Very sad.

Aaron Rubinstein Motorcycle crash.

A Bonanza Right? Beautiful sunset and rainbow!

PA28R-200 (Piper Arrow)

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

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

***** 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 haha that made me laugh

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

☀️

Hey thanks!

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.

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.

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.

Would twine be less susceptible to that kind of electrostatic?

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

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.

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

oooo that does sound cool

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

I'm glad you found it! I have two other video's exploring Boundary layer separation: kzfaq.info/get/bejne/m7ZdjLh1yp-sdmQ.html

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

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

+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.

thanks...

... ur Welcome.

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

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

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.

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)

+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.

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.

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

Yes

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.

Yeah, I think the material could be an insulator.

Man it sounds like we’d get along

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

Hi, I'd like to share a video I made on the subject of VG's :) kzfaq.info/get/bejne/m7ZdjLh1yp-sdmQ.html

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.

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

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.

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.

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

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

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

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...

Nooooo. I bet it will be awesome

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.

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 :(

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

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

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

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

@@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?

@@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!

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

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

Interesting. Thanks!

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

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

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

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

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

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.

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.