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You’ve probably seen it happen in the movies and wondered how it was even possible. If it was even possible. So how do planes fly upside down?
Planes can be flown upside down by either having symmetric airfoil designs (top and bottom are both rounded) or by altering the angle of attack as necessary to generate lift if the airfoil is asymmetric. The key to sustained inverted flight is being able to generate lift even while upside down.
Even after reading this article, we don’t recommend that you go get in your airplane and try to fly upside down! It’s disorienting, confusing, and dangerous. But with some airplanes, it is possible. In this article, you’ll learn how planes can be flown upside down, how dangerous it is, how long people can sustain being upside down, and if all planes are able to be upside down.
I’ll be the first to admit, I’ve never actually flown a plane upside down. But then again, I’d assume that the vast majority of pilots out there also haven’t either! So to ensure you’re getting the best content on the web, we had to drill deep into this one in terms of research and discussions with others in the industry to really figure out how planes fly upside down.
Can Planes Fly Upside Down?
You’ve seen it on TV or in the movies, right? That dramatic scene where the pilot needs to fly the plane upside down to save the airplane and everyone on it. We’re looking at you Flight and Denzel Washington. And while that scene was breathtaking, it begs the question: can planes really fly upside down?
The short answer is yes, some planes really can fly upside down! But that doesn’t mean you should go hop in your Cessna this weekend and go for an inverted joy ride. Not only are most planes not designed for upside down flight (even though some that aren’t designed for it can handle it in a pinch), but very few pilots are trained for it.
So if some planes actually are capable of upside down flight, how do the pilots do it and what enables the planes to be able to fly while inverted?
How Do Pilots Fly A Plane Upside Down?
Keep in mind that throughout this article, we’re focusing on airplanes that are designed to be able to be flown upside down. Not on the cinematic experiences of commercial pilots flying an airplane full of people upside down as the only way to survive. That said, the concepts of inverted flight remain the same regardless of if we’re talking about a stunt plane or an airliner.
In the most general sense of the idea, flying upside down needs the same four components of flight any plane needs to fly. That’s because how planes fly remains the same regardless of if they’re inverted or flying like normal. The four forces that act on a plane and are required for flight, in any case, are thrust (power), drag, gravity, and lift. Three of those four remain more or less the same even if a plane is upside down.
The key here is lift. The plane must be able to generate lift no matter its orientation if you plan on staying in the air. One of the issues with flying upside down is that the wings of an aircraft are typically designed to generate lift only while being flown right side up. That’s because an airfoil is usually designed with a rounded top and a flat bottom.
This forces air to move faster over the top than the bottom, causing higher pressure to be built up underneath the wing and lower pressure to be over the wing due to the different airspeeds. This difference in pressure is really how planes are able to generate lift and actually fly through the air. So when the airplane is inverted, this effect is opposite, and the plane would naturally generate downward force instead of lift.
This can be overcome by simply altering the angle of attack. This is basically just the angle that the front of the wings makes with the airstream that you’re flying through. Even if the airfoil is designed to only generate lift while right side up, that’s also really only the case during the climb and the cruise. Otherwise, you wouldn’t be able to descend, right?
When the pilot descends towards the airport to land, they tip the nose forward, changing the angle of attack. This helps to reduce the effect of lift and allows the plane to drop in altitude. This same principle can be applied while inverted. Regardless of the airfoil shape, the pilot can change the angle of attack and generate lift by deflecting more air downward and creating an area of high pressure below the wings.
To do this while upside down, the pilot would need to raise the nose of the airplane. But since everything is inverted, that would be like lowering the nose of the airplane during normal flight. This can quickly become disorienting if you aren’t trained for it and understand how to handle it, but we’ll cover that more in-depth in the next section.
Airplanes that are designed for upside flight, such as stunt planes and acrobatic planes, have much simpler airfoil designs. On these planes, the wings are rounded on both the top and the bottom, creating a symmetric airfoil that does next to nothing when it comes to generating lift since the air moves across the top and bottom at the same speed.
The reason for a symmetric airfoil is so that once the planes are upside down, they are able to be flown exactly the same as when they’re right side up, albeit with the angles are directions of course being flipped. The ways that the pilots generate lift in these types of plane relies almost entirely on the angle of attack.
While flying right side up, the pilots will fly with the nose raised every so slightly to deflect air flow downward and generate lift. If they go inverted to begin flying upside down, the pilot will tilt their controls the opposite way. This will force the nose to angle downward, but while inverted, this will of course be upwards and generate lift in exactly the same way as before!
So overall, to fly upside down, the key is being able to generate lift. This is accomplished through different airfoil designs and altering the angle of attack.
Is Flying Upside Down Dangerous?
Flying upside down is incredibly dangerous for anyone, even those who are trained to do so. Flying in general can always be a little difficult and stressful, that’s part of what makes it so thrilling and why after all these years I still get an adrenaline high while flying! But for someone not trained in flying upside down, doing so would very likely lead to a disaster such as a plane crash.
The main reason why flying upside down is so dangerous is simply because of the pilot not being ready to handle it and all the changes that come with it. As you just read above, there is nothing particularly special about upside down flight in terms of the physics. But just think about it as a pilot. Suddenly you’re inverted and everything is different. Everything.
Here are some of the main things you’ll need to keep in mind to safely fly upside down:
- Everything is upside down so you need to think about everything opposite. Up is down, left is right, etc. It can become very confusing and very disorienting very quickly.
- Since you’re flying in negative-g, you’ll have to bank the opposite way to turn the way you want. I.e. bank left to turn right, right to turn left. Rudder control and turning will be the opposite of normal.
- Your compass will be backward. If you’re flying north, east will be on your left side and west will be on the right.
- Systems aren’t designed to be inverted like that. Avionics will freak out, autopilot won’t know what’s going on, the fuel system might quit working, etc.
That all goes to say that without proper training and understanding of flying while inverted, it can be very dangerous.
Can All Planes Fly Upside Down?
As much as we’d like to say that all types of planes can be flown upside down, that isn’t really the case. Stunt planes and acrobatic planes are designed specifically to be flown either right side up or upside down, so it’s not a problem for them. And while the pilot can adjust the angle of attack in other aircraft to generate lift while inverted, it isn’t very practical in most planes. Especially not something like a commercial airliner.
Stunt planes and fighter jets can effortlessly roll as they’re flying since they’re designed to do so. But something like a Boeing 787 is not designed to so easily roll over and fly upside down. The size, weight, aerodynamics...everything. It would all be fighting against going inverted in the first place. But if a commercial pilot was able to get the plane to go upside down, then theoretically it would be possible to maintain flight for a short time.
The same goes for personal aircraft, such as the ones you might own. While it might be possible, we definitely don’t recommend trying it any time soon!