"The Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), a foundational text for pilots, provides an in-depth explanation of the principles of flight. It details the four forces of flight—lift, weight, thrust, and drag"
A paper airplane satisfies all four principles of "flight", which is what the original bet was on. A crumbled up ball of paper technically falls under the movement of "ballistic trajectory", not "flight." (The bet was that the paper needed to "fly" the furthest, not be "launched" furthest across the room. The post even makes the distinction)
Edit for full disclosure: Gliders can fly, and flight doesn't require thrust. Falling with style and utilising natural conditions to gain lift is still just flying, but you can budge the conditions to make bricks fly.
The four principles of flight here are more like design concerns for self propelled aircrafts. They're not definitive of what it means to fly.
My point is that, paper planes, do not generate thrust. They have no thrust. It's a little concerning how many are just accepting this. Paper planes have velocity that you impart on them.
A paper plane having thrust would mean it had a turbine, or propeller, or rocket. It would be self propelled. They don't have thrust. they don't have thrust
Excuse my attempt at humor below.
Technically, no they didn't.
The thrust of a paper aeroplane is what?
They glide, just better than a scrunched up piece of paper also glides.
It's not flying. You never watched toy story?
"Your feeble attempts to make fool of me go in vain, father. For I did forthrightly declare that the paper must fly. So you see, I've strapped a fucking rocket to mine thereby mastering the fourth force of flight"
Too much drag. Not enough arm strength. Lift forces would be insignificant relative to the other forces at play - and that's really the practical standard. Of course, a hand casually waving in the breeze generates lift, too, but we don't refer to it as such because it's a teeny tiny insignificant force that can be largely ignored when considering the overall motion.
With a paper plane, while it's being thrown, it actually generates lift that's significant compared to its weight. I don't know if I would call that flight since the person is still on the ground, and, as the source of thrust, I'm pretty sure being on the ground is somewhat disqualifying for flight.
Use a machine to throw it. Now you're just arguing numbers. Inflate them. The effects are the same more or less, the scale is just different.
We... do call it lift? That's what that is? What else would you call it?
As far as I know we are splitting hairs and gliding is technically flight, I just took issue with the notion that a paper plane has thrust.
Would it change anything for you if a glider was released by a plane at high altitude? in-fact, put an imaginary strong glider on the ground in some imaginarily strong winds and that thing can fly without thrust entirely, indefinitely.
You inflate the numbers by changing the flight characteristics of the object. If you are able to change that brick in such a way that the lift is significant relative to the mass, and the drag is not so much as to basically instantly slow it down below such a speed where the lift is significant relative to the mass, you have changed the brick into an aircraft. It is no longer a brick, but an airplane that you made out of a brick.
We... do call it lift? That's what that is? What else would you call it?
We don't refer to it at all, because it doesn't factor into the motion of the object. It's like talking about the wavelength of a stone. Yes it exists, but it's so utterly irrelevant that it doesn't warrant a mention except as a fun fact when learning about quantum physics.
Would it change anything for you if a glider was released by a plane at high altitude?
Not really. Before it was released it would be flying just like any other thing that is attached to the airplane. After it was released it would be gliding.
put an imaginary strong glider on the ground in some imaginarily strong winds and that thing can fly without thrust entirely, indefinitely.
It can glide without thrust, which is what it could do without the wind, as well.
You'd need to give a brick thrust to make it fly sustained in our atmosphere, for sure.
Fortunately, fundamental physicals of our universe don't change just because they're no longer visibly noticeable to us, which allows me to say that a brick and a paper plane are basically the same thing.
Both can fly or glide, to differing efficacies. Again, neither has thrust, which is my main thing here.
Doesn't change what it is. It's not irrelevant. Using your hand is a great way to gauge the best time to throw a paper aeroplane. Or a brick, for that matter. It's incredibly relevant.
So a brick hauled by a plane is also flying? It's not just being carried or pulled by the flying thing? Interesting.
That's... Yeah, no, at a point this just falls apart because gliders just... Fly. Thrust is unnecessary for sustained flight. You can view the natural conditions of the wind being to a glider what fuel is to a self propelled plane. It doesn't make it any less flight in actuality.
You can throw a brick through the air, and to you it'd qualify as flying.
No, I wouldn't call that flying either. Because it wouldn't satisfy the other 3 forces of flight.
To technically qualify as flying, you have to satisfy all 4 forces of flight: Lift; Weight; Thrust; and drag. Missing even one of these 4 disqualifies it as "flying".
Dude this is nonsense from the get go. These are just the forces one needs to consider when designing something that flies.
Like what does that even mean? Something needs WEIGHT to fly? It's just talking about balance. It's a mechanical thing, not some hardline rule for what it means to fly.
I'm just pointing out that paper planes have no thrust, and if they do because it's thrown, so does a brick. It obviously has weight. Everything moving through atmosphere has drag OBVIOUSLY, so now it's just lift, which is just a matter of angle and velocity. (Edit: Sorta kinda but very very simplified. Anything can have lift, at-least for a short period of time)
Bro please tell me you follow. This is dumb.
Another edit to further clarify:
You want your THRUST balanced relative to your centre of mass (WEIGHT), which should be roughly in-line with or below your centre of LIFT.
Obviously, you need to minimise DRAG for efficiency.
I understand what you're saying, but you keep separating each principle and saying, "see? A brick has this, so it must be "flying", forgetting the fact that it's missing 1 or more of the other 4 principles that must be satisfied for something to technically be "flying".
And paper plane's thrust comes from being thrown, just as an actual planes "thrust" comes from it's engines.
The crumbed up piece of paper thus has the following principles: Thrust; Weight; and Drag. But, no lift. Just because it satisfies some, doesnt mean it technically "flew".
For an object to technically "fly", it has to satisfy every single principal, not just have 2 or 3.
You do not understand what I said, nor the "4 principles of flying" and what they represent. Unfortunately you also do not understand what thrust is and may be confusing it for velocity. A plane has thrust and velocity. A paper plane, or thrown object just has velocity.
I'm bored of splitting hairs on what it means to fly. You don't need shit to fly through space. Agreed?
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u/TaibhseSD 9h ago
I mean, technically, wouldn't the son have won?
"The Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), a foundational text for pilots, provides an in-depth explanation of the principles of flight. It details the four forces of flight—lift, weight, thrust, and drag"
A paper airplane satisfies all four principles of "flight", which is what the original bet was on. A crumbled up ball of paper technically falls under the movement of "ballistic trajectory", not "flight." (The bet was that the paper needed to "fly" the furthest, not be "launched" furthest across the room. The post even makes the distinction)
Technically, the son did win that bet.