A physicist can become a pilot. But does a pilot have to become a physicist? I don’t think so.
In fact, I’m sure of it.
It’s perfectly okay for a pilot — a good pilot, a really good, safe, conscientious pilot — to have only a passing understanding of important scientific theories. Theories like, how does lift work?
I believe that with all my heart and soul. Let the fireworks begin.
The great and powerful Paul Bertorelli recently published a piece on AvWeb titled, “Wait, you mean Bernoulli had it all wrong?” This short article garnered quite a bit of attention.
Paul is demonstrably braver than I am, so I doff my hat to him in taking the lead on this issue.
Although, contrary to the title, the thrust of his piece is not that Bernoulli was mistaken. In point of fact, it’s not so much that Daniel Bernoulli blew it, as it is that a long line of well-intentioned flight instructors have explained his discovery…let’s say poorly. I include myself in that pool of unsophisticated scholars.
A week after Bertorlelli’s piece ran, Isabel Goyer published a supporting piece in Plane & Pilot Magazine that took up for Bertorelli. I shared that piece via social media and was intrigued by the responses. All were respectful, but they took various perspectives on the topic, which got me thinking.
What if the topic in question wasn’t lift, but was something else that directly affected aircraft in flight? Would we still believe that it’s essential for pilots to understand the subject down to the molecular level? Probably not, although that’s essentially what the hubbub is about when it comes to lift.
You’ve been taught, and I’ve been taught, and pretty much every pilot in existence has been taught, that lift occurs because an air molecule traveling over the upper, curved side of an airfoil has farther to go than a molecule of air traveling under the flatter side. Because it has further to go it has to move faster, and because it moves faster there is a drop in air pressure, resulting in lift.
That’s sort of true. At least in parts. But it’s also largely incorrect.
Still, it’s what we’ve been teaching and learning for the better part of a century. Which raises an interesting question. If it is indeed important that pilots learn about the science of lift to the molecular level, does it matter at all if the information they learn is correct? That would seem to be somewhat important, at least to my mind.
So as I said, I began to wonder if we should be encouraged to understand other forces that affect flight.
Gravity for instance. Now, I know it is weight, not gravity, that counters lift. It’s weight, along with lift, thrust, and drag that make up the all-important Four Forces of Flight.
But gravity certainly plays a role when we discuss weight. That being the case, how precisely do you suppose a pilot has to understand gravity to fly safely? Do we need to have a thorough understanding of what Einstein proposed about gravity and space/time, or is it sufficient to understand that gravity acts downward, toward the center of the earth?
Like the theory of lift we’ve been taught, the belief that gravity acts toward the center of the Earth is not entirely correct. At the very least it’s incomplete. But it is a way of viewing the phenomenon that is practical, understandable, and can reliably guide our actions to keep us safe.
Let me propose something radical. Brace yourself.
Perhaps it’s not so bad to be ignorant of the fine details of a topic, provided you have an understanding of how the topic in question will affect you in the pursuit of specific activities.
In other words, if you don’t understand how lift is created, but you know how to apply it to your aircraft – you win. If the movement and speed of individual air molecules eludes you, but the importance of Angle of Attack is deeply rooted in your psyche, then as a pilot, you’re in good shape.
Is that so wrong?
Jeff Goin is one of the smartest, most experienced pilots I know. He’s also absolutely gonzo nuts about sharing his knowledge with others. His day job has him plying the skies in transport category aircraft. But when he’s home he can often be found just a few dozen feet above the ground, swinging beneath the canopy of a powered parachute.
The man flies fixed wing, rotor-wing, weight-shift, and pretty much anything he can lay his hands on that will get him airborne. He’s so thoroughly enthralled with flight, including the simplest and most basic machines that will get him there, he’s written the bible on them. Literally. He wrote The Powered Paragliding Bible.
Thanks to Paul, and Isabel, and Jeff, I believe I’ve changed my formerly errant ways when it comes to teaching about lift and drag and such. Yes, I’ve been converted and now subscribe to Goin’s exceedingly simple but easily supportable hypothesis regarding aerodynamics.
Which is this: “Everything you need to know about aerodynamics can be learned by sticking your hand out the window of a moving car.”
Now that’s teaching a practical level of knowledge I can get serious about.
OK, I know that I speak for a large majority of GA flyers that are afraid to jump into the dark waters of this shark pool. BUT, it is New Years Eve and I can always make like this happened last year and doesn’t count in the overall plan for the new year.
All that I was taught and what I have taught to high school physics students(split air flow, faster air, rejoined at trailing edge, low pressure area, lift) is in error, at least partly. What is going on? I too played with models out the window of my dad’s ‘53 Chevy. I often visualized a “pillow” of air that I balanced my model on, as it moved faster the pillow got harder and my model was pushed away with more force. There must be a simpler explanation that will help the majority of us understand what is going on without earning a PhD in that process. I thought I was going to find that at the end of your article. I was disappointed to say the least…….I either missed it or you left the silent ignorant majority hanging. Perhaps my AOA. Is wrong?
If all this is true – air flowing over the top of the wing travels faster than the air under the wing produces a low pressure above the wing and high pressure below the wing….OK how do we explain an airplane that is flying UP-SIDE DOWN That is inverted?
Can you visualize a positive AOA on an inverted wing? It takes more AOA to fly inverted because the wing must compensate for the small lift force created by the airfoil shape and the down force of the tail.
The fictitious “Centrifugal Force” is all over the training information on rotorcraft.
So is the Coriolis “Force”.
The FAA deems to take training so seriously. It would help if it wasn’t based on old wive’s tales.
https://en.wikipedia.org/wiki/Centrifugal_force
If a person looks at the 4 forces diagram they can get the wrong idea.
The static CG is located forward of the center of lift to provide stability. The dynamic weight moves with the elevator application and the CG range limit is established by the critical angle of attack of the elevator and horizontal tail plane.
If the CG limits are exceeded the main wing can exceed the critical angle and enter an unrecoverable stall. If the CG is aft of the CG limit there will be instability and over control will be almost certain.
The tail pushes downward and works on the arm from the CG to the center of pressure on the elevator. With a foreplane the surface lifts upward.
Stalling the elevator reduces the tail forces and the CG pitches the wing to a lower angle of attack.
I’m sure somebody has a GIF that shows this on a series of slides.
But that is why CG is so important, do your W&B and don’t exceed the certified limits unless you have a parachute and all risk insurance.
The question likely should not be “do we need to know physics to fly safetly” but rather “do we need to be taught the proper concepts in physics that apply to lift, drag, and even more critically, load factors (F=Ma) to fly safely?” And the answer to those questions are: yes.
In every phase of flight physics principles are core that what is happening. If all you know is that you push that knob or pull on that lever and read that number then “hope” for the best; how is that going to keep you out of trouble?
Stevie Wonder uttered a great lyric once: “When you believe in things that you don’t understand, then you suffer.” Think about it.
As an airline pilot I’m glad I understand the physics of flying so I can keep out of situations where a plane stops flying for the safety of my passengers and crew. Do I need to know what makes a plane fly? Yes, but more importantly I need to know what stops the plane from flying. Keep the dirty side down.
As Langeweische said in ‘Stick and Rudder’, forget Bernoulli’, on page 7. He describes flying as an ‘art’.
He wrote this book in 1944, and spends the first 100 pages describing how the ‘angle of attack’ is so important in keeping the aircraft flying.
I have recently re-read this book after first reading it 20+ years ago, when I started flight training.
I find it more useful and instructive now as an experienced pilot.
Exactly!
When I was a kid, back in the day before all cars were air conditioned, on road trips my brother and I always took books and plastic model airplanes along. Holding the airplane out the window, watching the prop(s) turn in the wind and maneuving the wing taught us about AOA and lift. My dad, who instructed for the USAF for almost 10,000 hours, said it was very useful flight training, I agree. It’s easier for me, after nearly 50 years of flying on my own to visualize what the wing is doing because of what I learned with my arm out the window lo those many years ago!
I did the same thing. My airplane of choice was a Revell Grumman Cougar. I’d give anything just to sit in one.
“Do you need to understand the science of flight to be a good pilot?”
Let’s rephrase that to “Do you need to understand the science of flight to be a pilot?”
The short answer is “No”.
However, if you want to append any comparative adjective to “pilot” – (i.e. good, better, best, outstanding, superlative, etc) – you need more than “stick and rudder” skills. The “how and why” are just as important.
You don’t want to be this guy:
Q What makes an aircraft fly?
A Money.
Q How does a helicopter fly?
A It beats the air into submission.
Joking, of course. But you get the idea. Knowledge is never out of fashion.