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.

He can't play it fast and loose with Airplane or Car guys. We know the difference ;)

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

I bet your Prof. throw in a tons of math to make sure you won't get the idea.

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.

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?

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.

@@BoycottKZfaq289 you're forgetting the biggest breakthrough of the Mustang, which was reduction in cooling drag versus it's contemporaries

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.

Agree

Its a Commonwealth CA-16 Wirraway

It looks like a greedy mosquito

@@BariumCobaltNitrog3n It does, doesn't it?

Glad it was helpful!

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.

Thank you!

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.

I would hardly call Aerospace Engineering a "niche subculture".

Many thanks!

Glad you liked it!

You are very welcome

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.

Thanks, will do!

Thank you very much!

Glad it was helpful!

Thank you kindly!

Glad you liked it!

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?

Thanks for watching

Glad it was helpful!

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.

Glad you enjoyed it!

I believe the maths was in place before powered flight.

good concept

Glad you liked it!

Glad you enjoyed it!

Glad you liked it!

No problem 👍

I was once a lecturer in Scotland

It's Canada Geese....and only Canada Geese. Not Canadian.

@@xqqqme Is that Canadian English or Canada English? LOL! Ok okaay Canada Geese. But suppose you made a gravy from the drippings of a baked Canada Geese; wouldn't that be a Canadian Grease gravy?

Studying nature can always teach us, but nothing natural is moving anywhere close to the speeds of even the slowest air crafts, so the point is kinda moot.

Haha this is so true.

Thanks for watching!

Thank you very much!

Glad you enjoyed it

You are welcome!

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.

Glad you enjoyed it!

It's easier to claim a "breakthrough" than to develop an actual improvement. The market may respond to either, at least initially. Hopefully the actual improvement survives, but that is far from guaranteed.

It is simple. A laminar flow has say 1/5 to 1/7 of the drag compared to a turbulent boundary layer. So: be laminar as far as possible is the goal. Laminar boundary layers a sensative: wobbles in the surface, small dents, specs, bugs, rivet heads, rain; cause transition to a turbulent boudary layer. So you aircraft has to be, and stay in a mint condition. Can that be realised?

@@louisvanrijn3964 I'm sorry but if you try to educate someone who has a really good grasp on a concept, you should read what you wrote. Boudary layers a sensative on you aircraft. One is a typo, but ignoring the red lines under words is a bit...wild punctuation, you animal!

Thank you so much 😀

Thanks for the visit

Thank you! Cheers!

Thanks for listening

Thank you too!

Its true that if the prop is at the rear and doesnt receive clean air, than it makes at noise and also adds to the dynamic loading on the prop itself. It is however, aerodynamically more efficient over all as the wings and fuselage receive clean air

@@ElectricAviation : Additionally with a prop at the rear, the wing and fuselage do not see the localized higher air speed of the prop wash nor the turbulence induced by the prop.

@@ElectricAviation I believe it is due to the fact that the air comes in laminar. If they achieve their goal, and there is little to no turbulence at the back, it may make no difference to the prop.

Glad you liked it!

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.

Glad it was helpful!

There is a method where you let compressed air out from the wing surface to energize the boundary layer. What you are talking about is something similar

I wonder if the heat would cause adverse effects though. Remember he said cooling the surface can increase laminar flow. There are many prototypes that use the exhaust gases over the wig to generate more lift at low speeds though.

See Blackburn Buccaneer.

Glad you liked it