Aero-TV: NASA's Prandtl-D Project - Preliminary Research Design to Lower Drag

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CAUTION: Everything You Thought You Knew About Aerodynamics Is About To Be Tested...
When ANN CEO and Editor-In-Chief, Jim Campbell, attended the AMA Expo 2016, he probably never expected to get a lesson on advanced aerodynamics at a show that featured recreational radio controlled airplanes. However, he learned some amazing things about new aerodynamic research and is sharing it with you in this video.
Jim visited with, Albion Bowers, who is the Chief Scientist at NASA Armstrong. Among other things, Bowers is working on a program titled, ‘Preliminary Research Aerodynamic Design to Lower Drag.’ It’s called the PRANDTL project and is named after a researcher who started a search for aerodynamic solutions in the 1920s and 30s.
The project has set its sights on determining the minimum induced drag for a wing, and a key part of the research is being performed by radio controlled model aircraft.
During the video you’ll hear a fascinating discussion of advanced aerodynamics while watching video clips of NASA flying their research model aircraft. This video is much more than the story of the model aircraft; it’s a fascinating review of advanced aerodynamics. Try this for example, “Yaw becomes propulsive and you don’t need rudder pedals.” It’s also pointed out that birds don’t have a spin problem, and the same principle can be applied to airplanes.
Anyone who is interested in the research of advanced aerodynamics must watch this video.
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FMI: www.airbornetv.net, www.aero-news.net, www.aero-tv.net, / aerotvnetwork , vimeo.com/aerotvnetwork, / aeronews , www.nasa.gov/centers/armstrong...

Опубликовано:

4 фев 2016

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Комментарии : 59

@matthewallen3375 Год назад

Al is SO energized talking about this Incredible project. I have built this from Simple Dollar Tree Foam, and can't wait to learn more. Thank you Al for finding a way to test these 90 yr old, nearly forgotten theory, despite the limited support.

@kenwebster5053 5 лет назад

Hi, I designed and built am 8' span RC flying wing sailplane in about 1978 and it flew pretty well. I didn't know any aero maths then but had build modified and designed model aircraft from a young age so was familiar with the basics of flight. For that model, I just built a series of smaller free flight models to find the minimum reflex required for stability before designing the larger RC version. One of those FF models flew out of sight and was never recovered. I chose a cambered profile and the root was not reflexed, the wing was swept and the tip chord was 60% of the root and reflexed from about 75% chord, the nose, mean chord reflex point and trailing edge being is a straight line and the profile transitioning linearly from root to tip. Since then, I got a 2nd place in LSF Australia with a different modified model and later I studied Martin Simmins model aircraft aerodynamics and wrote a program to predict the performance of RC sailplains of different sizes, profiles and aspect ratios. But this was a hobby and life got busy with family after this. I became aware or Ludwig Prandtl and the Horton Brothers and their bell shaped lift curve, but have been unable to find the maths for this. I have seen plan form and spanwise lift distribution diagrams in texts which, assuming the wing is untwisted seem to suggest that the local Cl can be expressed as = elliptical chord / local chord x mean Cl. This seems way too simple an expression to be true but I have not been able to find any resources that go into this. It seems to me, there must be a way to model the spanwise lift distribution but I am highly suspicious of my expression above. Can you please point me in the right direction on this and on how to model the bell shaped lift curve? I have seen diagrams of the bell curve but not actual values or expressions. I'd be very grateful for your assistance and hope my maths is up to it still, I did calculus in both high school, and in my cartographic course and continued to use some higher maths as an analyst programmer in the GIS industry, retired now though. I suppose I am too old now to do much with it but I have been curious about these things a long time and would very much like to learn more on it. Thanks, Ken

@TheJustinJ 3 года назад

Basically, just make the wingtip produce zero lift inboard of the tip and slightly negetive lift betweent aht point and the tip where lift becomes zero again. It's the same concept as an elliptical distribution, but twist the wing more before it reached the tip, and reflex the tip slightly (reduce washout slightly) as it appreoches the tip and calculate with the lifting line theory from there to get the bell shaped curve. This works by making the lifting portion of the wing sort of truncated inboard of the tip. Lift. Creates downwash, and zero lift creates no downwash. So the wing is producing downwash along it's span until the point inboard of the tip where the lift goes to zero and then slightly negetive out to the tip. The outboard portion produces no lift and therefore no downwash. This means that the wingtips trailing vortices as normally seem, actually eminates from the point inboard of the wingtip where lift goes to zero or negetive. The trailing tip vortices now trails from a point inboard of the tip. So when it tries to roll up and over to spill onto the top surface, there is a zero loaded portion of wingtip right there to stop it and gain back some additional lift from it. It happens that the additional lift when properly implemented becomes a forward thrust (using the air pressure under the wing that's rolling up as a vortices at the tip). The calculation to get this right is probably quite involved. It will also mean your wing needs to be larger because the outboard portion makes no lift, therefore invreasing the inboard wing loadong. And It will probably be a trade secret for a while.

@nissimnave 8 лет назад

so much passion!! great content!

@BALAZSER1 6 лет назад

My first plane I built over 15 years ago was a Zagi XT flying wing. I still have it, and occasionally fly it. I love flying wings !! Thank you guys!!!

@Krzemieniewski1 3 года назад

Cool videos on your channel with those flying wing.

@romanovrex 5 лет назад

This is very welcome, thank you.

@efox2001 8 лет назад

Excellent video, please, do interview him again!

@Dionm01 8 лет назад

Shakers, movers and disruptors, I like it. I like what he said as an Lehman, I don't understand very much in what he said to be honest, but that's OK. We need more people like him to shake the industry which in turn makes the industry better for the future. Great job Jim in finding him. Dion

@pfurtado1 6 лет назад

Thank you for this fantastic lecture on the future and your enthusiasm for nature perfect lessons on efficiency.

@israelcamdyn3520 3 года назад

instablaster...

@markhuebner7580 3 года назад

Thanks! Great video hinting at the benefits of applying Prandtl's equations. Where are those applications of the equations documented? Thanks for the great video!

@bartofilms 6 лет назад

This is great information. A few years back I saw an experimental model like this but with a lazy Susan engine pod at top center.. The wing is diamond shaped, not swept. It would rotate in flight to flly end-wise. So wing tip becomes the nose. This would be for super-sonic , high altitude flight. If this is possible it could change air travel completely.

@lasensaciondel3d568 5 лет назад

I love his passion great men great hobby is honor

@aaindtharivalan8720 Год назад

How much angle of dihedral did it require. Couldn't help noticing the dihedral at the center.

@the1realanalogman 8 лет назад

Outstanding! Looking at the extreme taper, it gives the "impression" that tip stalling would make it a hand full to manage. Not sure how much control input was occurring, but it looked rock-solid! Love to see a powered version!

@rong-jiechew1565 9 месяцев назад

Anyone have have reading on the 'winglets produce thrust' part at 2:50? Sounds interesting but I do not fully understand.

@robohippy 3 года назад

I got out of hang gliding about the time the first double surfaced models came out. That was about 85 or so. The design you have here is almost identical to what they developed back then.

@ericoschmitt 9 месяцев назад

in aerodynamics, the devil sits on the details.

@5c0u53 3 года назад

Not sure i understand this, what make it different than the multitude of 'flying wings' we've been flying RC for years ?

@timelord-zj8qd 2 года назад

wait a minute how come THRUST generates at the flat winglets?

@Dryle3583 4 года назад

I think aerodynamicly correctness is a plus when you are trying to acomplish a goal, and to correct aerodynamicly speaking you need a test which means a million dollar wind tunnel!!!

@RPMoto 4 года назад

So this is a fancy version of the Zagi

@philipdow9862 4 года назад

Where can I find a plan for a small RC version

@ericoschmitt 4 года назад

I wish I could get those plans as well!

@edwinator46 Год назад

you can buy a kit

@Wemdiculous Год назад

I don’t understand the limitations for wingspans at airports… Just park it sideways at the terminal, 🎉 now you can fit 5 times more planes at your terminals because their length is so short it’s inconsequential compared to the width of 727’s

@DaylightDigital 5 лет назад

Really annoyed that I can't find the 1932 paper... :-(

@mohanpannirselvam4102 4 года назад

www.ornithopter.de/daten/prandtl.pdf

@andrewilijic9563 4 года назад

Here is the more recent paper, it’s pretty readable. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf

@sdknstar601 6 лет назад

is that ArduPilotMega??....so that's mean GCS is Mission Planner....am i right?...

@amanieux 5 лет назад

i don't get it why this focus on wingspan ? why can't you just design a longer wing that folds ? the extra weight for the hinges can surely be compensated by the higher efficiency in flight.

@benthurber5363 5 лет назад

Cost and complexity. Or he might just be overthinking it. A lot of what he's talking about in presentations is the constraint of span vs mass. But, yes, the wingtip on his model isn't really producing lift, so maybe folding would be favorable. I believe the 777 just got approved for folding wingtips and it doesn't use this wing. But, even then, with the increase in point-to-point airline travel, that size is actually pretty favorable. Greatly increased range and fuel economy for a given mass would change 'everything'.

@utuberlesmouches 7 лет назад

Read "Nurflugel" !

@TiborBerki 4 года назад

Read it! It's all in there...

@FlyMIfYouGotM 6 лет назад

This guy is about as excited as a little kid in a candy store! No doubt all those interns loved working with him, I know I would have.

@gabedarrett1301 4 года назад

I'm still confused as to how the ailerons contribute to yaw

@danbenson7587 3 года назад

To roll the wing up, the lift on that side is increased. Increasing lift increases drag. So the plane yaws to that direction. This countered by rudder. For 70years adverse yaw has been addressed. The most common fix is differential Ailerons: the rising wing aileron goes down 1\3 and the descending wing aileron goes up 2/3s. So most of the roll power is from the descending wing. There are other methods. Bowers arguments may have benefit for long wings, but 50% improvement? Besides, planes fly straight way more than turning. It’s all compromises. Cheers

@SladkaPritomnost 8 лет назад

Why swept wing and not plank? Isn't swept a more draggy problem than plank? Most birds don't have swept wings even albatross doesnt.

@discotechwreck 8 лет назад

+SladkaPritomnost Commercial airliners are designed for high altitude, high speed flight where swept wing designs are most efficient. Most Albatrosses don't cruise at 900 km/h ;)

@Traqr 8 лет назад

A swept wing is inherently stable in roll because a slip sideways causes the "forwards" wing to present a greater frontal area than the "trailing" wing. Birds have nervous systems that allow them to stay on track; it's still easier to build dihedral and sweep into a wing than computerized "active" stability. Besides, inherent stability allows them to isolate the aerodynamics they're trying to test & demonstrate. If they had computers flying it, they wouldn't know for sure whether the dynamics were due to design or programming.

@peachtrees27 8 лет назад

desperately trying to understand this... ugh!

@thlement7626 6 лет назад

This is how I see it: By having a 'bell-shaped' spanwise lift distribution, you can get up-wash instead of down-wash near the wing tip. This increases the effective angle of attack near the tip. If the angle is large enough, the wing tip can actually generate thrust, similar to how sailboats can sail into the wind. How is it beneficial? Normally, the pilot will need to use the rudder to counteract the adverse yaw when performing a turn. Now, the adverse yaw can be balanced by the yawing moment generated by the wing tip. Thus, eliminating the need for a rudder.

@PieterSadie 3 года назад

Instead of having to create drag on the wing tip like the B2 bomber to induce turns, this wing tip creates thrust, so only does it initiate turns, it counteracts yaw. You will see that the wings are twisted at the wingtips in order to create this effect. This effectectively eliminates the need for a tail fin.

@jeancarton1611 7 лет назад

again nasa is reinventing the wheel!!

@larrynla 5 лет назад

True in a way. This part of NASA resurrected a long-ignored study by Ludwig Prandtl. So you are wrong. They rediscovered the wheel rather than reinvented it, which is the kind of thing NASA should be doing instead of competing with commercial aviation companies.

@timelord-zj8qd 2 года назад

arent't hang gliers use this theory for 40 years now?

@Alistratov1971 2 года назад

Как здорово,когда есть настоящие увлечённые инженеры...А у нас все вымерли:(

@joereyes8835 5 лет назад

It couse my attention and I do like at first what he was saying about this design, But when he mentions Mars and what he would like to do at 12000 feet with this plane, he lost me First thing came to my mind, Atmosphere, is there air in Mars? What is the atmosphere like in mars? So keep dreaming about Mars that I keep flying around in my earth.

@Dryle3583 4 года назад

Because your a past particple and thats your money not anyone elses

@herks3842 8 лет назад

Been talking about it for two years, but can't seem to publish any hard data. Seems more like a publicity strategy than actual science. Can't see much different from what the Hortens did 70 years ago. Still waiting for a report ???????

@SimpleKeep 7 лет назад

He has released his research paper including the relevant equations and wing twist distribution. On Wings of the Minimum Induced Drag Spanload Implications for Aircraft and Birds: ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20160003578.pdf

@mithrandir1313 7 лет назад

The loss of laminar flow due to sweep ain't worth the theoretical improvement!.. also... "Proverse Yaw" is simply the drag increasing on the correct side with aileron input rather than the incorrect side..... I will become a believer when I see a successful sailplane with this configuration!!

@Phos9 6 лет назад

ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-xnlJpziK75k.html You do actually have a reduction of drag because the wing tips are actually creating slight downforce when the ailerons are at neutral. Making downforce might seem like a red flag, but if my understanding is correct, it causes reduced vorticity and the induced drag is less than if you were creating the lift and downforce separately. I think the downwash from the aileron being deflected downwards is actually making thrust against the wing vortex, which is further inboard than a conventional wing.