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This is just a postulation upon a few thoughts.

I think it is intuitive to understand that in fighter jets, in a dog-fight scenario, higher turning speed, as in closing the angle between the chasing plane's nose and the tale of the fleeing plane, is beneficial.

One possible solution, I as someone without no knowledge can think of, is bursts of thrust from beneath the wings, which not only helps with turning but, probably with sudden maneuvers?

I am sure that this has a logical reason to avoid since it has not been developed, and I am keen to understand why.

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    $\begingroup$ Related: see questions tagged [thrust-vectoring] $\endgroup$
    – ymb1
    Sep 23 '21 at 0:19
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    $\begingroup$ The Harrier was able to do this to an extent using VIFFing. One drawback was that as thrust reduced at higher altitudes, so did the usefulness of VIFFing. (Source: Designed for the Kill by Mike Spick) $\endgroup$ Sep 23 '21 at 4:14
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    $\begingroup$ "One possible solution, I as someone without no knowledge can think of, is bursts of thrust from beneath the wings", another (after vectored thrust) is to use control canards. $\endgroup$
    – mins
    Sep 23 '21 at 18:15
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    $\begingroup$ In modern fighter jets maneuvering is less limited by the ability of the aircraft to make the turn but more the pilot's ability to handle the g force. $\endgroup$
    – TomMcW
    Sep 23 '21 at 18:17
  • $\begingroup$ @TomMcW … as was the case already in WWII. A spitfire couldn't pull as many Gs as the F-16, but without a G-suite the pilot couldn't handle as much either. Cue Pierre Clostermann's anecdote: he chased enemy in a dive, made the kill, but was too close to the sea to pull out, so he pulled the trim, promptly lost consciousness and woke up a few moments later after the plane now pointing almost straight up lost most of its energy. So at high speed, even a spitfire could pull more Gs than the pilot could handle. $\endgroup$
    – Jan Hudec
    Sep 23 '21 at 20:15
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Wings are the most efficient known way of creating force perpendicular to the direction of flight. At the cost of relatively little force in the aft direction (the drag) a wing can create a lot of force perpendicularly (the lift, which is tilted to the side to make turn). They do it by using a lot of air as the reaction mass, which is the reason why wings with longer span are more efficient at this.

Therefore simply making the wings larger is more efficient way to turn then adding “lift” engines or turn jets. Because the wing acts as a multiplier of the engine power as long as the side needs to be sideways (from physical point of view this is possible because force perpendicular to the motion path does not do work).

So to make a fighter with good turn rate, they just make the wings larger until

  • they can't make them strong enough to withstand the force, or
  • the pilot won't be able to handle the force without fainting anyway.

The later suggests that remotely-piloted vehicles can get significant advantage as their pilots don't feel the forces and cameras and computers can be made to withstand a lot more force than humans. But it will still be done by using large enough wings because that's the most efficient way.

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  • $\begingroup$ The design of 5th gen fighters makes a lot more sense suddenly! I do see your point about the wings but let's say a chasing plane and a fleeing plane have the same turning rate, what I had in my mind was a sudden increase in that rate for the chasing plane, so that it would have the latter "in sight"? What you described, as I understand it, is a "generally" better strategy towards improving maneuverability $\endgroup$
    – NeuroEng
    Sep 23 '21 at 23:00
  • $\begingroup$ What's the difference between “burst” and increasing turn rate? To an extent this occurs because higher turn rate does incur higher drag, but in a dogfight, maintaining energy is important, so the pilot has to always think whether tightening the turn is worth the slow down. But there is no specific mechanism that would only give bursts of force, just general mechanisms that have trade-offs. Closest is engine with emergency power that can only be used for two or five minutes before the engine would overheat and fail. $\endgroup$
    – Jan Hudec
    Sep 24 '21 at 4:56
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Well, where is this extra underwing burst of thrust going to come from? You'd have two basic options: A) add some extra engines under the wings with the exhaust nozzles pointed down, B) use the existing engine(s), and run some ducting from the engine to under the wing, with some valves to open and close to control the thrust. Also, getting a very quick "burst" from a engine is difficult, as they have mechanical inertia and take a few seconds to spool up. You get much faster thrust response from an afterburner, so you'll need one of those.

Both of these are going to add a lot of complexity to what is already a very complex system, and most importantly they are going to add a lot of extra weight. Every extra pound you add the airframe means either less payload (e.g. less missiles), shorter range, or shorter loiter time. So presumably no one has done it because the increased maneuverability is not worth the cost.

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  • $\begingroup$ Thank you for the answer, would you say that the added weight would actually limit the maneuverability, making the whole process rather impossible, or would it be the "logistical" issues, like the ones you mentioned (e.g. payload restrictions) that would be of concern? cuz when thinking about a small nation requiring air superiority but only in a defensive manner, would not that make sense? to sacrifice, for example, range for better control/maneuverability? $\endgroup$
    – NeuroEng
    Sep 23 '21 at 22:57
  • $\begingroup$ Jan's answer is probably better than mine. Wings are more efficient than engines if you want force perpendicular to the direction of flight. So yes, you could sacrifice, say, 10% of your range to get more maneuverability by way of adding an engine. But if you just make the wing bigger, you would only have to sacrifice, say, 1% of your range for the same gain in maneuverability. $\endgroup$
    – Daniel K
    Sep 24 '21 at 1:45
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Actually, this has been done with one military aircraft: the Harrier. Since the Harrier can vector it's thrust nozzles downward for vertical takeoff or landing, it can also move those nozzles downward while in fast forward flight.

The pilot moves the exhaust thrust downward while in forward flight, and the aircraft takes a sudden leap upward. It was used with some effectiveness by the British during the air battles of the Falklands war, when they faced the agile A4 Skyhawks of the Argentine Air Force, flown by expert pilots. As a British pilot ruefully noted after the war - Argentina turns out such good Formula 1 drivers, we should have guessed that they would have very good pilots.

The technique is known as 'viffing', which comes from Vectoring In Flight, I believe.

There is a problem with this technique: it eats airspeed at a high rate.

And, in modern air combat, airspeed is life.

So if you're going to do this, you'd better get your opponent on the first try, or they'll have you at low airspeed and low energy if you miss.

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