Things Flight Instructors Taught Me Which Were Wrong!

[@ardag1439]

The reason airfoils generate lift is because the full form of Navier-Stokes equations get so ugly that Earth pushes them away.

😂😂😂

[@scottmanley]

I'm going to steal that.

[@jajssblue]

This is the same way helicopters work.

[@LupusSolitus]

Wait! Doesn't Mr C Norris push the earth away? If so, this would mean that Mr Norris is in fact responsible for the generation of all lift, not the Navier-Stokes equations.

[@imaner76]

😂 I didn't mean to laugh at this, I'm just unsure how to stop.

[@Mythilt]

When my brother, who has a degree in physics, was in naval flight school, they had a class on 'aerodynamics and flight'. A little into the class the professor gave the high-school reason wings work, and when my brother and a couple of other students started to react, asked them if they had engineering or science degrees, and when told yes, said. "You are going to hate this class."

[@kennethc2466]

"Myths about flying which I found on the internet"...that are not taught in school. Check your emotional drivel at the door. Does ANYONE who watches this channel, need that, er, 'knowledge', of the 'internet'? "When my brother, who has a degree in physics" ...appeal to authority, instead of physics. You know, a logical fallacy. ZERO explanatory value. My physicist sister in law, works for CERN, and can't fly my Piper Cheyenne, nor even taxi it. Check your logic errors, and false equivocations. You speak like a spoiled child, begging for belief. "asked them if they had engineering or science degrees" In which you have NEITHER!...yet have stolen valor from. Spoken like a kook who appeals to emotions, instead of the mathematics required for both. Oh, and another appeal to authority. You know, a logical fallacy, again. Also, a private pilot's license requires NEITHER DEGREES. You're quite self refuting, from a clown who could NEVER pass a private IFR course. PS, ALL naval, er, in your false words, 'aerodynamics and flight', ALL adhere to physics. BY DEFINITION! Please see naval ACM technique, and TRY YOUR BEST to see ANYTHING that doesn't meet current physics, or ANYTHING that nullifies it. Speak up, station wagon 'pilot', in your, er, 'knowledge' of "FLYING", let alone NATOPS. Please show your 'expertise', IN MATH, and not, 'my bla bla knows bla bla more than bla bla". Step up, clipped wing TROLL!

[@eekee6034]

Why do you need an engineering or science degree? I could see it was wrong when I was 12! You just need to be in the habit of observing things (such as smoke) and thinking about your observations.

[@zyeborm]

​@@eekee6034 good for you, tell everyone how smart you are and then get a cookie

[@empireempire3545]

@@zyeborm How 'bout you go and get a snickers? The guy points to an important problem - most people loose their natural ability to observe and think critically when they transition from being kids. It is absolutely required for STEM, but as he points out, everyone can do it and everyone would benefit from it.

[@gurk_the_magnificent9008]

At least the dude was up front about it!

[@jameslmathieson]

This video has reinforced my belief, as both a mechanical and AI/ML engineer that has built and flown hardware in space, that RF engineers are dark wizards in possession of eldritch magic.

[@oldfrend]

i think that about electrical engineers in general. like no one can convince me that electromagnetism isn't dark age magic - we just know how to manipulate it better. flows of pixie dust generating force energy? cmon.

[@patrick_test123]

Like your field isn't even more whichcraft. 😂

[@sphaera2520]

EM is totally magic. Circuit boards, antennas, hell the entire electrical grid are just more or less gigantic/complex magic “circles” that cast the appropriate spell.

[@owensmith7530]

I used to know some RF engineers. When you hear them say things like "the RF doesn't like going round tight corners on the PCB and will spray out of the corners" you know you're in the twilight zone.

[@NorseGraphic]

Amplitude-modulation and Frequency-modulation is well known, but to really pack the data you’ll need phase-modulation. The amplitude and frequency is constant, while the information is encoded though the signals phase. The way they set it up was to determine what phases represent individual bits (as in computing bits: ones and zeros). By increasing the number of distinct phases, you could pack more bits in a single frequency-cycle. Back when I learned this almost 30 years ago, this is how broadband-internet communication was based on. Things might have changed drastically since then, as I’m not involved with this stuff anymore.

[@sergarlantyrell7847]

I remember the beginning of my Aerospace Engineering degree, were in the first Aerodynamics lecture, the lecturer pretty much said 'All that stuff you've been told in school about how wings work is basically all wrong.' Then the next year, we were told that what we'd been told the previous year was still only a simplified version and was only part of it.

[@wormfood83]

Sounds like Chemistry degrees.

[@r3dp9]

Same thing happened when I learned weather. The instructors warned us up front that everything we would be taught was a gross oversimplification that we needed to memorize to pass the tests. Once we got out into the real world, we'd see for ourselves how real weather (mis)behaves.

[@michaelwoodhams7866]

For a couple of years, I taught physics to student pilots part time. One of the things I told them was "I am a physicist, not a pilot. If anything I say is contradicted by your flight instructor, do what the flight instructor says." I'm also reminded of a time when friends of mine were taking online classes for scuba diving. I would listen in to their lessons, and very often I could say to myself "Aha! I know the physics behind this thing!" (E.g. why you don't try to hold your breath while ascending.) Having said that, I'm not confident that, left to my own devices, I'd have figured out every single safety critical procedure ahead of time before it killed me.

[@Pho7on]

It's really just the principles behind engineering versus science at play. Science is all like "what a cool phenomenon, this could take decades of several PhD careers" while engineering is like "lol wing go brrrrrrrrrrrrr."

[@justincase5272]

It's like the difference between understanding linear and radial motion and riding a bicycle. Even expert knowledge of the former will not keep you from falling. That can only be learned by doing. Ground is indeed very important, but one still has to accumulate 40 hours of instruction and solo time practicing and re-practicing everything before the check ride!

[@falxonPSN]

​@@Pho7on engineering is, at its basis, applied physics. The key word is applied. The vast majority of engineers are interested in how to achieve specific outcomes using various skills and knowledge. While the original basis for that knowledge might be an interesting fact to them, it's far less useful than ways they can actually apply the knowledge.

[@floridanews8786]

You should know better as a physicist 😜

[@DrWhom]

Yes, I had the same experience in scuba class: there was no need whatsoever to get into a physics-penis contest with the instructor, who was nice, and would probably safe my life if I did something dumb like forgetting to inflate my buoyancy device upon surfacing.

[@BimmerDreamer325i]

I’m a CFII who was taught and was teaching the “lighthouse” VOR explanation, but now I stand corrected. Thank you Scott, you have made me a better Instructor.

[@dougaltolan3017]

Sitck with the lighthouse model as an introduction, it's not as far from reality as Scott woukd have you believe. But do add that the beams aren't so sharp. Think of it in similar terms to describing a vhf reciever... Most people woukd say that all other frequencies are filtered out, leaving the carrier.. That is as far from reality as the lighthouse model is. Unless you want to explain super hetrodyne circuits, stick with the basics.

[@filanfyretracker]

@@dougaltolan3017 VOR the friendly light house, you can pilot your craft towards it. Normal light house, please do not pilot towards it with your craft. its warning you about the rocks.

[@kukuc96]

@@filanfyretracker Not that you are likely to hit the rocks while you are flying. Unless you are flying at exactly sea level.

[@zyeborm]

I mean as an analogy it's pretty darn close really.

[@korenn9381]

@@kukuc96 he said craft, so that implies planes in the air and boats on the water.

[@dwaynepenner2788]

As a former flight instructor and now a “trades” instructor the more I teach the more I find this type of experience to be true. I now teach basic concepts as “models or analogies that will get us by until you have an interest or need for more accuracy”. In fact this is often the way of scientific discovery.

[@mdrocketry]

Oh my hell, I feel so validated. My entire flight instructor career, I tried my best to fix those last 3. I'd like to think I made an impact on my students and my peers, but MAN! You hit all my pet peeves as a CFI! VOR was my favorite thing to teach, I had such a fun lesson for it haha

[@VictoryAviation]

Care to share? I’m doing CFI right now and will be doing II next semester. I’ve always felt like understanding the VOR system is way more complicated than needed.

[@mdrocketry]

@@VictoryAviation it's like a 10 minute lesson, it'd be hard to type out. I basically just taught the Doppler VOR, starting with basic Doppler effect, then to spinning a speaker in a circle. Spinning a speaker around in a circle as if it were on the end of a rope would cause the doppler shift to look like a sine wave. Then, depending on where you're at relative to the spinning speaker, that sine wave 'starts' at a different spot. Man, this is really hard to teach without drawing haha. Basically, when the speaker is coming 'towards you,' you get a high frequency. When it's going away from you, you get a low frequency. When it's not moving towards or away from you, the frequency is neutral. You draw out where the sine wave starts for east of, west of, south of, and north of this 'spinning speaker', making sure to start from the same position if the speaker every time. The only way this is probably making sense is if you already know what I'm talking about haha I'm so sorry Finally, you tell them about the reference speaker that's in the middle of the spinning speaker's circle. The reference speaker only broadcasts what you'd hear if you were north of this setup. Draw the sine wave you'd hear if you were north of the setup over the other ones you drew earlier, in a different color. Now you can point out that the phase difference is the radial you're on. Then you fill in the details. It's not a literal spinning speaker, it's like 40 transmitters emulating a spinning speaker. It's a mix of AM and FM modulation to be able to get it all into one signal. The plane's VOR receiver has to have its clock calibrated to make sure that its frequency is right, because all it's doing is measuring the VOR signals against what you've selected on your CDI. So if its clock isn't calibrated correctly, you get deviations, hence the 30 day VOR checks. ILS doesn't have this problem. Man, what a mouthful. If this doesn't make any sense, maybe I'll make a video. It's a very visual lesson.

[@qazwer001]

As a student glider pilot the bernoulli principle bothers me to no end. Same with VOR, I'm a ham radio operator but haven't done much with it. The common explanation always sounded wrong but I never looked into how it actually works.

[@zaphurnusprime3695]

@@mdrocketryThank you for typing this out!! I look forward to looking into VORs more to make sure I understand them better; do you know of any good videos, Advisory circulars, etc. that dive deep into VORs and other nav equipment?

[@mdrocketry]

@@zaphurnusprime3695 kzbin.info/www/bejne/iGG5q5ScZpmGgbM I believe this video is the one I heavily based my lesson on. When he starts talking about phase difference, I draw it out in almost the exact same way as he did.

[@nathand.9969]

Hi Scott: I'm a CFI in training, and I wanted to say thanks for this video! I am going to incorporate its knowledge into my lessons. Blue side up!

[@CR-iz1od]

blue side up unless flying over water 🤣

[@floridanews8786]

Blue side up..the ocean right. JK 🤣

[@toolkit71]

Ok, I worked with another engineer that designed software for the automated landing systems with a new jet back in 2003, he said the autopilot could land the plane so well....he also said that they had to change the code to "fudge" the landing line because of all the test planes hitting the exact same spot and then causing issues with the runway....So the "fudge" factor was just to give a 50m target front and back for the automation in case a plane had to automatically land...Love the channel been here for a long time and this was amazing.

[@ASpaceOstrich]

I love that. Automated system being so accurate that it causes physical damage to the runway.

[@DejonckheereWard]

Its crazy how often having a random fixed offset has been useful in any automation. Like on the internet, Imagine the chaos if every windows computer decided to update the second a new update was available

[@Systox25]

But many accidents are in too much trust and lack of understanding in the automation. Landing is hard so practicing it all the time sounds like a good idea.

[@DeuxisWasTaken]

@@DejonckheereWard for updates I think they rely on the fact that different computers will check for updates at different times (which they design software to actively encourage) and that they can first ask the server "hey is there an update available" and adapt to instructions like "yeah, check back at " instead of just immediately trying to pull a file from a known address and clogging everything up. Random offsets are crucial for many other things like network clashes though. If two computers try to send a packet at the same time on a network segment that can't handle it it results in a collision where neither packet goes through. If they were to attempt again after the same interval they would just collision-loop indefinitely, so they choose a random offset within defined margins.

[@Patrickf5087]

​@ASpaceOstrich not that hard really, it's amazing how weak concrete is in general, but you have to remember tgise airplanes weight TONS plus the speeds they hit the run way at 55mph going laterally and coming down at probably 2in per second.

[@casualbird7671]

I loved the silly METAR bit at 3:35 to point out how many mixed units there are

[@jvtaylor3]

Wait till you find out we mix English and French words into those METARs :)

[@RalphEllis]

Luke… FU = Smoke. (fume) GR = Hail. (grains) BR = Mist. (brume) PO = Dust Devil. (??) The best one is Potable water. Or Pour Table - water for the table. R

[@EnderMalcolm]

As someone trying to add Aeronautical jargon to my homemade weather station *Holy fuck it's complicated*

[@Ice_Karma]

@@RalphEllis Dust devil in French is "tourbillon de *po*ussière" (whirlwind of dust). 😺

[@gilliganxl]

​@@RalphEllisI love saying BR mist is BABY RAIN lol

[@eriklundin9436]

Thank you for making this video! I spent many years teaching people to fly, and ended up with a lot of students who had inherited much of this nonsense. Nothing scared me quite as much as when I went to get my CFI/CFII at a Part 141 school. I had previously completed the full EMT course at CP Aviation in Santa Paula, CA, so I was very familiar with spins and how they behave. During my CFI training at the 141 school, I had to complete "spin training" with one of their CFI instructors. It became immediately clear from his demonstration that he had never experienced a spin. The aircraft (a very... well loved... C150) began to enter the incipient phase of the spin and then just didn't go any further. An aerodynamically stable spin never developed and the plane would just be in a dive by the time the instructor began to "recover" from the "spin". I asked if I could show him what a spin actually feels like, and to his credit he let me try it. It took full aileron input throughout the spin to make the plane spin at all, and he was absolutely shaken at how violent it was compared to what he had experienced in the past. This school had trained literally hundreds of CFIs in this plane, none of whom experienced a spin in their "spin training".

[@DrWhom]

That said, was the recovery technique the CFI taught sound in and of itself - albeit perhaps a bit harder to put in practice when you are actually in a spin?

[@XPLAlN]

@@DrWhom ….and maybe the instructors at that school had read the Cessna 150 AFM notes on intentional spins, particularly “careful attention should be taken to ensure that the aileron control is neutral during ALL PHASES of the spin…” And the problem was perhaps that they were not applying full rudder and elevator as the airplane reached the stall?

[@electronicsafrica]

i bet there was a brown strip in the underpants ;)

[@Deltarious]

About shock cones: while it's absolutely true that they're not sonic booms they *do* have a very nice habit of typically happening right around the upper transonic region on a typical mildly humid day so you will often see them right around the same time the aircraft begins technically going supersonic (because of course some of the airflow will still be transonic until you go even faster, often around mach 1.2)

[@jerseyshoredroneservices225]

Why does the cone quickly dissipate as the plan continues to accelerate?

[@LloydWeeber]

The cones are where decompression is occurring AFTER the air has been compressed into a shock cone and because of the rapid reduction in pressure that air is suddenly cooled below the dew point and a cloud forms. If the plane flies into drier air the lesser amount of moisture will result in an unnoticeable decompression cloud. It might be there but you won't see it. If the plane returns through moist air at lower speeds the shock/decompression effect will be different and the cloud may not form.

[@tumpio314]

Hello Scott, mathematician pilot from Finland here! I struggled a bit with similar things when I got my license. One thing that you didn't mention here is about the graph at 12:36. It was taught to us (and it might have been on the officials tests too) that the point of the minimum drag is where the induced drag and parasite drag curves intersect. Mathematically there is no reason that the minimun is exactly at that point, with general curves. The minimum of sum of decreasing and increasing functions is generally not where their values are equal and it is not enought that both functions are quadratic. It's probably around that point in this case but not exactly at that spot. I think most sources claim this but they don't say why. :)

[@TheTechnoPilot]

Commercial multi-IFR pilot here who always crazy deep-dived into things beyond normal lessons and I just learned something new when it came VORs! Makes an incredible amount of sense, especially the Doppler shift and I love it! Thanks for sharing Scott!

[@SapientPearwood]

I'm a phd aerodynamicist, not a science educator or communicator, so I'm probably not the best person to figure out how to communicate lift to non-fluid dynamicists. That said, my preferred explanation is that wings create lift because they turn the flow downwards. If your air came in straight and is now pointed downward, then you must've transferred some upward momentum to the wing. This is a complete explanation in that it explains all possible observations, and it's a correct explanation in that it directly invokes the specific physics that navier-stokes is modeling in the context of a wing. The "flow turning" explanation is also consistent with the Kutta Condition explanation from potential flow theory. But most importantly to me is that even in the "lay-person" explanation, it still directly invokes Navier-Stokes. That's because the explanation for why the flow turns is that a no-slip boundary layer makes the flow want to stick to the top surface of the wing even as it curves away (i.e. the Coanda Effect), which turns the flow downwards. It explains stall because after a certain point the flow can't turn that hard and just separates. It explains flat plates because the flow is sticking to the top surface which is angled downward. Flow turning is obviously the correct explanation, but I think it is also an explanation that should be palatable to non fluids folks, plus it sneakily invokes boundary layers and separation which are truly at the heart of what N-S is trying to say.

[@douglascooke1926]

My CFII was a retired science and math teacher. He was great at explaining all of this. Even better, he just wanted to fly and cover his costs, so getting my PP certificate was very inexpensive. He flew west over 10 years ago.

[@mzaite]

Sadly not enough CFi’s like that these days. Most schools actively don’t even want them. Preferring pilot puppies who can be easily exploited.

[@Silverhks]

As an outsider I've never understood how using new pilots as CFIs to build hours made any sense. The best teachers are the ones who have been there done that, IMO

[@douglascooke1926]

@@Silverhks he wasn't a new pilot. Had been flying for decades.

[@Silverhks]

@@douglascooke1926 oh I got that. I was talking about the industry not your specific CFI.

[@korenn9381]

@@Silverhks It's also because of the flight hour requirements for airline pilots that was set into law by the US. Flight instructor is one of the few ways new pilots can get the required hours that also pays some money. Mentour pilot has some good videos about how dumb this system is (that was created by lawmakers, not aviation experts)

[@tledeboer1]

The cabin class piston twins I fly have a history of being filled with Jet A. And I had it happen to me personally. So if I’m not present for the fueling. Which is rare. I pop the cap and take a sniff. Jet A has a pretty distinctive smell even when mixed with 100LL. But you’re definitely correct about the failure after take off. There’s usually enough of the correct fuel in the strainers, lines & filters for startup and taxi. But it runs out after that.

[@benjaminthomasson]

Lift is throwing air down.

[@mb106429]

It is ridiculous that there's no window/clear pipe section in the fuel nozzle and filler so yiu can just see the fuel in there and the fuel you are putting in. also in cars there is flow and return lines so the fuel at the engine is the same as the tank within a couple of seconds

[@MattMcIrvin]

When I first learned about VOR (messing around in Flight Simulator software) I had a vague idea that the beacon was sending out 360 tight directional beams that somehow had their heading encoded in them. The "lighthouse" explanation is at least closer to correct than that!

[@Skinflaps_Meatslapper]

That's what I was taught as well, but I had to laugh, ain't nobody got time to engineer all that business...or even figure out what to do with adjacent beam scatter bouncing into your receiver and giving the needle a seizure. I mean, it probably wouldn't be quite so bad 150 miles away on flat ground, but if you're in the mountains there's no way you're going to get a single beam heading your way without ten others bouncing around you too.

[@keylargo70]

I flew airliners for 30 years and never understood how a VOR works. I know now, but the aircraft I fly today have no VOR equipment. So interesting to learn, but essentially usless information. In 50 years of flying I know how to use a VOR but have had no reason to know how it works. The same way you don't need to know how radar or any of the other electronics works to use it. This was a fun video to watch and hear how some of the BS is put to rest.

[@jmirodg7094]

The simplest explanation that I give for lift that is perfectly physical is the lift is generated by throwing mass downwards the same way as a propeller throw mass backwards to generate thrust. It is simple and perfectly true. For the stall speed it really depends of the aircraft and what is limiting their altitude and for personal aircraft that are relatively slow it is more the decrease of power of the engine that limits the altitude for transoceanic aircraft it is usely define by what is called the cofin corner, as you fly higher your stall speed increase and you have a hard limit from the buffet given by the rigidity of your wing (more precisely it'modes) and the exitation from the transonic effects. and when the tw meets there is not much options for the pilot.

[@davidkavanagh189]

As Scott was getting at in the video, there isn't one explanation. Your explanation would not be true for a wing in ground effect where a large proportion of the lift is compression of air and associated reaction force with the ground. For some reason, we pilots seem to thrive on wanting to know how things work and be right about it, often without reason. I like Scott's point that pilots really don't need to know, apart from some key details. Makes a good argument for amending the way these things are taught to new students.

[@liam3284]

A propellor uses lift to throw the air behind it, The wing is using lift to throw air "downwards".

[@HerraTohtori]

I would say the wing certainly tries to "throw" air down (more accurately it tries to curve the airflow around it), but since there is more air on the way that stops the air being thrown, and you instead end up with a high pressure zone below the wing and a low pressure zone above the wing, and that pressure differential supports the wing. The explanation based on action and reaction is also accurate, but the pressure zones distribute the action on a fairly large amount of air, which means the visible downdraft of a passing wing seems "insufficient" to satisfy the explanation from a reaction principle. Kind of like when you hang an object onto a spring. It causes the spring to stretch above and compress below the object until there is equilibrium of the forces and the spring supports the weight of the object. The air sort of does a similar thing to a passing wing, but in a much more dynamic way. I guess since we're talking about air, we could call it... aerodynamic.

[@kindlin]

One explanation that I liked is that it's mostly due to the air flow around the wing being directed downwards, but not because it hits the wing, and not because the suction picks up the wing, but the suction sucks the air flow down, causing it to flow more downwards than before the wing had passed, and subsequently pushing the wing upwards.

[@andrei-lucianserb1771]

@@davidkavanagh189 The only 100% true physical explanation is the mass being thrown in a different direction which causes the wing and aircraft to move in the opposite direction. Newtons 3 laws of motion are always true. These laws together with the various forces that act on a particle and the properties of such particles are what all of physics is about. Everything else are just ways to solve complex problems in a simpler manner. All the complexities come from the enormous amount of particles and their interactions through forces and the 3 laws of motion. To calculate the perfect interaction between a wing and the surrounding air you would have to know the position and velocity of every single air molecule, and then calculate the forces caused by the electromagnetic interaction between every molecule of the wing and the air, and then calculate the new positions and velocities, and now also consider that all the molecules of air affect each other and you also need to perform the calculations for them as well. So you end up with an impossible to calculate situation. All the physical equations that specifically target aerodynamics are just calculating the effects on average. That makes them practical. Explaining something with the equations of aerodynamics is great for explaining the general situation and the observed effects on average. But these effects are secondary effects always caused by the primary effects which are caused by the laws of motion and forces. This is why mass being thrown in a different direction is always a correct explanation, even though it may not be practical. But it is never false, no matter the situation. The universe does not “know” aerodynamics, it only “knows” the fundamental equations, everything else are just consequences of those fundamental equations, which can also be described through equations.

[@admlorenz]

When you're training, please do one thing, and don't develop bad radio communication habits. -flip talking -superfulous or redundant statements that unnecessarily tie up the frequency such as "checking in with you", "this is N1234 and we are here with you", adding "when it helps" to the end of a transmission, stating "any traffic in the area please advise", making long initial radio calls before communication has been established. The AIM discusses why these statements/practices cause problems and explains proper radio communication techniques. It's great that so many pilots are trying to be friendly, but it's a problem when you're preventing others from being able to communicate.

[@svtraversayiii9453]

Great video! And I really like the spaceflight videos too. For what it's worth, I learned to fly in 1964 when VORs and FM broadcast radio were both relatively new. We all learned the AM/FM explanation you give in the video and had little trouble with it. I had just started my airline career as Neil Armstrong walked on the moon and last flew in 2004 [Tokyo to Vancouver Boeing 767]. Now skipper a sailboat.

[@mcmann7149]

I must ask, guessing that you did Pacific routes during that period, was there anything different from flying to Anchorage or to Honolulu and then on to Asia or was it similar sans the obviously longer time in the cockpit?

[@kedrednael]

I literally spend a couple hours yesterday searching for different explanations of why clouds form, also from planes flying through air. Now Scott Manley is explaining it beautifully. Thanks!

[@glenmcgillivray4707]

Clouds are weird. But It wasn't till one day folks explained that lift requires a much larger system of air movements that i could sit back and understand WHY Reverse thusters actually can allow an aircraft to reverse. After all, You are blowing backwards with as much air as you are pulling back into the engine. Even allowing some energy from burning fuel, logically the aircraft should mostly stay still! But when the air from the engines pushes on all the other air around the aircraft, suddenly you have a much larger mass of air moving in the same direction, and you just have to capture the pressure and energy of that air against the airframe, and it pushes your aircraft around. Nifty. Also explains why the vortexes at wingtips lose a lot of lift when actually they aren't anywhere near the aircraft itself. But because there is a big circulation of air going up because of the energy you are spending, the general behavior is for less air movement down, and thus loss of lift.

[@aaroncuilty9306]

As a brand new CFI (working on my CFII), this is great! And yes, there's alot of watering down of the 100% factually correct explanations in order to get the necessary info across without overwhelming people. But its a blast digging into the roots of what the real answers are! Great vid!

[@mzaite]

The key is making it clear it’s an ANALOGY. Just like Quantum Mechanics, it’s important to make it clear it’s a way to think, not the “truth”. Good luck on the double-i!

[@diGritz1]

I only ever have one recommendation regarding learning materials that very few suggest. It's NTSB accident/incident reports. I've read through 100's and the "pilot errors" stick with me. Before and during pre-flight they are always in the back of my mind. Did the same thing post SCUBA Cert as well.

[@scottmanley]

Yes, I know a lot of things to not do.

[@roberthaston459]

Actually, the lighthouse metaphor perfectly describes........a TACAN military navaid. These operate in the same frequency range as DME. They originally used a mechanically spinning drum. I got FAA certified as a TACAN mechanic before I wound up flying for the USAF. The antenna are about the size of a kitchen garbage can. You can fly an approach to a moving ship deck in IMC conditions (which is nausea inducing). Interesting side note. The ILS glide slope acts as if it comes from the antenna base. So that 3 degree glide path is actually a conical section cut by the vertical plane of the runway. You can see this by flying it very slowly in a helicopter. The tower and antennas are carefully placed for the design aircraft's glide slope antenna for Cat 2 and 3 landing systems.

[@kayjay7585]

Wings generate lift is SO much more SIMPLE: Preservation of Momentum. To elaborate: you can steer any object though a medium by orientating the object so it pushes more of the medium in one direction than it's opposite direction, given it's traveling at sufficient speed relative to the medium (because at too slow speeds the pushed particles in the medium can dissipate their momentum in other directions as well - cancelling each other out). So fundamentally, all we need is orientation, geometry and speed of the body. I'm too tired to keep typing. Maybe I'll finish the detailed explanation tomorrow...

[@drmoseley]

Scott, my initial flight instructor was a physicist from Fermi Lab (outside Chicago) who explained that if Bernoulli was the only reason wings created lift, a Cessna 172 would need to rotate at 700 knots. Newton bears much more responsibility for lift (for every action, there is an equal and opposite reaction).

[@my2cents366]

He missed that.

[@MiG82au]

That's wrong though. It's not Bernoulli or Newton nor is it a summation or the two, they're describing different aspects of the flow. One is looking at the pressure on the wing and the other at the momentum of the flow. There's no basis for the 700 kt comment.

[@Anvilshock]

How does one give a rotation in knots??

[@drmoseley]

​@Anvilshock Rotation occurs around the lateral axis as the pilot pulls back on the yoke to effect a takeoff. The planned speed for this is referred to as 'rotation speed'. In a Cessna 172, this occurs somewhere around 55 knots.

[@Bluswede]

A high school buddy of mine was high in the pecking order of computer system 'wranglers'(?) at Fermilab. He worked both Beams and Collider sections starting fresh out of electronics school in '83-4...only adult job he ever had! Lost him to cancer a couple years ago... Likely groundwater contamination from the local potato crop got to us as kids, it hasn't QUITE gotten me yet.

[@Aliyen]

Watching you talk about VORs reminds me of when I taught students about IFF interrogator sidelobe suppression. The methods we humans come up with are really amazing sometimes.

[@flywithjohn6385]

Scott, I just got my PPL too. Your video about lack of instructor availability and bad weather earlier in the year really resonated with me because I had the same experience. This one also resonates strongly because I've had several instructors and they seem to disagree about so much, but in the end they're all good and safe pilots. Although perhaps they could be better about admitting what is an opinion and not a ground truth.

[@anthonycanalese2142]

When studying mechanical engineering, specifically fluid dynamics. I was tought that Bernoulli's Theorem (equation) has many restrictions in it's applicability for the fluid that is being analysed. One of those is that the density of the fluid is constant. This means that the fluid cannot be compressible. Air is a gaseous mixture and is demonstrably compressible. Ergo, Bernoulli's equation is not able to be used to describe the fluid flow of air around an airfoil.

[@lluminatus]

Glad to see someone share my fascination with the engineering beauty behind VOR`s and especially doppler VOR`s! I teach Radio Navigation for commercial pilots, and all your explanations are spot on! The entire syllabus for commercial pilots both for EASA and FAA is packed with oversimplifications masquerading as complex and precise theory. It is an astute observation on your part, one which i try to instill in my students, and which makes you a safer pilot in my humble opinion! Happy landings!

[@jnbfrancisco]

I attended a pilot ground school in Clovis NM in 1971 or 72. I quit when the instructor said that when you return the rudder pedals to center after moving the pedals to compensate for adverse yaw created by the alerions when rolling the aircraft to perform a turn, the rudder actually stays displaced. Somehow according to the instructor the rudder position is not relative to the pedal position at that time. I knew that to be hooey and decided I would not pay for misinformation anymore.

[@Arturo-lapaz]

right you were, but change flight instructors , interview a recomended one and explain your experience.

[@alexlandherr]

I once took some weekend extracurricular science courses held at KTH in Stockholm by some Masters Students; one of whom was studying aeronautical engineering. As he put it: “Lift is a really complicated thing when you get into it.”

[@GreenBlueWalkthrough]

Yet it's intuitive to understand like stick your hand out of a moving vehicle and you'll feel lift and drag and what shape does what.

[@pyropulseIXXI]

How is it complicated? You can easily generate lift with a perfect rectangular wing with a slight angle of attack. It is just deflecting fluid down, and a fluid deflected down imparts an upwards force on the object doing the deflecting. And if you consider the fluid as a particulate and not a continuum, you just get colliding 'balls' that impart momentum to the wing after every collision. I fail to see how this is complicated. Obviously if you also create a faster air flow over the top, you'll get reduced pressure on the top, which allows the imparted momentum on the bottom to have more of an effect, thus creating more lift.

[@murphy54000]

@@pyropulseIXXI The specifics are where it gets complicated.

[@alexlandherr]

@@murphy54000Which was the point of my teacher’s comments.

[@mskiptr]

@@pyropulseIXXI But the gas molecules will also interact with each other

[@p39483]

Bernoulli's principle is a physical reality on par with Newton's f=ma. The faster moving air on top of the wing is a necessity because there's lift. Lift implies a pressure differential which by Bernoulli implies a velocity difference. Some would say that's working backwards, but then "what causes lift" is a nonsensical question since all we have are equality relations such as the lift equation, which if solved for area, would seem to indicate that area causes lift.

[@TheJonititan]

Regarding max altitude its worth remembering that those speeds are straight line trimmed flight. One of the failure modes is failing to account for additional speed required for a turn.

[@JoshuaPlays99]

Yup that's a good way to induce a wing drop and high altitude spin.

[@MrJdsenior]

You NEVER want to be at max altitude, because you are inches and scant downside MPH delta from the high speed stall and low speed stall totally converging, which explains what you said, skin deep level. That is even more true if you are flying a four engine aircraft with only one outboard engine still functioning, for several reasons, most especially turning away from that engine. My father in law flew B24s, read what the manual (or the training film, I forget, that's on YT) says about handling that flight configuration, its not heartening. He also got shot down and ended up ditching over occupied Poland, losing engine after engine until the plane was in that mode. He said after he trimmed, bailed, and hit the silk, the plane started to make a big lazy circle and he thought it was going to run smack into him. A "bring me my brown pants" moment.

[@kcouche]

FINALLY! Someone says out loud what I've been teaching regarding lift. So how about this simple statement. Lift is generated by wings by causing air to move downward. One way or the other, the wing causes air to move down, and the opposite of that is lift. Lift is a combination of the angle of attack (how much you force the air down) and speed (how much air you cause to go down. And of course, the simple statement that all this is true in "low speed" aerodynamics. Call me when you need info on air foils, wing plan shapes, etc.

[@muadeeb]

My favorite theory is these are lies told to "children". The VOR and lift explanations are perfect examples of that. Subjects too complex for the audience, but still give an answer

[@mzaite]

Go into any Pilots Lounge for any airline at any airport and you’ll be amazed how true “For children” is in this case. You can taste the stupid.

[@WarrenLacefield]

@@mzaite Nah, I wouldn't stay "stupid" at all - but I would say "human." Who pays attention to physics consciously when walking or running, even if they studied it. Most pilots do actually know and attend to lots more details, physical and mechanical, than many automobile drivers who may have no clue for how cars work. And they do certainly know how to fly, how to "dwell within" planes (cars, bicycles) as extensions of themselves and their bodies. But of course there is also lots of BS and memes, etc., especially in lounges and bars. 🙂

[@jamesphillips2285]

@@WarrenLacefield It was pointed out to me I am more physics-minded than average after jerry-rigging a 10 speed derailleur to tension a loose single speed chain one day. Did not realize how much bike physics I ignored, even after an adult bicycle safety course. One day I was turning left in front of another vehicle turning left to get on to the road I was leaving. Because I was rushing: I got a pedal strike which put me upright. I could have saved it by cancelling the turn: but chose to force the bike back into a lean instead. Second pedal strike folded the front wheel in half (oops, did not even think of that). I somehow somersaulted over the bars, landed on my feet and caught the bike before it hit me in the face. A bystander thought I was hit by the car patiently waiting for me. TL;DR: As somebody interested in physics, I STILL managed to crash into level ground: because I did not understand bicycle geometry well enough.

[@filanfyretracker]

@@Styrofo4m I honestly thought VOR was purely omnidirectional, just a big powerful radio station that you tuned your navigation into and the arrow pointed at it. As I have heard rumors of pilots using AM stations when losing other navigation and not knowing the VOR but also not in radio range. AM broadcast radio can have extremely long range, Especially clearchannel stations(the broadcasting term, not the corporation Clearchannel Communications).

[@DABrock-author]

⁠@@filanfyretracker That’s the ADF, Automatic Direction Finder, that does that trick. And yes, you can tune in and navigate by AM radio stations.

[@KiithnarasAshaa]

Furthermore, the mental image of a 500' antenna spinning at 30 revolutions per second is _absolutely terrifying_

[@CraigGood]

My instructor would go off on a rant about how wrong the Bernoulli theory was. Highly entertaining. That fuel myth is a great one to bust. I didn't know that one! You are in for SO much fun getting your instrument rating. You'll wonder how you ever dared get in a plane before.

[@mzaite]

Yea It took until a CFI refresher course for someone to just Bring in some jars and clearly demonstrate it. Stole that demo right quick.

[@Alfred-Neuman]

That has nothing to do about aviation but when I was young I studied offset printing and one of our teacher was talking about image compression and said "all the compression algorithms are all degrading the quality of the original files without exceptions!" One girl looked confused and asked "But what about Zip files?" and the teacher just stupidly responded with the same thing "ALL the compressions are degrading the quality of the original files!" and continued talking about other stuff... I didn't say anything a that time but even after 20 years it's still bothering me... 😆

[@jeremyfiggins4176]

I worked as a line serviceman for a few years in the late 90's. That "fact" was in both the Exxon and Chevron training manuals. I'm shocked it isn't true.

[@freeculture]

@@Alfred-Neuman Lossy vs Lossless compression 🙂

[@CraigGood]

@Cancer McAids I was being terse because Scott covered it. I mean that Bernoulli is an incomplete and inadequate explanation for why wings work.

[@BenEater]

No explanation or model will ever perfectly explain the underlying thing. The only question is whether the model is useful, considering its constraints. Navier-Stokes is wrong at relativistic speeds, but it’s good enough to design airplanes. The “wing pushes air down so plane goes up” model of lift taught by CFIs is wrong in a lot of other ways, but it’s good enough to fly airplanes. In fact it’s a better model of lift than Navier-Stokes because you can actually apply it while flying. No one is solving partial differential equations in the cockpit.

[@andrewschaible4104]

I have always wondered how a VOR system works from a radio engineering persepctive. Never expected Scott Manley to be the one to give the details. Excellent! Thanks for this.

[@c.j.garner9772]

Thanks for sharing this! I’m a CFII and I’m definitely guilty of teaching students that VORs are like light houses (When looking up sources from other pilots that analogy was the most common explanation). I’m surprised that the FAA doesn’t respond to misinformation and clarify what is true and what is false. But then again I’m not. They are just another government organization… But thanks for doing their job for them! Good luck with your instrument rating, and Fly Safe!

[@Skinflaps_Meatslapper]

I mean, they kind of are, but that analogy breaks down when you associate a VOR with the same kind of tight beam you'd see on a lighthouse, or when they say each of the 360 beams are unique and identifiable by your receiver. A better analogy would be it's more like a lighthouse with a spinning flood light, and you're measuring the exact moment that it's the brightest (let's just say the change in brightness is linear and obvious). On top of the lighthouse there's a red beacon that pulses when the light is pointing due north, and with enough extrapolation you can figure out what radial you're on. For example, if the flood light takes 12 seconds to make a full clockwise rotation, and the beacon flashes once every 12 seconds as well, then you can simply time the seconds until the flood light is at it's brightest...if it's 6 seconds after the red beacon flashes, then you're due south of it. If it's 3 seconds after it flashes, you're due east of it...hands of the clock, etc. My analogy breaks down past this point but it might be an easier (and a little more accurate) analogy to teach in ground school.

[@jobblejosh9713]

Oh there's almost certainly technical papers that go into the correct way a VOR/DVOR/VORTAC works; important knowledge for the technicians and engineers who design and maintain those systems. It's just that a rudimentary simplified version of it is 'good enough' for pilots. Pilots have other things that are more important to learn about (like all the things that affect how a plane flies and how to predict and manage them); it's unreasonable to expect to both cram their heads full of technical knowledge that they'll probably never need to worry about (because if the NAV system has a fault on the ground, procedure is probably just 'let the engineers deal with it', and if it's in the air it's either switch to the backup or adopt a different approach), and expect them to remember all the other important bits. Like how when we learn physics in high school, we start off with 'atoms', then go into 'atoms and orbital shells', and then go into 'suborbitals and Pauli exclusion'. You can't understand the complex stuff before you understand the foundations of it, and the complex stuff isn't really relevant unless you're going into a field that demands it. No one can know everything.

[@murasaki848]

I can at least assure that when the FAA teaches its maintenance technicians about navaids at the Mike Monroney Aeronautical Center in Oklahoma City, they teach the facts. 😁 It's funny, though, that when I was in the Air Force so many years ago and taking flying lessons off-duty, nobody said anything about "lighthouses", and TBH this is actually the first time I've heard it. They just said there's two signals and when the instrument in the aircraft compares the fixed signal with the varying one, it can tell what bearing it is from the VOR. They didn't describe it in quite the detail Scott does, but I got the gist anyway and didn't need the simple, incorrect explanation. Maybe it helped that I knew already about AM and FM and fairly simple analog circuits that do phase comparisons and produce an error voltage that deflects a needle, which is why all this stuff could be invented way back in the 1940s.

[@murasaki848]

@@jobblejosh9713 I like to give the example that I don't have to teach you about n-channel MOSFET transistors or boolean algebra to show you how to run your computer.

[@tonypeden8092]

I always put explanations of lift this way. The pressure differences that occur above and below the wing are measurable and verifiable but that really only explains *what* happens, not why. The why is much more complicated and I've concluded most of the people smarter than me have their own preferred theory rather than having converged on one explanation.

[@xcoder1122]

While driving with your car, put your hand out of the window and hold it horizontally. Now slightly tilt it so that the side in driving direction is higher than the other one. Is your hand pushed upwards? Yes it is. That's how a wing creates lift regardless of shape as your hand is still flat. It's the same way as the pitch elevator works. The Bernoulli effect is just a 2nd way to produce lift and according to NASA it is responsible for 20-40% of the lift of an airplane but the majority of lift comes from the fact that the wings are slightly angled, so air pushing against them while the plane goes forward is partially forced to move downwards and a counter force will push the wing upwards. That's why planes can fly upside down. If they do, they totally lose the Bernoulli effect advantage which will now actually even pull them down but that can easily be compensated by just increasing the wing's angle which will then still create enough lifting force.

[@ebashford5334]

The reason wings are shaped that way is prevention of stalls at higher attack angles. At a high attack angle the air foil top curve better maintains faster, smoother airflow at the top which makes turbulent air less likely, thus reducing drag. For flat thin jet fighter wings, a canard forewing can serve (among other things) the same function as it redirects and organizes air flow over the top of the delta wing at high angles of attack, making for better maneuverability at low speeds and prevention of stalls.

[@nettsm]

It’s great to see everyone accepting each other for who they say they are. This channel discusses hardcore science and I believe most people here have the basic tools to understand what’s being said, maybe because of involvement in some kinds of engineering projects. On other science-related channels you might get ridiculed for sharing your involvement in great engineering projects.

[@baomao7243]

+1 VOR explanation. As a project, I started writing code to build an SDR VOR receiver. Immediately one recognizes nearly all the high-level “how it works” models are COMPLETELY wrong.

[@pembroke9792]

Hi Scott, I may not be learning to fly a plane, but I can guarantee you one thing and that is that even if the FAA manual is hopelessly wrong on a subject. That is the explanation you need to use in your exams if you want to pass.

[@KeepEvery1Guessing]

When I got my private and instrument (in New England), there were still 4 colored airways left in the country, but they were in the north central US, and I never got to try one. It would have been fun at least once. You hear Morse N on one side, A on the other side, and if you were centered, they blended into one continuous tone. Later, when I was a partner in an Arrow IV we had it good: We had an RNAV box, which processed the signal from a VOR/DME to allow you to create a virtual VOR at your way point of choice and fly one of its radials. That was also the only plane I ever flew with an HSI. NDBs were fun too, although I never had to use one in anger after the instrument flight test. GPS existed when I started flying, but it wasn't legal for navigation at first, and later you would need a certificated receiver, to which I never had access. Old technology. Good times. At least I can still use CW (Morse code) as a ham. My flight instructor was always amazed by the fact that I didn't have to look at the dots and dashes on the chart in order to ID a nav-aid. Fly safe, or at least, don't name it after me.

[@kerryhaycock9446]

Thanks Scott , that was a great explanation of Doppler VOR . Suddenly I’m back in my days as a young Navaids engineer with the AU Departmant of Aviation and that is exactly how I remember their mechanism of operation . I remember a Goniometer device way back then that used a switchable cluster of rigid metal transmission lines to achieve the variable phase shift required to drive the elements. To fit in their enclosure they had to vary from straight to highly curved , looking like some kind of magical sculpture of tubing

[@bbgun061]

Am I right in thinking that the second version has the advantage of no moving parts?

[@homomorphic]

What pilots need to know to be good pilots is: 1. How to recognize and avoid mission continuation bias and to not commence a mission unless all parameters are well within safe ranges. 2. To assume that all of your equipment can and will fail and to know how to determine what equipment has failed and in what way. 3. how to remain calm in a crisis and how to appropriately manage the crisis. Understanding how the principles of flight and navigation work; that is easy, the hard part of being a good pilot is not allowing your emotions or biases to influence your decisions. Being a pilot is more about being a good manager of one's self and the equipment than anything else.

[@franklauter7466]

I had a physics professor as a aerodynamic filight theorie instructor... He has a prepared fax-paper to be send out to every TV- Show showing stuff like the loving air molecules that agree to come together again at the end of the wing.

[@Arturo-lapaz]

guaranteeing zero lift

[@UncleKennysPlace]

17:47 _Cardioid_ would be a good term, recognized by people that record sound, at least.

[@CH1K3N99]

The explanations used for explaining car spoilers I find have often been a pretty simple and succinct, including stalling which would be their equiavalent to transitioning to an airbrake vs spoiler.

[@TheAnticorporatist]

My dad flew A4s and A7s in Vietnam and he tells the story of how the squadron had gotten a new skipper who had previously been a prop pilot and how, as the XO, he had to be the one to subtly remind him to speed up as the stall speed of the jet was significantly slower than that of the props that he had driven before and the whole flight was freaking out as his speed, which he thought was fuel optimal, had everyone on the verge of falling out of the sky. Thought that you might get a kick out of that.

[@m0rtez713]

Sounds like a popular guy. I hope they sorted it out before an accident. I wonder how command reacted to this one squadron being always late though.

[@Skinflaps_Meatslapper]

I'm pretty sure you meant the stall speed of the jet was significantly *faster* than a prop plane.

[@Anvilshock]

@@Skinflaps_Meatslapper Higher. "Fast" in itself is a speed. A "fast speed" is an acceleration.

[@Skinflaps_Meatslapper]

@@Anvilshock A fast speed is defining a speed in relation to a particular frame of reference, not an acceleration. An acceleration would be called an acceleration. If you're attempting to correct someone, be correct.

[@Anvilshock]

@@Skinflaps_Meatslapper "Fast" contains a time component as it means "a lot over time". Speed, too, has a time component as it means "distance over time". "Fast speed" therefore means "a lot of distance over time, over time", so, distance over time squared. Which is an acceleration. If you're attempting to correct someone, stop trying to shoehorn some excuse into justifying the average fumblebuck Anglophone who couldn't give two flying rats' arses about what they're slurring in a vanity-stroking attempt to use terminology.

[@gtxviper]

My uni dissertation was on sub-sonic aerofoil design. Two out of the three (idiots) reviewing the dissertation were small single engine "pilots". They marked me down because they couldn't get past the equal transit time thing... even with all the practical experiment footage and SW flow simulations. Not that I'm still sore about it.

[@Arrman2]

I'm a physics teacher. I always feel it's my duty to explain the working principles behind the phenomena I teach. The more insight I have as a teacher, the more accurate my analogies whenever I have to use them to get my point across. When I have to use an analogy I always tell my students beforehand. I encourage them to ask me how it "actually" works when they're interested and want to learn more.

[@paulromsky9527]

Great video. I find it odd that the FAA endorses that VOR simply measures the time the spinning node arrives with respect to the omni directional node, when it uses that partially but uses more of a phase difference, but they explain how a Localizer/Glideslope uses two frequencies and a phase difference.

[@sixter4157]

As a child I always wondered what the buildings with the "bowling pin" were. I liked to think it was some sort of special bowling alley. I was excited when I got into aviation as an adult that it was a VOR beacon. Never could afford flying lessons. I enjoy the knowledge.

[@duradim1]

I have watched several videos over the last couple of years trying to understand lift and not being settled on the longer path but faster speed explanation. It just never rang true. It is all about low and high pressure which makes the most sense and your video illustration helped out a lot. Thank you. Now I can go to bed.

[@connecticutaggie]

Interesting discussion. On thing this made think of is "what is the goal". As an Engineering Instructor my immediate answer it to convey knowledge (truth) but it seems that that truth is not necessarily the most important thing when flying a plane but rather correct behavior. So, it seems that maybe simple explanation that is easy to remember and comprehend is better than a complex one that is hard to understand because it requires knowledge that a typical pilot does not have.

[@dinosaurus4189]

I think learning falsehoods just leads to confusion later down the line when the student has to unlearn them.

[@galfisk]

I believe in simplification, done in a way that while not explaining the nitty-gritty details, it also doesn't teach anything you'd need to unlearn later.

[@isaacplaysbass8568]

Ooooh! More myth dispelling please Scott! So cool. PS: I look forward to your flying videos.

[@cachon6]

My aircraft design and flight mechanics teacher always hated the Bernoulli explanation. He always asks in his exams “Why do airfoils/wings generate lift?” and the expected answer is “They push air downwards, creating an opposite reaction”

[@praetorfenix69]

This is my favorite explanation too. It's so much easier to understand in terms of Newton's laws than the very vague idea of a "difference in pressure"

[@galfisk]

I teach skydivers, so to differentiate ram-air wings from round parachutes, I tell them that the rounds can only generate drag, which is a force exactly opposite to the direction air is being pushed, while the wings create lift, which is sort of perpendicular and a lot more efficient.

[@mzaite]

Yeup all Newton, Bernoulli just gives it some efficiency spice. Anyone who’s ever strapped a sheet of plywood on the top of their car knows you don’t need Bernoulli to make lift.

[@stivi739]

Same as why does a round shaped car doesnt lift when goin fast like a plane wing lol

[@whodatcatt]

@@mzaite Deflection or lift?

[@littleferrhis]

As a CFI I sent this to my instructor groupchat. I taught VORs completely wrong(I taught it as a radio beam spiraling outwards until it hit something). I mainly used the Rod Machado video he did for how a wing produces lift, which is closer to what you mentioned. As one guy put it, you can’t really explain how a wing produces lift without a lot of math, and pilots are allergic to math.

[@JamesNoBrakes]

And I don't think the Bernoulli Principle is generally taught as "two molecules locked together that have to meet at the end", I've always heard it more like you said it, curved surfaces and longer paths. You can start to get pretty close with the lift equation and how much lift is produced, even if it's not quite accounting for everything.

[@seancarroll146]

Once again you changed my understanding of vapor dynamics, thank you Scott, keep it coming.

[@scottfranco1962]

Thanks for the fuel color thing. I actually had someone contaminate my fuel, I found out about it later when the FAA called everyone who had fueled at that station. The owner was not talking, but we speculated that one of the ramp rats had dumped some jet-a into the 100ll tank. The owner lost his ability to get fuel. Anyways, the "jet a plus 100ll equals no color" thing was told to me several times then. In fact, I noted when checking the drains after fueling that, in fact, the blue color was gone or very light, and the owner gave me a...pardon me, "untrue" (trying to stay civil here) story about the fuel arriving by accident without the blue dye. The central fuel provider (the one with the trucks) told me this was, indeed a rasher of.."untrueness". Its good to see that demo of what really happens. So why would an FBO lie about his fuel like that? Say You have a really big tank, with 1000's of dollars of fuel in it, and some minimum wage kid manning the fuel truck dumps jet A into it. Now you have to dump that fuel and that money, and even that is a problem because the EPA does not appreciate you dumping fuel down the sewer. So you test the fuel, it does not seem too bad, and yadda yadda.

[@wilfdarr]

Not only do you have to dump it, you'll likely have to pay to dispose of it! Unless you have a waste fuel burner, you're pretty much SOL.

[@nighthawk9264]

When it comes to stall and angle of attack, don’t forget that not only Mach and compressibility play a role, but also the Reynolds number, which increases linearly with speed.

[@nevadahamaker7149]

Regarding fuel color, the new G100UL fuel developed by GAMI is amber in color and is designed to turn green when combined with 100LL. As you are in California, it's likely you'll be burning G100UL before anyone in another state.

[@tangydiesel1886]

Thank you. I knew it was 100ul, but forgot the G in the front.

[@MusicmatchJukebox]

Loved this video, Scott. I’m a CFII and very grateful for the contribution this video will hopefully have in aviation. I would love to see you talk more about how we teach GPS systems knowledge, what you agree/disagree with as you get more into your instrument training. We teach a lot about trilateration, RAIM, and a comprehensive overview of how WAAS works (maybe not so comprehensive by your standards!). Anyways, appreciate this video tremendously!

[@chriscreasey007]

Brilliant video Scott. I'm a pilot and a physicist and have spent a long time thinking about how wings work too. IMO I think its the trailing edge and the fact that it is designed to be sharp that is a key feature of most aerofoils. In normal un-stalled flight the air would have to accelerate significantly to go from the trailing edge bottom surface to the top surface. This effectively sucks the air over the top surface. This creates lower pressure on the top and also pulls the air down and F=ma does the rest. My evidence here is that when a wing stalls it is the airflow at the trailing edge that changes the most and starts to wrap around to the top surface which is when it all starts to get more stressful! Would love to hear your and others thoughts on this theory!

[@Fooney1]

So the curve at the front creates the low pressure on top by making a vacuum when the fat part of the wing gets skinny again? And then the trailing edge seems to scoop down a bit I assume for ever more pressure and lower stall speed? I dunno makes sense to me.

[@prational]

Here's another fact that I have even heard very seasoned pilots explain incorrectly. The question: is lift greater than weight when the plane is flying at a steady climb rate? The answer is no, the only time lift would be greater than weight would be in a turn or for a brief period when you pull back on the stick and the angle of attack increases. Then the lift is momentarily greater than weight and causes the aircraft to pitch up and assume a flight path that is not horizontal. Check any good flight dynamics book. A plane gains altitude because of excess thrust horsepower, not excess lift. Next time you are on a commercial flight put your arm on the arm rest with your elbow free to move. At takeoff as the plane rotates you should feel your arm get momentarily heavier. This is the moment when lift is greater than weight.

[@mitchellminer9597]

Hmmm. I'm going to argue that it depends on the attitude of the airplane. If the plane is really pitched up, the thrust from the propeller is going to be lifting the airplane, some. On the other hand, if the plane is dead level at high power, with maybe one notch of flaps, it will be going up with all the lift coming from the wings. I like your point about temporary cases.

[@prational]

@@mitchellminer9597 Hi Mitchell Again, do a vector analysis of the forces acting on the aircraft's center of gravity during a steady climb and you will see that lift is less than weight. You'll see that indeed it is the thrust of the engine that is lifting the plane and at a 90° climb angle it is all thrust horsepower lifting the plane. en.wikipedia.org/wiki/Aircraft_flight_mechanics#:~:text=In%20straight%20climbing%20flight%2C%20lift%20is%20less%20than,it%20to%20climb%20and%20gain%20extra%20potential%20energy.

[@TheDuckofDoom.]

The fuel dyes used in the old gasolines did interact in an obvious way, but jet-A is not dyed at all (and some is very clear if produced through hydrotreated refining). The way to test for suspected Jet in gasoline is to wet some paper and let it evaporate for 10 minutes, 100LL will dry up and jet-A will remain. Some gasoline in a jet is not a problem, turbines will burn it just the same with minor short-lived lead residue on the turbine section. In practice the chance of having Jet-A dispensed from a nozzle that fits a gasoline tank is very remote, may be plausible if somebody is using 5 gallon cans for transfer and uses accidentally grabs the parts wash can(JetA is good parts wash, so is undiluted biodiesel), but JetA(#1 fuel oil, kero) should be stored in blue, and gasoline in red, #2 fuel(common diesel) should be in yellow. I suppose a small plane with a STC for highway gasoline could risk being filled with #2 fuel oil, the test is the same evaporation from paper.

[@mzaite]

You can just feel it too. Gasoline drys out your skin, Jet-A feels oily. If your Avgas fees at all oily you have a problem. Besides the skin cancer risk of course. But after a thorough preflight, nothing cleans your hand better than avgas you’re pulling from the sumps.

[@bbgun061]

@@mzaite Avgas might clean your hand but it coats it in lead.

[@drmaudio]

Many of these things are in the FAA manuals. They were originally intended to be easy ways to visualize things, rather than technical explanations. This gets canonized, and then becomes dogmatic "truths". As an instructor who understood a little about aerodynamics, I would always let them know that this wasn't technically correct, but expresses what they need to know and if they want the real explanation I would refer them to a good reference or explain it over lunch sometime.

[@bluenadas]

Your explanation of VOR is also incomplete but more correct than others.There is a second frequency on the rotating cartiod that provides better accuracy at the receiver.

[@randyscorner9434]

Next address the gyro attitude indicator and how it works ... while also dealing with gyroscopic precession...:) And why the rotating mass is actually set an angle inside the instrument... I loved this episode. So many discussions I had with my flight instructors regarding physics and engineering tradeoffs.

[@rapauli]

Predictable crash when the airport runway slab is considerably hotter than the reported air temp of the airport. Especially at early dusk of cooling air after a hot day -- the concrete runways retain daytime heat. You may calculate your weight for a cool 70 degrees, but the rising heat (a few feet from your wings) will be considerably hotter. My lesson was years ago.

[@bwmanarific]

wow thats something new I didnt know! thanks

[@terminalpsychosis8022]

Excellent description of high altitude "stall". Them guys are BOOKIN' it just to get up there. They ain't letting off the thrust, it's just there's no more air to push. These snippets of technology, and the encouragement to go learn more in deeper (longer) vids, is what's so awesome about this channel. Well, and Kerbels. ;-)

[@jamesstonehouse3448]

I spent 19 years as an avionics tech, 15 of those in a calibration lab on gear that was used to set up DVOR sites. This is the first time I ever heard the lighthouse explanation. I'd always worked with the phase relationships and that lighthouse thing just seemed really weird

[@tykjpelk]

Actually I'm a physicist and I don't know how wings generate lift, so they're technically right. I was dating a marine engineer during my studies and she was constantly complaining about hydrodynamics and she showed me the Navier Stokes equations. Fuck that, I'd rather take more quantum than fluid mechanics next semester.

[@Ed-hz2um]

I used to demo lift to students by placing a plastic spoon near a column of running water. As the spoon's curved surface touches the water, it's pulled into the stream. You can also see that the water does not return to vertical flow upon leaving the spoon...it curves away. Action-reaction. If you then visualized this setup in a horizontal plane, you have a pretty good idea of how lift is generated. Much simpler than describing the Navier-Stokes equations. By the way, Scott, I learned much more than I ever wanted to know about VOR signal generation in this video. Sheesh!

[@Ellwood420]

You used degrees C, but then feet! 😛 It blew my mind that aviation is crazy like that.

[@MalfosRanger]

Americans use metric and US custom everyday.

[@ModernClassic]

I'm pretty sure I've seen both explanations for VORs but never really cared which was correct outside of whatever the right answer was for a written test. But knowing how they really work does potentially explain part of why the needle bounces around so much even in a glass cockpit. It just doesn't work like a system shooting out 360 single-degree beams - it's a lot less accurate than that. Anyway, you'll find a lot more stuff as you move along that you'd think pilots would know but we don't actually need to. At the airline I'm currently in training for, they actually told us "we don't want you to build the planes, we just want you to fly them." There's already enough we need to know as pilots and there's always more to learn (I'm taking a break from studying right now to comment on this video), but then there are other things related to flying that are more like answers to trivia questions as far as piloting itself goes.

[@Ro32da72]

I've spent 30 years fitting avionics kit to light aircraft, I still learned lots watching this. Love your physics deep-dive stuff Scott; thanks dude. ❤👍

[@Krzysztof_z_Bagien]

There's a DVOR less than 4km from my house; I "found it" at the edge of a nerby forrest during a hike with my wife a few years ago (not that it's hidden or anything, you just can't see it well from a road) and at the time I didn't know what that was. Later I learned that's a DVOR device, and now I know how it works exactly :D

[@RalphEllis]

Did you know that the early VOR receivers were electro-mechanical - a vast box of gears and valves, that made the calculations. They worked well, but newer electronic systems were 1/100 th the weight and power consumption. Did you know that VOR and ILS systems were going to be phased out and replaced with GPS. But then someone opined that GPS signals will be the first thing knocked out during a Solar CME (or a war), so could not be relied upon. So it was decided to keep the old-fashioned VOR and ILS, as they are more robust systems. R

[@i_Kruti]

0:01 The intro is invented

[@thomasmaughan4798]

When VOR was invented, digital electronics did not exist. Matching phase or detecting phase difference is relatively simple electronics. I had it wrong too and part of that system was invented by my grandfather at Bell Labs. I can see now that phase comparison is easy and low-tech.

[@RNMSC]

As someone who has taught electronics, not flying, I'd note that a huge part of being a better instructor is to understand at what level the student already understands, and needs to understand in order for the material being taught to be useful. One of the radios I worked with in the Army had dials that you adjusted to adjust the frequency that they transmitted and received at. Low gigahz microwave spectrum. Each of these radio frequency control dials had a vernier gauge built into them. Universally these gauges were being used wrong, but because everyone was using them the same way, the equipment functioned for the soldiers. How did these veriners get used wrong? Keep in mind the veriner is numbered 0-9, and is supposed to be used to fine tune the last digit by aligning the digit 0-9 with a digit 0-10 on the main dial. The method that was being used was to first get the first part of the frequency set up, then drag the pointer for that reading to the last digit on the vernier. On a micrometer or set of calipers, this would give you a measurement that was off by as much as the width of the vernier scale, and this would also affect tuning as well. Let's say that the first digit is for the difference between 1 ghz, and 2 ghz in hundreds of mhz. The second digit then is for tens of mhz, and the vernier allows you to adjust for mhz. Except that they way that these tuning methods were applied, the actual operating frequency would be off anywhere from by nothing, to 10 mhz from the specified frequency. Again, this did not end up being a problem, because nothing we were working with in the field was providing a digital value for the frequency, and this radio had other quirks (Don't ask about the baseball bat in the calibration room, or why Pvt George was found across the radio van unconscious after that big thump. They are unrelated stories.) What I'm getting at is that while I don't expect any of these radio operators to become machinists, as long as they used the tools they were provided in a common way, it may not have been the 'right' way, but it would work. So they ended up being taught in how those tools were going to be used in the field. If it works, don't "fix" it. But it may be a good idea to move people who really do understand how that equipment works into a roll where that knowledge may better serve the needs of the service.

[@snarfster42]

So refreshing to see the correct description of both variations of VOR. Thanks!

[@DiCola119]

I'm guilty of a couple of these, especially the temp/dewpoint concept. Would love a part 2 if you have more!

[@andrewjknott]

The lighthouse analogy is a semantic simplification. By continuously measuring the signal strength and filtering to just the maxima, it is effectively creating a lighthouse effect.

[@bbgun061]

That's not what the receiver is doing. It's not filtering anything, it's measuring the difference between the phase of each signal.

[@Arise4Fries90]

The student has become the master.

[@elorea]

Obviously he is the Master the Only Master

[@RalphEllis]

Well informed, he is. May the force be with him. R

[@Kokiriboy001]

This is the type of video that should go right into your 'greatest hits' playlist. Great video!

[@kevw172]

I was so thankful I had a great flight instructor during my training. Actually I had 2, they were both great and taught things correctly.

[@KittyGamingYT]

When you were talking about the water vapor pressure being 1.7% of the atm at 15 deg Celsius, you underlinded the wrong part of the chart (kPa instead of atm) @ 6:07

[@scottmanley]

One atmosphere is roughly 100kPa

[@theheresiarch3740]

VOR beacons also still broadcast their identifiers in Morse code. I don't know if they still make pilots learn Morse or not, but I've been learning it and that's the most important context where it's actually still used.

[@AlanTheBeast100]

Since the morse code is on the chart / plates in dots and dashes you just need to 'see' the code and 'hear' the code - you don't need to 'know' the code.

[@RalphEllis]

Modern VOR and ILS receivers are so clever, they can decode the morse for you, and display the identifier. Aviation is no fun anymore….! R

[@AlanTheBeast100]

@@RalphEllis I agree that that sucks! When MLS (never emerged due to GPS) was being developed, the station ID "tones" were generated at the receiver from the digital code from the transmitter - not from tones made by the transmitter as has been done in every ground transmitter since before WW II. (Look up radio-range where you had to listen for the dash-dot or dot-dash to know which side of the airway you were on. When on airway - continuous tone....)

[@mzaite]

@@RalphEllis also a lot of Voice IDs now too.

[@paulsengupta971]

@@AlanTheBeast100 Heathrow has MLS.

[@roysmith5902]

Like yourself, I went into my pilot training already knowing more about aerodynamics and physics than the instructors who were teaching me. Like yourself, this led to lots of frustration. Eventually I figured out that I just needed to just suck it up, regurgitate back the official FAA party line on the tests, and get on with life. I think the key to understanding how wings work is to stop thinking about what causes lift. The air does what it does. The equations are just ways for humans to understand what's going on. Bernoulli's equation doesn't cause lift; it just provides a model to help understand certain aspects of how a moving fluid reacts. To the extent that it helps you predict how a wing will react to changes in airspeed, AOA, etc, it's a useful model. Most pilots do not have the math and physics background to understand a more complete model, but you gotta give them some explanation beyond "it's magic".

[@asdpyro]

I was in the same boat for my private, knowing and understanding (the science) much more than my instructor. It was constantly frustrating hearing incorrect explanations for so many topics. All of my instructors have been better pilot's than I am given the mass of hours they have over me, but some of the knowledge they are passing along is flawed. It's frustrating to also see some of this misinformation included in the ground school materials and videos that are available. Better to mention that it's an analogy or simplified explanation and allow people to look into the science deeper if they have the interest.

[@bbgun061]

I've heard that the air on top of the wing actually ends up *behind* the air on the bottom. In other words, it's accelerated (more than most assume) and reaches the trailing edge of the wing first. Is that true?

[@DrWhom]

Equations don't cause anything ; they just describe. And so it is with all of physics. I don't understand why so many people, many of them academics, believe science is about causes