Aviation Stack Exchange is a question and answer site for aircraft pilots, mechanics, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
In Top Gun, Maverick's F-14 enters a flat spin after flying through another F-14's jetwash, forcing him to eject and causing the death of Goose.
Is this scenario possible or was it only created for theatrical purposes?
If not, how does it happen, and how can it be avoided, especially for other types of aircraft such as the B-2?
The F-14 is special; to stop the flat spin you need to pull on the stick. Then the spin can be recovered from.
This is different from what you learn about regular spins, where pushing the stick would be a better recovery method. In a flat spin, the forward fuselage dominates the aerodynamic forces, and we all know there are no control surfaces which could influence this flow. Wings and horizontal surfaces are fully separated, and elevator deflection is mostly useless. As others have pointed out before, a flat spin can only be stopped by shifting the center of gravity forward or deploying a spin chute. The F-14 was an exception.
Early on, the Navy lost several F-14s due to flat spins. They then studied the phenomenon at Pax River, and in the end Bill Bihrle found out that the elevator shields airflow from the two vertical tails of the F-14 when the stick is pushed, but moves out of the way when the stick is pulled full aft. You have to know that the elevator of the F-14 is a full-flying surface, and the movement range is from -20° to +70°. At +70° it is almost in line with the airflow in a flat spin, and now the vertical tails are no longer in the wake of the elevator. They now can reduce the high yaw rate, which in turn reduces the high pitch-up moment of the rotating fuselage. With the lower inertial pitch-up moment, the elevator then has to be moved back to neutral, and the drag from wing and elevator is enough to pitch the aircraft fully down and out of the spin.
Naturally stable flying wings never enter a flat spin; their spin modes are all fairly steep due to the lack of a strong inertial moment from the lengthwise distribution of masses.
I guess I now need to explain the inertial moment which causes the high pitch attitude in some aircraft. The axis of the spin rotation is close to the aircraft's nose, and the tail has the biggest distance from this axis. In a flat spin the axis of rotation is even more back, close to the center of gravity. All parts of the aircraft rotate with the same yaw rate, and the centrifugal force from this yawing motion grows linearly with distance from the spin axis. This difference in centrifugal force along the lengthwise coordinate of the aircraft pulls the aircraft in a near-horizontal attitude.
Watch this movie of the spinning XB-70 to get an idea how it looks. Depending on elevon settings, the spin axis is somewhere between the cockpit and the forward tip of the wing triangle. With the damaged configuration (watch without sound for no distraction) you get a typical flat spin with the spin axis close to the center of gravity since there are few suction forces acting on most surfaces - only drag and the nose vortex (more on that below) remain.
If you have a configuration which is prone to flat spins, you need to change the shape of the fuselage tip. A rotating fuselage tip at high angle of attack will produce vortices at its side, and the yawing moment of these vortices will grow stronger with increasing yawing motion. This is why a flat spin is self-stabilizing. One way to suppress these vortices is the placement of small spoiler strips along the nose (which fixes the vortex position and reduces this self-stabilizing effect), and another is to make the nose shape flatter.
Unfortunately, this can only be done long before take-off.
Regarding the "Top Gun" scenario: If the F-14 is at high angle of attack and the jet wash hits it asymmetrically, the airplane could enter into a spin. But from there it is still some way to the fully developed flat spin, and I would expect that a skilled pilot could recover from this momentary upset.
I have recovered from a flat spin doing upset training in a Extra300L. Here's the video (you'll notice a secondary stall at 0:33 because I pulled too hard in the dive).
It's interesting to note how one enters such a spin: first you enter a regular spin, and let it develop fully, then you do everything wrong: add full power, pull back on the sick, and depress the "soft" rudder in the direction of the spin.
What happens is very interesting: the spin starts to accelerate as the point of rotation moves from somewhere in front of the nose, backwards until it's inside the plane and the nose is moving one way (EG port) and the tail moving the other (starboard). It rotates a few times per second.
The recovery was fairly standard in the Extra300L: just PARE, and you're out in a second (that feels like an hour)
The key to recovering from a flat spin is partly in the aircraft's design (aerobatic aircraft are built to handle "flatter" spins than normal aircraft and recover more readily), partly in the loading (specifically the location of the center of gravity), and partly in how "flat" the spin actually is.
There is going to be a point for any aircraft where you simply don't have the control authority to recover though (absent something extreme like mounting JATO bottles to the wing and firing them opposite the direction of the spin to stop the rotation).
There are definitely instances where pilots have been able to recover from a flat spin though - one example being is the Piper Owner story Jay Carr pointed out. Aircraft can sometimes even recover on their own, such as the "cornfield bomber" which actually recovered itself after the pilot ejected.
I can't locate the article, but I recall early in my training reading a story about an instructor and student who entered an inadvertent spin while practicing stalls. The spin went flat, and they were only able to recover by literally climbing forward onto the glare shield to move the center of gravity far enough forward that the nose dropped and normal spin recovery procedures were effective.
As for avoiding flat spins, they're best avoided by avoiding spins entirely, and by applying prompt and correct recovery inputs if a spin is inadvertently entered (spins tend to "go flat" as they progress, so recovering early minimizes the risk of a "regular" spin going flat).
How easy that recovery is depends on the aircraft's loading (center of gravity) - as illustrated by the "climb onto the glare shield" example above.
Every airplane type has it'd own unique way of spinning. It can happen to also have an irregular spin path with a partial flat spin.
In a flat spin, you almost have no authority on the controls, but the center of gravity (CoG) in a forward position (all planes are usually designed in that way) will convert the flat spin into a dive spin and so by gaining again authority on the rudder you can exit from the spin sooner.
It's the higher weight in the forward position together with gravity being the main cause of converting a flat spin into a dive spin. Most modern light planes are designed to automatically exit from a spin, even without any action from the pilot. It is also quite simple to exit a spin, but how varies from plane to plane. Usually, you put full rudder against the spin direction, push the stick slowly forward a bit and wait. Aerobatic planes enjoy doing spins without any extra risks compared to normal flight.
The real problem is the high loss of altitude while waiting to exit from the spin. The plane will have a high vertical speed, so the danger comes from if there isn't enough altitude at the start of spin. A spin while landing is usually deadly. With unlimited altitude, every plane mathematically would exit sooner or later from any kind of spin, simply due to air friction, but this is theory since altitude is always quite limited. Another problem for spins, is that you may not realize that you are spinning at all and so take wrong actions.
Military jets are different. They are built to be dynamically unstable for better reactivity. I don't know much about them. Still, with a CoG in a forward position, they too, should convert a flat spin into a dive spin. The main problem is still enough altitude. A few rotations may be all you have before reaching the ground.
To intentionally enter a spin, you need low speed; it's a stall condition of only one wing, which will drop, starting an auto-rotation which then converts to a spin. All this can be easily avoided with enough speed. Even if the engines are dead, you can always glide to the ground at the speed you wish.
A flat spin is a spin where, the aircraft is in a balanced state. It just spins round and around like a spinning top. It won't recover because the forces acting on the airplane are in equilibrium. Controls and engine power become completely ineffective.
Can it happen? Yes, depending on the airplane design and center of gravity. If CG is aft it's more likely.
How to avoid? To spin, you must first stall. Avoiding stalls and proper stall recovery procedures are ways to go.
My instructor, who was a military pilot, told us that one F-16 pilot entered a flat spin when he was playing around. He did not want to eject as the tapes would show that he lost a completely good aircraft on his own, not due to failures or accidents. He climbed out of the cockpit towards the nose. This upset the balance and tipped the nose down. He then climbed back and recovered the aircraft.
I took a CFI student for mandatory spin training in a Cessna 152 Aerobat. He did 3 spins to the right and recovered. After completing his 3 spins to the left the recovery procedure did not work so I told him to repeat. The second recovery also failed so I took the controls. The spin by this point had developed into a flat spin with the nose to the horizon and a much faster rotation than normal about the center of the aircraft and a very high descent rate. I too tried the recovery procedure to no avail.
Prior to the flight, the student taught me the spin recovery technique as if I were the student. Though I had heard "move the control wheel briskly forward" a thousand times, this time I pondered why "briskly" was so important. I remembered my ponderings in the midst of our flat spin, with the yoke all the way forward. I then brought the yoke back the the aft position and again threw it "briskly" forward. When I did, I noticed a slight rock in the aircraft's pitch. I repeated this, slamming the yoke all the way aft and forward again. Each time the plane rocked more and more. After doing this about 6 times, the aircraft rocked (pitched) far enough nose down to regain air flow over the rudder and allow for a recovery.
The student and I were extremely dizzy after spinning so fast for so long. The student was so shocked by the experience that he quit his flight training.
Back at the flight school I reported what happened. A mechanic told me that a flat spin can sometimes occur with the right amount of fuel in the tanks, somewhere around half full. He said that the initial spin can sling the fuel to the ends of the wings - that coupled with the rotation can create a sort of gyroscopic effect and force the plane into a flat spin. Not sure if that is true but it seemed plausible at the time because we had half tanks.
I do not claim this is the proper way to recover from a flat spin in any aircraft but at the time I had run out of options and this seems to have saved my life.
The best recovery technique for a flat spin will vary from one aircraft to another. I had a radio-controlled model airplane of a basically conventional high-wing design (but a fair bit of dihedral and no ailerons) that could be put into a very flat spin. Recovery was ONLY possible if I applied power; rudder and elevator alone wouldn't do it. In fact adding power would bring the plane out of the spin even if the rudder and elevator were kept centered. Then I added ailerons to the wing and found that applying ailerons INTO the spin was also an effective recovery technique. Again this technique was effective enough that it would effect recovery even if the rudder and elevator were kept centered.
I flew Harvards for 7 years (1961 to 1968) in Calgary (CYYC), doing Cloud Seeding (Hail-Suppression). The pre-modified MK2’s on occasion would go into a flat-spin. We didn’t practice it but were told to rock the AT6 nose up then down by applying full power and at the same time pull back all the way on the control column, then immediately push full forward on the control column at the same time as pulling power back to idle. Hopefully this would force the AT6 to get nose down to build up speed. Then recover to level flight. They then rectified AT6 flat spins by adding lead weights to the motor-mounts which is ahead of the CofG. The MK4’s had the forward extra weight built in during manufacturing, which solved the problem. JH
I have only done flat spins in a Pitts S1.
The inverted ones are oscillatory with a lot of buffeting and control snatching, but recovery is quick (rudder not shielded by tail plane and elevator).
Upright flat spins are smooth and stable, rotation not that fast and sink rate comparatively low.
To enter, start with a normal left rudder power off spin. After a turn, add full right aileron which flattens the attitude a fair bit and then add power. The nose comes up to the horizon and the bank angle is about 25 deg to the left.
I watch the altimeter closely. Power-off recovery apparently takes some time but I have not tried it as I use the technique described in Alan Cassidy’s book, Better Aerobatics. Which is leaving the power on (the better airflow over the tail overcomes the nose-up gyroscopic effect of the left yaw); full opposite - Right- rudder then make sure the stick is in the rear, right corner, then move it to the left rear corner, then easing it forward while holding full left aileron. The S1 stops very quickly after that, centralise and pull out.
Looking at the F4U with the cowls and panels off and seeing that huge R2800 so far forward, I was reminded of the Vought test pilot, Boone Guyton saying to another pilot “if you are thinking about spinning the Corsair, don’t”.
Rotating masses and Conservation of Angular Momentum etc. I wouldn’t spin anything without type specific instructions or good advice, but the Pitts S1 has all the masses close together, is well sorted and understood. It is the most honest machine I have flown in 48 years.
Flat spin is worst case scenario of pilot mistake and fatal for all types of aircrafts, except fighters, and with thrust to weight ratio of no less, than 0.72-0.75. Thus even military A10 will be lost if it happens, let alone any passenger aircraft. Modern aircrafts have CG moved to nose with massive engines though, and have a chance to move nose down, if at early stage of flat spin. If developed, and plane goes as falling leaf, or rotating stbilised,theres no chance to recover.
