Al Bowers and the Prandtl Wing

[@hifinsword]

A picture is worth a thousand words. A model of what you are talking about would be all I need for this to make sense.

[@victordewey6782]

Wow, Al Bowers diluted! A simple explanation in less than 10 minutes without using mathematical equations! Excellent!

[@The1Pope]

Wow! This man has worked on this idea for over 20 years and just a few have heard and acted upon what he is saying. I'd like to try it out but I can't find exactly how the Prandtl Wing is made or how to contact Mr Bowers. Other geniuses include Robert J Englar (ret) who pioneered Circulation Control that would help airliners take off at survivable speeds yet fly faster with less drag. He used up 40 years of his life working on something great that no one paid attention to. His work also could be applied to tractor trailers for extreme fuel savings. At least he got to follow his passion. I love Al Bowers' passion too. Thank you for posting your interview.

[@markhuebner7580]

Thank you! Amazing clarifications of the mystery of the flying wing, still wrapped up in the hidden details of Mr. Prandtl's equations and your previous videos detailing the reduction of the angle of attack along the wing span moving from the root to the tip. Oh, if only more details were available!

[@FlyMIfYouGotM]

I would love to see an RC model kit built with this wing or at least a pre-cut foam core wing. A couple of years ago, after seeing a video on Mr. Bowers research, I started playing with a 1' span flying wing made from a scrap piece of 1/4" blue insulation foam board. It didn't really even have a proper airfoil. I twisted the foam to approximate a wash in and wash out at the tip. The thing flew fairly well but what was really amazing was how stable it was. I could launch it upside down, sideways even backwards. No matter how I launched it, after release, it would immediately right itself and fly straight and level!

[@pascalfust1035]

I am happy to read that, because I was thinking exactly the same. If there was an appropriate kit to play with, kids (and engineers) could work on a working piece to study. Would you mind giving some more information about your built?

[@FlyMIfYouGotM]

@@pascalfust1035 Mine was just a piece of scrap blue insulation foam board from either Lowe's or Home Depot. They no longer have blue, just pink but it's pretty much the same thing. I used some scrap that came from the part along one of the fold lines. That gave me a bit of a rounded leading edge to the wing. The wing halves were about 11 1/4" length each. The wing root was 2 5/8" and that tapered to 3/4" at the tip. The CG was about 2 3/16" back. The wing was swept back about 3 1/16" and the two wing halves were hot glued together with low temp hot glue and then taped. I hot glued a 1/2" piece of a Popsicle stick on the nose, (rounded end of the stick forward) and hot glued a 3 1/2" coffee swizzle stick on the Popsicle stick. That wasn't enough weight so I hot glued a 3 1/8" piece of a regular drinking straw over the over the swizzle stick and then added a small piece of modeling clay inside the tip of the drinking straw to balance. There is no dihedral, the wing was a flat bottom and I just hand twisted the wing tips upward, starting 2 13/16" from the wing tip, upwards about 3/8" to try and approximate Prandtl's/ Mr. Bower's wing with a minimum of time and materials. I may be totally off base on my take on this but at the time I didn't have anything but a KZbin picture and a scrap piece of insulation foam board. I was surprised how stable this flew for a free flight flying wing. It had a flat glide and it only wanted to fly straight, level, right side up. I will add a picture as soon as I can if you are interested. The info I have should be enough to throw something together.

[@pascalfust1035]

@@FlyMIfYouGotM Sounds simple and still effective. I guess that the twist you applied on the board resulted in a linear twist. Even though Bowers highlighted the importance of non-linear twist, I find it amazing that you came up with stable flying performance. I would definitely be interested in your findings and pics

[@FlyMIfYouGotM]

@@pascalfust1035 Do you have a Dropbox or other way I can send you pics? The twist probably were more or less linear but I tried to apply more twist as it got closer to the tip. I just played with it until it trimmed and flew well. I do find it interesting that Al Bower's groups work was used to redesign noisy blades on computer cooling fan for the ISS. The redesign resulted in a 24% increase in airflow and an 88% reduction in noise. This redesigned blade did this while using LESS electrical energy! With all of the hoops jet engine designers typically jump through for just a 1% or 2% improvement in performance you would think they would be falling all over themselves to take a look at this. NOTHING!!! Personally I think Mr. Bowers may be able to get the attention of more people in aviation if he picked a big piece of low hanging fruit. Wing or jet engine turbine blade redesign is expensive and carries lots of risk. Redesign of props for small planes in relative terms would be inexpensive. If you owned a small single or twin engine prop plane would you be interested in a 20% increase in thrust, an 80% decrease in prop noise and a 20% or even 30% reduction in fuel burn by just changing props? This is a potential market that, if properly tapped, could eventually lead to even bigger and better things. In this video, Mr. Bower explains some of these things with prop design starting around 39:50. kzbin.info/www/bejne/mHTapZZ6g6dka6c

[@pascalfust1035]

​@@FlyMIfYouGotM Yeah, I got Dropbox. I can share that with you. How about sending me a PM @ [e-mail]?

[@ChristopheSmith]

Could one build a paraglider using the Prandtl theory ? Are modern Hang Gliders are nearly there ?

[@joesephjoestar4449]

This is my exact thought. I am literally obsessed with this idea.

[@MichaelBlaber]

birds dont have to deal with engine torque, which notoriously requires rudder control

[@captarmour]

Great Video! Any calculations, tests with coaxial propellers? how significant the noise reduction?

[@lowkateng153]

Prandtl fan…..Same voltage, Same diameter, 24% increase in flow, 88% reduction in noise kzbin.info/www/bejne/mHTapZZ6g6dka6c

[@Allen46u5k]

BAS, John Montgomery figure out how the air flows over the surface in a circular flow in 1895.

[@pylon500]

So it turns out the 'Prandtl' wings look like Horton wings, because Horton wings ARE Prandtl wings! Still unsure what the deal is with the theory? High aspect ratio flying wings (provided they're not so small that the Reynolds numbers ruins them), using laminar sections and having the centre of gravity/washout relationship just slightly positive from zero, will always have a good L/D ratio. The requirement for vertical surfaces on swept flying wings has always been know to be minimal (if at all), however, pitch and roll control inputs (which negate most of the Prandtl theory) can have secondary reactions in yaw, so maybe small winglets are the answer. The concept of 'drag rudders' just sounds so weird when trying to optimise drag reduction!

[@arhedler]

If you'd actually followed the discussions (possibly in other's of Al's videos), the Prandtl design eliminates the adverse yaw issue on rolls, so the plane yaws appropriately on roll inputs, providing coordinated turns with no tail section required. There is no need for winglets or "drag rudders" at all; the washed-out wingtips are effectively the "winglets" folded out in line with the rest of the wing, and since the lift profile of the wing is generating the vortices at about 70% of the wing's length, the vortex ends up pressing up on the washout, providing forward thrust, effectively reducing the drag on the wing. During a turn, this forward thrust on the outside wingtip negates the adverse yaw commonly found on standard wings. For an example of "drag rudders", you need look no farther than the B-2 bomber.

[@pylon500]

@@arhedler All that you are saying is effectively correct, swept flying wings rarely suffer from rolling adverse yaw. However, this has been a known fact for probably longer than NACA/NASA has existed. In simple terms, when rolling any aircraft, with simple control geometry, it will induce a yaw. The act of rolling is usually to initiate a turn, and once rolled, the wing needs to be pitched to increase the now angled lift vector to maintain a level turn. On a wing and tail aircraft, this mean applying up elevator, which will increase the angle of attack of the outside/downward aileron, thereby increasing it's drag and thus adverse yaw. On a swept flying wing however, the pitching effect is induced by the equal raising of both elevons. An assortment of consequences now result, the 'outside' elevon has now been raised by the same amount as the inboard one, usually effectively bringing it to zero deflection, while the inboard elevon has now doubled it's deflection, thus increasing it's drag purely by it's amount of displacement (compared to the outside), 'hey presto' an impersonation of differential ailerons! Other effects come into play with swept wings in this situation as well. Image a straight flying wing, a 'plank' (very popular as a simple RC slope soarer), once rolled to a bank angle, it will try to slip into the turn, a 'pilot on board' reaction would be to increase both roll and pitch (thus more inboard drag) to complete the turn. On a swept flying wing, this induced slip has a secondary effect of presenting more leading edge on the inboard side, creating a STRONG dihedral like effect and trying to roll the wing level, as such even MORE roll and pitch will be applied to a swept wing to maintain a turn. This is where the idea of drag rudders usually comes from, that and the real world need to induce side-slipping to be able to land in a crosswind. Note; I have seen these concepts of induced angles of attack and odd airflows and lift vectors, that can be shown to be producing 'thrust', this is generally rubbish as the pressure differentials and angular flows ON A MOVING AIRCRAFT/WING, will never amount to more than the oncoming airflow, thus the best you can hope for is a minimal reduction of drag in that area. (I once had someone try to tell me how much 'thrust' winglet can produce, so I drew a picture of a Jumbo Jet covered in winglets with no motors and said, "All we have to do is push it, and it will fly forever!" Pylon500; Free flight and RC modeller, hang-glider and sailplane pilot, Ultralight flying instructor ~4500hrs, ultralight designer and builder (building #4).

[@flappingflight8537]

@@pylon500 looks like you still didn’t assimilate ( don’t take it like offence , just trying to help you) what Al Bowers and the previous commentator ( in this thread) are saying. The difference between the Prandtl bell shaped lift distribution wings ( BSLD) and the regular one is that on the regular flying wing you have to achieve the pro verse you by creating more drag on inner ( to the turn ) wing ( the more drag pull it back ) when on BSLD wings you achieve the pro verse you by increasing the thrust on the outer ( to the turn) wing automatically with rolling the craft in the turn ( increase of the lift on outer wing automatically increase the thrust as well ) . On BSLD wings pro verse you is a result of pushing outer wing forward instead of pulling inner wing backward as is on the elliptical ( Prandtl’s achievement as well ) lift distribution wings. Hortens have been much more engineers than scientists . The engineers usually like to keep their design secrets when the product of scientific work lose any meaning if you keep it secret just for your own consumption . On the other hand Prandtl hasn’t been engineer/ pilot who was building / flying real planes so he probably even doesn’t looked at the problem of adverse / proverse you and especially for the tailless flying wings planes as Hortens do . Here Al Bowers has come to figure out and kindly share and explain to all of us what Prandtl and Hortens works can result of and how the nature ( the birds ) prove theirs theory and practices by using them millions of years .

[@ChristopheSmith]

Birds: kzbin.info/www/bejne/gHzCin2dqMyioZo

[@autophile525i]

Are you a pilot?

[@atlas108]

I thought you didn't believe in natural selection, Al.

[@gordonquigg9389]

"The Gordon Quigg Principle Of Wing Lift" I'm 64 years old, and ever since I was 3 years old, making model balsa wood gliders with my dad, I have thought that the Bernoulli theory was a myth, a hoax, and all wrong. First of all, scientists that should know better, for centuries, have addressed the issue wrong and backwards. Comparatively speaking, and to put things in proper context to analyze the subject scientifically, in order to expose the reality of the situation, the air is not moving through the wing, the wing is moving through the air, in which the wing has the power of mass, momentum, speed, and power, and the air does not. Air is minding its own business, and here comes a high speed efficient bird at 60 mph and slices right through it. Did the air speed up, or slow down? No! Because it wasn't going anywhere! It didn't have time or the ability to speed up or slow down because by the time the wing sliced through it and the air had not enough time to react, the party was over for the air. So, the bottom of the wing is just simply doing what they call planing on the air it is hitting. The air on the bottom of say a half foil wing (flat bottom, full curve on top), is barely disturbed, whereas the air on top that was having a Ho hum nice day, gets thrust upwards and out of the way to make way for the volume of the wing, which creates the most drag for the wing to push through. That air gets relatively highly compressed and pushed up and out of the way instantly, and as the wing going 60 mph does that, it leaves the air that was on the top side of the slice, packed up and pissed off. But back when the wing was half way past those air molecules that we are talking about, the wing's curve on top is now peak and pulls away from those molecules, and they haven't had time to react, so packed up above the wing they stay, long enough for a vacuum to be created as they try to break off of the wing's curve pulling away from them, thus, creating an amazing amount of lift. By the time the air molecules that got pressed above the wing are able to press themselves against each other and get back down to where they were before getting sliced, the wing is long gone and the air rejoins the other air that was below the wing, almost effortlessly, the more efficient the wing is that sliced through it. Now if we were talking about a wind tunnel with a stationary wing, the wind on top doesn't speed up to meet its buddies on the bottom side. It gets pushed up with drag and actually slows down, and is late to the party when they join up with the air molecules down stairs again with no means or way to catch up to the position they were in before hitting the wing and slowing down. So sorry but Bernoulli is, Wrong... So in summary, The Gordon Quigg Principle is: a standard gliding bird wing foil, such as a pelican or an albatross, has a good amount of simple planing lift on the bottom, and a really good amount of vacuum lift on the back of the top, while the air is relatively still and the speeding wing slices through it. And that my friends, is The Gordon Quigg Principle of how and why a foiled wing lifts, in many ways, the opposite of Bernoulli's Principle, and all those highly educated scientist's who blindly dogmatically follow him.

[@rotorismo]

that was a clear explanation for me

[@_Skitter]

I am unsure if you realise you've basically just described 'lift' but with different words and no regard for frames of reference. According to the air, it's standing still (for a definition of still) and the wing comes and slices through it, yes. To the wing, if one was on said wing, the air is racing over it's surface constantly. You can see this in aerodynamic studies when they provide two images, one from each perspective. All you have to do is replace 'vacuum lift' with 'low pressure air' and 'planing lift' with angle of attack and you're explaining, to us, the principles of flight. 'The air rushes back to meet...' yes, this is basically what high/low pressure flow is and what Bernoulli's observations cover. You've explained, using a different set of words and a different perspective on the situation, to describe the exact same phenomena. My thoughts on the matter. I'm open to hearing your replies.

[@sluffnut7507]

The behavior of the airflow over the wing shouldn't be fundamentally different in free flight vs in a wind tunnel. The fact that the air or wing is stationary relative to the ground makes no difference when we are describing air flowing over a foil. It's only a question of the relative velocity of each element. Defining one element as stationary is just a matter of defining your reference frame.

[@Airsails]

Nothing new here. Swept flying wings have been around for a long time. The reason conventional aircraft have tails is for stability. Thankfully most people realize it is not wise to sacrifice stability.

[@froqstar]

This is not about swept flying wings, this is about not requiring vertical surfaces.

[@cowboybob7093]

Control is the key, not stability. Empennage has an "elevator" that elevates the nose for climbing by pushing the tail down. Empennage has a "rudder" that steers the fact that the wings are not covered in nerves connected directly to the pilot's brain to fire tiny muscles that use hundreds of feathers to make constant adjustments - The adjustments are _CONTROL_