Measuring fighter aircraft maneuvering performance

Maneuvering performance can be divided into several types. Those types are transient maneuverability, angular maneuverability, energy maneuverability and endurance. Transient maneuverability denotes aircraft’s ability to quickly switch from one maneuver to another. Energy performance measures aircraft’s ability to gain, lose or maintain energy (speed and/or altitude). Angular (turn) performance measures aircraft’s ability to achieve and sustain a certain turn rate. Endurance measures aircraft’s ability to stay and fight without refueling. All these characteristics are important for winning a fight, and thus measures should be found to reliably measure them. There is also a significant overlap: acceleration (energy gain/loss) is in nature energy maneuverability characteristic, but is also part of transient maneuverability. Similarly, pitch and turn onset rates, while transient in nature, also factor highly in turn performance (up to a point). And too short endurance can force the pilot to preserve fuel, thus negatively impacting aircraft’s actual energy and turn performance.

Most important characteristic is transient performance, as it enables pilot to confuse the enemy and keep himself out of danger by remaining unpredictable. Endurance is of major impact as well, as many pilots had been shot down as they tried to leave the fight. Between angular and energy performance, neither offers a clear advantage in a traditional dogfight but they require very different fighting styles. Angular performance did gain importance in era of missiles. No longer can the pilot escape by simply outrunning the opponent; even if he does manage to leave missile’s effective range, fact that he will still be within missile’s aerodynamic range means that maneuvering will still be necessary. However, since optimal angular performance requires staying near aircraft’s corner velocity, and loss of speed below it means lower turn rate, energy performance is still important insomuch as it factors into angular performance and allows staying in the fight.

Simple measures commonly used by enthusiasts and even industry are not enough for the purposes of aircraft evaluation. Neither maximum turn or roll rate can be achieved instantaneously; turn and roll onset are major factors in determining aircraft’s ability to quickly initiate a maneuver. Even nominal turn and roll rates vary depending on aircraft’s altitude, speed and load limits. When it comes to energy performance, thrust-to-weight ratio only really comes into play during rare vertical climbs; typically, it is thrust-to-drag ratio which is far more important. Thrust-to-drag ratio determines level flight acceleration, while thrust-to-weight, thrust-to-drag, lift-to-weight and lift-to-drag ratios all determine climb performance. Endurance similarly cannot be measured by how much time aircraft can spend on a certain engine setting, as pilot of higher-performance aircraft can throttle back while still outmaneuvering lower-performance aircraft. Neither does it have much relation to range or combat radius, as different aircraft have different thrust-to-drag ratios, and thus aircraft with lower nominal endurance (endurance at equal engine setting) can achieve higher range/endurance by virtue of requiring lower engine setting for equal performance.

Therefore, the best way to measure aircraft’s maneuvering performance is to give it a set of maneuverability tasks to accomplish in different conditions. Altitudes for measurement should be 15.000, 30.000, 45.000 and 60.000 ft. Starting speeds should be maximum cruise (dry thrust) speed, standard cruise speed, sustained turn corner speed, as well as Mach 0,9 and Mach 0,5. What will follow are example proposals of tasks that could be used for measurement.

TRANSIENT TASK 1: From level flight, roll 90*, pull a 90* instantaneous turn, roll 180* in the opposite direction, pull 90* instantaneous turn, return to level flight.

TRANSIENT TASK 2 / ANGULAR TASK 1: From level flight, pitch up to maximum combat operational g, pitch down to level flight, roll 90* in either direction, pull 90* maximum instantaneous turn, return to level flight.

TRANSIENT TASK 3: From level flight, pitch up to maximum operational angle of attack, pitch down to level flight. Roll 90* in either direction, pitch up to the maximum operational angle of attack, pitch down, roll and return to level flight.

ANGULAR TASK 2: From level flight, complete a vertical loop, roll 90* and complete a horizontal loop.

ANGULAR TASK 3: From level flight, roll 90*, pull a 90* instantaneous turn, roll 180* in the opposite direction, pull 180* sustained turn, return to level flight

E-M TASK 1: Sustain maximum g horizontal turn until speed drops by 100 kts. After that, roll into level flight and accelerate at 0 g until lost speed is recovered, followed by climb to the starting altitude.

E-M TASK 2: Climb from lower to higher measurement altitude. Perform a 180* instantaneous turn, then return into level flight and accelerate at 0 g until lost speed is recovered. Regain lost altitude.

ENDURANCE TASK 1: Complete as many previous tasks as possible while utilizing no more than 50% of the internal fuel.

EDURANCE TASK 2 / E-M TASK 2: Gain a total of 150.000 ft of energy in a series of 1 g accelerations. Repeat as/if possible.

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8 thoughts on “Measuring fighter aircraft maneuvering performance

  1. Request please.
    At first thx for your wonderful work. I saved many of your articles as precious archives. Then, is it possible to enable a possibilty to print your article into .pdf file ?
    Regards

  2. Thx for your answer.
    Indeed, nevertheless, there are articles that embedded draws, and schemas. Moreover, no one knows the next. U can write articles with ….many schemas….As Napoleon said “Un schema vaut mieux qu’un long discours” 😉 It is a joke!
    Again great thx for your work.

    Regards.

  3. A bigger problem preventing objective testing is that the military industrial complex might not like how it exposes their aircraft.

    The assumption they have is that an agile airplane is only good for dogfighting. In reality, you need an agile fighter to dodge incoming missiles too of the BVR variety that they advocate for.

  4. Continous turn rate is much more important in BVR ,(” Angular (turn) performance”?) expecially supersonic one, if you have a signifcant ceiling advantage and speed: if you are superior in all this aspects, such as Typhoon vs all other fighters,excpet f22 for some of them, nnd extremely superior to subsonic only fighters,draggy,low energy ones,low max ceiling such as sukoys, you will ever be able to decide if mantein combat bvr or not :(that means bvr for sure since you have enormous advantages); matter is completely different if you are on air to ground mission…Trsut to drag ratio is also important: that is why even f16 has signficant advantage over sukhoys in reagining energy in transonic envelope: wht we know is that vs high energy fighters such eurocanards, vectorial trust is more a disadavantage then ana advantage in air to air role, such as training between f22 and typhoon has showed….The famous “cobra manouvre” looks like a clear invite to be shooted down in this sense…

    • 6g at mach 1,6…impressive.Of course you should tell everybody that the F-22 and the F-15 can also do that…
      And an old F-14 could pull 7g at mach 2….so the Eurofighter is not «superior to all other fighters».

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