soldiers. After countless sleepless nights, Boyd finally put forward a concise and beautiful mathematical expression for evaluating fighter maneuverability:
In physical terms, the quotient obtained by dividing heat by temperature indicates the degree to which heat is converted into work.
Physical meaning: the symbol of the degree of chaos when a substance is in microscopic thermal motion.
1: Physically, it refers to the quotient obtained by dividing heat energy by temperature, indicating the degree to which heat is converted into work.
2. Functions used to describe and characterize system disorder in science and technology. Social science also uses it to compare the degree of certain States of human society.
3. Entropy is a biological order and a mental behavior phenomenon. Scientists invented the measurement of disorder quantity, which is called entropy. Entropy is also the degree of chaos and the total amount of internal disorder structure.
Specific residual power of fighter = (thrust-drag) * speed/weight.
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