Laminar Flow Aircraft: The most promising development in Aviation
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- Опубликовано: 14 сен 2022
- The Holy grail of Aircraft Development. Laminar Flow Aircraft for up to 30% fuel saving in Aviation Industry @AviationNation
My Apologies. Its the B-24 Liberator. 
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It's a B-24 Liberator.
My apologies. I had written B-24 on the script but for some reason kept reading it B-54. I guess I had too much of the P-51 Mustang on my mind.
@@ElectricAviation It's ko I have bouts with dyslexia too.
@@ElectricAviation
There are four methods to reduce skin friction; high Re numbers, which destabilizes the laminar boundary layer at high Re and was the motivation for Werner Pfenninger at the ETH Zürich to introduce suction to prevent the instabilities , rolling flow emanating in the 45° clip like vortices to cause transition. below the turbulent boundary layer, a laminar sublayer always exists, on a uniform pressure distribution, according to Ackeret, the thickness of this sublayer grows proportional to the square root of the distance x reducing the shear friction
tau = mü× du/dy. the velocity u is of course in the sublayer linear with the height y. That is a reduction of the velocity gradient du/dy, the viscosity mü is indeed a function of temperature, decreasing by a factor of (T/To)^ .78
together with the running length x increasing the Rex = U× rho × x ÷ mü
That is the Reynold's number effect.
It is now clear , that in supersonic flow, the increase in temperature decreases the skin friction caused always by the sublayer gradient and viscosity. together with the wave drag reduction, (Ackeret's relation 1/sqrt(M²-1) ), the drag coefficient reduces with increasing Mach number ( which BTW was coined by Ackeret in honor of Ernst Mach) ..
After wind tunnel testing at ETH, Pfenninger went to Northrop to realize the concept of suction on a highly modified B-66, the X-21, partially succesfull.
The pressure distribution determines the velocity at the top of the boundary layer and is close to the potential flow, calculated for the airfoil shape AND the angle of attack. Using conformal mapping techniques or singularity distribution techniques .
The Stratford pressure distribution produces a shape, where the velcity gradient du/dy is zero after the maximum velociy distribution, the boundary layer just short of separation all along the pressure recovery region to the trailing edge.
This fact was used by Liebeck to construct his famous airfoil sections resulting in L/D ratios around 600, the best ever achieved with initial laminar boundary layer stabilized by a negative pressure gradient dp/dx followed by a transition triggering postive gradient to full turbulent boundary layer and then by the Stratford zero skin friction pressure distribution, just barely stable TURBULENT B.L. pressure recovery to the trailing edge. No too sensitive to AOA. This idea of enormous reduction of the turbulent boundary layer skin friction by near Stratford stable pressure distribution with a very small friction coefficient cf is by far better than trying to maintain laminar B.L. in a positive pressure gradient flow with suction.
Talk to Liebeck , at Boeing !
@@ElectricAviation
By the way, it was Pfenninger, who first designed and tested the Celera like body shape at the ETH, called the Zürich body, drastically reducing the drag coefficient in a rather LIMITED Reynolds number range . The data is available from the Institute of Aerodynamics at ETH or in the famous book by Sigmund Hoerner, Fluid dynamic drag, on the graph , skin friction of bodies of revolution, were it is called Zurich body, but no image is shown. So the original publication is recommended, from ETH, remarkable is the shape of the tail end, obviously not on the aircraft, with the pusher propeller. Talking propellers, the contra rotating coaxial propellers have a much better propulsive efficiency , 92+ % , compared to large 4 blade Hamilton Standard propellers, peaking at 85% , due to the angular momentum recovery
The efficiency of GA smaller propellers is in the order of only 76% for controllable pitch ones
@@ElectricAviation The reason, moderately swept wings are difficult to achieve natural laminar boundary layer of NACA 66216, 66212 , etc sections is the fact that the local angle of attack changes, increasing towards the tip, due to the interaction (Biot Savard) with the opposite wing. There is some, but NOT significant cross flow at cruising conditions, low lift coefficients, when the forward pressure distribution is flat.
Go and measure it in a wind tunnel, low turbulence one, where with thin oil the transition can be observed.
3 dimensional CFD designs permit spanwise constant pressure wings to be designed so that the crossflow inside the boundary layer can be almost eliminated. Outside the crossflow happens ONLY with separated flow. Not a cruise condition.
Only in viscous flow does the pressure influence the cross flow, never in potential flow. where pressure is determined by energy conservation, in incompressible flow called the bernoulli equation.
The Liberator was the B-24 (not the B-54) and the P-51 flew less than a year after the B-24 (not over a decade later!)
He can't play it fast and loose with Airplane or Car guys. We know the difference ;)
Your videos are information rich, accessible to the non-aerospace engineer, and generally top-tier. I find myself pausing, getting screenshots, and replaying more portions of your videos than any others I see on RUclips. Thanks for the excellent content - the type of content that changes RUclips from a distracting time-suck to a genuinely enriching experience
Great to hear!
👍👌
I hope you got the screen shot of the Mustang that was really a Zero? OPPS
@@dickmick5517 actually I don't think it is a Zero...2-seater... is it a British B-24 Blackburn Skua dive bomber? or a British
T-6 trainer?
And most of his information is wrong, Ben @llahneb
Anyone designing a modern efficient plane needs to address laminar flow at some level. Both the 787-8 and 787-9 employ natural laminar flow on the engine nacelles. Hybrid laminar flow on 787-9 and the 787-10. It also will be used on the two 777X models. I think this is on the tail surfaces.
If you have not had the pleasure to fly on a 787 I highly suggest to board one. Really an amazing passenger aircraft, and the "business" class (1st class) is stellar!
Also, the 737 max winglets are designed for laminar flow
There is a size limitation to laminar flow.
So while certain surfaces/components on an airliner can have laminar airflow , the aircraft fuselage cant.
Am the designer of Honda and Boeing 737 curvy wings , but since 2013 am sitting off surface
@@ajs9688 how so?
Way better explained than when I studied this stuff 20 years ago at uni. Well done!
I bet your Prof. throw in a tons of math to make sure you won't get the idea.
The Celera drag reduction vs standard designs is amazing. It's a shame for Celera that it doesn't scale up, although it would probably look like an airborne Blue Whale. Thanks for rounding out the video on an optimistic note with the promise of similarly efficient designs like the double bubble. I love flying and it would be great to make it much more sustainable.
Totally agree
If the limiting factor for scaling up the Celera is Reynold's number, why not just decrease its speed, with an increase in size?
@@johndavidwolf4239 Yes true. We have got used to flying at 400 mph or more. Problem is the slower moving aircrafts of upto 200 mph, would not find traction with business community and this aircraft is pitched towards them
@@ElectricAviation Yes but it would make sense for freighter planes.
The B-24 Liberator was able to fill the air gap over the Atlantic, leaving U-Boats nowhere to hide. Its long range was made possible by its high aspect ratio laminar flow wing, known as the Davis wing. By the same token, the P-51 Mustang would be able to escort bombers all the way to Germany and back due to its extended range made possible by its laminar flow wing. This despite the Supermarine Spitfire Mk IX of similar size being equipped in some cases with an identical Rolls Royce Merlin engine
Your information is correct, the B24 was a great success in the war and indeed after in to the 1950s.The Mustang was the most successful fighter plane in the 2nd WW as long as it had the RR engins which replaced the Allisons
Drop tanks helped a lot too.
The wing of the Spitfire was very efficient aerodynamically, being eliptical which reduces induced drag. However, being a thin wing it was not good for wing tanks (only a few examples had small wing tanks). By Comparison, the P51 could carry a lot of fuel from the get go. This more than anything else accounted for the difference in range performance. I am not saying the P51 wasn't more efficient overall than the Spitfire. According to the late Lee Atwood (of North American) it enjoyed a significant advantage in cooling drag alone. What I am saying is the laminar flow wing is probably the least of it, considering the Spitfire wing was also notable for its inherently efficient eliptical planform, and most of the range advantage was due to the P51 carrying nearly 3 times the internal fuel of most Spits.
@@XPLAlN Let's not forget the combat performance as well. While also reducing drag, laminar flow over the wing results in lower stall speed or higher stall angles. As a result, even with square edge wings, the P-51-D3 when fitted with the Rolls Royce engines could turn fight just as well as a Spitfire. The more powerful and efficient engine in tandem with the laminar flow benefits meant that it could accelerate faster out of a turn, hold more energy through the turn, and enter the turn at higher angles without stalling than it's predecessors. This meant that it outclassed the BF-109s and FW-190s that were still being used as supplements to the Me-262, and was even on par with the overall performance of the Me-262, not counting maximum speed and altitude.
And that's not all. The P-36 Hawk also benefited from laminar flow over the wings because the wing design swept forward at the trailing edge, helping to push that cross flow under the fuselage where it could give the plane more tail authority. While the flat nose and cooling flaps on the cowl required for the radial engine certainly doesn't help efficiency, overall drag, or top speed, this plane outperformed many aircraft from it's time simply because of it's wing design, short fuselage, and ability to outmaneuver all of the faster, sleeker designs of the time. In addition, because of the wing design pushing more air to the root of the wing rather than the edges, it had a much higher DNE speed than similar planes with straight wings, but suffered from compression dives far more.
@@TheDustyShredder you're forgetting the biggest breakthrough of the Mustang, which was reduction in cooling drag versus it's contemporaries
this is an amazing synopsis into an aeronautical engineering principle that I had absolutely no clue about. Thank you for sharing your knowledge!
Glad it was helpful!
"this is an amazing synopsis into an aeronautical engineering principle that I had absolutely no clue about. " It was intentional, to make sure you remain clueless.
Ty for a lovely visit. You answered every unexplained term right away. Yes it’s a B 24, and there was one more word I didn’t get near the end but of course I can’t tell you what it is because I didn’t get it! All in all very well done.
0Nice video; At 0:58 you call a fighter a P51 Mustang, but that's not a P-51. It may be a Curtiss P-56 Hawk - at any rate, it has a radial engine. Also, just prior to that, you refer to the B-54 Liberator. The Liberator was the B-24.
Agree
Its a Commonwealth CA-16 Wirraway
9/18/22. Excellent presentation of 'Laminar Flow' effects on both wing & fuselage of aircraft. Numerous video 'clips' of laboratories testing smoke flow over wing shaped surfaces as the wing is rotated clearly demonstrates the two (2) air 'drag' issues (natural & paracitic) you articulate through this lecture. Absolutely great visuals of aircraft in flight while your voice over explains the history of wing designs, few examples of 'perfect' laminar flow achievement but also newer body designs which reduce drag thus achieving greater fuel efficiency. Related effects of handling characteristics were covered as well. Great video to watch & learn. A+ ! Carry on Sir!👍👍👍😊
When I was at University, some 50 years ago, a friend from the Mechanical Engineering Department, was researching power within laminar flow, by utilising the COANDA Effect.
I often wondered since then, what had happened to that idea ?
Don't forget the Kutta-Joukowski theorem!
"I often wondered since then, what had happened to that idea ?" It got consigned to the trash can, because it works.
Probably the best part of watching a video that has nothing to do with anything I'm interested in is reading all comments from people fully immersed in the subject matter. So much niche subculture in the world
I would hardly call Aerospace Engineering a "niche subculture".
You sound like my subsonic aerodynamics professor! That was a very concise explanation of laminar flow and I agree with you on every point. I think we can adapt our acoustic perforation technology, used on nacelles, for boundary layer control suction but wet wings complicate things. But at least the sonic pressure levels won't be over 160Db!
Glad it was helpful!
Unexpectedly lucid discussion of the importance of laminar flow in aerodynamics. The Celera has the appearance of a dirigible with wings which made me think that it would never fly, but it appears that it has flown. Clearly, this is an area that needs to be explored by those who are qualified to do so.
It looks like a greedy mosquito
@@BariumCobaltNitrog3n It does, doesn't it?
That was a super interesting video! I loved to see the modern designs and the evolution of it!
Thank you!
This video was Awesome! :-) Super easy to understand and great visuals! Thanks so much!
The biggest reason active laminar flow was never pursued was the maintenance.
These days we have handheld rust stripping lasers. It would be a lot easier to do the maintenance these days.
We worked with NASA in the 70s and 80s on Laminar Flow Control panels made for the leading edge (LE) and 70% chord of wings intended to go on commercial a/c. We produced titanium wing panels with 0.0025 diameter, trumpet-shaped holes, 0.010 on center in square and diamond patterns for installation on a testbed a/c. The actual flight test results were outstanding and exceeded calculated expectations. These tests were done using only main wing panels while the program was intended to replace all LE surfaces (nose and vertical and horizontal stabilizers). There was virtually no difference in maintenance from normal paneled surfaces and an added benefit was that the vacuum pumps used for LFC could be reversed for pressure pumping deicing fluid out through the same holes and result in additional savings. The potential issue with insect hits was negligible as the LE was protected by the slats during TO and landing and the deicing fluid could flush debris away. The ultimate limiting factor was the overall cost of replacing existing wings and other surfaces with new versions to the (then) cost of $4M per a/c.
@@bbayerit That's what I get for trusting the news.
Also reinforces my belief that legacy aerospace hasn't been trying for decades.
@@bbayerit interesting, thanks… what were the effects of rain on the flow…? what were the reasons given by manufacturers for new aircraft for not adopting the techniques that you were researching…?
@@jtjames79 hmm, that’s not really fair…. the new technologies that have gone into the 787 for example are pretty amazing…. The outside shape may be quite similar to other jets in production for the precious 50 years, but what it’s made of and what’s inside it are very different…. airlines are very risk averse, for very good reasons, so trying to make a Quantum leap into something like a lifting body is something that they’re not ready to do, it would be in their view almost certain business suicide…
@@louisvanrijn3964 Reflective paint, or even just a nice bright white. I'm also just saying rust stripping lasers are commercial off the shelf so anything less power than that is also commercial off the shelf.
Gunk tends to be dark colored, so it's kind of like laser hair removal. You obviously would want to carefully tune the laser.
You could also use a fiber optic laser(s) and carefully target each hole, but you would probably need some sort of robot arm, otherwise a worker is going to be picking up and moving that laser(s) a lot.
Dad was a USAF TEST OILOT. He once described creating B-47 wings with an internal vacuum and perforated wings. The vacuum was to suck out the disturbed boundary layer.
I worked at Honda Jet in Greensboro .....Contract toolng guy with Pete Payne .....and Larry Tedford years ago .....great info thanks !
Excellent review. I liked the diagram of the swept wing explaining the purpose of a swept wing.
Build bigger, thirsty, powerful engines to go fast, or improve efficiency to do it with less. This is true of cars, boats, aeroplanes and even radios! Yup, a great radio is useless without an antenna! Gotta look at the 'whole' package. But every little bit helps. Thanks for the insightful video!
Very well put together. Thanks for a wonderful video!
Many thanks!
Excellent video - thank you!
Use of tubercles on the leading edge can also have laminar benefits. Dr. Fish did the research on this.
The Celera 500L looks like a good basis for a long endurance drone aircraft.
Bloody well researched & presented- nice one ☝️
Thanks for the brilliantly clear breakdown.
Thanks! You are a great teacher of these concepts
I always marvel at the effort applied to make smooth surfaces, when nature's air fleet (bats, birds, months) have fuzzy surfaces.
The reason is that nature's way of flying involves capturing energy from vortices. This requires fuzzy surfaces. We cannot achieve that level of complexity at large scale. Hence we rely on mechanically simpler mechanisms of propulsion. This means we fly very differently
8OO' per SECOND✈️ N O T realistically attainable. VS. 7O feet per second 🦉
Any man carrying aircraft is much larger, and consequently operates at much higher Reynolds numbers than any living flying creature. Even pretty low performance aircraft cannot operate at the slow speed of all but the fastest birds. The flight envelopes are so different that flying must be approached differently.
@@herbertshallcross9775 Yep. Aerodynamics change so drastically at different speeds. I am still shocked at the vertical stabilizer of the X15. You look at that and think it would just be a nightmare in the wind but no, it works.
Man, you earned a subscription.
Very cool video, dense in information yet easy to comprehend. Well done!
Glad you liked it!
Thank you for the word 'empennage'. A new one added to my brain.
Thank you Sir. I very much appreciate your instincts on the best way to transfer your knowledge to your listener. You know what to say and when to say it to minimize confusion while maximizing absorption.
You are very welcome
Excellent video. Really great content and well explained!
Fantastic presentation on laminar flow control.
Glad you liked it!
You know, sailplanes have been using laminar flow technology since the 1960s. A modern sailplane is among the most efficient, in terms of lift-to-drag, of any aircraft design. Why no mention?
Top class education. Loved every bit of it.
Great video! This is the kind of content that makes me wonder how big media companies stay in business.
Fascinating, thanks very much 🙂
Excellent information provided. Thanks..
Bravo to the forward thinkers who created the Solara 500L. I wonder what benefit might be derived from ducting the fan?
Ducting a fan causes less induced drag around the tips of the propellor, it also reduces sound. ducted fans often have stator blades that also reuse abit of the energy lost in the circle motion that air behind a fan makes to convert it to backwards motion.
@@dageogaming4478 - Realizing those facts, and appreciating all the other ways they optimized the Celera, I was just wondering out loud why they chose not to duct the prop. Wondering about the tradeoffs - weight, drag, disruption of laminar flow?
@@patrickmulvany6479 ducted fans do increase weight and parasitic drag, this drag is a bigger part of the overall drag on higher speeds. I can't tell for sure how it affects laminar flow. ducted fans have their pro's and con's, it's a compromise that has to be made based on what the aircrafts role and flight conditions will be.
What I have wondered about on the Celera is the CG range. How do you balance it full vs. empty?
Great video! Thank you!
You are welcome!
So well explained - thank you.
Glad it was helpful!
Thankyou for the clear explanation.
Wow I learned a lot from this, thanks!
Excellent aeronautical engineering analysis of laminar flow. Interesting and informative. (subscribed)
Look like a real engineer made this video. Very well done
Thank you for this superb video!
Glad you liked it!
Very informative, thank you. What of the "Coke bottle" shape on fuselage design?
super nice video, very well explained, subscribed!
Cool. Thanks for sharing.
Thanks for watching!
Awesome video - nicely done!
Thank you very much!
It always amazes me how a single revelation changes everything forever.
I believe the maths was in place before powered flight.
Amazing stuff, thank you.
Glad you enjoyed it!
Thanks, I learned something.
Excellent stuff bro
Really succinct and clearly told. Thank you!
Glad it was helpful!
Didn't know about the laminar flow drone. Thanks, will be interesting to apply this to model planes etc.
No problem 👍
Thanks for sharing. I understood some of it. Interesting.
Glad you enjoyed it
VERY GOOD. CONGRATS.
great info, thanks!
Glad it was helpful!
Nice job! Thanks!
Thank you too!
amazingly educational. wow. good job.
The B-24 and the P-51 were both designed in the early 1940's, not ten years apart.
Excelent video. Thank you
Glad you liked it!
Excellent video.
Thank you very much!
Excellent presentation!
Thank you kindly!
👏. Well done….well researched documentary
This info is relevant to aircraft that run on batteries as they need to be very efficient.
Excellent presentation. Keep up the good work!
Thanks, will do!
Excellent video, thanks.
Glad you liked it!
Outstanding video
Thank you so much 😀
The B-54 was an aircraft purposed by Boeing and was a derivative of the YB-50, itself a derivative of the B-29.
It was canceled before the prototype was completed and it never flew. Likely due to the fact it was a piston powered bomber designed in the jet age.
The USAF Discovered in Korea that the time of the piston powered bomber had come to an end.
The plane hiving its wing blown off is a B-24, probably the best heavy bomber of WWII.
What is the sound barrier in denser air? How do we increase the density of air whilst creating lift and then slow down air when the density is reduced?...
Good analysis
Go look at the corrugated steel body of the Ford Trimotor cargo plane from the 1930s it helps,even when it's low tech .
Nice job 👍 Very interesting!
Thank you! Cheers!
Fascinating topic, thanks for the video
Thanks for watching
Really good information!👍👍👍👍
Glad you liked it
Great post my friend.
Thanks for the visit
how much of laminar flow is used in marine vehicles? Does anyone study fish? The reason I ask is the medium of water has considerably more resistance than water. (I'm not quite sure if that impedes or enhances laminar flow) I any case what do you think the effect of using shark skin like texture (which is like narrow spines or teeth) would have on flow?
Im sure the shark skin would be effective but also unimaginably expensive and complex. Also modern, high speed boats use an ingenious trick where they put a step in the hull (stepped hull) that forces air under the boat, so its a lot less friction because as you said, water is much thicker than air.
Can ion propulsion on the surface and body of the plane theoretically reduce drag?
Maybe you can create a video explaining how the tooth-like denticles on shark's skin reduce drag? I see there's some research in to applying the same techniques to aircraft wings.
Tabulators are already used to reduce lamination separation bubbles, but these don't seem to be the same as dentricles, as sharks have them all over their bodies (I believe), and not just in front of where the laminar separation region would be.
That reduces that profile drag. It similar to golf ball indentations. It doesnt reduce the skin drag
Sharknado helps explain a lot of things.
Interesting but I imagine trying to produce such complex shapes over the area of an aircraft would be unimaginably expensive.
inducing very local vortices can re-energise the air flow in the boundary layer, keeping the overall flow attached. You can see this in small 'tabs' on the upper wing of aircraft giving lower stall speeds and better behaviour at the stall. You sometimes see them on performance cars.
This was fascinating. Can one look at it like this?: when you have turbulence in the wake of an aircraft, the air is moving, so energy has been transferred from the aircraft to the air. In order for this to happen, work has to be done - this shows up as a drag force. With laminar flow, if perfect, the air behind the aircraft closes up and isn't moving, so less energy has been transferred to the air and so less drag. I would think the Celera won't scale indefinitely because the Reynolds number of the flow goes up with the dimensions so turbulence will happen more easily.
EXCELLENT
Thanks for listening
Thanks!
Thank you so much. That is very kind of you
Next step... Apply a high voltage plate at the front of the wing or even a material that builds static as the air hits it at high speed and laminate the back half of the wing with a positive charge to attract the negatively charged ions in the air due to the negative at the front of wing
I can see my street at 11:43. I'm always looking up hoping to catch the Celera. My wife saw it, and got excited. She has become an av geek like her husband.
I learned something today.
Cars of the future also need to use these breakthroughs! Fuel mileage would increase at the cost of sexy car body styles. God Bless
good concept
Wonderful.
Many thanks!
I watched your other Otto Celera 500L video too. Both are succinct, technical, yet accessible to non-AV geeks. Thank you for creating videos that a layperson can understand. Otto's press release website has not had an update since 2021. Have you heard any news about the plane?
is there any sort of ground-effect interaction that could destabilize the plane during landing?
Are there any problems with the location of the propeller? Propellers like "clean" air too, and the wake of the fuselage is definitely not clean. Is that one reason the Beech Starship and the Avanti are so noisy? Great video, though.
Correct. You will notice ALL pusher prop aircraft are noisy because, even if airflow along fuselage is smooth, the prop inevitably passes from high pressure region to low pressure as it rotates. And this alone makes for noise pulses. The prop would have to be either fully above or below the wing which has obvious other issues.
My bet, aside from it going nowhere, is that this aircraft will have CG problems, payload deficiency, unsafe pilot visibility, very high takeoff and landing speeds and be deadly in icing conditions.
Laminar flow is a nice idea. A wish.
I'm wondering if this might make the noise inside the aircraft quieter as well.
Good video but I kind of laughed when you mention the B-24 since it has four huge egg beaters totally disrupting the air flow. Perhaps they got good numbers in a wind tunnel but not in real life. Where can I find out more about the relationship of Reynolds number to Laminar flow? How does the coefficient of lift of the NACA 671015 compare to say an Eppler 205? What about using the vacuum holes as a means of extending pins into the airstream to improve the lift coefficient during slow speed operation. The pins would make the air more dynamic. My concern with Laminar flow is the increased risk of lift failure during icing.
Haha this is so true.
12:00 The Reynolds number is proportional to the ratio of the pressure forces to the viscous shear forces
( ½ density × V²× chord × span) ÷
( viscosity × du/dy × chord×span
× [½V÷du/dy × 1/chord] )
= density × V × chord / viscosity
= pressure × area / shear stress × area
[ ] = factor of proportionality
du/dy = boundary layer shear velocity gradient
Amazing information, I am not an aerospace engineer, but very nice information, thank you!
Glad you enjoyed it!
we need a teflon sleeve with shape shifting to dynamically adapt to air flow. even without shape shifting, we need to have ridges to provide lateral assistance to flow, imagine a flexible system where the ridges raise up and curve based on airflow