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I am asking this question pertaining to a game I'm designing.

It is well known that many modern jet fighter aircraft can fly at supersonic velocities however I read that this top speed is hardly ever used in combat situations, owing to things like larger turn radius etc.

Can someone tell me a rough estimate of what is the range of speeds most dogfights take place at for modern world jet aircraft?

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  • $\begingroup$ As designed or in practise? $\endgroup$ – SMS von der Tann Oct 21 '16 at 22:30
  • $\begingroup$ Practice ofcourse, say jet fighter engagements in gulf war $\endgroup$ – user1062760 Oct 21 '16 at 22:31
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    $\begingroup$ Mach 0.7, the speed of highest turn rate. See here for more details. $\endgroup$ – Peter Kämpf Oct 22 '16 at 7:32
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Modern Air Combat Maneuvering takes place between about 350 to 600 KIAS; There is no specific speed but each aircraft has a specific optimal cornering velocity which gives it the greatest rate of turn in order to maximize its maneuverability. Pilots will seek to maintain this speed when entering a merge as it can give them the greatest maneuvering advantage in order to turn inside on opponent or for jinking to evade a cannon or a missile shot. As an example, the Lockheed Martin Block 50/52 F-16C has a cornering velocity of 420 KIAS.

Traditionally air combat has been about energy management. Fighter pilots have something in common with economists in that they are engaged in the art of managing the flow of currency; in the case of the pilot that currency is energy and not money. The total energy state of a fighter is:

current energy state = energy in - energy out.

The current energy state is the sum of the kinetic energy, proportional to the square of the velocity of the jet and the potential energy of the jet, which is proportional to its height above the ground. Energy leaves the system in the form of parasite and induced drag acting over a distance as well as loss of altitude, which is proportional to the flat plate area of the jet, load factor, AoA, etc. Energy enters the system at a rate proportional to the amount of jet fuel burned; this supply is limited to the fuel onboard which again affects the mass of the jet, the induced drag, etc.

So keeping this in mind, a good fighter pilot will seek a way in which he/she can maneuver through space, gaining the best speed and turning performance for the least amount of energy consumed, in order to land in an advantageous position to employ the weapons against an enemy jet. These kinds of speeds vary between if the jet is on the offensive or defensive in relation to a threat.

So a pilot maintaining that optimal energy state is in the best position to attack, or defend against an attack, and a pilot in a very low energy state is very vulnerable - "low and slow, you're outta dough" - and could be quickly killed in a multi-jet furball.

The cornering velocity is preferred for this reason if maneuvering is anticipated (a given if the jet is about to enter a merge).

With the advent of terminal homing, beyond visual range missiles allowing pilots to stand off from the fight and shoot a threat before it could get close enough to turn with them, higher speed cruise, along with a capability to maneuver well at those higher speeds has become an advantage. It allows a pilot to more quickly close with an enemy aircraft into the missile's 'no escape' zone, fire, and then turn and dash from the threat, minimizing their presence in an enemy's 'no escape' zone whereby enemy missiles simple don't have the available energy to catch you. This was the basis for supercruise - supersonic cruise without the use of afterbruners - on the ATF / F-22 program. Combined with good frontal stealth to minimize the detection range by enemy fighters, supercruise could give a Raptor jock a major advantage in the BVR areana - near invincibility in BVR engagements against non stealthy fighters, if the published results of the Red Flag and other military exercises are to be believed.

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    $\begingroup$ "killed in a multi-jet furball" That's what happens when a giant cat licks up the planes and coughs them out again? $\endgroup$ – David Richerby Oct 22 '16 at 12:28
  • $\begingroup$ @DavidRicherby That's fighter pilot slang for a many v many dog fight. $\endgroup$ – KorvinStarmast Oct 22 '16 at 17:37
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Average Velocity versus Energy

Average speed would not be the metric I would use to characterize a fight. As has been mentioned, pilots have a certain amount of energy stored in the aircraft configuration and this is what is important. As a pilot, I exchange velocity for altitude (kinetic for potential energy) in a tactical way, like moving chess pieces across the board. This exchange of velocity with altitude comes at a cost though, and the one who manages it the best will win the fight given similarly performing aircraft. In a fight you will have to turn.

To give an average speed, and engagement in the A7-E will extend anywhere between 120 and 650 knots. Given an equal distribution of speeds that would give an average speed of around 385 knots, or 0.6 of the maximum airframe speed.

In my opinion a better metric would be the energy at the start of the engagement and how that is dissipated by the given maneuvers made. This rate of energy loss is specific to a given airframe and maneuver. The turn in the A7-E you wanted to maintain was, if I remember correctly, around 17 units AoA. That said, the principle metric of a fight would be the rate of energy loss.

Remember though, I might chose to lose energy to force my opponent into a particular performance regime within their own aircraft envelope, and in so doing gain an advantage.

This has to also be placed in the context that, "Who gets sight, wins the fight," which is a broader statement than whoever sees the other first will win. It is about cunning and deceit. There are no rules to the fight, except the rules for energy loss and who wants to survive, who is willing to perish.

I entered a fight at maximum airframe speed and at some point ended up taking my opponent straight into a canopy-to-canopy vertical climb. In this position the one who runs out of airspeed and departs into a nose down attitude will lose. I remember thinking don't flinch here. It was a remarkable experience, because the other pilot did the same thing. All I remember is slowly rolling over his canopy within 50 feet, helpless with near zero airspeed, and looking into his cockpit as he looked at me. I had no control over the airframe, and I assume he didn't either.

Finally, you might be in the best fighter pilot in the world, and in the seat of the best aircraft in the world, but if I can out maneuver you prior to the fight with deception and guile I will kill you. This is air combat.

Play in my Sandbox

An aircraft has a sweet spot within their performance envelope, and wants the fight to be fought there. The other aircraft has its own sweet spot and wants the fight to take place in their sandbox. How I keep you in my sandbox, and stay out of yours, is what is important to survival.

Each aircraft has its best turn rate, and when turning in a fight this is where you would want to stay, minimizing energy lost for angles gained on the enemy. It takes discipline to stay at this turn rate, because although your adversary may be gaining angles on you, and creating anxiety by becoming more threatening, they may be losing an unacceptable amount of energy that can be used to your advantage later.

Velocity and altitude is how it gets parsed out. I can exchange kinetic energy for altitude, reducing my speed, and increasing my turn rate. The adversary is using the same credit/debit system of energy. From a neutral position and similar aircraft, who wins the fight has to do with managing the losses more efficiently then the other pilot.

Each aircraft will approach an engagement differently. For example, the A7-E was not designed to be a fighter, and before being retired shared the skies with high performance fighters like the F-16 and F-14. Our tactic for dog fighting was different than what the fighters did.

Bugging Out and Pitching Back

Consider a simple scenario: two sections of similar aircraft in a head on neutral engagement. Both flights have sight. The A7-E's will be in a combat spread with the wingman around a mile abreast the lead. The lead will attempt to split the section of the opposing aircraft. The desire is to pass them with 0 angles, and at least one of us splitting their formation. The attitude I took in an engagement was, "I will hit you head on." And in that mentality I would pass by frighteningly close with a closure over 1200 knots.

Near passing the other flight the lead would call, "Bug out, bug out," which was the call to the wingman to unload the aircraft to negative 2 G's and accelerate to the highest speed possible while honoring the fight. As the opposing section begins to turn, the A7-E lead will call, "Pitch back, pitch back," and both section and lead begin pulling up at max turn rate turning into one another. As the airspeed decreases the turn rate increases, exchanging airspeed for altitude converting it as efficiently as possible. Towards the apex of the climb the lead and wingman "crossover,", exchanging sides and engaging the adversary head on once more: one mile abreast. Getting the nose directed back into the fight with as much energy as possible, and unloading the aircraft once more.

If the A7-E flight has been successful they will pass the fighters with 0 degrees in angle, or head on. Any difference from head on means that the fighters have gained in the fight. In this scenario the A7-E is using its complete envelope. From maximum range airspeed, to unloaded and maximum airspeed, to low airspeed regimes with high turn radius.

Cunning and Deceit

I want to emphasize this aspect of the fight, which in my experience was not explicit in our training. We were taught the performance envelope, maneuvers, things one can do at certain points in an engagement, but we were not taught how to fight. Here is a case in point. Any game has to be able to effectively capture this.

One of the missions I did as an A7-E pilot was to run missile profiles directed at the Battle Group. In the brief I would be given a radial, distance, and altitude to begin the profile. It was nice for sight-seeing, but not a lot of fun. On one such mission I had my front radio on my controller's frequency, and started flipping through the digital frequencies on the second. Sure it was a long shot, but I was just riding into the Battle Group. I wanted to have some fun.

I would turn to a frequency and listen for maybe 5-10 seconds and move on. On one frequency I heard the controller calling, "Alpha-Bravo-214, your target is at your 2 o'clock, 40 miles, 25,000." I listened longer and realized this was the flight of 2 F-14's being directed to intercept. After a minute or so I had learned that the lead was using the call sign Raven, while the wingman was Dutch.

I listened to the intercept, and just prior to 8 miles, which is the rough rule of thumb for visual contact, I called out, "Dutch, bogey on your six! Break right, break right!" The call for a "break" was a call for an immediate hard turn. After the call there was a long pause. Then I heard the lead call, "Dutch where are you?" The wingman answered back, "You told me to break right." Then there was the standard radio call for an intruder on the net. I was never intercepted that day.

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