Theory of Flight -- Part 1: Forces and Lift

[@rogerleblanc-717]

Hi Don, good job as usual. Totally agree with your statements, one must not forget that as AOA increases and lift increases, drag increases as well. The drag scale on your wing profile simulator shows the drag as a constant value. Interesting to note that the pressure differential between extrados and intrados is reel and we mesure that every session in our wind tunnel. As you very clearly explain, the origin of this differential has more to do with the circulation of air around the profile than Bernoulli's theorem. The Newtonian lift generated by the third law of motion also apply to the fuselage, horizontal stab and all the aircraft components involved in the deflection of the relative airflow. On a large commercial aircraft such as the Boeing 747 and the like, the surface area is really impressive... Finally, nice to see the old CC-115 Buffalo SAR aircraft. As a former SAR pilot (424 Sqn), I can confirm that this was quite an exceptional aircraft in many aspects including STOL capabilities. You great ability to summarize the information and your enthusiasm is appreciated. You are a great teacher!

[@DonJoyce]

Thank you so much for the kind words, Roger! Nice to hear confirmation of the curved airflow model vs Bernoulli....you would not believe how nervous I was to present it this way...and took a huge amount of time to research this until I felt confident! SO many of us just have Bernoulli drilled into our head from an early age, it's hard to believe it just isn't the reason for lift! You are absolutely correct regarding the drag increasing with the lift as the angle of attack increases. I looked at the simulator again...it is actually showing the increased drag but it is hard to see it because of the scale of the graph, but the (tiny) numbers in the top right do increase. I was a bit disappointed also that no dramatic drag increase showed at the stall point, which is why I cut away quickly to other graphics. Very cool that you are a former SAR pilot! My father was in the air force and I saw plenty of Buffalo's when I was a kid (Summerside and Downsview). I intentionally showcased Canadian planes in this video of course! And my uncle actually worked on the Arrow project! Safe and happy flying!

[@PinetreeLine]

Awesome job Don! I sure wish I had all your latest videos before my test. Excellent stuff! LOVE seeing the Arrow!

[@DonJoyce]

Thank you, Doug! I've learned a lot along the way too! Btw, my uncle worked on the Arrow!

[@DroningVeteran]

Very informative Don. I loved the drag not that type of drag lol.

[@DonJoyce]

Thanks, Dan! LOL...I get a lot of mileage out of that tutu!

[@MulligansDen]

Wow, just wow ... from a 74 yr old .... where were you back in the early days of my education .... this is probably the clearest, most informative and SO well done video, youtube should hire you as a consultant. Thank You!

[@DonJoyce]

Thank you so much! I very glad to hear it was clear and informative...it was a lot of research and work to put it together. I certainly learned a lot!

[@alexp286]

I read a lot about this matter in internet (I think it was too much because it confused me a lot) but this video is the clearest and the shortest explanation of the real science.

[@DonJoyce]

Thank you, Alex! It took a lot of research and thinking to boil it down...and it makes sense!

[@flightographist]

Thx, I'm an experienced certified/licensed/rated PG pilot in CDN. Awaiting the arrival of my first drone, gonny license of course but going through your study materials as a re-fresh before taking the test; you have it all going on, your watchers shouldn't have trouble passing.

[@DonJoyce]

Thanks!! Good luck with your drone exam!

[@tv-beautifulkorea1229]

My dear friend. Thank you for sharing this great video. Have a happy weekend and see you again.👍🌹🙋🏻‍♂️

[@DonJoyce]

Thanks!

[@HowToGuyChannel]

Very very Knowledgeable guy.. Well done Don ✋

[@DonJoyce]

Thank you so much, HTG!! I certainly learned a lot putting this together!

[@davestredulinsky]

Well done Don. An excellent lesson on the theory of flight. Thank you for sharing.

[@DonJoyce]

Thank you for watching, Dave!

[@gregb5149]

Nice! I was never quite convinced about the theory of flight we learned in high school.👍

[@DonJoyce]

Ha...yes, same here! The truth is far more complex!

[@tomlay4824]

Hello I Have passed the exam for advanced operation, I failed 3 times :) but wont give up, your videos are awesome and thanks for taking the time to produce this content. I was wondering where i could find the information about, what to do when you hit a bird.... maybe you would know where to look. Thanks a lot.

[@DonJoyce]

Congratulations on passing your Advanced exam, Tom! It's a very tough exam, so a great achievement! Hitting a bird....interesting topic! I haven't seen anything said about that, other than the bird typically "wins"! I've heard anecdotally that eye markings and bright colours can keep birds away...but I'm not convinced.

[@neel0074]

good one sir

[@DonJoyce]

Thanks!

[@robertgallant6422]

Feels like I'm back in school (at age 53 lol) and totally enjoying it!

[@DonJoyce]

Thanks, Robert! Yes, some really interesting learnings in here!

[@Ahsennase]

Enjoyed this one Don!

[@DonJoyce]

Thanks! Glad you enjoyed!

[@RODPIKERDRONESUK]

Well done Don great information and video thanks for sharing cheers

[@DonJoyce]

Thank you, Rod! I learned a lot putting this together!

[@MargieAndaya]

Another Nice tutoria thery flytel thank you

[@DonJoyce]

Thanks for watching, Margie!

[@400AGLNET]

Nicely Done Don

[@DonJoyce]

Thanks, Mel!!

[@billbishop8915]

Don - You have done a number reviews on various drones; i.e. flight performance, distance, etc.; however, there is one test that no one has done and I've experimented and that is the "Line of Sight" test. Question: At what distance do you loose sight of the drone. For me, the distance I lost sight of my Mavic Pro 2 was 850 to 900 yards (note I have 20/20 vision). My Phantom 3 it was 950 to 1,000 yards. I don't have a dji mini 2, but I would believe the distance is shorter than a Mavic Pro 2/Phantom. So, at what distance do you lose sight of your drones?

[@DonJoyce]

Hi Bill! WOW...that is a GREAT question! But first, I don't do drone performance reviews (you might be thinking of Captain Drone or Air Photography...both great Canadian channels). Regarding visual line of sight (VLOS), there a number of factors that would affect this range: drone size, motion, altitude (ie head on profile vs looking up profile), background texture/lighting, glare... so it would be difficult, but INTERESTING, to devise a repeatable test. Did you google this...somebody must have tried this! For me, I find I can generally see my Mavic 2 Pro out to about 500m. For sure, when I flew my Phantom 3 (now sold), I could see it farther away.

[@thekeytothegate]

There’s a photo of Don in a pink tutu at 2:48 😂

[@DonJoyce]

Impossible! Lol

[@sharifhasan9435]

Lift is caused by the flow of curvature - that I learned from the lecture of the Cambridge University professor. But I am still confused, because the kites are flat and they still get lift. Can you please explain?

[@DonJoyce]

You are correct that lift is caused when the airflow is re-directed, but the surface causing the re-direction does not have to be curved...it can be flat or curved in any manner....as long as the airflow is re-directed downwards. The reason a traditional wing is more curved on the top is to encourage a smooth entrainment of the flow over the top surface. As soon as that top airflow separates from the wing surface, turbulence results, leading to reduced lift and potentially a stall. Watch the video again with these points in mind and it should be clear. This is complicated stuff!!

[@JohnDrewMedia-Halifax]

Oh boy. I had it all wrong. Although not sure I’d be able to explain this to my 10 year old as easily. Maybe you could make one for kids. Might help me understand it better as well. Lol. Thank you for all your efforts as always.

[@DonJoyce]

Lol. Yeah, it's a BIT complicated.

[@davidoickle1778]

Afro Arrow. Nice touch!

[@DonJoyce]

Thanks! Your typo makes for an interesting image!

[@nadaemad1779]

great video

[@DonJoyce]

Thanks, Nada!

[@zammer1]

What happens if the bottom of the foil is flat in the simulation and only top is curved?

[@DonJoyce]

Hi Nezam! There's a link to the simulator in the description...lots of fun!

[@zammer1]

@@DonJoyce interestingly enough, I have a collection of vintage pocket watches

[@Polat06410]

you are rejecting NASAs research i didnt understand it why do you think bernoulli is not related to lift

[@DonJoyce]

If my explanation of lift was not sufficient, please watch the videos in the description.

[@dallascowboy2221]

@@DonJoyceI’ve watched at least one of those videos but all the others give Bernoulli’s principle and Newtons 3rd law. What I’ve also read is it’s a combo of them both based on different situations. For example, the flat wind flys due to an increased AOA. Again your explanation was excellent up until the Mr B was discounted 😅. Lastly most people think the Equal Transit Time theory is Bernoullis principle and I thought that’s why you were rejecting it but you didn’t even mention the debunked ETT. On to your next video 👏🏽👏🏽

[@DonJoyce]

@@dallascowboy2221 Please watch the aeronautical engineering videos referenced in the description. They provide a more complete explanation of why Bernoulli's Principle is not the explanation of lift.

[@natibased7145]

Love it !!

[@DonJoyce]

Thank you!!

[@channelforeveryone..9535]

Thanks

[@DonJoyce]

Thanks for watching!

[@Compuscience-Python-Prog-Exps]

I watched a video about him, and I thought in my mind that the air blowing over the wing would only keep it restricted. It's the wind underneath the air screw shape Air Foil. The video says that was right. I should show you. I thought he was wrong, it didn't make sense. The plane or helli would be restricted. Push the Air downward and the machine, lighter than the force downward would LIFT UP the CRAFT YEAH. No, the air would be lighter like you said. If it did, you would only restrict the fact. lol I watched my drone and my prop shapes. I truly did, but I thought hey the guy must be right. I just knew it didn't make sense from watching my own drone. From seeing this video, I know now, I was right all along. I even told my buddy that didn't sound right, because of the shape of my props, that told me EVERYTHING about how the props work. Blow the Air downward, beneath the props, and the drone will lift, once the air is pushing harder and faster than your drone weight, AWAY YOU FLY lol Thank You for putting my mind at ease..

[@DonJoyce]

The theory of lift is remarkably complicated. I'm glad my video helped.

[@Compuscience-Python-Prog-Exps]

@@DonJoyce When you also mentioned the shape of the air foil, that looked like that saying the Air Screw Theory, they once conceived propellers to be.

[@carlageorge8130]

Awesome

[@DonJoyce]

Thanks!

[@user-qq1bi2mw1j]

Uwhat is lift augimantation

[@DonJoyce]

Lift augmentation devices are features like flaps on wings to increase lift under specific circumstances. Plastic surgeons also do lift augmentation...but that's probably not what you are asking about.

[@vlatkopopovski2685]

The authors have two wrong scientific approaches: researching the creation of Lift force and Low pressure at upper side of the wing, relative to the ground surface and Earth. I explain the aerodynamic cavitation and existence of Lee side aerocavern, and creation of Aerodynamic force.

[@DonJoyce]

After clarifying your OWN credentials, would you care to let viewers know which of these engineering professors have it 'wrong': Professor Krzysztof Fidkowski, University of Michigan Engineering or Professor Holger Babinsky, School of Engineering, Cambridge University?

[@vlatkopopovski2685]

@@DonJoyce Dear Don Joyce, I am trying to contact you on facebook

[@vlatkopopovski2685]

There is NO Lift "force" and NO Drag "force" it is Aerodynamic force. Lift and Drag are just components in coordinate system for mathematical calculations.

[@vlatkopopovski2685]

Further, in physics, wind force and aerodynamic force are different. The wind force strikes the object, and the aerodynamic force is which the object receives at right angle to the contact surface. The force object receives is always normal to the contact surface and air pressure always acts normal to the surface of the body. This has long been well known, and I don't know why in flight theories and aerodynamics books this is (mostly) omitted.

[@DonJoyce]

Thanks for the brief treatise you sent me. Until it has been peer reviewed (I am not an aeronautical engineer), I suggest you contact the professors I list above to discuss. In the meantime, calling them 'wrong' is perhaps an overstatement. You just have an alternative theory.

[@hurleyvcr]

Hi Don, I sent you a message on messenger, not sure if you have it.

[@DonJoyce]

I don't think so. A bit of a firehose right now.

[@hurleyvcr]

@@DonJoyce was just wondering if you are related to Ray Joyce , I worked with him at Orenda engines...?lots of people there from the Avro days

[@DonJoyce]

@@hurleyvcr Nope...I have an uncle David who worked on the Arrow project back in the day.

[@XPLAlN]

The Coanda effect is what you get when there is a jet of air over a surface. You do not get it without the jet. Therefore it is a special case and does not apply in general to the flow around a plain airfoil moving through a freestream. This myth has taken hold of late, probably because of YT videos like this being made by amateurs who have not done the hard yards in college learning aerodynamics properly. Likewise, whenever I see this claim that flying inverted contradicts the Bernoulli Principle, I know the person making it doesn’t really know what they are talking about.

[@DonJoyce]

I hope you've told the aeronautical engineers in the references.

[@XPLAlN]

@@DonJoyce lol. Ok let’s check these YT videos that you cite. Firstly, one finds in the Fidkowski video that he explicitly states the coanda effect does not apply to a plain, unblown airfoil. As I said to begin with. There is no coanda efffect happening unless there is a jet blowing across the surface. Note, I am not saying the Coanda effect isn’t an example of attached flow, I am saying attached flow cannot in general be attributed to this phenomenon. Now, this Fidkowski fellow may be luke warm on applying Bernoulli to external flows, but there is a massive list of textbooks by authors of the highest credentials, both in terms of academic qualification and industry experience, that reference the Bernoulli Principle as it applies to lift. Here is but a small sample: Aerodynamics for Naval Aviators, H H Hurt Mechanics of Flight, A C Kermode, R H Barnard, D R Philpott Aircraft Design a Conceptual Approach, D Raymer AP3456 RAF Manual of Flying ….And the article “An Aerodynamicist’s View of Lift” by Charles N Eastlake is easily found. Come back to me if you can identify a specific error in there, or the other references. Two videos you should watch kzbin.info/www/bejne/mmXaYnyvaduJg8k and kzbin.info/www/bejne/e2TMkIt-obt2m7c Now the Holger Babinsky video: he spends the first 15 minutes debunking Equal Transit Time, not Bernoulli. He then expounds on Bernoulli Theorem in general before offering the streamline curvature as an “alternative explanation”. The key word being “alternative” as opposed to “the only”. He even jokes that David Beckham “does a quick calculation of Bernoulli’s equation” before taking a free kick (yeah maybe that was a Freudian slip).There is nothing in that video I have noticed which debunks Bernoulli. But again, if you have identified a part of the video where he explicitly does so then please quote it or give the time link so I can respond…. What I am saying is, after examining your references (and I had seen them before) I find nothing in them to support your “bogus Bernoulli thing” comment. But I do find that one of them explicitly contradicts the Coanda part of your video.

[@Compuscience-Python-Prog-Exps]

I've been flying my Mini 2 drone around and I had learned from a video, such as one like this, where the propellers were once called AIR SCREWS. They actually screw themselves up into the sky, when we think about it. I've had a lot of drone flying experience since I got the drone last year. I just love it. Thank you for your Help...

[@DonJoyce]

Glad you enjoyed this!

[@Compuscience-Python-Prog-Exps]

@@DonJoyce Enjoyed! That's just an understatement. When I saw that video of the air flow over the wing in that Bular guy's theory. How can wind flow over the wing to lift it up? It's all underneath the wings or propellers. Propellers have to slow down, while landing right? so it can fall with gravity such.

[@hurleyvcr]

Well Don, I didn’t plan on watching the whole video at first but your presentation drew me in and I ended up watching it twice, thanks for the refresher.

[@DonJoyce]

LOL! Thanks for watching...twice!

[@johnlueck]

Great explanation. Thank you!

[@DonJoyce]

Thanks, John! Enjoy the rest of this 3-part series!

[@ParkwayProduction]

great vid as usual

[@DonJoyce]

Thank you!! Part 2 (Control Surfaces) will be out shortly!

[@hypercom]

Always a joy to follow your posts 😊

[@hypercom]

The university 🎓 of flying ✈️👍

[@DonJoyce]

Thank you, Daniel!!