So apparently the F-35 is quite manoueverable after all, after seeing the recent videos of the demo team doing tight loops, flat spins, and high AoA. How does it manage to do that without vectored thrust or canards?
There are several factors related to maneuverability. One is just having good instantaneous turn rate, which practically comes from having a good lift-to-weight ratio. This can come from either having a big wing, or the ability to fly controllably at high angles of attack without stalling. Relaxed stability aerodynamics also helps to get good lift while turning, as then both the main wings and the horizontal stabilizers can produce usable lift instead of horizontal stabilizers producing negative lift.The ability to fly controllably at high angles of attack without stalling practically consists of two parts: 1) not stalling the main wing to get lift from it, and 2) staying in control, which means keeping fresh air flowing to the control surfaces and not stalling them.Another very important factor for maneuverability is the ability to keep performing tight turns for a long time. Flying tight turns causes high induced drag in the wings, so a good thrust-to-weight ratio is very important for this. Relaxed stability also helps, as it can reduce the induced drag from the wings because the wings have to fight less against the horizontal stabilizer.Then, there are also some minor points, like rolling speed.So, this is how these relate to the F-35:Even though F-35 weighs much more than previous single-engined fighters, it also has a very powerful engine, the most powerful engine ever put into a fighter. It can give huge amounts of thrust, making the thrust-to-weight ratio good, especially on real combat loads. Many other fighters also have good T/W ratios on paper, with a clean configuration, but in order to go to battle, external ECM, sensor and targeting pods and external fuel tanks are needed. The F-35 has all this equipment installed by default, and huge internal fuel tanks, needing no extra weight for those, as well as avoiding the detrimental aerodynamic characteristics attendant to such external loads.F-35 has advanced relaxed stability aerodynamics. Itu2019s not wasting lift from the main wings for countering the horizontal stabilizers. Its intakes are designed so that they work effectively as wing leading edge extensions(LERXs), which allow the wings to function at higher angles of attack without stalling.And F-35 has widely-spaced outward-canted twin vertical stabilizers, which means that when flying at very high angles of attack, these stabilizers are not directly behind the body of the plane, and therefore keep getting undisturbed air. On planes with single vertical tail like F-16, at high angles of attack, the body of the plane disturbs the airflow to the vertical stabilizer, making it ineffective. The F-16 becomes uncontrollable at about a 30 degree angle-of-attack, so the flight computer of F-16 prevents of from ever reaching the 30 degree angle-of-attack. (The actual limit is something like 27 degrees).Also, the flight computer of F-35 is more advanced than on many other planes, and can use the control surfaces of the plane in creative way. When some control surface is no longer functioning well in some strange situation, the F-35 can stay in control by using other control surfaces to compensate.Also, the rolling speed of F-35 is excellent, because as a single-engine plane, most of the weight is very close to the centerline of the plane, giving it a very low rolling inertia. Twin-engines planes have the heavy engines considerably further away from the centerline of the plane, increasing inertia and thus decreasing rolling speed. The advanced flight computer further helps the rolling speed, being able to use all available control surfaces to perform the roll.So what about the lack of canards? Canards typically give two benefits:1) They Function as horizontal stabilizers that do not produce negative lift.2) If situated close to the wings, as in the Rafale and Gripen, they can act as vortex generators allowing higher angles of attack without stalling the wingsBut the F-35u2019s horizontal stabilizers are typically not producing negative lift, because of the center of pressure is not really behind the center of gravity, so the plane is a relaxed stability design.Further, the clever intake design already gives most of the benefit conferred by the canards for high angle-of-attack lift.So, the canards donu2019t really have much of an advantage over the F-35u2019s design, and the F-35 has separated twin tails for high angle of attack controllability, which none of the eurocanard planes have.So, what about vectored thrust then?The point of vectored thrust is to allow retaining control at very high angles of attack/stall conditions. It does practically nothing when flying at normal angles of attack, such as when performing a sustained high-g turn. But the good control surfaces and control computer already allow the F-35 to stay in control for quite high angles of attack/strange situations, and flying (practically dropping) in a stalled condition in air combat is generally a very bad idea, as that means bleeding a lots of energy and becoming a sitting duck that cannot evade, an easy target for an enemy who pulls up and then dives from above to attack.
