When I clicked, I only planned to watch a few mins, but your enthusiasim is contagious
@albertburton41514 жыл бұрын
Great explanation on Ducted Fan operation.
@dtruque4 жыл бұрын
Likewise! This wasn't even what I was looking for but couldn't stop watching and learned a ton!
@marcdraco21898 жыл бұрын
What a terrific teacher this guy is! Can't beat a guy who gets excited by what he's teaching.
@manjujohn12957 жыл бұрын
Marc Draco h
@omepeet20067 жыл бұрын
Must be a Kiwi guy, as he also said "ear preesure".
@barking.dog.productions17776 жыл бұрын
He did a great job. All good for school children. The title was click bait for adults... It should have been titled: What your clueless 8 year old needs to know about ducted propellers...
@dennisnollen68616 жыл бұрын
@lil Oofy guGhGGHGhHhhZZUGzGhuGHHUZHhzU zu ZzHuGZGzZHgzzhUGGHHFFhGgHhGgZfuYhuGzGgGuG7GUHHGGGGHF uhh UGGghHgzuGHHhZHUHghZzGffUghHGYgHHhgZGHZuyzFhuzUHhuggZUhHgzZg8GgGHHFhGGgGgGGZfGHyzG uGzFUgGZZHZHuHUUZyUFHG
@dragan32906 жыл бұрын
@@barking.dog.productions1777 a lot of dumb ass adults need this! Lol. Some engineers don't know that cos they don't get taught or too stupid to remember 😂
@andyzynda64604 жыл бұрын
This guy would have made me love to go to school when I was a kid. I'm old, and he makes me want to go now. Well done mate!
@jmerlo41194 жыл бұрын
Go
@steadymotion75675 жыл бұрын
What a great teacher! No fancy words, just a very economic explanation. What a pleasure to learn from you, sr.
@curtzblues4 жыл бұрын
I worked for a major industrial fan mfg'r, axial and centrifugal equipment with 40-100 hp motors; every design factor discussed here was critical for performance. This was all spot on.
@justingriffin25462 жыл бұрын
Interesting comment, ...I'm currently researching designs for a stationary duct for manned electric copter,. Do you think the duct has a negative affect on vehicle speed when rotating the blades?
@sumarianson5 жыл бұрын
A teacher who can explain what others would deem as complex in a simple and easy to follow way. My 10-year-old daughter can understand this! Great presentation!
@jimbodingo44565 жыл бұрын
Yes please do explain what happens when you tilt a ducted fan, I thoroughly enjoy your videos, thank you
@gdubb69055 жыл бұрын
Absolutely interested! Plz do sir
@nathanbanks23545 жыл бұрын
kzbin.info/www/bejne/ZqTXnWSLbsqpsLc
@gdubb69055 жыл бұрын
@@nathanbanks2354 thanx Nathan
@Umarluch5 жыл бұрын
Upvoting!!!!
@MrSpaz125 жыл бұрын
Gyroscopic effect. Take a bicycle wheel and hold it by the axle as it's spinning, then try to rotate it on its axis. It will fight to keep its current plane. Well, looks like I was wrong. Hmm
@BobbyMulqueen5 жыл бұрын
You've got a way that makes seemingly complicated theory understandable, and your enthusiasm is infectious - something my teachers lacked!
@matthewerasmus48033 жыл бұрын
I was most impressed with the explanation of why ducting a propeller increases efficency and thrust. Best explanation I have ever heard. Thanks
@stevencraigduncan54365 жыл бұрын
You sir are an asset to this planet. Thank you for this video. Your love for the subject is apparant. Profess on.
@Ben31337l5 жыл бұрын
Too bad he teaches misconceptions...
@BrentPlusSarah6 жыл бұрын
Do you have a video comparing thrust, before and after the ducting? I am very interested in the actual gain or loss in efficiency. Thanks!
@pilgrimhere6524 жыл бұрын
I want to build something at home, my two sons dont believe I can make it, but if I have to watch this videos a thousand times, I'll do it, I know a good result can be achieve .I'm learning a lot from all this information.thank you.
@area2echo9 жыл бұрын
Ok Bruce let us all in on the military failure....Great learning video thanks for taking the time out to teach us! Keep up the awesome work!!
@thecaveofthedead5 жыл бұрын
This is the single best explanation of flight physics I've ever found.
@smitboraniya67522 жыл бұрын
I was researching about propellers for my project, I have spent many hours on understanding how it works but this video is the summarisation of all my understanding. You have amazing teaching skills sir.
@ussweeneyd5 жыл бұрын
60 years after I could have really benefited from a teacher like this!
@greenmarine54 жыл бұрын
they say 90% of failure is operator error.....
@4.0.45 жыл бұрын
The enthusiasm is mesmerizing and contagious. What a great lesson!
@hushurpups33 жыл бұрын
Thank you for being the most enthusiastic entertaining person to ever talk about aerodynamics
@projects4home5 жыл бұрын
You are amazing. I really appreciate the efford you put into this. You are the only one so far, who can actually explain the science behind flying. I needed this info for my custom drones! Cant wait to see more about this!!! Thank you soo much.
@harukoyama95155 жыл бұрын
You are a great amazing energetic teacher. Not just learning the knowledge you teach. But also the way u deliver the knowledge.... Thank you. Learn a lot from you. Will watch all your class.
@dstone17014 жыл бұрын
Back during my seafaring days, my ship had a ducted bow thruster. I always thoght the duct was simply to prevent the prop from being damaged in case it hit the bottom (we used it a lot for mooring at the pier or getting underway - it eliminated the need to use tugboats) in shallow water. Now I know better. Thanks so much for making me one of 'today's 100,000'.
@toasty40000006 жыл бұрын
4:45 This is the first video I've seen of yours, and I was trying to prepare myself for you to only mention the Bernoulli effect on its own (in regards to lift) and I am so glad that you didn't! Happens so much by people who want to sound smart. Great video, thank you for the effort you put into it!
@flitsies8 жыл бұрын
I like your videos because they are very informative and easy to understand, you have a passion for your subject and you often make complex subjects real easy to get to grips with.
@R3apr4 жыл бұрын
I was actually searching for dust collection duct work and stumbled across your video - watched the whole thing and now I have learnt something new - well done
@cburgess75 жыл бұрын
Woah, I've been trying to understand these concepts for years, and just like that, in about 20 minutes, everything about aerodynamics, drag coefficients, etc has suddenly made sense. It was an epiphany among epiphanies for me in aviation
@laragrimes8559 жыл бұрын
Great video Bruce! Thanks. I'm gonna assign it as required watching to my physics and engineering students. We'll see if they spot the centrifugal/centripetal thing. Should make for an interesting discussion. After your last video I created a project for them to design and 3D print guards for the 450 quad they are building and programming from scratch. These propeller guards are what we needed to make the testing safer for them. As usual, great job. I'm looking forward to the bench test, but I may not show them that one. They'll need to generate the numbers themselves to compare the efficiency of their different designs. BTW...you are getting quite famous at University of the Pacific in California and the feeder high schools in the area. Keep 'em coming!
@bernardomartineztari4 жыл бұрын
Dude, you are probably one of the most enthusiastic presenters I have seen in a very long time! Great presentation and very informative!
@HiVisl5 жыл бұрын
What an inspiring teacher! Your explanations are stellar. I was interested from start to finish. You have a great teaching gift!
@trevorh64388 жыл бұрын
So what happened to the ducted project that failed for tilting the duct?
@lx81118 жыл бұрын
if the duct is tilted relative to the air flow, then a low pressure bubble develops inside the air intake. when the propeller reaches it, will loose load and when it exits will get loaded back. vibration, unsteady air flow. engine surges gasping for air, then it chockes with too much. no project ever tilted the air intake.
@badw01f238 жыл бұрын
Alexandru Vatamanu wow.. i was way off. i was talking about gyroscopic forces 😂
@OFGW8 жыл бұрын
Trevor Hurd it was called the Avro Car I believe. When the vehicle began forward motion by tilting what in effect was a giant duct, the vehicle lost lift. No matter how much energy was applied, all efficiency was lost and it could not conquer the smallest ground based obstacles.
@deathcoder7 жыл бұрын
how much tilt are we talking about? a drone tilts about 45 degrees. Is that enough to produce this counter effect? can ducts still be used efficiently in copters without tilting ducts?
@rc-hr8oi7 жыл бұрын
Also interesting for me, but never saw a single ducted multirotor or even a project of it
@chrisroddick38994 жыл бұрын
I have watched you on Xjet for years and enjoyed all the banter on the field with your buddies but didn't realize you are such a great teacher !!
@seigeengine8 жыл бұрын
The important problem with people's understanding of the pressure explanation is that the air doesn't have to end up at the same place at the same time. The air DOES move faster over the top of the wing, but not because of any need to get to the other side at the same time. Similarly, the idea that it's A and B is misses the important bit that you can ENTIRELY model wing physics by either looking at deflections of mass, or entirely by looking at pressure. Wings deflect air downwards, both below and over the wing. At the same time, you can equally say that wings work by generating lower pressure over the wing and higher pressure under the wing. They're not separate. They're two ways of describing the same thing.
@seigeengine8 жыл бұрын
It's just not as intuitive for people to understand ideas like that the wing can cause air that passes OVER it to be deflected downwards too, or to think of the air being deflected under the wing as creating a high pressure zone. Honestly, it took me a lot of time and reading stuff on the NASA website, research papers, etc. to really feel like it made sense to me, so I don't exactly blame people.
@The1stImmortal8 жыл бұрын
Not up on the engineering and maths of this by far, but my intuitive reasoning says of course it deflects the upper flow, because it creates drag - the air will slow closer to the surface, (and that will slow the air above it a bit and so on) and (just like with water or light,) slowing one side of a stream will bend the airflow. Am I on track or way off base here?
@seigeengine8 жыл бұрын
The1stImmortal It's actually the opposite. It increases the speed of flow over the top of the wing. Remember that I said it decreases the pressure above the wing. If it slowed the air, it would be increasing the pressure above the wing.
@The1stImmortal8 жыл бұрын
I meant in the context of deflecting the air above the wing as well as below. What's the mechanism by which the airflow is sped up over the wing btw, since equal transit's bs?
@seigeengine8 жыл бұрын
The1stImmortal It has to do with the shape of the wing. As the wing passes through the air, it generates a low pressure region over the wing, and a high pressure region under the wing. Fluids flow from high pressure to low pressure, so air entering the high pressure area under the wing slows down, and air entering the low pressure area above the wing speeds up. The simplest way to understand this I can think of, is imagining shooting tennis balls at a large inclined board. When they hit the bottom, they get deflected down, but there's a region behind the top of the board where no balls pass through because they'd be blocked by the board. That region is a low pressure zone, and the surrounding air pushes into it. It gets complex after that, because air isn't like a bunch of tennis balls being shot at the wing, and is really like an uncountable number of tiny tennis balls whizzing around in every direction really really fast that the wings are slamming through. Which is why the air can push in behind the wing whereas the tennis balls aren't going to just get sucked in behind the board. Also, the air is all like this, so the regions of pressure change and air speed change are substantially larger than you'd expect thinking of it like a bunch of tennis balls, since air getting sucked into a low pressure zone is leaving it's own low pressure zone behind, which then gets filled by the surrounding air, creating a pressure gradient "bubble." This also is a great way to discuss the other important thing to understand. While wings can deflect air/generate pressure differences by being inclined as they pass through the wind, they can also be made curved, which does basically the same thing, but without having to angle the board.
@Mfacius8 жыл бұрын
Yes please do another video about what you mentioned in this video, please.
@GonEyal5 жыл бұрын
the video: kzbin.info/www/bejne/ZqTXnWSLbsqpsLc enjoy :)
@samkelleran87903 жыл бұрын
@@GonEyal thank you!
@owlswait6 жыл бұрын
Excellent presentation with no unnecessary drivel. Learned so much in such a short period of time.
@robgrune32848 жыл бұрын
excellent. Could you please explain the pros/cons between paddle-shaped and scimitar-shaped propellers?
@fahimhasanakash5 жыл бұрын
Who needs a University When you Get Teacher like him In *KZbin* *Love* Form 3rd World. 👍👍
@EngineerHank5 жыл бұрын
@@petemiller519 But without the course, one cannot calculate the shapes and sizes needed making the project cut and try and very expensive.
@hermankoji5 жыл бұрын
@@petemiller519 in their pay chk
@kimrick85605 жыл бұрын
YT is actually YTU. Two Russian guys. TY Russia! Dopamine hit for them.
@hectornonayurbusiness26314 жыл бұрын
👍👍👍
@suprememasteroftheuniverse4 жыл бұрын
@@EngineerHank You don't need "the course". We get all the books and classes on online. Indeed, anything that you "learn" in college is already in books but you are too lazy. I bet that you had read no books in college. Only sat there your f@t @ss listening thinking that learn is some passive action of absorption. Learning is active.
@Fozzy19574 жыл бұрын
Brilliant!!! Although you broke my heart saying that it was a failure due to tilt. I was thinking "why aren't all choppers made like this", then you dropped the bombshell. Great video though, thoroughly enjoyed it, well done and thx
@jsmariani41805 жыл бұрын
Wingtip vortices occur without spinning as mentioned in the video, if I understand him correctly. Some modern airliners use winglets to prevent this, thus improving efficiency.
@normandeboer61185 жыл бұрын
Winglets reduce wingtip votices, not prevent...
@shodanxx8 жыл бұрын
BTW turbine blade tip clearance for a 12 inch turbine should be between 0.020" and 0.033". That's about 0.3% of total diameter. For a 5 inch prop you wouldn't want more than 0.015" inch of a gap. Here's a trick for achieving that, paint some thick but soft material in your duct at the place where the prop would be. This is an abradable seal. The prop itself will machine the duct surface until you get the tightest gap that your structural integrity can handle.
@ChristianNally6 жыл бұрын
How much more air should we expect for a given prop if it's ducted?
@paulbade35662 жыл бұрын
@@ChristianNally That will depend very much on the aspect ratio of the prop blades, number of blades, and rotational velocity.
@dieselmanworkshop58725 жыл бұрын
I have struggled for years trying to understand how a wing works, You took a few minutes and now I see it,and so much more, THANK YOU sooo much mate :)
@dann96865 жыл бұрын
Could you make the duct spin or mold it so it was part of the propeller?
@philliptoone9 жыл бұрын
Excellent video. Thank you. It is always a pleasure to listen to someone explain things well, even if you already understand the principal. I look forward to seeing your test results. But even more so, I look forward to hearing about how all of this relates to multirotors. As I was watching this video I was wondering to myself how these principals are effected by the aerodynamics of a tilted vehicle in fast forward flight. I am unaware of the related military history lesson you mentioned and look forward to hearing all about it in a future video.
@zenman82699 жыл бұрын
It has been obseved that in FF Flight the two rear motors have to work harder. There has not been a satisfactory scientific explanation for this. Probably has to do with the aero dynamics of a tilted multirotor
@philliptoone9 жыл бұрын
zenman8269 I've noticed this with my "toy" grade quadcopters with brushed motors. The rear motors burn out long before the front ones.
@zenman82699 жыл бұрын
Phillip Toone Its a bit of a mystery I guess, how and why the high pressure and low pressure areas are arranged on a multirotor in FFF .
@anandtewani75915 жыл бұрын
Someone should pick such people off the internet and just treasure them in one big reputed university. you won't require any sorts of ppt or high graphics 3d animation just to teach the students, rather only by this simple method of teaching, you would get some exceptionally highly skilled people on this planet Earth.
@robmedina46313 жыл бұрын
Very interesting! Thank you for sharing your knowledge. I knew ducted propellers will give the Lilium evtol an advantage but now I’m more confident that they will simply beat everyone once batteries become better and better!
@tylerferalio55458 жыл бұрын
What happens if the duct is attached to the outside of the prop blades and spins with the prop?
@sebastianmort76948 жыл бұрын
Great question.
@jstefa28 жыл бұрын
you have a larger rotating mass with more gyroscopic effect and a less responsive and more stable quad... you also eliminate all the losses of the gaps between the propeller and the duct, but you increase the load on the motor since higher rotating mass... dunno if its worth it tbh since no one ever went into production with a patent like that.
@lilushan18 жыл бұрын
I think it will have more drag/friction... and also motor load will be increased
@sok88888 жыл бұрын
If you throw a spinning baseball, it will curve, right? Well, a spinning duck will act the same. Your RC plane will try to go side way.
@tylerdeveneux68688 жыл бұрын
sok8888 instructions unclear and now my duck is angry with me.
@andrewstabback47475 жыл бұрын
Hes either a Kiwi or lived in South Australia for too long but what a great teacher.Id love to learn from him all day! Great passion.
@Lilmiket10008 жыл бұрын
man he'd make a really good fast teacher lol. their wasn't one thing he said that i didn't understand.
@TheJamesRedwood8 жыл бұрын
It's the New Zealand accent. : )
@mahkokhan8 жыл бұрын
Lakario Davis there is one thing i don't understand!
@nopethegeek8 жыл бұрын
Lakario Davis I agree. Easily explained what would otherwise be a complex topic. If he was never a science teacher, he missed his calling!!
@videos400585 жыл бұрын
bro dont confuse hearing with understanding hypothetical theories, because later after you had lunch ... you forgot everything. Thats what i call hearing. You heard the man but not able to reproduce or use his knowledge. And it makes you look silly, Some of it its really wrong. Why dont we use tease blade yet? not because o people like you or him but because of real science. chhers.
@shanebruce23385 жыл бұрын
@@videos40058 what's a tease blade. you'll have to message me, and I'll take months to read that.
@bobert4him8 жыл бұрын
Brilliant explanation. What if the prop tips were embedded into a ring that spun around as part of the propeller? This ring could be recessed within a groove in the inner circumference of the tube portion of the duct, thereby maintaining the general integrity of the tube inner shape. Yet, there would be zero blow-by because the tips would be embedded.
@Turboboob8 жыл бұрын
bobert4him exactly what i was thinking. ive seen these on toy helicopters
@BrightBlueJim7 жыл бұрын
Propellers with rings cause another problem: they add a lot of extra surface area that produces a lot of drag, which in turn puts more load on the motor driving the prop.
@spectre24666 жыл бұрын
What if the medium that the ringed propeller was using was water instead of air, would this be a beneficial use for say a submarine? I would think that since you don't need to move a water/submerged prop as near as fast as a air prop that the extra resistance from the ring would be worth it for less cavitation creating a quiter and significantly improved drive system for a submarine or is this theory incorrect as well? Just whondering because I want a really efficient propeller for the sub I plan on building.
@SaltiDawg20086 жыл бұрын
@@spectre2466 You may be interested in the fact that the US Navy constructed and tested a full scale propulsor in the late 1970s and into the early 1980s. It was fit to a couple of Submarines. It was also tested in a smaller scale for possible use on torpedoes. Good insight on your part!
@ElectricGears6 жыл бұрын
@@BrightBlueJim Another practical problem is that making the ring thin enough will make them very weak and the segments between the blades will bow out. This will cause even more turbulence/drag plus pumping losses if it's tightly enclosed in a shroud.
@Choqtaw3 жыл бұрын
So, this is going to be more difficult in smaller models to find a clearance between propeller and duct wall which makes for significant gain. And if the propeller edge is too close to the wall, it catches and gums up the works. As soon as you begin increasing the distance between propeller and wall the benefit drops off. But the propeller won't move well, won't go without friction and power loss, when the blades connect with the wall. You can't connect the propeller to the wall and get good thrust. Or can you? What if the propeller and the wall are one piece? Or rather a section of the wall or a ring is one with the propeller but separate from the rest of the wall. Flush with the main wall the ring portion of the propeller has free movement. Mounted as of a bearing.
@martharichardson48655 жыл бұрын
i wish to say I appreciate this gentleman explnations and why you must be a teacher good job
@Ben31337l5 жыл бұрын
Not really, i think it's a load of rubbish.
@tomclark62717 жыл бұрын
Thanks for taking the time to produce your videos. Very intersting! However, after having taught the principles of aerodynamics to children (young and old), I have found that most people have the most difficulty with grasping the concept of atmospheric pressure. Simply put, it is the weight of the mass of air above you, about sixty miles high at sea level. A collum of the air we breathe which is one sqare inch at its base, and sixty miles high, weighs almost 15 pounds. The most important thing to realise is that we experience this weight as pressure because we are inside of the air. It's called "internal sideways pressure". NASA's "new" theory of lift is just a matter of angle of attack. Bernoulli's theory holds the most water with me because it best explains how turbulateors work to increase lift without increasing airfoil airspeed. And, the reason why you don't readily feel the pressure is just because you're used to it. Don't try living without it, your blood will boil!
@johntomik46325 жыл бұрын
When flying at cruise in a fixed wing airplane you usually have a negative nose down attitude. Negative aoa
@petarpetrov44182 жыл бұрын
I had Aerodynamics teachers in Air Force Academy but you are much better the way you explain the subject.
@hiswordinwood27425 жыл бұрын
I love this guy! What fun it would be to have him as a neighbor!
@MystikSquash5 жыл бұрын
Have you made a video on the effects of the angle of attack issues with the ducts yet? I’m working with a ducted drone and I’m looking for more information like this to expand my knowledge on this subject. Thank you for all you do for the community. 🙏🤟🏽🔥
@lewweingarth6 жыл бұрын
Simple stuff, not so simple to understand, explained simply. Well done.
@dogzer8 жыл бұрын
I want to propel my drone with ducks. Would that be efficient?
@downloopdeviant8 жыл бұрын
Very. You'll get around 40 hours of propulsion with a loaf of old bread.
@stc28288 жыл бұрын
not efficient cuz duct are too heavy
@dogzer8 жыл бұрын
宋泰成 ducks are not that heavy, birds have hollow bones, so I'm surprised they're not the primary source of thrust for drones and flying devices in general.
@johnyu-eh4id8 жыл бұрын
Jose Díaz Are you gonna pay the ducks? They do a lot of hard labor
@buzzwerd80938 жыл бұрын
Between the SPCA and PETA, would the trouble be worth it?
@vgaulin8 жыл бұрын
I am interested to know what military aircraft failled because of tilting duct fan? Thank you
@gregoryphillips1428 жыл бұрын
yeah me too
@wireflight7 жыл бұрын
ditto
@pwrovld6 жыл бұрын
It was the Avero Car project
@SaltiDawg20086 жыл бұрын
Who said it was an AIR craft?
@jexter65786 жыл бұрын
@@SaltiDawg2008 lol
@joaquimpipa48425 жыл бұрын
I would like to thank you for this lesson, its something I should have known long ago, after all most of us have flown on jets throughout our lives. Thanks again
@nooneunique5 жыл бұрын
Heya, Yeah i would like to know what happens when moving lateral with a ducted fan said. what was the US Project name from the 50s. I think Canada had something similar also
@Fee.15 жыл бұрын
I want to knoowww
@drainquest96125 жыл бұрын
Hiller VZ-1 Pawnee
@GregoryAllenMansheim5 жыл бұрын
Brilliant, you are! You should have your own channel doing just this! Encore! Bravo! Well done!
@trevortrollface440 Жыл бұрын
that first bit was the best and quickest explanation of lift i have ever heard
@LeoH3L19 жыл бұрын
The vortex bit is wrong, the low pressure region does not get flung out, I suppose you could argue that the high pressure does, but circulation at the tip occurs because the high pressure region towards the tip trailing edge trys to flow around the tip and gets left behind by the advancing blade, also the "packet of air" principle with curved aerofoils is flawed, there is no reason that the air above and below have to meet up again, it's better to consider the pressure distribution around the entire cross-section not just the top.
@xjet9 жыл бұрын
Leon Hostad yes, there has been some debunking of the effect that Bernoulli's theorem plays in how a wing creates lift but the spanwise flow of air (induced by centrifugal force) does see a flow between the low and high pressure sides of the propeller at the tip -- and a resulting vortex being formed.
@LeoH3L19 жыл бұрын
Got to disagree about how that spanwise movement is caused, it's not down to centrifugal force, but down to the pressure difference; under the wing or prop you have higher than atmospheric pressure, and at the tips normal pressure and above less than atmospheric, the difference between under and tips causes a spanwise flow out, and the difference between the tip and the upper causes a spanwise flow in, that causes a rotating airflow, if it was down to centripital forces then tip vortexes on wings wouldn't form, but we know they do.
@xjet9 жыл бұрын
Leon Hostad Yes, it's primarily a pressure differential but there is still a centifugal effect. Spin a flat disk and watch the airflow across the face of that disk -- you'll see that centrifugal effect plays a part because there is a pronounced flow from the center of the disk towards the edge. This is in fact (partly) how Tesla turbines work.
@Espensoreide9 жыл бұрын
Leon Hostad sorry but that part of his theory is right. the air wants to travel from the high pressure to the low.
@LeoH3L19 жыл бұрын
Never said it wasn't, I only said that centrifugal force is negligible, so much so it can be ignored, the main reason for circulation around the tip is the pressure distribution below the wing, around the tip, and above the wing.
@fuyingbro9 жыл бұрын
I would like to see a video of what you were talking about with multirotors and ducts. And the American experiment with them.
@kiwiredbeard76326 жыл бұрын
Bloody good lesson mate !! Well explained !! I just bought an electric jet unit for my kayak which operates exactly as you explained , a prop in a tube/nozzle, I was curious as to why it was more efficient, Thank you
@sparrow0829 жыл бұрын
Yes please do a video on why ducted fans don't travel well in fast forward flight. I remember seeing that project and always wondered why it didn't work. I have always wanted to bould a flying wing with twin ducted fans. Something like the FT Crackin with the Jets in the middle of the wings. I know that if the wing is stalling or producing a lot of left, the fans can cut out due to lack of air from the low pressure zone above the wing and you need to duct air from underneath the wing to keep the thrust up. Can you do a video on that and other physics related aircraft issues More airplanes please...and drones, and drone airplane hybrids Sincerely Adam in Iowa
@niq8729 жыл бұрын
Adam Sparrow there have been videos of ft versa wings with edf's on them
@sparrow0829 жыл бұрын
I was talking more about the vacuum above the wing interfering with the inlet of an EDF. Also things like a forward sweeped wing can be more stable then a straight or rear sweeped wing. Or how a Canard doesn't add much more lift surface but dose add a lot more lift.
@M3nd0zaBrack3n9 жыл бұрын
Adam Sparrow id also be interested in why we dont build props with winglets on them, effectively making it a self contained ducted prop.... probably materialstrength.
@tastiger919 жыл бұрын
Mendoza Bracken Like aircraft wings now.
@THEfromkentucky9 жыл бұрын
Mendoza Bracken Hartzell makes a Q-Tip propeller with winglets. The problem is that propellers are already under a LOT of strain along the radius and the added structure needed to support a significantly bent tip adds a lot of weight and cost. Hartzell says they are more efficient but also a lot more expensive.
@qibble4555 жыл бұрын
Great video. I'd like to see a whole series like this on various topics:)
@amaechichizota38413 жыл бұрын
You make the whole teaching process very fulfilling.
@AmanGupta01419 жыл бұрын
Please make a video of why tilting the ducted fan proves fatal ??
@titanninjawarrior5 жыл бұрын
My wife heard the video and said she wanted to see how adding ducks helped the wind turbine XD then frowned when I said "ducts"
@kbruh30575 жыл бұрын
maybe the flapping of the duck wings might, umm sorta maybe ahm, help the turbine, no?
@blurryflag64665 жыл бұрын
adding ducks sounds great
@suprememasteroftheuniverse4 жыл бұрын
Voiceless consonants can be a problem. Imagine doubling them.
@greenmarine54 жыл бұрын
that's because your wife thinks on a higher plain than you do, she already knew the common sense answer, she wasn't expecting such a dumb answer.
@jmerlo41194 жыл бұрын
Lol. Mine sat on the hoover´s duct and off she went, quacking through the window. XD
@tonyswatermaker31585 жыл бұрын
Very simple and clear explanation. Your love to teach is part of you. Only two questions: what's the right space between propeller and duct and what's the percentage of efficiency of this system? I'm looking forward to your next video on these questions. Be good.
@ZOMBIEHEADSHOTKILLER8 жыл бұрын
so wouldnt it be best, for all, or at least most, non ductable props and rotors to have winglets on the ends?.
@MBaadsgaard8 жыл бұрын
No, answer, just want a notification when someone gives one :)
@seq1654328 жыл бұрын
know what? might not be a bad idea to find some cheap slightly oversized plastic props - mildly heat and bend down the tips
@jeffreykaney85518 жыл бұрын
that has been done, google Q-tipped propellers
@6Twisted8 жыл бұрын
Martin Baadsgaard I posted the answer but it's been blocked. He made a video explaining why it doesn't work.
@cannissolis6 жыл бұрын
it was done on a british design of helicopter rotor which I think was taken up my US military (the technology, that is)
@TWmarkjohns5 жыл бұрын
Definitely do the tilted duct video , thanks for the video it was very interesting
@ibrahimsued49064 жыл бұрын
Yes, you are a great, amazing teacher and man. I showed your video to my teatcher wife and she was so proud, and amazed too; Loved the explanation. Congrats.
@lesliecruzado27938 жыл бұрын
Loved your video. I found it by pure chance thinking it was something completely different. I'm looking forward to watch more of them.
@solidstate04 жыл бұрын
What about : (i) The additional drag caused by the duct? (ii) The additional weight of the craft due to the duct itself? Will this not offset the effect of the energy saved by deploying the duct to begin with?
@ardybooks23383 жыл бұрын
Great video! Loved the content, however one thing to realise is that the lift provided by a wing and therefore the thrust produced by a propeller is mainly due to the Coanda effect which we have recently acknowledged that proves that the flow of fluids conform to the shapes they are moving against, so the air gets deflected down because of the airfoil shape and in Newton's 2rd law, every force has an equal and opposite reaction, creating lift.
@justingriffin25462 жыл бұрын
thanks for the comment, i was wondering about that...I'm currently researching designs for a stationary duct for manned electric copter,. Do you think the duct has a negative affect on vehicle speed when rotating the blades?
@tianlun20018 жыл бұрын
The weight of the duct will need to be lesser than lift force gained.
@ColinRichardson8 жыл бұрын
Alan Fok just thinking the same thing
@volundrfrey8968 жыл бұрын
No really? Maybe that's why my super aerodynamic lead car was such a failure.
@TheTotalhunk7 жыл бұрын
Yes, they're made of "Duct Tape"
@simonruszczak55637 жыл бұрын
+Völundr Frey Maybe a concrete car instead. A concrete model aeroplane could fly (Mythbusters, TV programme).
@PilotoZ5 жыл бұрын
Oh! I wanna know what that effect was, for sure!
@dozer50695 жыл бұрын
See here: kzbin.info/www/bejne/ZqTXnWSLbsqpsLc
@It_makes_emotional2 жыл бұрын
You are really a best teacher to teach about duct propulsion
@markmiller68444 жыл бұрын
With the piece of paper he actually demonstrated the Coanda effect. To demonstrate the Bernoulli effect you would have to use an actual rigid flat plate.
@aeroboy144 жыл бұрын
I'm guessing if he had used a rigid plate, it wouldn't have risen no matter how hard he could blow? Like if he hung the paper straight down with no curve and blow on one side, it would just push the paper away from you and it wouldn't move towards where you are blowing, basically the opposite of what he is claiming?
@vatandas15424 жыл бұрын
One can NOT apply the Bernoulli principle on two seperate airflows. The airflow over and the airflow under the paper are two different flows. The paper was lifted because of the reaction force generated on it to the downwards routed (turned) airflow. i.e. the air was forced to go down whereas the paper (wing) forced to go up ....as a reaction.
@DavidL-qb8cl4 жыл бұрын
@@vatandas1542 he was blowing on top of the paper, not on the bottom
@vatandas15424 жыл бұрын
@@DavidL-qb8cl yes. Blowing trough the upper surface created a downwards routed airflow (due to the initial downwards deflected paper) . An upwards reaction force was generated on the paper. Similar to how aircraft wings generate lift.
@Deontjie6 жыл бұрын
Why don't they duct helicopter propellers? Even if it is just to save the main and back rotors, if the rotors touch the ground or trees?
@Eotarc6 жыл бұрын
Weight becomes an issue. The tail rotors on some models are housed within the tail.
@gerald40276 жыл бұрын
The main rotor has to be able to decapitate zombies.
@audigex5 жыл бұрын
Some tail rotors are indeed ducted for this reason... for a main rotor it adds far too much weight to be worth doing though
@tomriggs26375 жыл бұрын
They did in Avatar..cool looking! Can't wait for graphene..
Could listen to your teaching and enthusiasm all day - such clarity and zest - pity we aint got teachers like this in the UK (theyre only interested in the dosh )
@jasonvoss19846 жыл бұрын
Design idea: what if you enclose the propeller fully in a very short tube, but have zero gap between tube and outside edge of the propeller. So when it spins the entire tube spins. Then no chance of vortices at the outer edge of propeller. Just an idea. I don't know how well it would work in practice.
@jasonvoss19846 жыл бұрын
I guess the raised tip on the far end of passenger jet wings is to help this same issue of vortices spiraling off the end of the wing/propeller.
@alexandervanwyk76695 жыл бұрын
Amazing, can the wingtips be a bit more practical than a duct?
@stephenchase66115 жыл бұрын
New wing design have winglets on the end to suppress the vortex and make the wing lift more efficiently
@PetrincicBrosRC5 жыл бұрын
Great, great video my friend. I have been testing many EDF units lately and their thrust and this video is perfect for me to understand some things about how the exhaust of EDF unit should be. Thanks for making this video and big salute from Slovenia, Pilot Robert
@GregJoshuaW8 жыл бұрын
I'd like to see that next video. thanks!
@135iN555 жыл бұрын
As an aero engineer by education, a fighter pilot by trade, and an RC pilot by hobby, I can say with certainty that the RC community as a whole has more practical design knowledge, derived from the physics lab in the sky known as the real world, than all of global industry's aero engineers, combined. We have limitless real world data on ducted fans--none are real-world efficient. They are too heavy, too draggy, practical implementations have airfoils with too low aspect ratio to control back-pressure, and they need extreme RPM to produce comparable thrust to a prop that puts the same weight and power into a larger, lower aspect ratio, traditional design. All you have to do is listen to them to know they convert a lot more electricity into sound than an efficient, quiet, high thrust prop. What they do provide is terribly power hungry, higher speed solutions. Much like any jet vs. prop trade study. At 1:1 scale, props without ducts are as much as an order of magnitude cheaper to operate in the real world, empirically captured by gathering cost per flying hour stats. It's why the USAF is interested in LAA, and why they switched from the T-37 back to the T-6 II. If you have a req to go faster, they can make sense given power to burn.
@ErikssonTord_25 жыл бұрын
Absolutely right, sir! Through aviation history, there have been maybe 10 ducted propeller aircraft that has reached production, none very successfully. it was thought for a while to be a great way to control noise, but it was proved that low-rev propellers were more efficient and much lighter.
@CarGuyCole3605 жыл бұрын
Amen
@flyyynt5 жыл бұрын
@Jerry Moody If you mean turbofan jet engines, the duct does improve efficiency because it increases mass flow of air (thrust) - although this isn't true for higher possible speeds, which is why fighters don't use them. However, this would happen even if there wasn't a shroud around the fan, (as in turboprops) but the duct does multiple duty in controlling/slowing the inlet air necessary for the engine and fan, protecting the fan, and containing broken blades.
@WJRHalyn-jw2ho3 жыл бұрын
Good to see you've got all your ducts in a row... !!! 04:30 - You could've also drawn that wing level first, to illustrate that the pressure from below is not necessary; and that the longer trip for the airflow over the top, even at dead level forward motion, will generate SOME lift. (A lot of people assume it's only the air slamming into the underside that generates all the lift.) Then, draw a second wing WITH a tilt, and then add the "Newtons and pressure" details regarding the air pressure on the bottom to highlight the incremental increase gained. Just for demonstration's sake. I used to teach college. Your other explanations delineate the important elements of the physics of this so well, I started to wonder what would happen if, instead of embedding the prop inside a cylindrical tube, you attached a cylindrical "section" of a tube right to the prop..... it would work better with a prop with at least three blades, and possibly ideally with four (in terms of attach-points for the ring to the props' tips), but with the cylindrical section travelling WITH the blades, I wonder if there might be further reduction in chaotic vortex energy in any good measure. To visualize: imagine a 4-blade prop that is 10" in diameter. You create a very light cylinder of tough metal, thin plastic, or ideally, carbon-fibre, that is 10" in diameter and 2" in height. You then attach the propellor blade tips to the inner aspect of the cylinder/ring at the 1" mark down from the top of it. In other words, the blade tips have an inch above and below them of that thin wall of the cylinder. When the thing spins up to speed, there would be less air "thrashing" between the end of the tip and a stable but unattached outer cylinder, and all the vortex-induced turbulence would be contained in the ring (at each blade tip point) and forcibly directed downward instead of churning around in intervening space. There would also be a certain amount of centrifugal compressive force magnified within the inner aspect of the cylindrical ring at the most distal point, since air pressure couldn't help but be significantly increased due to compression from the blades' very high speed of rotation and compressive actions being funneled over into a very small area with nowhere to go but down (for at least an inch, anyway). It might be interesting to test what height-to-diameter ratios would work best with such a design; the trade-offs being: 1) weight vs area/zone of highest compressive action within the cylindrical ring, 2) total mass of the ring vs motor stability & oscillation cancellation (basically, keeping it EXTREMELY finely balanced), 3) comparing putting a flare around the intake or not such as you describe at about 15:30, because not only would air being drawn in be being drawn over the curvature, creating some lift, but the curved part (being part of the cylindrical ring) would be spinning at insane speed too, and (relative to the relatively motionless air about to be pulled in) the lip would have air going crosswise (very shallow diagonal relative to its spin) creating another extremely low zone of air pressure as Bernoulli dictates. Worth investigating? I haven't the time & resources at the moment to do so myself (just recovering from a nasty session of cancer in my head & corresponding radiation & chemo recovery), but I think there might be a few more tweaks such as this that could be engineered into an effective prop design that translates more rotational energy into vertically compressive/airflow energy. I've just had another enhancement modification to that pop into my mind, but I'll quit for now. Maybe this has already been done somewhere, anyway........ PS: In your intro paragraph, I'm pretty sure the word is spelled "theorem"... no "u". XD
@RonJohn638 жыл бұрын
10:19 The winglets on the end of modern aircraft serve the same purpose.
@DarcyWhyte8 жыл бұрын
Oh brother the equal transit theory is back...
@LaurentLaborde8 жыл бұрын
The fact that the equal transit time theory is false doesn't mean that Bernouli is wrong. The Bernouli principle is obviously true. But, there are absolutely no reason for a bunch of atom to go faster to meet their buddies on the other side of the airfoil at the same time. None. And, indeed, they don't.
@zutrue7 жыл бұрын
I always worry a bit when someone is so....absolute. Natural reflex.
@ryantatman30317 жыл бұрын
The "knobs" do something called "tripping the boundary layer" which can be very helpful when form drag is a large portion of the total drag on a system. Form drag is the drag caused by the wake of the object. This type of drag is dependent on the largest cross sectional area of the object defined by a plane normal to the flow direction. Another large contribution to drag is "skin drag" which can be thought of just like friction between two solids. Skin drag is dependent on surface area exposed to the flow. A good example of this trade-off is a golf ball vs. an airplane wing. Without going into too much detail, tripping the boundary layer changes the flow from laminar to turbulent which reduces the flow's tendency to resist a change in direction. This allows the size of the wake to lessen, which reduces form drag, but the cost is an increase in skin drag. In summary, adding dimples or "knobs" to a surface in a flow can decrease it's drag if the drag is dominated by form drag and form drag is dominant when the object has a large cross sectional area when compared to its surface area. Propellers are much like wings in that their drag is not greatly defined by form drag, so dimples would be detrimental, but some sections of a fuselage might benefit from dimpling. Speed and other things have effects on this phenomenon, but I think that is beyond the scope of a KZbin comment.... If you are interested in the topic, look up some of these keywords: Form Drag Skin Drag Induced Drag Boundary Layer Laminar Flow Turbulent Flow
@Cowcharge7 жыл бұрын
I always hate seeing that ruin an otherwise great explanation. It's such a common misconception.
@ArbitraryOnslaught6 жыл бұрын
Actually its the parasites on the humpback, the knobs... counter ..the parasitic draaagggggg pfffffff
@sunilkumarkakade84155 жыл бұрын
One Hell of an Amazing teacher makes you want to sit over for the longest possible time in anticipation
@moderatefkr66665 жыл бұрын
As an empiric learner, very few people can teach me. But I've learned a great deal from your vid. Thank you. What effect does narrowing the tube towards the outlet have on thrust? And would you be able to create a semi turbine effect if you had dual counter rotating truncated props in a tapered tube? What I have in mind is a medium pitch 3 or 4 blade prop I'm the front, with a similarities aggressively pitched prop behind. They would need to be specially made props with their pitches finishing at squared off ends that fit tightly in the tube, and also exactly mimicking the taper. This might make it easier to calibrate the clearance tolerances by varying the motor/prop mountings using shims. Have been thinking about this idea since before I watched your vid the first time - about three years ago! Would really appreciate your thoughts on this proposal.
@paulbade35662 жыл бұрын
Check out the videos by Agent JayZ on turbine engine compressor sections.
@rctv-uk31269 жыл бұрын
Brilliant work Bruce, looking forward to seeing it in action. ATB Malc
@arhitray86762 жыл бұрын
Sir your teaching style is excellent.
@Peter-8985 жыл бұрын
I'd love to see a video on the affect of tilting a ducted fan
@1arritechno5 жыл бұрын
Hmm, the Gyroscopic effect is a serious problem for Aircraft . Also any wanted change to rotational velocity (RPM) is delayed by the greater inertia,, plus extra weight, combine to make it less viable on Aircraft but acceptable on Ships. On full size Aircraft , many have "variable pitch propellers" ; this would be structurally more difficult to accomplish with a ducted propeller as the torque would cause extreme stress upon the hub mechanism. Also with conventional type Helicopters, the necessary Cyclic pitch with rise & fall of "main Rotor blades" would make ducted versions non viable.
@cdreid99995 жыл бұрын
thanks man ive always wondered this
@ronaldbaudilio3 жыл бұрын
Simply amazing ! Thank you for taking the time to compose this video as well as all of the other videos in your channel. They have been very informative and educational for my current endeavor.
@robinderoubaix5866 жыл бұрын
Love it - thanks! Would love to hear about how the US Military "duct up" in its design
@TheRobAbreu6 жыл бұрын
Awesome video RCModel Reviews, I love the way you teach... Your information on this Topic.. a very funny way of learning... Thanks Mate.. Keep up the Great Work...
@pooorman-diy11045 жыл бұрын
why not drones/multicopter use ducting fan ?? ..it would be safer for people ...right ??
@mickael96625 жыл бұрын
@@pooorman-diy1104 A lot of multicopters actually use ducting fans
@pooorman-diy11045 жыл бұрын
@@mickael9662 thats safer drones .. and more efficient 'i believe
@jatutube1234 жыл бұрын
Sir, You are a University in yourself. Lovely teaching style.
@stronklytyped9 жыл бұрын
Great work mate. Thanks for your thorough explanations. Please don't hang us on a cliff though :D What happens when it's tilted?
@jacksonkr_8 жыл бұрын
That's the magic of good vloggers! He's selling us a little bit and I'm not even mad because he's got a lot of amazing knowledge to dish out.