Visual Angle of Attack Indicator

[@Jesse-cx4si]

We missed out on so many more years of great videos from this guy. RIP and God bless your family. So sad.

[@raymondgoubet]

Very sad.

[@Jesse-cx4si]

Aaron Rubinstein Motorcycle crash.

[@lcfflc3887]

What the hell happened?

[@lcfflc3887]

@@Jesse-cx4si deanm motorcycles, is that what really happened?

[@SammSheperd]

Fun fact: The plane in the opening picture is the plane I trained in and took my checkride in for both Commercial pilot and Certified flight instructor.

[@TheStickyBusiness]

A Bonanza Right? Beautiful sunset and rainbow!

[@SammSheperd]

PA28R-200 (Piper Arrow)

[@TheStickyBusiness]

A Cherokee then, they look very similar. Very beautiful.

[@SammSheperd]

Yes your comment was censored and I approved it, and deleted the copy one. That's a cool idea, I'll look into it a little. Especially FPV, That would be cool

[@TheStickyBusiness]

***** yes super cool and a great way to train. would be awesome to train cross wind landing this way and how to recover from stalls and spin stalls. To much "flying wild Alaska" and "worst place to be a pilot" LOL

[@billville111]

70 years ago it would cost millions of dollars to acquire this data. hahahaha

[@thelongranger55]

billville111 haha that made me laugh

[@airgliderz]

True now and 70 years ago because if the government managed the experiment or was paying for it it would cost millions

[@The6698Clown]

I'm going to study Aircraft Mechanics next year in college. Not only is this video AWESOME, it's also EDUCATIONAL! Thanks Samm!

[@j69chevelle]

Looks like that airfoil stalls between 20 and 25 degrees AOA. Awesome visualization! Thanks for this!

[@j69chevelle]

Would love to also see how AOA acts in tight turns with a steep bank angle. Relative wind seems mysterious to me when it comes to steep and tight turns.

[@zsblendorio]

Great video! Thank you. I finally get it after watching multiples videos and reading, it wasn’t until seeing it did it all make sense. Thanks again!

[@TheRattleSnake3145]

golfball sheet looks like it worked well.

[@SammSheperd]

It did look that way, but I feel the strings may have had some electrostatic attraction or something. It's hard to compare results with different surfaces. It felt and looked to me insignificantly different when it comes to how the aircraft behaved during similar AOA.

[@Rahviel80]

try printing your own pattern with a thin layer of PLA, then gently put it in to 70 c warm water and when its soft warp it around the airfoil and you may have a indented surface that is formed to fit other shapes. May work may not, never tried it.

[@SammSheperd]

Rahviel80 Neat idea! The stuff I got was a thin flexible cast of epoxy over a 3d printed mold. I've also thought of making a dimpled roller to just press some dimples into the taped surface.

[@wvb93]

Would twine be less susceptible to that kind of electrostatic?

[@Gustavnorell]

What's the program u use to draw before printing? Thanks for a good production!

[@panosk1418]

that was a great experiment ! Well done Sam

[@cobracar1]

Great Video! I am going to show this to my kids - I am trying to teach them about aircraft, and get them really interested. This will be a great way to understand AOA. Thanks!

[@MikaEriksen]

That sunset is beautiful!

[@appiahallan]

☀️

[@sohail1855]

Hello Pilots, Do I understand it right that, Stall will happen when you have a large angle of attack at relative low speed? But if, with the Same Angle of Attack, the speed is much higher, then stall won't happen. Right? And the plane will climb up of course. Right? If not right, Then how come that fighter jets and other acrobatic planes can climb straight vertically? I suppose this is because of their high speed, which provides enough lift, no matter in what direction or angle they move. So why can't normal plans in a critical angle of attack give full thrust to gain more lift? The air is the same everywhere in the sky. Why behaves the air different if we want to fly in an angle which is not parallel to the horizon?

[@ruthdiez587]

Hey, The entire angle of attack question seems unintuitive at first because it's a lot of different systems interacting. The amount of Lift, (which under normal flying conditions pushes you up away from the ground) that a wing produces depends on 3 basic factors: the wing geometry, the relative speed of the air, and the angle of attack. The plane's goal is to produce enough lift to balance the weight pulling in the opposite direction. Imagine an airplane wants to slow down, but not lose altitude. Since the airspeed has decreased, the lift will also decrease and the plane will begin to lose altitude since it's lift is unable to balance gravity's downward pull. However, a pilot can counteract it by pulling on the yoke and increasing the angle of attack increasing lift back to balance. It's important to note though that angle of attack is relative to the wind the plane feels, not the ground. One might think that these are interchangable if there are no vertical updrafts or downdrafts but let's revisit lift: If an airplane is almost at it's stall AoA and it increases throttle to start moving faster, but keeps the same angle relative to the horizon, it's lift component will increase and it will start rising. Since it's now rising, the air that the plane "feels" is now falling downwards. This changes the airspeed AoA, and it's not the same as it's angle to the horizon. On the topic of fighter jets and flying up like a rocket, you are on point in mentioning the speed that they can keep. Even a Cessna 150 can fly vertically (although only very very briefly). The main difference though is the power of the engines. Most airplane engines could lift very little without wings. A Cessna 150 has a static thrust of only about 140 kgs. That's what it could lift if it pointed straight up without aerodynamic lift from the wings (not enough to lift even its 500kg empty weight). If you were to get a fighter jet like the f16, it has a thrust with afterburners of about 12,000 kg while the empty plane weighs only 8,500; It can much more easily climb straight up. I hope I've answered your question! Let me know if any part isn't clear and I'm happy to explain :D

[@sohail1855]

@@ruthdiez587 Thank you very much for such a detailed answer. So I repeat what I now understand of AOA. If there is any misconception, you may correct it please. The Flight Path of a plane is not always its angle of pitch. But a plane can fly with nose pitch up, but still not climbing or descending, or only descending. That's why its AOA can be smaller or greater in this flight path attitude. But when a plane is near stall AOA and then we give more throttle to accelerate, then it will begins to climb again. Therefore its relative wind changes, because its flight path changes. Since flight path and relative wind are always parallel en opposite to each other. So to reduce the AOA we can do two things: 1- Lower the nose pitch. But with that we will loose altitude, if we do not give more throttle. 2- Give more throttle in the same pitch angle. That will change the flight path and plane will climb. Therefore the AOA will be smaller due to changed flight path and accordingly relative wind. Am I right now in my understandings about AOA?

[@ruthdiez587]

@@sohail1855 That's right! If someone studies fluid dynamics they might be able to find a few problems or edge cases where this theory falls apart, but for everyday flying use it's more than enough!

[@EversonBernardes]

Funny to find this video completely by accident. A few days ago I was reading about laminar flow and occurred me that one could probably spoil the flow over the foil to prevent boundary layer separation until it gets to a higher angle of attack and get some extra lift at the expense of some added friction drag. And here you are, doing exactly that :D

[@SammSheperd]

I'm glad you found it! I have two other video's exploring Boundary layer separation: kzbin.info/www/bejne/m4GQioh6mp57fJI

[@EversonBernardes]

Thanks! I'll watch them (and you've got a new subscriber :D). As a further thought on this topic, I looked around to see if VGs have ever been applied to props and saw very little about it. I imagine that if one carefully directed the turbulent flow created by the VG towards the prop root, you could mitigate some of the spanwise flow, reduce induced drag, lift bleed and in effect create a "virtual" duct. The fact that I've seen very little about it probably speaks counter to this idea, but I'm curious, nonetheless :D

[@adamt5986]

This is a life lost too soon. Just discovering this guys fascinating channel now.

[@eco19911]

those winglets looked pretty cool!

[@MichaelWilliams-cn1wb]

I think you should take a look at the work done by the German akakfleig " gliding" researchers concerning sailplane wing design .They looked at various methods of controlling boundary air control and laminar flow characteristics.You don't need to attempt to reinvent the wheel here ,this information is already in the public domain.

[@willconway40]

That, is amazing. Never really thought about how even relative wind can change the AofA. Thought it was always based off ground, thank you!

[@SammSheperd]

You were thinking that AOA and attitude were the same! I'm glad you thought it was amazing! It really is mind opening to realize this. WWII dive bombers would sometimes stall when when trying to pull out of a dive. Turbulence? well the quickly changing wind directions that you are flying through is just changing the AOA (and thus lift) rapidly making things shake. Getting lift from a thermal? Uprising air increased your AOA.

[@Tryin2FlyII]

Very interesting video and great instrument that you came up with. I have often wondered the same thing it is a good way to monitor & visualize the effects of the AOA. Great video-Thanks for posting

[@confuseatronica]

that lighting effect where the red sunset glow is much brighter -inside- the rainbow is really pretty also lol at the dramatic sunset over the golf ball dimples

[@evansaut1]

Great idea! Thanks for sharing! Going to use this on our race car to see what AOA the wings are really working at.

[@welshpete12]

Fascinating ! on early planes a device like this was fixed on to the strut of the wing as a airspeed indicator .

[@icanacoustics-noisevibrati624]

What a great video from a true engineer.

[@sam-rs8wg]

thats cool, it looks like your wing stalls from the inside out too.

[@ignasanchezl]

I love it. And the type of research you do is my favorite part of aviation.

[@namibgtv6]

I really like your experiments. One thing i noticed in your video, as the stall is induced, it is clearly evident by your telltails that spanwise flow is starting to occur before the wing finally stalls, and the boundary layer seperates. What i would suggest if you havent already tried it, is to install wing fences just inboard of the ailerons over the wing. On real aircraft equipped with these they are usually installed where the flaps and ailerons meet. These will avoid, or rather reduce spanwise flow, and along with vortex generators will significantly re energise the flow and subsequently delay the seperation of the boundary layer. I once installed some on a scale Piper Cherokee that i built of blueprints, and it definitely improved slow speed handling. I also taped over all the gaps between my control surfaces and flying surfaces where hinghes were used, to stop cross flow between the two surfaces, even further improving handling.

[@filemonbonifacy9549]

Thanks a lot, it is so Simple and was so chalange for me to imagine.. you help me with ATPL exams preparation 🤛🏿

[@stephenyoungblood3683]

Greater that 20! Pretty impressive!

[@tedk2814]

I think I actually learned something here. I'm a student pilot and in reading about stall and wing types, some portion of the wing will stall before the other and I couldn't understand this. In your video, I watched the tell tails, they seemed to indicate the inboard portion of wing stalling before the outboard wing. then with the vortex strips added, the wing seemed to stall about mid portion first. Thanks for making this video!

[@Observ45er]

+ted K., Wings typically have "washout". This is a twist in the wing so there is less AoA toward the tip so the tip stalls last and you maintain aileron control further into the stall.

[@tedk2814]

thanks...

[@Observ45er]

... ur Welcome.

[@matthewrichardson828]

I just built an AOA and Slip Air Data Computer for NASA and USAF. All new C-130's are outfitted with a boom, not unlike the one you made, and will use my computers to take measurements for flight test and acceptance tests. Usually those vortex generators are used on the wings in front of control surfaces to clean the air a bit for the surface to be more effective.

[@SammSheperd]

Very cool! Have you seen my video on vortex generators?

[@matthewrichardson828]

***** Just a couple minutes ago. lol

[@13megaprime]

Samm, my thinking is that the vortex generators alone did not help because the wing will stall at whatever the critical AOA is. The vortex generators did help in controllability, but they do nothing to change the critical AOA.

[@puchomoreno]

The thing is they just delay the point where the airflow Will separate. And at this scale the power to weight ratio is so high that It gets difficult to get a real size type of stall.

[@rhett1272]

Fantastic demonstration thanks for sharing

[@DumbledoreMcCracken]

Observational science rocks

[@robertosfield]

Great wee experiment. A variation would be to use a set of tell tails in front of the LE in place of the vane. You could arrange them in various ways - vertically a specific span location, spanwise, before and aft the wing.

[@SammSheperd]

oooo that does sound cool

[@oonniiigg]

the angle the stick makes with the vertical = the inclination angle of the elevator =the angle of attack ,you can put a measuring device on your remote control pitch stick control , I did a aerobatics course in a flyable aircraft AoA control is all about how far back your stick control is hope this helps .

[@SammSheperd]

+Gino Russo hi I'm a CFI and commercial pilot ASEL and AMEL. Elevator position is the primary flight control for AOA but not a direct indication. Example: I can land a C172 so slow that I run out of elevator just before touchdown, while other times full elevator would absolutely result in stall. Elevator position held constant I can change AOA with other controls.

[@vipertech9108]

Nice work on this experiment! That gauge worked really well! I did notice that when the stall was about to happen that the tell tails behind the gauge arm were the first to react, I guess the arm was being affected by the stall also? But it was really cool to visually see the stall angle and it was very consistent and predictable.

[@SammSheperd]

Yea there seemed to be a parting point just behind the indicator. I only noticed it when the VG's were installed though

[@puchomoreno]

vortex generators Will not add lift but Will make the Air flow for longer, thats why you feel It more controllable. It makes Air reach your ailerons.

[@SammSheperd]

Hi, I'd like to share a video I made on the subject of VG's :) kzbin.info/www/bejne/m4GQioh6mp57fJI

[@puchomoreno]

i've seen It already. I've also seen It around youtube in a real aircraft experiment. They tried It on a standard plane without vgs and then glued some over the wing. Change in stall speed and control was massive.

[@CuervoRC]

Amazing experiment, I liked it, I'll do something similar in one of my planes, ;)

[@pauljs75]

Seems to be a function of airspeed. Hauling it didn't seem to matter within the range of the gage. But cruising fairly slowly it certainly wanted to stall at any angle above 20°.

[@SammSheperd]

Well, the two main things that can be used to control lift in the air are AOA and airspeed. You could almost say that Airspeed^2 * AOA = lift. so when you have a high airspeed, you don't need much AOA, but as you decrease airspeed, then you have to increase AOA to have the same lift. If you get slow enough to where you need an AOA past the stalling angle then that is the limit to how slow you can fly. A wing will ALWAYS STALL at the SAME ANGLE no matter the airspeed, It's just that normally having both a high AOA and also high airspeed is not needed or else you'll just do backflips or break the wing. Pulling out of a high speed dive or making constant altitude tight turns are both instances when stalling at a high airspeed is very possible. The full equation is: Lift = (coefficient of lift (AOA)) * ((air density) * (Airspeed^2) / 2) * (Wing Area)

[@eco19911]

Hey Sam! Fantastic Vid!!

[@SammSheperd]

Hey thanks!

[@BalaTutor]

I would appreciate if you could make a video of what the strings on the wings represent, I guess it is something to do with turbulence detection.

[@SammSheperd]

When they start to be blown the other direction, that indicates a stall. See me vortex generator and slat wing video

[@SergioCreativoOficial]

Wow! Good job Samn

[@diveflyfish]

Well done. The dimple idea is a super one, but the scale of the dimples vs the wing chord may be better suited by a smaller dimple size. Again, great work.

[@j69chevelle]

Maybe the veins lower the airspeed before the stall AOA is reached. IDK

[@FBI816]

Hey Samm, I love the video! I am training to be a Flight Instructor and have used this video to help me understand angle of attack. I was curious if you could shoot another video of this same setup on the airplane but focus on just straight and level descents and climbs with and without power. I am curious what the AOA would be in a 20 deg climb with full power vs half power. I am trying to figure out the relationship between power-thrust-speed and the AOA because it seems as though when you were in a climb with full power, there was only a relatively small AOA. I don't know if Im making much sense. Its hard to put into words. Thanks! Love the videos

[@SammSheperd]

Excellent observation. In an unaccelerated, constant airspeed climb we can expect our AOA to be very similar to that of a cruise or descent of the same airspeed. First let's look at the things that determine how much lift a wing makes: The lift equation is (and I'm compressing a few things): Lift = AOA * (Air Density * Airspeed squared divided by 2) * wing surface area. Now the next bit to understand is that the only time we are ever producing more or less lift than exactly the weight of the aircraft is when we are CHANGING DIRECTION. If we produce more lift than we weight than we will change direction upwards, if we had the power to maintain airspeed and produce the same excess of lift long enough we would just make a nice circular loop. Anyways when we pitch up to start a climb, initially we increase our AOA so that we produce excess lift in the upwards direction and this changes the direction that we are traveling. But as we start to travel upwards, the relative wind (which by definition is opposite the flight path) also starts coming from a higher angle. So let's say we are cruising straight and level at 100kts and the relative wind is coming directly from the horizon and our wing's AOA is like 4º because the wing is mounted on the fuselage with an angle, in this case like 4º. So 100kt and 4º AOA = our weight. Now lets establish a climb to 10º above the horizon. We initially increase the AOA to like idk 6º, producing excess lift and changing our direction upwards. However once our nose is at 10º and we are traveling upwards, the relative wind is opposite the flight path. The wing is still at the same AOA. Of course now we get into more fun stuff like the thrust vector opposing gravity and the lift vector pointing back a bit. Eventually at a vertical climb we would be hanging on the prop and need no lift from the wings... Ugh this stuff sucks to think about so hard. Anyway hope that helps a little.

[@FBI816]

Yes, that helps very much! Thanks for your help, and the quick response. Best of luck.

[@ChuckPlains]

Great stuff Samm, very interesting. I'm now fully convinced that i need a 3D printer! :¬D

[@SammSheperd]

Thanks! I'm just taking advantage of the one at my school. They are so expensive and troublesome still. There are lots of ways to take CAD drawings and turn them into physical parts, but not quite as easy as hitting print! haha

[@JFrazer4303]

They fly BT higher pressure below and less pressure above. A plank flies by presenting A to the wind. This mimics camber above and slows and compacts air below. A ram-wing GEV certainly doesn't fly by bouncing air down, back up off the water and off the wing again & again. It traps and compacts air below and is lifted via pressure difference driven partly by the Bernoulli effect above. Same with a plane in GE or flying. Any reaction from bouncing air down is secondary. Consider also the wing-tip vortex-driven "parachute lift" effect used by planes with aspect-ratio 30°+) the huge vortices wrap around and capture a "bubble" of low pressure above/behind them, increasing lift, while piling up high pressure below (just like a plank or Ekranoplan). Charles Zimmerman working for UAC/Vought following the '30s Arup planes from Indiana, found that aspect-ratio 1.8-2.2 maximizes the effect, producing >4x the lift a normal wing could, if they can even fly at

[@PaulAnthonyDuttonUk]

Well what was the verdict on the dimple sheets then?

[@peterpetofi9588]

always make interesting videos. bravo. keep it up. tu fai sempre dei video interessanti. bravo. continua così.

[@F0LL0WJesusChrist]

It would have been great to have one on both wings to show the different AoA in climbing and descending

[@AugustusTitus]

Awesome work.

[@cristianoespindolacr6368]

Great video. Very nice.

[@MonteCarlos767ER]

Good work Sam

[@j69chevelle]

Maybe add some airspeed telemetry and do the experiment over again just to see if those airfoil modifications have a measurable affect.

[@davidfew5000]

recently that at 35,000 feet the critical AOA is between 3-5 degrees on an airbus, as the plane went over the apogee of the arc, and down the other side the AOA increased critically, fatally when the crew didn't respond ( Air France flight 477).

[@aimeeoneil7029]

I love learning about angle of attack

[@collinxsmith]

Neat video! Thanks Samm :D

[@milosbrndiar]

To work the Vortex generator should by more in front (maybe)

[@jasperamirante6490]

I'm starting to get interested in RC planes and stuff but living in Italy is having a hard time finding the materials... Where do you buy the foam for the wings and fuselage...?

[@SammSheperd]

This plane was made with insulation foam found in home improvement stores. Another great material is foamboard found in stores with a craft section. Normally used for school projects or presentations or something.

[@jasperamirante6490]

Thanks also i wanted to know if there was any website that published airfoil shapes or something to use..?

[@SammSheperd]

airfoiltools.com is where I go a lot but I decide what airfoil is best by researching the specific application, Such as googling best airfoil for flying wings etc

[@DefaultMando]

Hi Sam, I just came across your video. My question is, how did you attatch your angle of attack indicator to your plane? The plane you are flying looks like foam.

[@jono3079]

I'm sorry to be the one to inform you that Samm passed away in 2018 in a motorcycle accident. A true tragedy. You can see the details in his latest and final video made by his father :(

[@paucliment9280]

Cool visual experiment.Do you know how the tv show is going to be called or if it'll be on youtube?

[@SammSheperd]

Will be called "drone wars." I was supposed to be editing this in an airport or something. But I missed my flight, might not make it there...

[@paucliment9280]

Nooooo. I bet it will be awesome

[@ammars.dawood5566]

Hello, thanks for all of your amazing and helpful videos, i was just wondering what CAD program are you using?

[@jirivorobel942]

I'd guess that the reason why vortex generators and the golf ball dimple sheet didn't do anything is that the flow is already turbulent from quite close to the leading edge. That's what model airplanes do, no wonder with their rough surfaces and low Reynolds numbers. Actually there used to be a fun problem when plastic covering materials started to replace doped tissue: Some wings that worked well with rough japanese type tissue didn't fly when covered in iron-on film - laminar flow just didn't stick to the airfoil at that Re! The same sometimes happened when someone used glossy tissue and overdid the finish. The solution was to put some thick sewing thread spanwise, just behind the leading edge - a turbulator.

[@SammSheperd]

+nJiří Vorobel you sure know your stuff! Great real world examples too thanks

[@nRADRUS]

very interesting research.

[@daisybeagle6259]

Cept I’m not looking at the wing during landing!

[@MrRishik123]

Awesome stuff.

[@RedDevilSquadron]

Super cool project. I've always been of the assumption (at least from a feel standpoint) that I never felt any difference at high angles of attack whether I was coordinated or not in an R/C plane with VG's. @Samm Sheperd, would you agree this is due to the tiny chord size at such a small reynold's number? I've just assumed so but never actually investigated and my knowledge of aerodynamics isn't much further than what was required for my CFI checkride haha. Full scale planes with such a large chord size seem to be much more positively altered by having full span VG's.

[@SammSheperd]

Man it sounds like we’d get along

[@RedDevilSquadron]

lol I was legit asking though, cuz I have no clue if the reynold's number has anything to do with it. :-)

[@gogogeedus]

That is a great little device, would be handy on all planes, how does it get effected by turbulence, turbulence is a factor that can cause problems, I'm sure your device would make turbulence apparent.

[@rcairflr]

All planes? Commercial and business aircraft already have either AoA vanes or AoA is measured by the Air Data computer. Turbulence is a function of air flow and as such AoA would be affected by it no matter what type of device you use to measure AoA. Don't confuse AoA with pitch angle.

[@olaitanodulaja6413]

hello wonderful video!!! btw did you build the whole system including the plane?

[@SammSheperd]

Yes

[@aitorarregui2973]

Good job!

[@gogogeedus]

this is an awesome experiment and I think you can see that the angle of attack is less on the inside of a turn, is this a correct observation?

[@SammSheperd]

There shouldn’t be much difference but yea in a roll the AOA of each wing is a bit different

[@monkeymaster26]

Wow, amazing to see the wing stalling at different points! I did get a little motion sickness though :)

[@IxedBacov]

Very interesting experiement, thanks for sharing this

[@SnapPunchRobert]

Very cool.

[@LA6UOA]

Great exemplification! Thanks for sharing! Try more experimenting with the golf ball surface! That|s highly interesting?

[@shodanxx]

Does dimple paper improve anything ?What does it take to make a stall warning indicator ? Aoa + airspeed (+ fancy math) + ?

[@SammSheperd]

It sure looked like it did, but I can't rule out electrostatic attraction or other factors. I don't think it felt much different. Most stall warning indicators are actually AOA indicators. Piper and Beechcraft like to use a little tab that get lifted up when the airflow comes up at a sharp enough angle (cause of the high AOA). Cessna likes to use a funny whistle that sounds when the airflow goes across it at a high angle. Pilots are trained to know "stall speeds." But a wing can stall at any airspeed. since when you slow down you must also increase AOA to create enough lift, there is a lower limit to airspeed, just because there is an upper limit to a wings AOA.

[@eco19911]

Yeah, I think the material could be an insulator.

[@AdamDemas]

did you take note of airspeed? If so, did it have an affect on the stall angle?

[@SammSheperd]

+Adam Demas although you could make an argument with Reynolds numbers at this scale, airspeed is normally irrelevant to stall AOA.

[@AdamDemas]

Interesting. Thanks!

[@boogerking7411]

0:08 how can i make mg own smoke lines?

[@SammSheperd]

google around. I borrowed that clip from youtube but you could use dry ice and water in a bottle with a hole in the cap. Or better is a heat element with oil on it. or if you're super fancy you can make hydrogen bubbles in water with electrolysis

[@didierneeferc]

The vortex generators work pretty well actually

[@garypaisley]

Nice work! What Re # is your model flying at?

[@SammSheperd]

At estimated stall speed probably around 80k and at top speed probably up to 300k Assuming a 70º normal atmosphere, 10 inch chord, and speed range of like 10 - 45mph

[@turkisaeed5431]

If we get into a vortex ring state is that mean that we have a big angle of attack ?

[@SammSheperd]

That refers to a helicopter or drone descending into its own downwash or wake. It probably does have something to do with the rotor blades AOA but I’m not really sure.

[@HOLLYWOODlosANGELES]

*Efficace et pédagogique,* merci

[@didierneeferc]

Thats a pretty wide angle lens you used at the end

[@SammSheperd]

I never changed lenses, but yes it's very wide angle!

[@davidfew5000]

the Book 'Stick and Rudder by W Langeweische emphasizes the criticality of AOA and envisions a windsock mounted to the airframe as a way to 'see' the AOA. The takeaway.Always avoid a stall, If something goes wrong (stallwise/airspeedwise) almost always the proper thing to do is 'PUSH THE NOSE DOWN !. Make the wing point in the actual direction that it is moving...

[@US772]

Wind aloft may have changed your stall test results.

[@SammSheperd]

Once airborn, an aircraft is slave to the winds aloft and everything is relative to it. Airspeed remains constant with winds aloft regardless of groundspeed

[@keesanker4241]

Can you make a fully 3d printed rc plane?

[@SammSheperd]

+CookPiggy already did. Coming soon

[@keesanker4241]

thank you!

[@friarrodneyburnap4336]

Samm you never let us see the plane.. ?

[@JohnMGreiner]

6:37

[@EdwardChew]

thats so damn interesting to see!

[@andrewsrc7717]

:D :D it's becoming a trend on your channel and cool little gadget!

[@wr250John]

all the way across the sky!

[@malharjadhav8404]

why have you stuck those black threads on the wing ?what does it do please explain.

[@SammSheperd]

Their called tell tails and they're used to help see the airflow at the surface. When a wing stalls the boundary layer reverses flow and you can see that happen when the string flails around

[@ShawnMorel]

Such a cool idea for a concept that's otherwise poorly explained

[@sanjeetgill448]

just beause its lightweight is difficult to do this

[@atomicsteameng]

Pretty off topic, but I'd love to see you make a plane that whistles when it flys, so that it resembles the sound of a supercharger.

[@jericodawsonmarcos7529]

Whats the difference of this from drifting's angle of attack?

[@SammSheperd]

Well I just did some googling to see what that is and I think that when talking about car drifting, the drift angle, sometimes called angle of attack, is the difference between the car's longitudinal axis and the car's direction of travel

[@davidpearson9851]

your tell-tale (tail?) string is acting like vortex generators!

[@TheDuckofDoom.]

You aren't dealing with a perfect infinite wingspan. The stall angle along the span changes due to the effects of wing tip and by the body of the aircraft(and the joint details), small gusts can briefly effect the true AOA and reattaching flow can require a lower AOA than it took to detach the flow.

[@SammSheperd]

Yep

[@TheDuckofDoom.]

My reply was in response to the statement in the vid that you were having problems determining a clear stall AOA. ...though the vid was posted the better part of a year ago. I mostly reply to stimulate my own memory, it's been a decade since messing with sailboats and 15 years since studying fluid dynamics and aircraft design.

[@Arkferret]

any chance you can post the print file for this?

[@SammSheperd]

it was custom made to fit my airfoil. It's pretty easy to make tho

[@saulolucena9182]

I would sugest you that the stall angle is for a specific speed so measuring the stall angle needs the velocity it happenned, sry for the bad english, im seeing ypur videos and really like some Great ideas you have and a probably test too in my future project of a uav.

[@SammSheperd]

+saulo lucena stall angle has nothing to do with airspeed :)

[@saulolucena9182]

L=(1/2)*rho*(V^2)*S*CL If you Look to the lift equation, you can see that we have CL, this coefficient of lift varies for every angle of attack of the wing does, so, if you keep lift L (at least the aircraft weight ) you see that velocity Will depend on CL the aircraft is and for consequence the angle of attack it is doing at the moment, so every angle of attack has a specific stall speed

[@SammSheperd]

I know the lift equation by heart too. Fundamentally, ignoring the other dynamics of flying an aircraft, a wing stall only has to do with AOA. We call it stall speed, because in straight and level flight, in order the maintain altitude while decreasing airspeed we need increase AOA (CL), up to the point where we reach critical AOA, the. We can't go slower because we also can't increase AOA. If we just create less lift and start descending then the relative wind will change direction and to avoid stall we have to pitch down a bit and then we will speed up. A wing can stall at ANY airspeed. Eg. A dive bomber trying to pull out of a dive. Crazy g forces, loads of airspeed, but they would often reach critical AOA and have a high speed stall.

[@saulolucena9182]

now i got what you mean, to the Max stall angle you can reach to the minimum speed you can maintain the aircraft flying, thats yours maximum reachable angle of attack during a flight.

[@didierneeferc]

Really interesting

[@komentierer]

There is no such thing as a universal angle of attack for stalling a specific wing. The velocity of the surrounding air is a crucial factor.

[@SammSheperd]

The only argument in favor of your assertion that I can see is that at a small scale such as this, the Reynolds Numbers change quite a bit with change in air velocity. At these relatively low Reynolds number, when the airspeed is reduced, then the flow's ratio of inertial to viscous forces changes and the flow becomes relatively more viscous and the flow tends to stay laminar and experience boundary layer separation easier than it would at higher reynolds numbers. However it is a fundamental teaching in aviation that a stall has absolutely nothing fundamentally with airspeed and 100% to do with exceeding the wing's critical angle of attack. Stall speed is simply a result of a specific aircraft needing a certain amount of lift to oppose it's weight in level flight.

[@komentierer]

***** A stall is caused by the separation of air flow. The stall angle by definition is the angle at which the air flow at the upper side of an airfoil seperates which causes a loss in lift at a constant relative wind. But when the relative wind is not seen as constant, the possibly higher velocity of air causes the wing to stall at a much lower angle as the airflow is not able to stay as attached to the airfoil as with a possibly lower velocity of air.

[@isaiahphillip4112]

An airfoil will stall whenever the critical angle of attack is exceeded, what most theory of flight handbooks don't bother mentioning is that the critical angle of attack changes with airspeed and numerous other factors.