F-16 Fighting Falcon: Designed for Aerodynamic Instability

[00:00:00]Testing a prototype aircraft could be  tricky, especially when a high-speed taxi test turns into the first accidental  flight of this experimental airplane.

[00:00:12]Within seconds of taxiing, one wheel lifts  off the ground. The airplane starts to roll the left and the pilot tries to correct it  by rolling to the right. Before you know it, the back and forth became quite aggressive, in  what’s known as a “pilot-induced oscillation”. A disaster seemed to be inevitable, until the pilot  decided to power up and simply let go of control.

[00:00:37]He avoided an imminent crash by taking off,  which became the maiden flight of the YF-16, the early prototype of the  infamous F-16 fighter jet.

[00:00:49]Now here is the interesting part: that violent  oscillation wasn’t the pilot’s fault. The YF-16 was designed to be unstable. But why would the  US Air Force intentionally design and create a fighter jet that was unstable? Don’t be shy, say  the words with me, ‘cause It’s Not What You Think!

[00:01:13]Most of us have not flown an airplane, let alone  a fighter jet, but I bet you have some experience folding sheets of paper into airplanes. It was  always a bit of a lottery what you’d get, wasn’t it? Some paper planes flew straight no matter how  you threw them – a smooth and long flight. We all loved those ones! But sometimes, you’d end up  with utter embarrassment – a paper plane that would do all sorts of weird maneuvers, anything  but straight flight, and then quickly crash.

[00:01:48]You probably never made one of those weird  crashy paper planes intentionally … but that’s exactly what the US Air Force did, or more  precisely, the Fighter Mafia who was behind the idea of having an unstable design.  And that’s because they were fed up with American fighter jets losing in air-to-air  combat to the Soviet MIGs during Vietnam.

[00:02:13]During the Vietnam war, the US Air  Force realized the harsh truth that their fighter jets cannot win close air  combat, or what’s known as “dogfights”.

[00:02:23]American fighter jets were too  big, too heavy, and not very agile, especially when compared to a MIG-21 – the  flying Kalashnikov in the world of air battles.

[00:02:36]Take the F-4 Phantom, for example. It weighed  19 tons compared to the MIG-21 at only 10 tons.

[00:02:45]The dual engines of the Phantom allowed it  to fly farther and carry heavier armament, but it made it heavy and slow to maneuver.

[00:02:54]During the Vietnam war, the United States  lost about 3,700 airplanes in combat, 382 of which were F-4 Phantoms. If it wasn’t the Soviet  fighter jets, it was Viet Cong’s anti-air missiles that could target these fighter jets which had  grown increasingly heavy and unmaneuverable.

[00:03:15]The recipe for beating Soviet jets  was advocated by a small yet vocal group of engineers and defense analysts,  known as the Lightweight Fighter Mafia.

[00:03:27]Their solution was to trade excess weight and  heavy payloads for speed and maneuverability, to develop a simple fighter that  could fly so fast and turn so quickly, that adversaries wouldn’t be able to strike it  with missiles or machine guns. At the same time, the price had to be low enough so that the  US military could procure them en masse.

[00:03:48]In other words, the engineers had to work  their butts off to get this one done!

[00:03:54]After many sleepless nights … who am I  kidding. They just pulled an “Apple”.

[00:03:58]You know, how Apple makes things smaller,  and removes components from its products and calls it a “feature”? That’s  what happened here too, kinda!

[00:04:08]The previous jets were bigger. The  F-16 was made noticeably smaller.

[00:04:13]The older fighter jets had 2  engines. The engineers removed one, so the F-16 only had one engine. The  older jets were aerodynamically stable.

[00:04:23]The engineers removed that too! Now the  airplane was unstable! What a feature!

[00:04:31]But kidding aside, that was in fact a feature,  because stability and maneuverability are two sides of the same coin. To make the airplane  more maneuverable, it had to be made less stable.

[00:05:56]Look at passenger airliners. They’re built  for a stable flight. They are meant to move in a more or less straight line for  most of their journey and transport passengers to their destination,  no matter how small the leg room!

[00:06:11]A boeing 747 doesn’t need to make sharp turns,  roll quickly or climb up fast. But even more importantly, if the pilot did decide to do some  maneuvering, an airliner would quickly return to its level flying position – because it's designed  and built for stability, not maneuverability.

[00:06:32]This stability is achieved by having  the airplane's center of gravity in front of its center of lift and center of  pressure, giving it a nose-down attitude.

[00:06:42]If the pilot let go of all control in the middle  of a turn, the airplane would straighten up by itself, similar to how your car would straighten  up itself when you let go of the steering wheel after a turn, or how a bicycle would go  straight if you let it run free downhill.

[00:07:00]The airliners are designed after  our favorite paper planes which go straight no matter how you throw them.  But that’s not the case with the F-16.

[00:07:12]To make the F-16 more maneuverable, its  center of gravity was moved backward.

[00:07:18]Its wings were made smaller and highly swept,  in order to reduce drag. This airplane also incorporated the concept of “relaxed/negative  stability” – a tendency to change pitch and bank angle spontaneously. Congratulations!  You got yourself a very maneuverable airplane!

[00:07:39]But an airplane with such a design would  constantly be on the verge of flipping up and down, requiring constant adjustments to  its flight control surfaces just to keep moving in a straight line – practically impossible to  fly, kinda like those unfavorable paper planes.

[00:07:56]And that’s why in order to make the F-16 flyable,  they put a computer in charge of making all those little but constant adjustments, or as known  by its stage name, the fly-by-wire-system.

[00:08:11]Back in the 1970s, the F-16 became one of  the first fighter aircraft to use fly-by-wire technology. The system consisted of three  main components: the pilot's control inputs, a computerized flight control system, and the  actuators that moved the control surfaces.

[00:08:31]It was the computerized flight control  system that created artificial stability.

[00:08:36]This was accomplished by receiving feedback from  sensors about the actual position of the control surfaces, and then adjusting the commands as  needed to achieve the desired flight path.

[00:08:47]So if the pilot let go of all controls,  the computerized system would do all the work needed to smoothly fly  this otherwise unstable aircraft.

[00:08:58]That said, pilots still needed to learn a lot  in order to adapt to the fly-by-wire system.

[00:09:03]This required handling lots of data, such  as inertial and air data, accelerometers and gyrometers, radio altimeters, and so on … oh  and with power came a lot of responsibility.

[00:09:19]The F-16s may have one engine, but this Pratt &  Whitney F-100 engine can accelerate the pilot to a point that they’d feel 9 times heavier than their  regular weight. That’s what 9G would do to you, and if you’re not prepared, a G-LOC or G-force  Induced Loss Of Consciousness is in order.

[00:09:41]When the body is subjected to high levels  of gravitational force, there is a sudden reduction in blood flow to the brain, and a  brain deprived of oxygen will go unconscious.

[00:09:54]To mitigate this, the F-16’s pilot seat  is designed to tilt back at a specific angle during high-G maneuvers, which helps to  keep the pilot's blood in their upper body.

[00:10:06]On top of that, pilots wear G-suits. When high  G forces are detected, typically above 3-4 Gs, the inflatable bladders inside the G-suit apply  pressure to the lower body, pushing the blood back up into your head, where it’s badly needed!  But if all that fails, this is what happens: Note the rapid decrease in altitude.

[00:10:35]Thanks to the Automatic Ground  Collision Avoidance System, an imminent ground collision was detected and a  fly up maneuver to roll the F-16’s wings level and upright was initiated to give this student  pilot some time to regain his consciousness.

[00:10:56]These flying machines are  equipped with some top technology.

[00:10:58]But if you were to purchase an F-16,  which is possible, but not very probable, keep in mind that these airplanes would be  demilitarized before sale – stripped off of any advanced tech that could be used for military  purposes. They would of course leave the canopy on … which by the way is bird-proof – made  much thicker to withstand bird collisions.

[00:11:20]Can’t say the same about the birds  though — they aren’t F-16-proof … yet!

[00:11:27]The US government must sign off  on any resales of F-16 fighters.

[00:11:33]In 2021, “Top Aces” became the first private  company in the world to acquire F-16s.

[00:11:39]But only because they provide Contracted  Adversary Training to the US military.

[00:11:45]In a nutshell, they provide realistic  training scenarios, including advanced tactics and maneuvers, to help pilots improve  their combat readiness and survivability.

[00:11:56]The chances are, the government would not  sell an F-16 to a person who just wants to fly it for fun. Even if they did,  the owner would need to buy a two-seat version of the aircraft so he or she can  be type-certified by an instructor pilot.

[00:12:13]At a price of $12 million dollars  back in the 1980s, the F-16 became the first production fighter aircraft that  was designed to be aerodynamically unstable.

[00:12:22]Since then, many modern military aircraft,  particularly stealth designs, also exhibit instability as a result of their unconventional  shape. Take the F-117 Nighthawk as an example with its flat facets, which also demand a computerized  fly-by-wire system in order to properly fly.

[00:12:43]Aside from the F-16, other successful designs  like the F-14, F-15 and F/A-18 are all examples of warplanes that were influenced by  the Fighter Mafia’s principles of making fighter jets lighter and more maneuverable.  Although, they did mess up the nickname!

[00:13:03]At first, the F-16 was nicknamed Viper, because  it resembles a cobra as it approaches you, but generals didn’t want to  name something that flies after something that crawls! So the  F-16 was renamed to Fighting Falcon.

[00:13:21]With more than 3,000 Fighting Falcons in service  with the US and its allies, all parts, training, and manufacturing facilities can be pooled,  items can be shared, and stockpiling is reduced.

[00:13:34]But that said, the US Air Force is already  looking for a replacement for the F-16s.

[00:13:41]Most of these replacements, such as the F-35 or  F-22, are too expensive to build and utilize, so in the meantime, F-16 is being supported  until a new revolutionary airplane comes in.

[00:13:54]When would that be? “Never”  may be too loud a word for it, but it is estimated that the F-16  will remain in service until 2050.