How ducting a propeller increases efficiency and thrust
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- Опубликовано: 21 июл 2015
- By placing a propeller in a duct, the efficiency and maximum thrust can be increased, sometimes significantly. This video explains two of the mechanisms by which these improvements are obtained -- namely by reducing the losses due to the tip vortex which occurs when a propeller operates in free space and also by using an annular wing that harnesses the effects documented in Bernoulli's theorum.
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When I clicked, I only planned to watch a few mins, but your enthusiasim is contagious
Great explanation on Ducted Fan operation.
Likewise! This wasn't even what I was looking for but couldn't stop watching and learned a ton!
What a terrific teacher this guy is! Can't beat a guy who gets excited by what he's teaching.
Marc Draco h
Must be a Kiwi guy, as he also said "ear preesure".
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...
@lil Oofy guGhGGHGhHhhZZUGzGhuGHHUZHhzU zu ZzHuGZGzZHgzzhUGGHHFFhGgHhGgZfuYhuGzGgGuG7GUHHGGGGHF uhh UGGghHgzuGHHhZHUHghZzGffUghHGYgHHhgZGHZuyzFhuzUHhuggZUhHgzZg8GgGHHFhGGgGgGGZfGHyzG uGzFUgGZZHZHuHUUZyUFHG
@@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 😂
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!
Go
What a great teacher! No fancy words, just a very economic explanation. What a pleasure to learn from you, sr.
Yes please do explain what happens when you tilt a ducted fan, I thoroughly enjoy your videos, thank you
Absolutely interested! Plz do sir
ruclips.net/video/0stl1U9evzU/видео.html
@@nathanbanks2354 thanx Nathan
Upvoting!!!!
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
You sir are an asset to this planet. Thank you for this video. Your love for the subject is apparant. Profess on.
Too bad he teaches misconceptions...
Who needs a University When you Get Teacher like him In *RUclips*
*Love* Form 3rd World. 👍👍
@@petemiller519 But without the course, one cannot calculate the shapes and sizes needed making the project cut and try and very expensive.
@@petemiller519 in their pay chk
YT is actually YTU. Two Russian guys. TY Russia! Dopamine hit for them.
👍👍👍
@@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.
You've got a way that makes seemingly complicated theory understandable, and your enthusiasm is infectious - something my teachers lacked!
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!!
This is the single best explanation of flight physics I've ever found.
The enthusiasm is mesmerizing and contagious. What a great lesson!
What an inspiring teacher! Your explanations are stellar. I was interested from start to finish. You have a great teaching gift!
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.
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.
60 years after I could have really benefited from a teacher like this!
they say 90% of failure is operator error.....
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.
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.
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!
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 :)
Dude, you are probably one of the most enthusiastic presenters I have seen in a very long time!
Great presentation and very informative!
man he'd make a really good fast teacher lol. their wasn't one thing he said that i didn't understand.
It's the New Zealand accent. : )
Lakario Davis there is one thing i don't understand!
Lakario Davis I agree. Easily explained what would otherwise be a complex topic. If he was never a science teacher, he missed his calling!!
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.
@@videos40058 what's a tease blade. you'll have to message me, and I'll take months to read that.
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
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!
I was most impressed with the explanation of why ducting a propeller increases efficency and thrust. Best explanation I have ever heard. Thanks
Brilliant, you are! You should have your own channel doing just this! Encore! Bravo! Well done!
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!
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
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.
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.
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.
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?
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.
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?
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.
Yes please do another video about what you mentioned in this video, please.
the video: ruclips.net/video/0stl1U9evzU/видео.html
enjoy :)
@@GonEyal thank you!
You make the whole teaching process very fulfilling.
One Hell of an Amazing teacher makes you want to sit over for the longest possible time in anticipation
i wish to say I appreciate this gentleman explnations and why you must be a teacher good job
Not really, i think it's a load of rubbish.
Idk how I always find your videos, I don’t even use rc stuff (apart from a mini drone I have) but I love your physics/electronics knowledge. Subscribed!
Excellent presentation with no unnecessary drivel. Learned so much in such a short period of time.
I have actually struggled with the concept of lift, until this video, thank you so much!
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...
why not drones/multicopter use ducting fan ?? ..it would be safer for people ...right ??
@@pooorman-diy1104 A lot of multicopters actually use ducting fans
@@mickael9662 thats safer drones .. and more efficient 'i believe
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!
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.
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
Brilliant lecture. Anxious to see the practical example.
Brilliant work Bruce, looking forward to seeing it in action.
ATB Malc
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.
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 !!
Loved your video. I found it by pure chance thinking it was something completely different. I'm looking forward to watch more of them.
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"
maybe the flapping of the duck wings might, umm sorta maybe ahm, help the turbine, no?
adding ducks sounds great
Voiceless consonants can be a problem. Imagine doubling them.
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.
Lol. Mine sat on the hoover´s duct and off she went, quacking through the window. XD
that first bit was the best and quickest explanation of lift i have ever heard
Thank you for being the most enthusiastic entertaining person to ever talk about aerodynamics
I love this guy! What fun it would be to have him as a neighbor!
What about reducing the duct exit diameter,does it helps too?
Net result is not as good. Unless you are trying to blow leaves or dry stuff. The reason is that while the air is faster, there is less of it because it is harder to push through the opening. Imagine if you tried to duct it all into a straw. High speed, but not much air.
Though there are always special cases with particular power, particular propellers/impellers, or goals other than maximizing propulsive force.
And jets and rockets are very different animals than a propeller or blower applications of course, due to heated/combusting gasses behaving very differently.
And going very big on the outside is also an option. That is how you get hovercraft.
@@ChessMasterNate T = dM/dt (v-u) T thrust, N, dM/dt mass flow rate through the duct etc, kg.s^-1, v efflux velocity, ms^-1, u influx velocity, ms^-1
@@ChessMasterNate I would think that the right answer is you need to evaluate the fan(pump) curve for the prop over the intended speed range. Best would be to have a nozzle exit diameter that produces a pressure rise across the impeller that has the prop running at maximum efficiency on it's fan curve.
In general some amount of restriction will produce more thrust/kW up to a certain point. Eventually enough restriction will cause the prop to go into aerodynamic stall and completely kill it's efficiency
So only intake should be reduced to create high speed and air pressure correct?
@@WarPigstheHunReducing intake area just moves the fan higher on its curve without increasing its thrust
I love you sir! You are an incredible teacher and are able to explain things in super simplicity with visualization! Thank you!
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
I'd like to see that next video. thanks!
Great video. I'd like to see a whole series like this on various topics:)
You are really a best teacher to teach about duct propulsion
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
excellent. Could you please explain the pros/cons between paddle-shaped and scimitar-shaped propellers?
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.
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
zenman8269 I've noticed this with my "toy" grade quadcopters with brushed motors. The rear motors burn out long before the front ones.
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 .
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.
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?
You are such a great teacher. Thank you! Whiched I had you in school ...would have been so much more fun and open new possibilities. But I am here now to learn. Better late than never.
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. 🙏🤟🏽🔥
Definitely do the tilted duct video , thanks for the video it was very interesting
I had Aerodynamics teachers in Air Force Academy but you are much better the way you explain the subject.
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.
So insightful! Thank you good sir! I learned so much!
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!
When flying at cruise in a fixed wing airplane you usually have a negative nose down attitude. Negative aoa
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'.
Simple stuff, not so simple to understand, explained simply. Well done.
Love it - thanks! Would love to hear about how the US Military "duct up" in its design
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
Adam Sparrow there have been videos of ft versa wings with edf's on them
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.
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.
Mendoza Bracken Like aircraft wings now.
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.
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.
Thank you for sharing your knowledge with us. You are a great teacher! People like you make this world a better place by inspiring our youth through education.
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!
Could you make the duct spin or mold it so it was part of the propeller?
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
You make learning fun! I wouldn't have not failed so much if all my teachers would have taught as well as you did!
Oh! I wanna know what that effect was, for sure!
See here: ruclips.net/video/0stl1U9evzU/видео.html
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.
How much more air should we expect for a given prop if it's ducted?
@@ChristianNally That will depend very much on the aspect ratio of the prop blades, number of blades, and rotational velocity.
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.
Sir your teaching style is excellent.
I would like to see a video of what you were talking about with multirotors and ducts. And the American experiment with them.
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.
Winglets reduce wingtip votices, not prevent...
Also in the past we didn't have quads soo lightweight and so powerful, I'm aware of the project u mentioned hope u found a work around.. ur the best, going to watch next vid now!🙏👍
I could watch this stuff all day... thank you !
Oh brother the equal transit theory is back...
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.
I always worry a bit when someone is so....absolute. Natural reflex.
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 RUclips 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
I always hate seeing that ruin an otherwise great explanation. It's such a common misconception.
Actually its the parasites on the humpback, the knobs... counter ..the parasitic draaagggggg pfffffff
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
I want to knoowww
Hiller VZ-1 Pawnee
Excellent, I like listening to someone who helps me think.
Yes let us know the other principle you were talking about! Thank you for the video.
Please make a video of why tilting the ducted fan proves fatal ??
I'd love to see a video on the affect of tilting a ducted fan
Thanks papa,you are such a good teacher,you just answered the questions that were holding me back from flying my own ultralight
You just blew my mind ! I would love to watch more of the videos on the same topic.
So what happened to the ducted project that failed for tilting the duct?
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.
Alexandru Vatamanu wow.. i was way off. i was talking about gyroscopic forces 😂
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.
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?
Also interesting for me, but never saw a single ducted multirotor or even a project of it
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.
Check out the videos by Agent JayZ on turbine engine compressor sections.
Thank you so much for the very clearest explanation I have ever come accross.
Dude....I wish I had you as my high school physics teacher. Absolutely brilliant narrative !
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.
bobert4him exactly what i was thinking. ive seen these on toy helicopters
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.
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.
@@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!
@@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.
Ear pressure? Is it something to do with loud noises? (Seriously though - good lecture.)
A very good video sir thank you for taking the time to make it. Please so talk about the American experiment. I think I know which one but want to know for sure. Your teaching method is a lot of fun and your obvious enjoyment of doing so makes you a truly good teacher. I look forward to many more videos.
I wish my physics teacher was this talented! You make aerodynamics so much easier to understand!