Introduction to Aircraft Spins and Spin Recovery


Introduction to Spins and Spin Recovery – Video Transcript


Today we’re going to learn a little bit about spins. What’s important to understand here, is a lot of this will revolve around you having a fundamental understanding of a stall. I made a video on that previously, so if you have not seen that yet, I would recommend going back and watching that first and then coming back to this video as there’s going be some implied references to stalls as well in this video.

So, let’s break down what’s happening in the case of a spin. What is a spin? A spin is simply an uncontrolled condition of flight for an airplane where in which it is also stalled. That seems sort of simple, so let’s break that down a little bit more and talk a little bit about some of the different elements of a spin. To start with, the first main element of a spin is that we have to be stalled. So, we need the airplane to be in a stalled condition. The second piece is what is known as an incipient phase. The third is a fully developed spin and the fourth is the recovery. So, I want to walk through each of these different pieces and make sure we understand how they ultimately come together.

We understand how an airplane stalls, once again you can reference the previous video. Now how do we get into this incipient phase? Well really for the airplane to start to get into this uncontrolled condition, we are ultimately looking to have one wing become more stalled than another wing. That’s where this condition of a spin will begin. If we think about that a little bit further, how can we get into a condition where one wing is more stalled than another wing? The simplest example of this is becoming uncoordinated. So if we are uncoordinated as we stall the airplane what would happen? Well if we imagine for a moment that we become uncoordinated, and let’s say as we’re stalling the nose of the airplane, we yaw the nose to the right. Well what happens when we yaw the nose to the right is we suddenly have a larger volume or more airflow over the left wing, this outer wing, and less airflow over the inner wing, in this case the right wing. What does that mean? It means that they will be at slightly different angles of attack. What that equates to is, in this example, if that were to occur, we would say then that the right wing is more stalled than the left wing. The left wing is still stalled but maybe is closer to the critical angle of attack and the right wing in this case is much greater than the critical angle of attack. What will that result in? What would happen if we have two stalled wings but one wing is more stalled than the other wing? Well in order to understand that a little bit more, what we want to do is understand the physics behind what’s happening here.

Let’s take a look at a chart to better understand the aerodynamic principles that are taking place. If we do, we will notice that if we put a chart together, along the x axis will be the angle of attack, and along the y axis will be either lift / drag, either way, so some kind of force. If I do that, we could draw first this concept of lift relative to angle of attack. So, as I increased my angle of attack, we produce more and more lift. Which is true up until a certain point, which is known as the critical angle of attack. Once we reach that critical angle of attack, now lift will sharply fall off and produce less and less lift. What happens then with drag? Well as we produce higher and higher angles of attack, we create a larger pressure difference between the top and the bottom of the wing. Really what that results in, is an increase in induced drag. So, we would know that the same would occur for the drag curve. At low angles of attack, it would be relatively none and as we go to higher and higher angles of attack, the drag would become even greater. What we get then, is this condition where this drag line and this lift line are going to flip places. Where we are in normal flight conditions is between these, and what we see then, is after we exceed our critical angle of attack we get to a place where the more we increase our angle of attack the less lift we produce and the more drag we produce. So this is interesting! Once again, if we imagine our airplane with the right wing more stalled than the left wing, in that example, what we learned then, is if the right wing were more stalled, it would have less lift and more drag. Whereas in this case, then the left wing being less stalled would have less drag and more lift available. It’s still a stalled wing, but it is still producing relatively more lift than the right wing.

From that, we can get into another image of this airplane and what we see here, is exactly what I was just discussing before. We see that we have a right wing that is at a relatively higher angle of attack and therefore is producing less lift and producing more drag. Alternatively, on the left wing, it’s at a slightly lower angle of attack and therefore in this weird example, producing slightly more lift and less drag. What does that result in? Well this means that we have a condition now, where the airplane has less lift on the on the right side than it does on the left side so it’s going to roll to the right and it’s going to continue to roll to the right. Additionally, the right wing of the airplane has more drag than the left wing. What does that mean? Well that means that we would yaw to the right as well, and once again the more we yaw or the more we roll, the more aggravated that condition is going to continue to be. This is referred to as Auto roll and Auto yaw, meaning then this condition just perpetuates itself and the airplane would just continue to spiral around and around itself uncontrollably. This is why we referenced the idea of it being an uncontrolled, stalled flight condition. This would also be the time, once you’re into this phase where Auto roll and Auto yaw have taken over, this is where we would transition back to the fully developed phase of the spin. At this point now, the airplane is just going to continue to fall out of the sky and continue to yaw and roll around its center of gravity. At this point, the airplane cannot fix itself and would require intervention from a pilot in order to recover from this condition.

So now that we’ve worked through how we get the airplane into this uncontrolled spinned condition, let’s talk a little bit about how we’re going to recover from this particular condition. I want to make sort of a disclaimer really quick, every pilot’s operating handbook (POH) will have their own specific technique to recover for that particular make and model of airplane. You need to reference your POH for the specific way that the manufacturer recommends in recovery there, but in general, there’s typically four elements that go into some kind of spin recovery technique.

One of the first options is rudder in the opposite direction, meaning if we were spinning to the right, we would want to push left rudder. Second is pitched down, third is ailerons neutral and fourth is power idle. Some of these may seem obvious to you, others maybe not so much. Let’s break these down a little bit and discuss each one in a little bit more detail.

Step one, rudder in the opposite direction. Once again, in the example that we had previously, we were spinning to the right so ideally, we want to stop that auto yaw by applying left rudder. In a spin condition, our rudder is not a stalled airfoil, it’s still able to produce a force, in which case pushing the left rudder in that example would ideally reduce or entirely stop the auto yaw to the right.

Next is pitch down. Well pitching down, what is the function of this? We’re once again attempting to try to break the airplane out of a stalled condition. If the airplane isn’t stalled, then we’re not in a spin, we’re just simply in a steep spiraling turn, but it’s not a spin condition. So, pitching down is ideally there to, once again, try to break the stall or reduce our angle of attack.

Third on there was ailerons neutral. So, this is kind of interesting because inherently once again, in our example, if we were spinning to the right, natural instinct is to grab the yoke and crank it over to the left. What happens if we were to do that? What happens if we’re spinning to the right and we move the ailerons to the left? Well first, let’s think about the movement of the ailerons. As we move the yoke to the left, we know the left aileron will go up, the right aileron will go down, ideally then that means that the right aileron would have a greater angle of attack. However, if you recall as to what causes this whole auto yaw and auto roll specifically, it means the right wing is already at a higher angle of attack than the left wing. It is more stalled than the left wing, so by increasing its angle of attack even more by putting that aileron down, we’re going to cause this airplane to roll even harder into the direction of the spin. That auto roll will only become more aggravated. Now you might say, well let’s do the opposite. Let’s roll to the right. Okay, theoretically that may help in breaking the stalled condition, but this is not a normal reaction. If you’re spinning to the right, your reaction is not to roll even more right so it’s easier to just simply remember to keep the ailerons neutral. Don’t move them, just keep them neutral and that way we won’t have to deal with any negative impact of going the wrong direction.

The last item was power idle. Why do we want the power to be in idle? Well once again, the airplane is in this condition of auto yaw and auto roll. What does that mean? It means that it’s going to continue on this cycle indefinitely unless we break it. Adding power at this point, is only going to make that spinning happen faster, meaning it’s going to tighten the spin even more aggressively. So, we want power idle so that it’s not aggravated any further. Additionally, this is valuable because once we break the stalled condition, generally we’re now at a fairly low pitch attitude. If we have a lot of power and they’re at low pitch attitude, we’re going to gain airspeed very quickly and then we have potentially some issues as we pull out of this dive, that we could exceed g-force limitations or exceed airspeed limitations. So easiest to remember power idle, this will prevent any of that from occurring.

So now that we’ve walked through our four different phases of this spin, I want to just go over a few last key takeaways for you in this video. First is, as we stall an airplane or if we’re about to stall an airplane, remember to remain coordinated. These whole stall/spin pieces revolve around us being uncoordinated as we stall an airplane. So, it should be a key takeaway for you that as you ever practice stalls, or if you find yourself in conditions where you might be about to stall, remember to remain coordinated all the time. Number two – if the airplane does begin to roll into a spin, you should begin the recovery technique  immediately! What I mean by that is, you don’t have to wait for the stall to become fully developed to recover from it. If you see the airplane starting to yaw and roll to one direction, you can immediately begin your recovery technique or your recovery procedure. The last piece that I want you to take away from this, is the recovery pieces that we talked about are generally four elements that are found in all recovery procedures. However, different manufacturers have different recommendations, so always check your pilot’s operating handbook (POH). Make sure that you know your particular recovery procedure in your exact make and model aircraft. I hope this video has been very helpful and insightful and allowed you to learn a little bit more about spins.

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