Hi, aerodynamicist here, and uh, TL;DR it's a very common misconception, but *Bernoulli has nothing to do with generating lift* (and there is no debate on how lift is generated outside of armchair engineers on Twitter, we've understood how this works mathematically since Prandtl in the 1920s). 1) Bernoulli's theorem _only_ applies along a single streamline. You _cannot_ compare streamlines separated by solid bodies - such as an aerofoil - this violates the assumptions in its derivation from the Navier-Stokes equations. _Fun fact:_ if properly applied, *Bernoulli's theorem across an aerofoil actually predicts zero lift should be generated* _Corollary:_ explanations like 'equal transit time' (which is false, the air generally transits the top in a shorter time than the bottom) and 'bernoulli' predict the liftiest wings should have the shortest possible bottom and longest possible top. This is - as you show - the opposite of what high lift aerofoils actually look like. 2) Invoking "Bernoulli" and "Newton" as 'pressure' and 'momentum' respectively as two different methods of lift generation is wrong. They are the same thing! Newton's laws only tell you what must happen (in this case, air has been deflected downwards, so an equal lift force must be generated), not the mechanism by which this happens. The "why" - the way this momentum is transferred to the solid wing - is the pressure distribution that is created on the wing, and vice versa. This I think is where the main misunderstanding comes in - it is a chicken and egg problem, whether the lift causes the pressure distribution or vice-versa. In actuality, it doesn't matter, solving the differential equations does not give you an "order" in which these happen. 3) The most complete mathematical explanation of how a wing generates lift you can solve with a pencil and paper is the "Kutta-Joukowski theorem" in 2D and Prandtl's "lifting line theory" in 3D, both of which model the lifting surfaces as an infinite sum of vortices. It (and extended derived methods such as vortex lattice models) generate surprisingly accurate results for such a basic method! The reason people resort to 'explaining' it with methods like Bernoulli is good luck explaining vector fields to the general public and holding their interest for 5 minutes. Unfortunately explanations involving Bernoulli are so wide of the mark they can't even be passed off as 'lies to children'. 4) If you're wondering why the flow on your wings always looks separated from the peak despite them not being stalled (you draw a line around it at 20:21), that's because it is. Your tunnel has such low-speed air and is so small the Reynolds number (think 'aerodynamic scale') is equivalent to probably a large insect. That means you've formed a giant laminar separation bubble on top of your aerofoil that has then burst, effectively changing the shape of your wing.
Thank you for the concise yet thorough explanation and insight. We can always do better with our videos and look forward to diving further into some of these topics in the future. - G. Tabor.
Man I’m so excited y’all dropped a new video! I’ve watched the 2 electrical, computer science, and refrigeration cycle videos. Honestly, they’re up there in quality and production with channels like Veritasium and Engineering Mindset. Can’t wait to watch this and upcoming videos!!
I'm glad i saw this comment, so i know to check the channel out for previous content. I'm barely into the video and completely agree about the quality.
I cant tell if this is A)PBS general educational film B) An advertisement C) Workplace training film THAT means THIS is a great production. This must be a GREAT place to work if you're a geek and like building stuff.... Great job. 👇
What absolutely impeccable timing. I'm a hobby combat roboticist, and I've been doing research on and off for ages to dance around the idea of a combat robot with fan-enhanced downforce for better traction in the arena, but have only recently started actually working on the project in earnest. Proper fan design has always been one of the most daunting things to try and optimize, so this video couldn't have come at a better time.
I've been thinking about something similar but I've never seen anybody execute such an idea in combat robotics. If you do something with it please post an update!
@@bean_soups6407agreed. I'd like to see more about that to. Formula 1 race cars are the only system that I knew about that used fan/suction enhanced traction (I freely admit my supreme ignorance).
Whoa! I thought I knew the basics of fans and their blades. I was so wrong. This was a great video for helping understand which fan type you actually need, AND why it's so important to clean your fan blades. Thank you so much!
Thank you for making this highly informative video, lots of people think that fan aerodynamics and just aerodynamics are like black magic and you have demystified that quite a bit!
I appreciate the detail you presented in this instructive video. Nonetheless, I have - for many years - railed against the very high acoustic/noise output of domestic and even commercial ducted A.C. fan installations. Yes, I appreciate there are always compromises to any engineering result, but fan cavitation is about top of my list for irritating, and oft-times mood-altering (white) noise. Maybe you would be interested in covering fan design and cavitation issues in a later video. My simplistic view on this problem is that 'product' designers have no idea about how to move air at an optimal rate - silently. Maybe the Dyson fan is an exception. But then I am just a retired electronics engineer, so I know almost nothing about the subject. Keen to learn however.
Sorry, but at 19:00 you discuss that Bernoulli's principle is why lift is generated. I was also taught this in engineering school. Go find one of the videos discussing what really happens is that the air striking the stagnation point and separating causes a sharp change in pressure (which really is mostly near the first 1/4 of the airfoil) and this is lift cause. It has nothing to do with the difference in distance traveled. We were all taught wrong. Bernoulli is important in this leading edge regime. otherwise a great video!
Such hybrid anti-/matter could be the future of energy storage if we manage to create it and store it efficiently and safely at scale. I see how it could easily be used in a thermal power plant once the storage and handling bit is solved. It should also be possible to use it to generate power in other ways (without boiling water and spinning turbines). Maybe even future rocket engines.
This is an awesome video! OMG! I'm an EE but have a fascination with fluid dynamics & 30+ yrs experience as an VoIP/data engineer. If you guys are looking for an intern or janitor (i.e. any position), I would love to work/learn around your team. Again, awesome video!
This channel is a masterclass in learning everything from basic understanding up to advance knowledge. This channel deserves more views and subscribers. Similar to Veritasium, I'm amazed on how well this channel explains engineering and concepts from a layman perspective and also for seasoned engineers.
Wow, thanks, that's a very good overview! Anticipating the follow up 🤘 Yes, I watched the whole thing, just because it's interesting and really well made.
Great video! I was captivated (pun intended) the entire time. Although I'm not an expert, I don't find ordinary cheap desktop fans very efficient, I replaced the fan on an ordinary desktop fan with something I just 3D-printed, and got much higher airflow, and much lower power consumption, and significantly lower noise. Obviously that's mostly due to the fact that the original fan was designed to force air through the cage, but being designed for that meant that the original fan was ridiculously bad in multiple ways even without the cage, even compared to what an amateur like me can design and print.
For the longest time I was so confused about why people would say that the pressure falls with the faster the fluid goes, because I always thought that if you turned up the fan or pump you'd feel a HIGHER pressure... at least at the end of the tube or pipe, etc. Someone finally clarified for me that yes, there actually IS a higher pressure at the end, and said that's called the head. Thus, whenever someone says the other thing, they should follow up with saying that it's the pressure along the _side(s)_ that that applies to, but the opposite applies at the HEAD.
It can be confusing and you bring up some interesting points. We demonstrated static and total pressure head in the example starting at 5:52, and used the two to calculate dynamic pressure head. In this example, we varied the restriction in the system to see the effects. Later on at 11:55, we instead varied the speed of the fan and observed the changes to the pressure heads. Remember, static, dynamic, and total pressures are all intertwined in a system. We probably should have used the term "head" somewhere in these sections, so thank you for the feedback.
I'm part of the manufacturing process for jet engine and power turbine castings, so seeing the wind tunnel tests with smoke helped me understand many dimensional tolerances that we go by
The Exhaust calculation segment hit home with me. I'm a glass blower and I keep a system running for exhaust, Its the primary part of my build. The general idea is to move a lot of air but in some cases moving too much can cause issue as the incoming air can not be compensated and you end up with a negatively pressurized room but in reality it is not moving air Out of it and thusly negating the benefits of an exhaust system. I have walked into a lot of studios with enough air flow to pull doors open only to have the owner say.."Close the door, thee is too much draft.". 8/
Ive always used this argument when someone tells me its not a real force: Centrifugal force is the description of the experience of inertia during a curve.
"2000 cfm at 1 1/2 inches of static" 😂 Cubic feet for volume, inches for distances... What other weird mischief could we do? Oh, I know! Let's use inches as a unit of pressure too! Only thing left now is to express time in terms of ounces ;)
There is no "Lift method #1" or #2, the air on top goes faster, hit trailing edge SOONER than air on bottom, due to Kutta-Joukowski theorem, you can see that if you use pulse smoke in your wind tunnel. And with higher AOA (before stall), the speed difference is greater, thus higher pressure difference, and more lift. No matter if the airfoil is asymmetric (basically build-in AOA), symmetric, flat, or your hand. Meanwhile, Newton's 3rd law is always in the play, airfoil forces up, air forces down, you can't separate it from other phenomenon.
As much as I enjoyed and liked the video, I can not help but wonder if it didn't "miss" the role of "water screws/propellers". That if not directly involved/intertwined (?) with the "evolution of the fan/propeller" at least seems to be very closely adjacent.. After all air is just a "rarefied fluid" ::) Best regards
Theres a lot of "Hidden" turbocharging iinfo here if you're smart about turbos...🐚 This should be part of tuning videos for cars....static and dynamic pressure= boost. 🐚💨 Excellent 👌👌 ❤
Wow, how convenient that the fan law numbers match the mathematical powers they contain. I'm a fan of that kind of simplicity! Any chance that wasn't just a coincidence?
I fucking that this is marketing, and even i as a private citizen who has no plans to run any industrial project that might need your products am searching for an excuse to buy something.
There were fans prior to the invention of the electrical fan. In 1886 a belt driven ceiling fan was patented, so I assume the work on designing the blades began at some point earlier than the invention of the electrically powered fan. And then when I researched it immediately after typing this comment out I found that propellers were being designed as early as 200 AD.
There are definitely references to marine propellers or water screws that go way back, this has been mentioned in other comments as well. Leonardo DaVinci is cited often as the first to propose this idea for air propulsion. The Wright brothers are often cited as the first to create a working practical fixed pitch propeller, but you may argue Schuyler Wheeler's fan used a propeller too. When it comes to history and "firsts," there often seems to be much debate and a lot of gray area, with this topic being no exception.
Once again we get the "longer path therefore lift" myth... in this otherwise excellent video. Wings can generate lift even when the top is not a longer path, the much better way to think about this is the top surface redirects air to have a downward component, and this in turn means lift must be generated because if Newton's 3rd law of motion. How exactly the wing makes that happen varies depending on design and condition, but never because of longer path.
thank you that is really a very interesting video. Unfortunately I just don't understand MERICA, just like all the other countries on this planet don't understand it either. We only understand metric, so please display the units next time. I completely understand that you don't want to talk about it, but at least show it
Thanks, I got so lost when the formula showed up with all imperial units and the "x 4005". I guess at that point it's just acceptance instead of really understanding where it comes from. Apart from the above, amazing video 💪🏻
"They're called laws for a reason." Yeah, but then... mere reasons can just be any old insignificant, even accidental, thing. So more importantly, they're called laws for a _specific/special_ reason (similar to a purpose).
Now, introduce (bernoulli's principle). And when you think it all makes sense. Understand how a gasoline pump handle works. Did you ever wonder how it "kicks off" when the tank is full. It's all about "fluid dynamics" and (bernoulli's principle). "Dynamics", I did say Dynamics. This lesson he is talking mostly about "Statics". So, I guess I'm going to the next chapter. Oh well. Think about it. Google it. Then everything else just makes sense.
I want to concur that equal-transit time has been falsified. You are wrong to claim that that air speeds up over the top of the wing to keep up with the air passing under the wing. You are correct that the curved wing top helps to keep airflow attached to the wing.
Yikes. Sometimes I mess these things up as english is not my native language. My wife chuckles every time I switch up at, on, in, which seems to happen daily. - G. Tabor.
God I wish the imperial system would just go away already... When I saw 3/16 VS 1/4 in.WC it just felt like listening to static, at least use the same denominators lol
[DOWNVOTE] this video was fine for the first 18 minuets, there is nothing about that wing that would cause the air above the airfoil to speed up. Last I checked conservation of momentum was still a thing.
Companies posting good documentaries that are actually related to their industry… literally crying. The world is healing. Seriously tho, you can go find a ton of alright documentaries from the pace race era, but today your exxons and GEs and Fords just will not. Like. How do they expect to inspire a generation of good engineers
'pressure' is an emergent property of 'moving air', it's not 'why' fans move air... 'pressure' is not even straightforward, it's a tricky metaphor. I think you need to review first principles, you're confusing everyone with nonsense circular linguistics.
We didn't mean for it to be confusing. Unfortunately it's hard to get away from circular linguistics because pressure is what gets the air moving in the first place, and due to this air movement the duct will see different pressures thereafter.
The henson aerial steam carriage from 1842 was allready planed with something like a propeller en.wikipedia.org/wiki/Aerial_steam_carriage and da vincis "helicopter" had some sort of it. And then there are old windmills.
Finally, an only fans channel worth subscribing to!
😂
I'm blown away, literally
Hi, aerodynamicist here, and uh, TL;DR it's a very common misconception, but *Bernoulli has nothing to do with generating lift* (and there is no debate on how lift is generated outside of armchair engineers on Twitter, we've understood how this works mathematically since Prandtl in the 1920s).
1) Bernoulli's theorem _only_ applies along a single streamline. You _cannot_ compare streamlines separated by solid bodies - such as an aerofoil - this violates the assumptions in its derivation from the Navier-Stokes equations.
_Fun fact:_ if properly applied, *Bernoulli's theorem across an aerofoil actually predicts zero lift should be generated*
_Corollary:_ explanations like 'equal transit time' (which is false, the air generally transits the top in a shorter time than the bottom) and 'bernoulli' predict the liftiest wings should have the shortest possible bottom and longest possible top. This is - as you show - the opposite of what high lift aerofoils actually look like.
2) Invoking "Bernoulli" and "Newton" as 'pressure' and 'momentum' respectively as two different methods of lift generation is wrong. They are the same thing! Newton's laws only tell you what must happen (in this case, air has been deflected downwards, so an equal lift force must be generated), not the mechanism by which this happens.
The "why" - the way this momentum is transferred to the solid wing - is the pressure distribution that is created on the wing, and vice versa. This I think is where the main misunderstanding comes in - it is a chicken and egg problem, whether the lift causes the pressure distribution or vice-versa. In actuality, it doesn't matter, solving the differential equations does not give you an "order" in which these happen.
3) The most complete mathematical explanation of how a wing generates lift you can solve with a pencil and paper is the "Kutta-Joukowski theorem" in 2D and Prandtl's "lifting line theory" in 3D, both of which model the lifting surfaces as an infinite sum of vortices. It (and extended derived methods such as vortex lattice models) generate surprisingly accurate results for such a basic method! The reason people resort to 'explaining' it with methods like Bernoulli is good luck explaining vector fields to the general public and holding their interest for 5 minutes. Unfortunately explanations involving Bernoulli are so wide of the mark they can't even be passed off as 'lies to children'.
4) If you're wondering why the flow on your wings always looks separated from the peak despite them not being stalled (you draw a line around it at 20:21), that's because it is. Your tunnel has such low-speed air and is so small the Reynolds number (think 'aerodynamic scale') is equivalent to probably a large insect. That means you've formed a giant laminar separation bubble on top of your aerofoil that has then burst, effectively changing the shape of your wing.
Thank you for the concise yet thorough explanation and insight. We can always do better with our videos and look forward to diving further into some of these topics in the future. - G. Tabor.
These people are advertising their company with free education videos world peace would be achieved if everyone did this lol
Not even aggressively. Just very well made, basic information. That shows their passion for what they do.
Man I’m so excited y’all dropped a new video! I’ve watched the 2 electrical, computer science, and refrigeration cycle videos. Honestly, they’re up there in quality and production with channels like Veritasium and Engineering Mindset. Can’t wait to watch this and upcoming videos!!
Hey thanks for watching so many of them! We’re glad you’re enjoying them. Our next fan video should be out in the next few weeks.
I'm glad i saw this comment, so i know to check the channel out for previous content. I'm barely into the video and completely agree about the quality.
Well no crap. It's basically advertising.
As a mechanical engineering student, this helped me a lot in understanding fans.
My day off from the trade work, and this is my entertainment. LOL Always learning something new. Thank you!
I cant tell if this is
A)PBS general educational film
B) An advertisement
C) Workplace training film
THAT means THIS is a great production. This must be a GREAT place to work if you're a geek and like building stuff....
Great job.
👇
What absolutely impeccable timing. I'm a hobby combat roboticist, and I've been doing research on and off for ages to dance around the idea of a combat robot with fan-enhanced downforce for better traction in the arena, but have only recently started actually working on the project in earnest. Proper fan design has always been one of the most daunting things to try and optimize, so this video couldn't have come at a better time.
I've been thinking about something similar but I've never seen anybody execute such an idea in combat robotics. If you do something with it please post an update!
@@bean_soups6407agreed. I'd like to see more about that to. Formula 1 race cars are the only system that I knew about that used fan/suction enhanced traction (I freely admit my supreme ignorance).
Whoa! I thought I knew the basics of fans and their blades. I was so wrong. This was a great video for helping understand which fan type you actually need, AND why it's so important to clean your fan blades. Thank you so much!
Thanks for the video to authors and all participants. The video is awesome
This was air flow gold, it answered so many questions about flow, fan blades, and types. Great work
awesome this is such a comprehensive explainer video, please keep making them!
Thank you for making this highly informative video, lots of people think that fan aerodynamics and just aerodynamics are like black magic and you have demystified that quite a bit!
I appreciate the detail you presented in this instructive video.
Nonetheless, I have - for many years - railed against the very high acoustic/noise output of domestic and even commercial ducted A.C. fan installations.
Yes, I appreciate there are always compromises to any engineering result, but fan cavitation is about top of my list for irritating, and oft-times mood-altering (white) noise.
Maybe you would be interested in covering fan design and cavitation issues in a later video. My simplistic view on this problem is that 'product' designers have no idea about how to move air at an optimal rate - silently. Maybe the Dyson fan is an exception. But then I am just a retired electronics engineer, so I know almost nothing about the subject. Keen to learn however.
We are actually considering the topic of fan and duct acoustics for a future video :)
"...That was one of the things I was kind of _blown away by."_
HAHAHA, of COURSE he'd use that pun! I'm such a FAN of cheesy puns! 🤣
Yup, please keep these videos coming
I can't believe it, two weeks ago I was searching for this exact content, all I found was how to install fans haha. You guys read my mind.
I hope I retained at least half of all the useful information from this video. Thank you very much.🙏🏻
Lovely, new binge list added ❤+1
Sorry, but at 19:00 you discuss that Bernoulli's principle is why lift is generated. I was also taught this in engineering school. Go find one of the videos discussing what really happens is that the air striking the stagnation point and separating causes a sharp change in pressure (which really is mostly near the first 1/4 of the airfoil) and this is lift cause. It has nothing to do with the difference in distance traveled. We were all taught wrong. Bernoulli is important in this leading edge regime.
otherwise a great video!
thank you for releasing this video!
I watched this in parts because of how long this quality content is!
That was fascinating! Thank you
Great educational content
Such hybrid anti-/matter could be the future of energy storage if we manage to create it and store it efficiently and safely at scale.
I see how it could easily be used in a thermal power plant once the storage and handling bit is solved.
It should also be possible to use it to generate power in other ways (without boiling water and spinning turbines).
Maybe even future rocket engines.
Excellent video! - Thank you.
I wish this video had been available when I was taking introductory aerospace engineering courses. Well done!
This is an awesome video! OMG! I'm an EE but have a fascination with fluid dynamics & 30+ yrs experience as an VoIP/data engineer. If you guys are looking for an intern or janitor (i.e. any position), I would love to work/learn around your team. Again, awesome video!
this video deserves more views
Best HVAC videos of Al UA-cam
This channel is a masterclass in learning everything from basic understanding up to advance knowledge. This channel deserves more views and subscribers.
Similar to Veritasium, I'm amazed on how well this channel explains engineering and concepts from a layman perspective and also for seasoned engineers.
Appreciate the comparison. We're aiming for that kind of clarity.
Another absolutely fantastic video! Thank you for this amazing content!!
Wow, thanks, that's a very good overview! Anticipating the follow up 🤘
Yes, I watched the whole thing, just because it's interesting and really well made.
Great video! I was captivated (pun intended) the entire time. Although I'm not an expert, I don't find ordinary cheap desktop fans very efficient, I replaced the fan on an ordinary desktop fan with something I just 3D-printed, and got much higher airflow, and much lower power consumption, and significantly lower noise. Obviously that's mostly due to the fact that the original fan was designed to force air through the cage, but being designed for that meant that the original fan was ridiculously bad in multiple ways even without the cage, even compared to what an amateur like me can design and print.
That’s really cool. It’s interesting how one can bias a fan towards static pressure vs airflow.
For the longest time I was so confused about why people would say that the pressure falls with the faster the fluid goes, because I always thought that if you turned up the fan or pump you'd feel a HIGHER pressure... at least at the end of the tube or pipe, etc. Someone finally clarified for me that yes, there actually IS a higher pressure at the end, and said that's called the head. Thus, whenever someone says the other thing, they should follow up with saying that it's the pressure along the _side(s)_ that that applies to, but the opposite applies at the HEAD.
It can be confusing and you bring up some interesting points.
We demonstrated static and total pressure head in the example starting at 5:52, and used the two to calculate dynamic pressure head. In this example, we varied the restriction in the system to see the effects. Later on at 11:55, we instead varied the speed of the fan and observed the changes to the pressure heads. Remember, static, dynamic, and total pressures are all intertwined in a system. We probably should have used the term "head" somewhere in these sections, so thank you for the feedback.
Impeller Wheels working was a unique explanation.👍
Excellent work
I'm part of the manufacturing process for jet engine and power turbine castings, so seeing the wind tunnel tests with smoke helped me understand many dimensional tolerances that we go by
Love these videos
Amazing! These videos are awesome!
Amazing! Love this
The Exhaust calculation segment hit home with me. I'm a glass blower and I keep a system running for exhaust, Its the primary part of my build. The general idea is to move a lot of air but in some cases moving too much can cause issue as the incoming air can not be compensated and you end up with a negatively pressurized room but in reality it is not moving air Out of it and thusly negating the benefits of an exhaust system. I have walked into a lot of studios with enough air flow to pull doors open only to have the owner say.."Close the door, thee is too much draft.". 8/
Ive always used this argument when someone tells me its not a real force: Centrifugal force is the description of the experience of inertia during a curve.
Ha, I was surprised seeing Boris Boyarshinov here! :)
This is really good. I’m not in the market for any hvac or ventilation equipment, but I sure as shit subscribed anyway.
Really a fan of this video.
amazing
Brach Education style, I like, I sub.
It's like watching MajorHardware's Fan Showdown but on a bigger budget. Subscribed.
Thanks, we just checked his channel out and it looks like a lot of fun.
@@CAPTIVEAIRE you should submit a design.
Very great video.
Homie looks like the Quartering's brother. Fascinating video.
Thank Archimedes for bringing the screw to light which developed into propellers.
This is a VERY well made video. Truly excellent job in all respects.
It does misattribute lift to the Bernoulli Principle. See other comments.
"2000 cfm at 1 1/2 inches of static" 😂 Cubic feet for volume, inches for distances... What other weird mischief could we do? Oh, I know! Let's use inches as a unit of pressure too!
Only thing left now is to express time in terms of ounces ;)
There is no "Lift method #1" or #2, the air on top goes faster, hit trailing edge SOONER than air on bottom, due to Kutta-Joukowski theorem, you can see that if you use pulse smoke in your wind tunnel.
And with higher AOA (before stall), the speed difference is greater, thus higher pressure difference, and more lift. No matter if the airfoil is asymmetric (basically build-in AOA), symmetric, flat, or your hand. Meanwhile, Newton's 3rd law is always in the play, airfoil forces up, air forces down, you can't separate it from other phenomenon.
Excellent content
The correct name for centrifugal force is actually inertia - air in motion remains in motion.
As much as I enjoyed and liked the video, I can not help but wonder if it didn't "miss" the role of "water screws/propellers". That if not directly involved/intertwined (?) with the "evolution of the fan/propeller" at least seems to be very closely adjacent.. After all air is just a "rarefied fluid" ::)
Best regards
the wright brothers invented the airfoil propeller but not the propeller itself. As it stands that history section is pretty bad.
Theres a lot of "Hidden" turbocharging iinfo here if you're smart about turbos...🐚 This should be part of tuning videos for cars....static and dynamic pressure= boost. 🐚💨
Excellent 👌👌
❤
Wow, how convenient that the fan law numbers match the mathematical powers they contain. I'm a fan of that kind of simplicity! Any chance that wasn't just a coincidence?
I fucking that this is marketing, and even i as a private citizen who has no plans to run any industrial project that might need your products am searching for an excuse to buy something.
There were fans prior to the invention of the electrical fan. In 1886 a belt driven ceiling fan was patented, so I assume the work on designing the blades began at some point earlier than the invention of the electrically powered fan.
And then when I researched it immediately after typing this comment out I found that propellers were being designed as early as 200 AD.
There are definitely references to marine propellers or water screws that go way back, this has been mentioned in other comments as well. Leonardo DaVinci is cited often as the first to propose this idea for air propulsion. The Wright brothers are often cited as the first to create a working practical fixed pitch propeller, but you may argue Schuyler Wheeler's fan used a propeller too. When it comes to history and "firsts," there often seems to be much debate and a lot of gray area, with this topic being no exception.
7:57 What is the metric version of this equation?
This was a pretty "COOL" video; thanks! 😂
You did not correctly label the units, it was CFM/ft. Still a fun video. I don't recall talking about these in undergraduate fluids.
Once again we get the "longer path therefore lift" myth...
in this otherwise excellent video.
Wings can generate lift even when the top is not a longer path, the much better way to think about this is the top surface redirects air to have a downward component, and this in turn means lift must be generated because if Newton's 3rd law of motion. How exactly the wing makes that happen varies depending on design and condition, but never because of longer path.
I noticed some people commenting that Bernoulli's principle isn't really why wings have lift, etc.
My hands are very airfoil shaped. (says Freddy Kruger)
thank you
that is really a very interesting video. Unfortunately I just don't understand MERICA, just like all the other countries on this planet don't understand it either. We only understand metric, so please display the units next time. I completely understand that you don't want to talk about it, but at least show it
Thank you for your suggestion. We will consider this for future videos.
Thanks, I got so lost when the formula showed up with all imperial units and the "x 4005". I guess at that point it's just acceptance instead of really understanding where it comes from.
Apart from the above, amazing video 💪🏻
@ 34:05 "vvvvhhhhoooooo DAKADAKADAKDAKADAKA!"
Next up, the magic of crossflow fans right?
"They're called laws for a reason."
Yeah, but then... mere reasons can just be any old insignificant, even accidental, thing. So more importantly, they're called laws for a _specific/special_ reason (similar to a purpose).
"When I first turn the fan on..."
How many times did you turn it on, and why wouldn't this happen every time?
Now, introduce (bernoulli's principle). And when you think it all makes sense. Understand how a gasoline pump handle works. Did you ever wonder how it "kicks off" when the tank is full. It's all about "fluid dynamics" and (bernoulli's principle). "Dynamics", I did say Dynamics. This lesson he is talking mostly about "Statics". So, I guess I'm going to the next chapter. Oh well. Think about it. Google it. Then everything else just makes sense.
I want to concur that equal-transit time has been falsified.
You are wrong to claim that that air speeds up over the top of the wing to keep up with the air passing under the wing.
You are correct that the curved wing top helps to keep airflow attached to the wing.
No one has ever seen the flyer. Santos Dumont invented it.
"The big brother... _are_ called HVLS fans..."? "...Brother... are"?
Yikes. Sometimes I mess these things up as english is not my native language. My wife chuckles every time I switch up at, on, in, which seems to happen daily. - G. Tabor.
@CAPTIVEAIRE , you're quite good for it not being your native language! Thanks for your videos!
Why do we even have the _words_ "suck" and "suction," etc., then?
very practical explanation; sadly using medieval units of measure
Fan's only create what's _called_ a pressure gradient, CA? That's not the actual term? If that's the official term then why not just use it directly?
air can only be pushed not pulled
Yep! 3:23
Two third world countries are still using imperial units: the USA an Myanmar
everything ok, but, imperial units?
God I wish the imperial system would just go away already... When I saw 3/16 VS 1/4 in.WC it just felt like listening to static, at least use the same denominators lol
all hail the algorithm
Now super shop vacume experiments
[DOWNVOTE] this video was fine for the first 18 minuets, there is nothing about that wing that would cause the air above the airfoil to speed up. Last I checked conservation of momentum was still a thing.
This is how you make a 48 minutes commercial.
Companies posting good documentaries that are actually related to their industry… literally crying. The world is healing. Seriously tho, you can go find a ton of alright documentaries from the pace race era, but today your exxons and GEs and Fords just will not. Like. How do they expect to inspire a generation of good engineers
excellent mansplaining. I learned a lot.
Thank you, didn’t know you were still around sir.
14.7 PSI is the worst way to say 1 ATM.
I can’t argue with that…
hmm explaining something "scientific" but using fantasy measurements...
'pressure' is an emergent property of 'moving air', it's not 'why' fans move air... 'pressure' is not even straightforward, it's a tricky metaphor. I think you need to review first principles, you're confusing everyone with nonsense circular linguistics.
We didn't mean for it to be confusing. Unfortunately it's hard to get away from circular linguistics because pressure is what gets the air moving in the first place, and due to this air movement the duct will see different pressures thereafter.
You might want to look into that old British guy. Seems like he doesn't even know his own job. The kid should probably have his job.
even 6 min in, you explain nothing, diaf
The henson aerial steam carriage from 1842 was allready planed with something like a propeller en.wikipedia.org/wiki/Aerial_steam_carriage and da vincis "helicopter" had some sort of it. And then there are old windmills.