Highly interesting experiment here, thank you for filming and uploading! This is a great way to show to my new students what is meant by seperation/turbulent air flown etc. Pondering about attaching some Yarn to a PA28 and showing this ex in flight!
A stall occurs when the critical angle of attack is exceeded. Normally, yes, this occurs in a pitch up attitude, however this can occur at any attitude and airspeed theoretically, and often does in the case of tail stalls.
Thanks for sharing! I just recently became interested in aviation but didn’t know what really happens during a stall. Very informative and easy to grasp.
A stall is basically loss of lift. This is due to high angle of attack(and NOT just low speed). Low speed is demonstrated here, as it necessitates higher angle of attack to maintain level flight. Standard recovery is reducing angle of attack and increasing thrust in order to increase speed and therefore no longer need the high angles of attack. In other words - dip the nose and add full power to stop the aircraft from losing control, crashing and burning.
Its called “separation”, where laminar flow changes in turbulent flow. You see that the separation is only at the end of the wing. It can get way worse, where the separation already happens at the beginning edge of the wing. It shows that this stall was still a very mild one, which is controlled.
also, if the wings are swept back at all, when the root of the wing stalls and the tips (further back) still maintain lift, the front of the plane should fall faster, reducing the angle of attack, and adding some degree of self-recovery to the stall.
wing tips better keep flying. its called wash out... the tip should have less incidence than the root. this shows virtually zero washout. The stall hits all at once.
Thats cool. I did the same thing on a motorbike (not that it stalls) but I was getting turbulence around my helmet and wanted to see the airflow around the fairing.
The very tip and the inner wing seem to begin to stall at the same time. But the last few inches of the wing and aileron and the first yarn on the upturned tip show almost no turbulence or none at all. So the upturned tip seems to take the stalled air onto itself and leaves the nearest part of the wing usable.
+wordreet most wings are designed to have a little "twist" so when the root stalls (ie critical angle of attack) the tip has still some laminar flow. This allows the pilot to still have some aileron response so the aircraft is not entirely uncontrollable :)
+Javier Llaneza the twist is called wash out. but it's designed so that the plane is more stable, like trying to balance a pencil with two fingers is easier when they are further out on each end. if you try aileron input during a stall, you can aggravate it, and make it nasty lol
No, washout is designed so the wing has a different angle of attack on the root of the wing than on its tip. This allows you to have some aileron input and lift before the wing stalls completely. That's why the stall warning is installed on the root instead of the wing tip. You will get a stall warning before the entire wing enters the stall and therefore you can take action before it happens. It has nothing to do with stability. Stability is achieved by putting the center of mass ahead of the center of lift. If you put it behind it, the airplane will become more and more uncontrollable.
Javier Llaneza yea... So washout means twist..? And yes it does have some part to play in the stability near the stall speed. If wing root were to stall last, then the plane would wing drop and possibly cause a spin. And why would you want to be using aileron near the stall, doing that could make the down going wings AOA to go past 16 degrees and stall.
Yes it is. The wing is actually twisted for a few degrees from the root to the tip. The root has a slightly higher angle of attack, which means, that it points more "upwards". The tip has a slightly lower angle of attack, so it points more "horizontally". This has a crucial reason. The occurence of a stall depends on the angle of attack. The root has a slightly steeper angle of attack, meaning that the root will be the first spot, where the stall occurs. When the total angle of attack increases, the stall will move up to the midsection and finally the tip. You can see in the video, that the turbulence starts at the root, and within one second, moves to the tip. As the tip has the lowest angle of attack, the stall will occur at last. So if the root stalls, the tip still has laminar airflow. That way the ailerons can still control the bank angle, whereas in a stall, the ailerons have only little effect. Next, it gives the pilot some time to react. The wing doesn't lose all its lift instantly, but only the root, which the pilot notices due to the aircraft starting to descend rapidly. If the wing would lose all its lift instantly, the pilot would likely lose control of the aircraft instantly. The gradual loss of lift makes the situation much more controllable.
I find it very interesting that the segment of yarn closest to the trailing edge of wing is the most tattered... Meaning the most affectied by this test.
nice recovery! stalls are not nice but seeing the yarn lose lift makes for better understanding......... keep up the video's some of us are enjoying the ride. ps looks like you recovered in less the 50ft.
According to regulations, established by the Federal Aviation Administration, single engine aircraft to recover no lower than 1500 feet above ground level.
bigboyrise a landing is a timed stall. As the speed bleeds away the stall warning buzzer becomes active in the flare just before the wheels make contact. That certainly doesn't happen at 3,000 agl.
You have true, the wing tip rib have the same angle of attack as root rib. This it is the best for bigger lift.BUT if you spend lift, the airplane go down. In this small airplane it is no problem with lift.On the airplanes below 600 Kg it is no important. Every UL, or VLA are flying. No aluminium wing have different rib on the end of wing, as well no small airplanes from the aluminium have aerodynamic twist the wing.
If you watch more closely, the *root clearly stalls before the tip*. I don't know how much washout or camber change the DA40 has. The effect is not great, but very evident. ... For those who don't know, 'washout' is making the wing tip near the ailerons have *less* angle of attack (angle of incidence) than the root (by the fuselage). The wing is "twisted" This keeps the outer wing flying and allows the ailerons to have an effect while the inner wing (root) has stalled allowing the plane to start to 'fall out of the sky' alerting the pilot to the trouble. This allows the pilot to have control in milder stalls. ... Without something like this, the ailerons appear to be reversed near stall. While trying to raise a wing that has become lower, the lowered aileron causes that tip to stall, thus dropping that side rather than raising it. ... While it is true that washout reduces total lift by a small amount, it is a small price to pay for control in a stall. Actually, with washout it is only a partial stall (at the root only). It is enough of a stall for you to be aware of and executethe proper recovery while having the ability to actually execute that recovery without stalling because the ailerons still have some control. The Cirrus 22 has a step in its leadding edge that provides a similar change in net incidence angle. Cheers, ScienceAdvisotSteve
Observ45er Thanks for the 'washout' explanation. Clarified a few things. So what exactly happens at the critical angle that causes stall? And without washout, at stall, will it not be possible to just return the wing to a zero angle of attack and just restart the whole lift gaining process or is the pressure drag on the wing too much to allow that?
samuel mustapha Your basic stall... At the critical angle (usually around 16 degrees AOA) The air over the top of the wing goes turbulent. Thus, you see the tufts go crazy. (AH-Hem... This is the whole purpose of the video) This is because the air can no longer follow the upper surface smoothly and burbles away forming eddys (swirls). Because the majority of a wing's lift is created from the smooth airflow over the top surface, the wing looses a significant amount of lift and the plane will start to fall. All the pilot has to do is release back pressure on the control (and/or push forward) and allow the nose to fall so the plane both picks up airspeed and returns to a more reasonable angle of attack where the air can once again follow the upper camber currve and produce lots of lift once again. ... ... The problem of not having either washout or the equivalent effect of a dual angle of attack wing (less AOA on the outboard section) is that of control. If the wing is even *near* stall at the wing tip "Control Reversal" occurs. Near stall, if a wing starts to fall and the pilot starts to correct it, this will *lower* the aileron on that side (attempting to raise that wing). The lowering of the aileron will effectively *increase* the angle of attack and cause more stall and that tip will *FALL* instaead of rising. Thus the term "Control Reversal*. The pilot tries to raise that wing more and winds up upside down in a blink! Washout allows aileron control even when the wing root *has stalled* and the nose is falling because the wing tip is still flying normally. ... When a wing starts to fall, the natural tendency is to move the control to raise it and in this condition the wing just falls faster, major confusion factor for the poor pilot! -- Cheers, ScienceAdvisorSteve ... "Pressure Drag" is a non issue here. Typos fixed...
Washout is having the tip of the the wing at usually a two or 3 degree less of an angle of attack than the root of the wing. Tip will stall last. Ass mentioned above, helps tip stall. You end up stalling straight ahead instead of spinning. That's with some rudder to counteract engine torque.
oh noo all good till you said "aileron control to facilitate recoevery during stall entry." Dont you dare move those ailerons approaching the stall. The twist isnt designed for this, its there to give stability to the aircraft prior to the stall. If the out board sections are producing greater lift compared to the inboard section, then there is a greater arm (fxd) therefore meaning any distrubance/wing drop tendency is reduced
Wow, excellent.....look at that shit!!!! Wing totally loses its control dynamics at stall. Turbulence all over the place. If not recovered, plane essentially falls out of the sky like a lead balloon. EXCELLENT instruction !!
For a wing to generate lift you have to have a lower pressure on top than on bottom. This is done by making the air on top of the wing to move faster. That is why the top of the wing is curved. You get good lift during laminar flow which is when all the air is moving smoothly and quickly over the top of the wing. If you increase your angle of attack (pull up too fast) you can cause the airplane to stall. this is because it makes the airflow more turbulent (not smooth) which reduces lift. If you watch the video you can see that in the beginning all the strips of fabric are nice and smooth when the pilot is flying level. That's what we want. When the plane is pointed up too much, the turbulent (not smooth) airflow makes the strips of fabric go crazy starting from the back and going more to the front. If the pilot kept going up and the turbulent airflow got a lot closer to the front of the wing then the airplane could stall. The way to fix it is just to level the plane. I hope that helped.
why not do it at 3500 feet instead ? that way, if you are crahsing and saying "Fuck if I had just started the stall at 3500 feet, I wouldn't be heading* for those trees right now".
At a stall, all the worm were panic. That's what happen.
FDausCo jajaja that was paper dude
@@landocalrissian6778 😂😂
🤣
Interdastin
Got me laughing in a zoom class
Wow, wonderful way of portraying the turbulent airflow separation of the airfoil during stalls.
Thanks for this :D
Highly interesting experiment here, thank you for filming and uploading! This is a great way to show to my new students what is meant by seperation/turbulent air flown etc. Pondering about attaching some Yarn to a PA28 and showing this ex in flight!
I like how it stalled first in the root and moved towards the tips . Showing the wing twist in aoa. Providing stability in the stall
I could see that the plane's nose is up when the stall occurs, and to recover the nose is pushed down. very educational video thank you
A stall occurs when the critical angle of attack is exceeded. Normally, yes, this occurs in a pitch up attitude, however this can occur at any attitude and airspeed theoretically, and often does in the case of tail stalls.
@@RainbowManification scary. That’s why I don’t fly anymore.
Thanks for sharing! I just recently became interested in aviation but didn’t know what really happens during a stall. Very informative and easy to grasp.
Stal mean air not go on weng
Perfect illustration of how the twisted shape of a wing gives you aileron control for as long as possible.
almost zero washout
Had to come back to this after learning a bit more about wash-in/wash-out, cool to see the wing root stalling before the wing tip
A stall is basically loss of lift. This is due to high angle of attack(and NOT just low speed). Low speed is demonstrated here, as it necessitates higher angle of attack to maintain level flight. Standard recovery is reducing angle of attack and increasing thrust in order to increase speed and therefore no longer need the high angles of attack.
In other words - dip the nose and add full power to stop the aircraft from losing control, crashing and burning.
Nice example of the change from an adverse pressure gradient to a positive pressure gradient and seeing the back flow due to flow seperation
Thank you so much. Now I'm able to visualize stall in my mind
Great video! Those winglets appear to perform very well.
Thanks for posting this very useful and instructional video that can be used for engineering fluids analysis, great job!
The air when it stalls: BLUBLEWBELEBWLEBWLEBWLEBWLEBWLE
Its called “separation”, where laminar flow changes in turbulent flow.
You see that the separation is only at the end of the wing. It can get way worse, where the separation already happens at the beginning edge of the wing. It shows that this stall was still a very mild one, which is controlled.
This video illustrates vortices over stalled wing in great detail! Thx for sharing! Fly safe!
Wow, this is playing with one's life in the name of science! Respect.....
You are a Master of simplicity!... Thank you so much for that interesting video that shows what couldn't been seen...
Those are some strong leaches.
also, if the wings are swept back at all, when the root of the wing stalls and the tips (further back) still maintain lift, the front of the plane should fall faster, reducing the angle of attack, and adding some degree of self-recovery to the stall.
the yarn sure enough shows a loss of airflow that goes halfway across the wing surface at 0:28, and during a full out stall there is no airflow right?
wing tips better keep flying. its called wash out... the tip should have less incidence than the root. this shows virtually zero washout. The stall hits all at once.
Wow!! Boundary Layer Seperation perfectly visualized in real life.
Simple but sound. Well worth posting. Thanks.
Thats cool. I did the same thing on a motorbike (not that it stalls) but I was getting turbulence around my helmet and wanted to see the airflow around the fairing.
Actually it looks like the flow right near the wingtip is still fairly good possibly because of the raised tip section or am I mistaken.
The very tip and the inner wing seem to begin to stall at the same time. But the last few inches of the wing and aileron and the first yarn on the upturned tip show almost no turbulence or none at all. So the upturned tip seems to take the stalled air onto itself and leaves the nearest part of the wing usable.
+wordreet most wings are designed to have a little "twist" so when the root stalls (ie critical angle of attack) the tip has still some laminar flow. This allows the pilot to still have some aileron response so the aircraft is not entirely uncontrollable :)
Javier Llaneza I must try that. My RC aircraft are almost always entirely uncontrollable! :¬)
+Javier Llaneza the twist is called wash out. but it's designed so that the plane is more stable, like trying to balance a pencil with two fingers is easier when they are further out on each end. if you try aileron input during a stall, you can aggravate it, and make it nasty lol
No, washout is designed so the wing has a different angle of attack on the root of the wing than on its tip. This allows you to have some aileron input and lift before the wing stalls completely. That's why the stall warning is installed on the root instead of the wing tip. You will get a stall warning before the entire wing enters the stall and therefore you can take action before it happens. It has nothing to do with stability. Stability is achieved by putting the center of mass ahead of the center of lift. If you put it behind it, the airplane will become more and more uncontrollable.
Javier Llaneza yea... So washout means twist..? And yes it does have some part to play in the stability near the stall speed. If wing root were to stall last, then the plane would wing drop and possibly cause a spin. And why would you want to be using aileron near the stall, doing that could make the down going wings AOA to go past 16 degrees and stall.
Ingenious method 👊to portray this concept thanks ☺️🛩
Is it correct that the wing root had more turbulence than the tip? That means there is a washout on this wing?
Yes it is. The wing is actually twisted for a few degrees from the root to the tip. The root has a slightly higher angle of attack, which means, that it points more "upwards". The tip has a slightly lower angle of attack, so it points more "horizontally". This has a crucial reason.
The occurence of a stall depends on the angle of attack. The root has a slightly steeper angle of attack, meaning that the root will be the first spot, where the stall occurs. When the total angle of attack increases, the stall will move up to the midsection and finally the tip. You can see in the video, that the turbulence starts at the root, and within one second, moves to the tip. As the tip has the lowest angle of attack, the stall will occur at last. So if the root stalls, the tip still has laminar airflow. That way the ailerons can still control the bank angle, whereas in a stall, the ailerons have only little effect. Next, it gives the pilot some time to react. The wing doesn't lose all its lift instantly, but only the root, which the pilot notices due to the aircraft starting to descend rapidly. If the wing would lose all its lift instantly, the pilot would likely lose control of the aircraft instantly. The gradual loss of lift makes the situation much more controllable.
Just one question: why does this happen, is it because the change in the angle of attack, I mean, the critical angle?
I am sorry if this is a stupid question, but why does the airflow seem to separate from the wing closer to the fuselage first?
this was way more helpful than I expected it to be lol
Does this wing not have the roots at a higher angle of incidence? They didn't appear to stall first.
Separation of Vortex from the union surface(Vortex shedding) causes a sudden decrease in lift force and induce vibration.
I find it very interesting that the segment of yarn closest to the trailing edge of wing is the most tattered... Meaning the most affectied by this test.
PULL UP! PULL UP! PULL UP! + STALL! STALL! STALL! = WTF?
Airfrance 447
so, the reason it dives after the flow effect, it's intentional go gain speed and come to normal? Is that dangerous more than a couple secs in stall?
In easier words, the streamline of the airflow doesn’t meet at the trailing edge of the wing, and create a lot of vortex and turbulence created
To be recovered by 2000 feet AGL is the rule. You guys need to go flying and less youtube nitpicking.
Yah fuck off
1500agl
Nice thanks for showing it
brilliant example , well done
You can really see the air separation quite well there.
nice recovery! stalls are not nice but seeing the yarn lose lift makes for better understanding......... keep up the video's some of us are enjoying the ride.
ps looks like you recovered in less the 50ft.
Push forward, give full power, don't let the nose come up....she's flying again!🛫
Amazing video! Thanks!
excellent man! thank you, best explanation someone can have about this!
Among all types of stall, the most interesting one is indubitably the thin stall💦
This is a great video. I can now visually describe why an airplane stalls at the root first!
Thank you so much!
was that FOET or GFCS?
Looks like Mr Burns fingers when he goes bowling and puts his hand over the air vent
You saved my exploring aersopace engineering grade, I owe you a pizza
We where starting at 2500 ft above ground.
woah, great video! Thanks for this :)
Can I use this for a presentation?
Seb D did u?
According to regulations, established by the Federal Aviation Administration, single engine aircraft to recover no lower than 1500 feet above ground level.
Thanks for the video!
really nice video! good idea ;)
Great video awesome..Tim
3000 feet for multi engine aircraft, unless higher specified by the aircraft manufacture. 1500 is used for single engine aircraft
Great video thank you!
Smart idea. Thanks
isn't 3000 ft the minimum for a legal intentional stall manouver?
bigboyrise a landing is a timed stall. As the speed bleeds away the stall warning buzzer becomes active in the flare just before the wheels make contact. That certainly doesn't happen at 3,000 agl.
Very interesting!
Highly educative
Fantastic
Oh oh what about the "clean aircraft concept"?
Good job getting a DA40 to stall- it is not that easy to do! :)
Cool enough video
Boundary separation layer.
so, this is what birds feel already for eons on their feathers and skin ...
I noticed the same thing. It looks like the wing tip stalls immediately after the root does. Doesn't seem to be that great of a design..
exactly. its called zero washout.
the stall should progress from root toward tip. the last 3 ft of the tip should never stall.
Awesome...
I think all planes should come with these installed LOL
I wish i watched this video when i was still ppl student :)
hey. Aren't you a little low to be practicing stalls...?
good wing
theirs still a good 50% of that chord still laminar I want to see it all turbulent.
+Sebastion Telfair You're confusing turbulent and laminar flow with detached boundry layer.
nice
You have true, the wing tip rib have the same angle of attack as root rib. This it is the best for bigger lift.BUT if you spend lift, the airplane go down. In this small airplane it is no problem with lift.On the airplanes below 600 Kg it is no important.
Every UL, or VLA are flying. No aluminium wing have different rib on the end of wing, as well no small airplanes from the aluminium have aerodynamic twist the wing.
If you watch more closely, the *root clearly stalls before the tip*. I don't know how much washout or camber change the DA40 has. The effect is not great, but very evident.
...
For those who don't know, 'washout' is making the wing tip near the ailerons have *less* angle of attack (angle of incidence) than the root (by the fuselage). The wing is "twisted" This keeps the outer wing flying and allows the ailerons to have an effect while the inner wing (root) has stalled allowing the plane to start to 'fall out of the sky' alerting the pilot to the trouble. This allows the pilot to have control in milder stalls.
...
Without something like this, the ailerons appear to be reversed near stall. While trying to raise a wing that has become lower, the lowered aileron causes that tip to stall, thus dropping that side rather than raising it.
...
While it is true that washout reduces total lift by a small amount, it is a small price to pay for control in a stall. Actually, with washout it is only a partial stall (at the root only). It is enough of a stall for you to be aware of and executethe proper recovery while having the ability to actually execute that recovery without stalling because the ailerons still have some control.
The Cirrus 22 has a step in its leadding edge that provides a similar change in net incidence angle.
Cheers, ScienceAdvisotSteve
Observ45er Thanks for the 'washout' explanation. Clarified a few things. So what exactly happens at the critical angle that causes stall? And without washout, at stall, will it not be possible to just return the wing to a zero angle of attack and just restart the whole lift gaining process or is the pressure drag on the wing too much to allow that?
samuel mustapha Your basic stall...
At the critical angle (usually around 16 degrees AOA) The air over the top of the wing goes turbulent. Thus, you see the tufts go crazy. (AH-Hem... This is the whole purpose of the video) This is because the air can no longer follow the upper surface smoothly and burbles away forming eddys (swirls). Because the majority of a wing's lift is created from the smooth airflow over the top surface, the wing looses a significant amount of lift and the plane will start to fall. All the pilot has to do is release back pressure on the control (and/or push forward) and allow the nose to fall so the plane both picks up airspeed and returns to a more reasonable angle of attack where the air can once again follow the upper camber currve and produce lots of lift once again.
...
...
The problem of not having either washout or the equivalent effect of a dual angle of attack wing (less AOA on the outboard section) is that of control. If the wing is even *near* stall at the wing tip "Control Reversal" occurs. Near stall, if a wing starts to fall and the pilot starts to correct it, this will *lower* the aileron on that side (attempting to raise that wing). The lowering of the aileron will effectively *increase* the angle of attack and cause more stall and that tip will *FALL* instaead of rising. Thus the term "Control Reversal*. The pilot tries to raise that wing more and winds up upside down in a blink!
Washout allows aileron control even when the wing root *has stalled* and the nose is falling because the wing tip is still flying normally.
...
When a wing starts to fall, the natural tendency is to move the control to raise it and in this condition the wing just falls faster, major confusion factor for the poor pilot!
--
Cheers, ScienceAdvisorSteve
...
"Pressure Drag" is a non issue here.
Typos fixed...
Washout is having the tip of the the wing at usually a two or 3 degree less of an angle of attack than the root of the wing. Tip will stall last. Ass mentioned above, helps tip stall. You end up stalling straight ahead instead of spinning. That's with some rudder to counteract engine torque.
Slo mo looks like attack of the worms.
love yarn idea to show airflow
تدفق الهواء الجنيح طائرة ملاحظة خيوط بعد ثانية0:28 تدفق هواء شكرا
Great illustration, however, the flight recovery occurs too early. I would have loved to see the full stall.
Dance, worms!
oh noo all good till you said "aileron control to facilitate recoevery during stall entry." Dont you dare move those ailerons approaching the stall. The twist isnt designed for this, its there to give stability to the aircraft prior to the stall. If the out board sections are producing greater lift compared to the inboard section, then there is a greater arm (fxd) therefore meaning any distrubance/wing drop tendency is reduced
You learn that very quickly in the Tomahawk, AKA Traumahawk. Hello flat spins!
good! and that was a BURN! ahahahahaha greetings from Brazil.
still a bit low
Wow, excellent.....look at that shit!!!! Wing totally loses its control dynamics at stall. Turbulence all over the place. If not recovered, plane essentially falls out of the sky like a lead balloon. EXCELLENT instruction !!
wow this explains stall better than any Bill Nye the Science guy-esque video smh
Cool stuff... someone with some fluid expertise wanna remix this video with a voiceover?
Jay Smith gay
I have no idea what I just watched
Go learn how a plane flies and watch it again.
lmao
For a wing to generate lift you have to have a lower pressure on top than on bottom. This is done by making the air on top of the wing to move faster. That is why the top of the wing is curved. You get good lift during laminar flow which is when all the air is moving smoothly and quickly over the top of the wing. If you increase your angle of attack (pull up too fast) you can cause the airplane to stall. this is because it makes the airflow more turbulent (not smooth) which reduces lift. If you watch the video you can see that in the beginning all the strips of fabric are nice and smooth when the pilot is flying level. That's what we want. When the plane is pointed up too much, the turbulent (not smooth) airflow makes the strips of fabric go crazy starting from the back and going more to the front. If the pilot kept going up and the turbulent airflow got a lot closer to the front of the wing then the airplane could stall. The way to fix it is just to level the plane. I hope that helped.
@@AJohnson0325...also the stall starts at the wing root trailing edge and progresses down the trailing edge to the tip; then towards the leading edge.
@Nick Newman It was a sincere response.
Dancing worm! Wubwubwubwubwubwub
*ITS BENNY WORM*
the only one dislike is that pilot...
why not do it at 3500 feet instead ? that way, if you are crahsing and saying "Fuck if I had just started the stall at 3500 feet, I wouldn't be heading* for those trees right now".
Thk
zero wash out
No wondered it stalled…Someone put all those little strings all over the wing! Duh! 😉
veritasium
D'Alambert doesn't like this video.
It's terrible...
경비행기 나보네요 ㅋㅋ