planemaker
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1st Aircraft To "synergize" 6 Six Aero Principles

Sun May 20, 2012 9:11 pm

http://a4.sphotos.ak.fbcdn.net/hphotos-ak-ash4/225299_10150229381128623_192081688622_8735631_35004_n.jpg
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The "Synergy" aircraft design was unveiled last April at the CAFE symposium (EAS V) as well as at Oshkosh. It recently was in the news because they are now on Kickstarter to help complete the prototype.
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http://synergyaircraft.com/images/imgRendering3.jpg
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What is truly unique about this aircraft is that it integrates 6 proven aeronautical principles for the first time and "achieves both high speed and low induced drag in a structurally robust, lightweight form"....

Quote:
Synergy aircraft is the first example of an exciting new technology for fast, roomy, fuel efficient airplanes. Harmonizing six proven technologies for drag reduction at low cost, including:
  • Laminar flow
  • Non-planar configuration
  • Wake-immersed propulsion
  • Open thermodynamic cycle
  • Pressure thrust
  • Optimum volumetric displacement waveform

They already have a 1/4 scale flying model (and are building a prototype, hence Kickstarter)...

http://synergyaircraft.com/images/imgModel10.jpg

http://synergyaircraft.com/images/imgModel4.jpg

The Synergy website has all the detailed technical information and links to presentations...

http://synergyaircraft.com/index.html
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GST
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue May 22, 2012 7:37 am

Been following it for a year or more now, an extremely interesting project and I wish them luck. It doesn't seem to be going very fast, but such is light aircraft development with small teams.
 
aerodog
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue May 22, 2012 4:25 pm

Designs like this have shortcomings as well:

Short coupling, stability problems, spin recovery.

Small diameter inefficient propeller.

And pushers lack propwash over the elevators to help rotate the nose on short fields.
 
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue May 22, 2012 4:51 pm

Quoting aerodog (Reply 2):
Designs like this have shortcomings as well:

This is not a box-wing design but a double box tail design... very different distinction. That with the synergistic integration of the 6 aero principles listed minimize shortcomings while providing significantly greater advantages than any other 5 place aircraft on the market.
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PPVRA
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue May 22, 2012 10:53 pm

Only thing I wonder about is the single piloting position. In case of incapacitation, it's gonna be a handful getting the guy out of there, assuming it's even possible.
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planemaker
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue May 22, 2012 11:05 pm

Quoting PPVRA (Reply 4):
Only thing I wonder about is the single piloting position. In case of incapacitation, it's gonna be a handful getting the guy out of there, assuming it's even possible.

That's true... but what are the odds of having two pilots on board when one of them is instantly incapacitated? In any case, I noticed that on their Kickstarter page they make indirect reference to a possible solution...

Quote:
We think that in addition to all the best new technology, airplanes should provide, at a minimum:...
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planemaker
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue May 22, 2012 11:22 pm

Quoting PPVRA (Reply 4):
Only thing I wonder about is the single piloting position.

Sorry, didn't include this in previous reply but I just read this question (did you ask it?   ) in the FAQ on the Kickstarter website...

Quote:
Can there be more than one pilot? I think people would feel safer if there was side-by-side seating.

Yes! We keep forgetting to say so, as many are already familiar with the seating arrangement advantages of Synergy.

There are actually THREE places where we can fly the airplane.There is side by side pilot-copilot seating, with a choice of control configuration, right behind the front seat. "Solo" can only be flown from up front, but "dual" can be flown side-by-side OR tandem.

You can also have one instructor with two students, or a VIP passenger up front. (It's hard to tell the first side-by-side seats are pilot locations because the back instrument pylon isn't visible yet and the controls attach to the wing center section, still being built.)

In the event of an emergency, we intend for all passengers to have access to the new VP-400 system from Vertical Power, which is a new technology to safely and automatically put the airplane on the safest available runway simply by "pushing the Runway Seeker button." Even if that's not looking too good for some reason, a pull of the "big red handle" will deploy the ballistic airframe parachute.

Many other safety features are designed right into this aircraft from the conceptual level onward, including outstanding low speed handling.


[Edited 2012-05-22 16:24:11]
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Wed May 23, 2012 12:11 am

Welly, welly, welly, welly, welly, welly, well.

Quoting planemaker (Reply 5):
That's true... but what are the odds of having two pilots on board when one of them is instantly incapacitated? In any case, I noticed that on their Kickstarter page they make indirect reference to a possible solution...

You've pried open the gates of hell. 

But I'll refrain from a VP-400 debate in this thread, but I think your agenda is now clear. Clear as an unmuddied lake. As clear as an azure sky of deepest summer...


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tdscanuck
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Wed May 23, 2012 3:40 am

Quoting planemaker (Reply 6):
In the event of an emergency, we intend for all passengers to have access to the new VP-400 system from Vertical Power

Holy mother of...shields up!

For those who missed this debacle, I strongly suggest reading this thread (including the final closing post from the mods) before dragging the VP-400 into this thread:
New Emergency System That Flies Airplane To Runway (by planemaker May 3 2012 in Civil Aviation)

Tom.
 
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Wed May 23, 2012 5:26 am

Quoting tdscanuck (Reply 8):
Holy mother of...shields up!

I honestly didn't know about it until PPVRA asked his question and then I went through the website in more detail. Anyhow, that shouldn't be discussed here as what is really unique is the use of all the aero principles in one "package" to achieve a leap in performance. There is a detailed discussion (17 pages) in the EAA Oshkosh 365 forum thread started by the designer of the Synergy, John McGinnis. Here is his opening post:

Beyond Streamlining: Drag reduction in the 21st century

http://www.oshkosh365.org/userimages/37433/8f96621d-a56a-4c0d-8180-69b2e489da17.jpg

Quote:
This post is nerd candy; a lure for attracting some of our lunker aerodynamicists to the surface. Among the shocking but true insights to be discussed is the one most responsible for a half century of stagnation in drag reduction:

It takes HALF the power to fly at a given speed if the energy is used differently.

Early on it was decided that since the thrust required for level flight equals the drag, obviously the power needed should be that required to make that much thrust.

Not true.

We fly by moving air; usually, far more of it than necessary. If power is used partially to overcome drag and partially to make thrust, we double our efficiency. Less power= less weight=less fuel=less structure=less weight=less fuel=less structure...

Everyone likes to talk about how hard, complicated, and expensive this is. They base this conclusion on old tests in which it was complicated and expensive to apply to jets at 600MPH.

In fact, it's quite simple and easy. A little disruptive, I'd agree. But we spend far more time and effort on things that won't make one percent as much difference.

Let's talk here about some of the proven drag reduction technologies that we're not using. Since the object is to apply these things to new solutions, rather than continue to fail in their application to old airframes, please pretend that we are back in the 30's, 40's. and 50's, and that anything is possible.

Because it still is.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 1:40 am

Quoting tdscanuck (Reply 8):
Holy mother of...shields up!

This is not to bring up the "unmentionable" but merely to inform that the Wichita Biz Journal had an article about the talk that the vice president of Garmin gave at Tuesday's Wichita Aero Club meeting.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 5:04 am

Looks like something Santos Dumont would have built.
 
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 5:31 am

While a neat concept, there are a few details I'm missing:
1. Ruder control. Does the full up model have a rudder (more likely pair of rudders)? I've flown RC aircraft without using the rudder, but oh boy would lacking that feature make crosswind landing interesting.
2. What are the stall characteristics? I see the lack of prop-wash over control surfaces making recovery tough for a novice pilot.
3. What is the plane's projected speed? Fast doesn't tell me anything...
4. What is the plane's projected range?

Quoting tdscanuck (Reply 8):
For those who missed this debacle, I strongly suggest reading this thread (including the final closing post from the mods) before dragging the VP-400 into this thread:

I find that topic very interesting, but since the last topic went so far off thread (and became nasty), it might be left out of the loop for discussion. However, I do wonder if the VP-400 might become required for insurance... just a thought.

Lightsaber
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planemaker
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 7:36 am

Quoting lightsaber (Reply 12):
While a neat concept, there are a few details I'm missing:

Yes, very neat indeed! I've been following progress since they went public and the whole design is really impressive. This could really change general aviation... which is no small thing. It is good to see that are very close to reaching their Kickstarter target with 10 days to go.

Don't hesitate to fire away with any questions... I'll try to find the answers.

Quoting lightsaber (Reply 12):
1. Ruder control. Does the full up model have a rudder (more likely pair of rudders)? I've flown RC aircraft without using the rudder, but oh boy would lacking that feature make crosswind landing interesting.

There are rudder pedals (quite an original design) that control the twin "V-tail " rudders, steerable nose wheel and differential brakes.

http://a2.sphotos.ak.fbcdn.net/hphotos-ak-ash4/423302_3062034708063_1179309664_32432224_1342255093_n.jpg

Quoting lightsaber (Reply 12):
2. What are the stall characteristics? I see the lack of prop-wash over control surfaces making recovery tough for a novice pilot.

I read that stall characteristics are very benign... similar to a canard, and the aircraft is designed to be incapable of unintentional stalls and won't spin. Synergy has the "glider-like efficiency of a 46-foot wingspan packed into a much stronger 32-foot package". And the Synergy uses "flying" elevons on the box tails which require very little travel for control.

The large elevons (and the rudders) are visible in these line drawings.

http://synergyaircraft.com/images/imgIllustration.jpg

http://synergyaircraft.com/images/imgIllustration2.jpg

Quoting lightsaber (Reply 12):
3. What is the plane's projected speed? Fast doesn't tell me anything...

The designer isn't publishing any specific performance claims as he is anxious not to over-hype the aircraft. He realizes that many people will be skeptical until the prototype is flying. So, until flight testing confirms their projections they are not releasing any numbers.

Quoting lightsaber (Reply 12):
4. What is the plane's projected range?

Not published but I did read on one of the EAA forums that it had been estimated (a year ago) at over 1500 nm w/ std. reserves.

Quoting lightsaber (Reply 12):
I find that topic very interesting,

So does Garmin.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 11:03 am

According to the thread title this is the first aircraft to synergise six aero principles. Forgive me, but aircraft designers have been successfully synergising multiple aero principles since the Wright Brothers. It's an interesting aircraft design, but the Synergy website linked from Kickstarter promotes these "principles" as a sales pitch, rather as you might list the new design features of the latest BMW. There's almost no technical presentation.

No attempt is made to describe what these "principles" are. Some are well known, though the benefits aren't explained for the uninitiated. But what is the "open thermodynamics" principle? Why is putting the (very small) propulsor in a turbulent wake more efficient?

The success of the concept hinges on empirical results showing the claimed benefits exist. CFD and tunnel testing have been dismissed as not useful (or perhaps too expensive). An archived Oshkosh forum is cited in several places as a reference. Surely rather than expect his potential investors to read an archived discussion, the designer should repeat the key posts in a way which makes engineering sense, rather than use aeronautical rhetoric.

One sentence in one paragraph in the designer's opening Oshkosh post post, also quoted above by the OP, sums this up for me.

Quoting planemaker (Reply 9):
Quoting John McGinnis:
If power is used partially to overcome drag and partially to make thrust, we double our efficiency.

Meaningless.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 11:17 am

Quoting Jetlagged (Reply 14):

I totally agree, there is nothing to tell you really to back up their claims and the wind tunnel part is rather strange, wind tunnels are the perfect place to validate these things but as you say are very expesive to use. There seems to have been a lot of these small aero statups promising very similar things and with "wacky" designs that seem to die a death when they overlook something and run out of money. I wish them the very best but I won't be shocked if they aren't playing the skies in 10 years.

Quoting planemaker (Reply 13):
Not published but I did read on one of the EAA forums that it had been estimated (a year ago) at over 1500 nm w/ std. reserves.

1500nm is far too much (Assuming it does around150-180kts) you can't plan a flight that long as pee stops need to be accounted for.

Fred
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 4:37 pm

Quoting Jetlagged (Reply 14):
Forgive me, but aircraft designers have been successfully synergising multiple aero principles since the Wright Brothers.

What is unique about this project is that the 6 listed aero principles have never been integrated before... even though the principles are well proven, and results in really impressive drag reduction.

Quoting Jetlagged (Reply 14):
There's almost no technical presentation.

You are correct... there isn't a lot of technical details at this point for a few reasons.

First, until Kickstarter, virtually no one outside of the EAA knew about Synergy... and the designer was fine with that. Second, since the designer was not looking for any money... not via selling anything nor via investors, the web site was really more of a project status site than anything else. Third, the designer has patent pending on the design and after the many years he and his family have put into this project is justifiably leery in publishing technical details. Fourth, the designer is a very modest man in all sense of the word and is very reluctant to over hype the performance capabilities... he believes that the "proof is in the pudding" and that is why he is pushing via Kickstarter to be able to finish the demonstrator prototype so that he can have it at center stage next year at Oshkosh.

Now, having said all of the above, there is still a heck of a lot of technical information available in these videos for those that don't have the time or inclination to wade through the lengthy Oshkosk forum...

Synergy OSH 11 pt1
Synergy OSH 11 pt2
Synergy OSH 11 pt3
Synergy OSH 11 pt4
Synergy OSH 11 pt4B
Synergy OSH 11 pt5

Quoting Jetlagged (Reply 14):
The success of the concept hinges on empirical results showing the claimed benefits exist.

The designer totally agrees with you. However, the 1/4 scale flying prototype has provided data that has proved that the claimed benefits will be achieved in the full scale technology demonstrator.

Quoting Jetlagged (Reply 14):
Surely rather than expect his potential investors to read an archived discussion, the designer should repeat the key posts in a way which makes engineering sense, rather than use aeronautical rhetoric.

In addition to the response I gave above, it should be made very clear that John McGinnis (the designer) was not looking for any investors, potential or otherwise until the Kickstarter campaign (BTW, they originally turned him down because they felt that the project was "too technical" and Kickstarter really promotes more "artsy" projects - though I think that Synergy is a great piece of art!) With that kind of Kickstarter audience in mind (few having aero knowledge, if any at all) there is naturally a more conceptual message transmitted. That is why, for example, there is this picture on the Synergy website that makes some of the prinicples more accessible...
Quoting Jetlagged (Reply 14):
One sentence in one paragraph in the designer's opening Oshkosh post post, also quoted above by the OP, sums this up for me.

Quoting planemaker (Reply 9):
Quoting John McGinnis:
If power is used partially to overcome drag and partially to make thrust, we double our efficiency.

I don't blame you for not wading through the 17 pages of the Oshkosh forum but he does address all of the principles in detail, in addition to general and conventional approaches to aerodynamics. This is from the second page which gives a taste of the kinds of things that makes most people's eyes glaze over... 
Quote:
First thing we learn in aerodynamics is that there are four fundamental forces of flight: Thrust, lift, drag, and gravity. In steady level flight, thrust = drag and lift = weight. This statement is almost completely responsible for a frame of mind and a frame of reference that guarantees a poor result when dealing with viscous fluids. We may not fully understand why for quite a long time, but it will become perfectly clear in the future.

There are only TWO fundamental forces of flight: Gravity, and viscous fluid inertia. Because low viscosity fluids swirl when pushed upon, drag, lift, and thrust become interchangeable and quite inseparable, even when we design for one or the other. We use four representative vectors for easy bookkeeping, and I'm not arguing to toss the math (yet), but the fact is that most aircraft are designed as if lift was lift, and drag was drag. It isn't for long.

As the aircraft drags previously stationary air along with it, the air swirls. As the plane pushes an air mass downward, which it must do in order to fly, air swirls in to take its place. Responding insightfully to these behaviors can create lift with surfaces that are not wings, and reduce drag with surfaces that add greatly to the aircraft wetted area. Future planes even create LIFT by pushing the aircraft down!

I'll be posting a brief intro to the implications of the Gabrielli-von Karman limit shortly. What it shows is that we've only been effective in designing efficient aircraft with long wingspan (gliders under 100 mph) and with large commercial jets (over 400 mph).

The reason we have failed to reach achievable high L/D at useful speeds under 400 mph is due to ignoring the critical influence of low viscosity. Going fast enough renders the air a near-solid, going slowly allows weaker structures of high aspect ratio.

Winglets opened the modern exploration of non-planar wing design, a technology acting in harmony with viscosity in three or four dimensions. (Biplanes and various flavors of polyhedral did so long ago.) Winglets can provide a high span efficiency by acting against the high velocity swirl at wingtips. Optimizations reveal that winglets are most effective after a span limit has been reached. Yet while span extension will deliver the most drag reduction, it is at the expense of structure suitable for higher speeds. Creating thrust with a winglet is generally sub-optimal.

A tall winglet, located to also provide lateral directional stability, provides very high span efficiency, which is one of the major advantages to Rutan derivative canards
Quoting flipdewaf (Reply 15):
I totally agree, there is nothing to tell you really to back up their claims and the wind tunnel part is rather strange, wind tunnels are the perfect place to validate these things but as you say are very expesive to use. There seems to have been a lot of these small aero statups promising very similar things and with "wacky" designs that seem to die a death when they overlook something and run out of money.

You have to keep in mind that the principles are well established... he doesn't have to prove them. He is just using... harmonizing all of them for the first time in a single design. Now what he intends on doing is to "prove" the integrated design in the full scale technology demonstrator... which he has already "proved" in the 1/4 scale flying model.

Quoting flipdewaf (Reply 15):
1500nm is far too much (Assuming it does around150-180kts) you can't plan a flight that long as pee stops need to be accounted for.

It gives an indication of the specs. Of course, unless you have a strong bladder (or pee bottle) you probably are not going to try to fly that distance all in one go.  
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu May 24, 2012 10:43 pm

Quoting Jetlagged (Reply 14):
According to the thread title this is the first aircraft to synergise six aero principles. Forgive me, but aircraft designers have been successfully synergising multiple aero principles since the Wright Brothers.

I think the point was that this aircraft was the first to put these six particular princples together onto the same airframe.

Quoting Jetlagged (Reply 14):
But what is the "open thermodynamics" principle?

I'm curious about that too...all modern aircraft use the Brayton, Otto, or Diesel cycles, and those are all open cycles.

Quoting Jetlagged (Reply 14):
One sentence in one paragraph in the designer's opening Oshkosh post post, also quoted above by the OP, sums this up for me.

Quoting John McGinnis:
If power is used partially to overcome drag and partially to make thrust, we double our efficiency.

It's not as bad as it sounds...he's just talking about active flow control, which has been around for a long time and is well established in principle (harder to implement in practice).

Tom.
 
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Fri May 25, 2012 7:12 am

Quoting tdscanuck (Reply 17):
I think the point was that this aircraft was the first to put these six particular princples together onto the same airframe.

That is correct... its never been done before.

Quoting tdscanuck (Reply 17):
Quoting Jetlagged (Reply 14):
But what is the "open thermodynamics" principle?

I'm curious about that too

John McGinnis' explanation from the Oskosh forum...

Quote:
I had meant to address the topic of open thermodynamics quite some time ago, along with some of your other observations. It's not my language or term, and it has nothing to do with heat of the engine or cooling. Open thermodynamics refers in the physical literature to the use of an energy source to change, offset, or overcome the properties of an otherwise closed energetic system. Applied to aerodynamics, it merely refers to the various ways that experimenters like Raspet and Goldschmied successfully showed that the dynamic pressure concept that we use throughout our (closed) system of modeling reality is a simplified and incorrect mathematical construct, not the exact, true physics of fluid reaction.

For example, if a six-horsepower boundary layer control fan causes the performance of a 100 horsepower thrust increase, we are dealing with an open thermodynamic system, and the bookkeeping of the various components of the result will drive people nuts.

The consequence of using our familiar closed thermodynamic system of calculation is of very little impact unless we forget it is closed system, as we collectively have. When we forget that a proven 'better way' to use a given amount of energy is inherently at odds with our our prior way of figuring things, we still tend to rely on the familiar methods even when they lie to us.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Fri May 25, 2012 1:50 pm

Quoting planemaker (Reply 18):
John McGinnis' explanation from the Oskosh forum...

His explanation does not give me confidence...quite the opposite. *That* explanation sounds dangerously close to some other scientific hokum out there. He's absolutely right that you can use, say a 6 HP flow control fan to lower the thrust requirements of some other component (nothing new or controversial there) but that's *not* an "open thermodynamic cycle" by any definition I've ever heard of.

Furthermore, aerodynamics engineers aren't idiots...they understand what flow control is and how to book keep it. They don't think that airplanes are a closed system. I'm not sure this is really any new idea, and certainly not any kind of new physics, like he seems to be suggesting.

Tom.
 
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Fri May 25, 2012 9:14 pm

Quoting tdscanuck (Reply 19):
but that's *not* an "open thermodynamic cycle" by any definition I've ever heard of.

He states: "it has nothing to do with heat of the engine or cooling" and it appears from your statement, "all modern aircraft use the Brayton, Otto, or Diesel cycles", that your notion was in the engine realm of thermodynamics.

He also very clearly states: "It's not my language or term". A quick search brought up a NASA document (and Goldschmied, which McGinnis talks of, is in the references). There are several others documents.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Sat May 26, 2012 3:27 pm

Quoting planemaker (Reply 16):
The designer totally agrees with you. However, the 1/4 scale flying prototype has provided data that has proved that the claimed benefits will be achieved in the full scale technology demonstrator.

Obviously he's going to agree with his own idea. Don't make it sound like I agree with him. CFD may be beyond his budget but he's ignoring wind tunnel testing which should show some or all of the benefits he talks about. That makes me suspicious of the extent of his claims.

He says it's designed to give "ten times the fuel economy of a small jet at ten percent of the cost". Small jets aren't particulary efficient for such GA aircraft, so perhaps the target isn't that hard to achieve, but how can this vague claim possibly be verified?

Quoting planemaker (Reply 16):
With that kind of Kickstarter audience in mind (few having aero knowledge, if any at all) there is naturally a more conceptual message transmitted. That is why, for example, there is this picture on the Synergy website that makes some of the prinicples more accessible..

Clearly the Synergy website is a promotional exercise. It's written in clear marketing terms. If it was merely a status upate it wouldn't need the hogwash and rhetoric. The picture you refer to puzzled me but I didn't mention it. It tells an aerodynamicist nothing and a layman wouldn't know enough about tip vortices to get anything from it. It doesn't help the understanding of the non-planar wing at all.

Quoting planemaker (Reply 16):
I don't blame you for not wading through the 17 pages of the Oshkosh forum but he does address all of the principles in detail, in addition to general and conventional approaches to aerodynamics. This is from the second page which gives a taste of the kinds of things that makes most people's eyes glaze over

This is Tech/Ops, people don't glaze over at detail, but expecting anyone to wade through 17 pages of posts to find the pearls of wisdom is asking too much. The post you quote is still extremely general, and does not cover the open thermodynamics "principle". It also talks about biplanes and polyhedrals acting in harmony with viscosity years ago. Apart from biplane interference (which reduces lift) the main interaction with the air was increased drag. Polyhedrals, apart from a few triplanes, were never successful.

You seem very close to the project, given the way you promoted it and now defend it in this thread.

Quoting tdscanuck (Reply 17):
I think the point was that this aircraft was the first to put these six particular princples together onto the same airframe.

Of course, but it's written as if it's some kind of breakthrough. To be fair it's the thread title which makes more of it than the websites the OP linked to.

Quoting tdscanuck (Reply 17):
It's not as bad as it sounds...he's just talking about active flow control, which has been around for a long time and is well established in principle (harder to implement in practice).

I got the meaning, it's just the way he glibly claims double the efficiency as a result.

[Edited 2012-05-26 08:33:25]
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Sat May 26, 2012 7:45 pm

Quoting Jetlagged (Reply 21):
CFD may be beyond his budget but he's ignoring wind tunnel testing which should show some or all of the benefits he talks about. That makes me suspicious of the extent of his claims.

IMHO I would consider giving more credit to the aircraft design qualifications/experience and the 30 years of investigation that McGinnis has put into drag reduction research and design:

"For technical reasons, CFD software and wind tunnels don't really cut it at this level. But over the last year, serious students of aerodynamics, all over the world, have begun to realize that Synergy affects everything we know."

Quoting Jetlagged (Reply 21):
The picture you refer to puzzled me but I didn't mention it. It tells an aerodynamicist nothing and a layman wouldn't know enough about tip vortices to get anything from it. It doesn't help the understanding of the non-planar wing at all.

What it obvious to an aerodynamicist is that "Synergy" is 1) a "double box tail" and not a "box wing" aircraft and 2) that the wing tip vortices are being used to "synergistically" add to elevon down force.

Quoting Jetlagged (Reply 21):
This is Tech/Ops, people don't glaze over at detail, but expecting anyone to wade through 17 pages of posts to find the pearls of wisdom is asking too much.

It isn't too much if one is genuinely interested or curious. In any case, I posted the links to McGinnis' Oshkosh videos that "spoon feeds" the viewer the information.

Quoting Jetlagged (Reply 21):
Of course, but it's written as if it's some kind of breakthrough.

It is a breakthrough... no one has been able to "implement before" the 6 well established drag reduction principles all at once.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Sun May 27, 2012 3:53 pm

Reply #9 shows a picture of an ideal fuselage shape in which the aft section is truncated and the concave aft section is designed to capture pressure thrust. John McGinnis obviously designed this fuselage shape for an airplane with a 200 KT speed objective.

My question is would this ideal fuselage shape work on a Mach .8 airliner? If the airliner had a truncated aft section with concave sections, would the air at Mach .8 have time to flow into the concave aft sections and actually create pressure thrust? At what speeds does John McGinnis' ideal fuselage shape begin to lose efficiency and the pressure thrust no longer contributes to the reduction in fuselage drag?
 
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Sun May 27, 2012 6:02 pm

I noticed the *one* synergy not being applied in this design: A shrouded propeller. I noticed there was a concept in the 2nd video Planmaker supplied...

Now I like the idea of "open thermodynamics." In WW2, North American was the most famous for converting waste heat in the Mustang into thrust (as well as engine exhaust). But it was also done extremely well by Lockheed, Arado, and others. It is was expensive to engineer, but can be done quickly and cheaply by an "intuitive design team." It just takes someone who can cheaply apply the undergrad thermodynamics. However, some of the boundary layer claims make no sense. Boundary layer sucking and blowing is old technology (that still needs a lot of work).

I'd also like to know more about the laminar flow cross sections. My employer is spending a fortune on flaps and leading edge treatments as the latest laminar flow cross sections are *very* efficient, but with *nasty* stall characteristics. The maximum incident angles are *single* digit!    Now the laminar flow slides shown in the presentation aren't as aggressive as the one's I'm discussing. (Staying below 450kts avoids shock waves.)

Occasionally, the industry produces mavericks that 'break the rules' by figuring out the new rules.

But I see enough 'old school' improvements that there will be dramatic gains. e.g., why do current designs have such draggy oil coolers when the best fighters of WW2 used the oil coolers as 'jet thrust?'

Quoting planemaker (Reply 13):
So, until flight testing confirms their projections they are not releasing any numbers.

Wise policy. They could only look bad.

Quoting planemaker (Reply 13):
Not published but I did read on one of the EAA forums that it had been estimated (a year ago) at over 1500 nm w/ std. reserves.

   That is a long flight without a bathroom...   Single engine plane range is ultimately limited by the bladder.    However, I'm not seeing where that fuel volume would be stored... I looked at the videos and I noted the presented said there was a tremendous amount of fuel volume. I'm just not seeing where the fuel tanks are put.

Quoting planemaker (Reply 22):
"For technical reasons, CFD software and wind tunnels don't really cut it at this level.

Huh? CFD software certainly can 'cut it', it is the complications of the detailed application. I suspect no small shop could economically do the CFD. Since UTC could do CFD on a configuration such as this a decade ago, I refuse to believe the knowledge was somehow lost.

IMHO, cheaper for a small shop to build a demonstrator than a wind tunnel model. But CFD would allow further optimization of the demonstrator and a wind tunnel allows measurements that are horrendously expensive in flight. I've spent my career with even more complex 3-D aerodynamics. So its possible, just a question of cost.

Quoting TomB (Reply 23):
John McGinnis obviously designed this fuselage shape for an airplane with a 200 KT speed objective.

I see a faster design speed. Not much, perhaps 220kts to 240kts? (It is a propeller plane.) If the above range is accurate, 200kts would be a little slow.

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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Mon May 28, 2012 11:23 am

Quoting planemaker (Reply 22):
"For technical reasons, CFD software and wind tunnels don't really cut it at this level. But over the last year, serious students of aerodynamics, all over the world, have begun to realize that Synergy affects everything we know."

Yes, funnily enough that's the quote I had in mind. I recognise his experience, but he dismisses CFD and tunnel testing as "not really cutting it." Why exactly don't they? He doesn't explain and but cites unnamed people in support.

Quoting planemaker (Reply 22):
What it obvious to an aerodynamicist is that "Synergy" is 1) a "double box tail" and not a "box wing" aircraft and 2) that the wing tip vortices are being used to "synergistically" add to elevon down force.

But you said it was there to make the principle more accessible, which I took to mean for non-aerodynamicists. Anyway, tip vortices always act in that direction, it's just with his configuration there's a shortage of tail moment arm so he need all the help he can get. The picture envisions a magnified vortex, surely the opposite of what would be desirable to reduce drag.

Quoting planemaker (Reply 22):
It isn't too much if one is genuinely interested or curious. In any case, I posted the links to McGinnis' Oshkosh videos that "spoon feeds" the viewer the information.

If anything will make me glaze over it's video links to explain things. Again, I'm not saying the content isn't there, but watching well over an hour of video does not replace a few paragraphs of well written explanatory text.

Quoting planemaker (Reply 22):
It is a breakthrough... no one has been able to "implement before" the 6 well established drag reduction principles all at once.

Now you're sounding just like his website. There are only 6 well established drag reduction principles to synergise? And synergise "all at once"?  



[Edited 2012-05-28 04:36:51]

[Edited 2012-05-28 04:39:25]
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Mon May 28, 2012 4:40 pm

Quoting TomB (Reply 23):
John McGinnis obviously designed this fuselage shape for an airplane with a 200 KT speed objective.

He frequently speaks of the sub-400KT range. From what I understand, the current design point was influenced by his family size and suitable/appropriate engine. When (if?) John McGinnis' design ever goes into production (as a homebuilt kit or certified aircraft), a variety of engines could be chosen by owners, including turbines.

Quoting TomB (Reply 23):
My question is would this ideal fuselage shape work on a Mach .8 airliner? If the airliner had a truncated aft section with concave sections, would the air at Mach .8 have time to flow into the concave aft sections and actually create pressure thrust?

Not too much is available about Mach .8 airliners. Interestingly there was a presentation last year at the EA Symposium on 'pressure thrust'. This guy actually has a patent for "A System and Method for Drag Reduction Allows Thrust Output, Fuel Efficiency or Both to be Maximized"

Here is his very rough concept sketch based on an ERJ fuse...
,

'

Quoting Jetlagged (Reply 25):
There are only 6 well established drag reduction principles to synergise? And synergise "all at once"?

I know, it can come across as though there are ONLY six. 

BTW, they have added another first... Synergy is the first crowd-funded aircraft of the internet era.  

I'll get around to posting some replies to your posts tomorrow... and for lightsaber as well. In the meantime, everyone enjoy Memorial Day!
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Sat Jun 02, 2012 8:02 am

An update on the Kickstarter campaign. Synergy has raised close to $90,000 with only 42 hours left in the campaign.

Quoting lightsaber (Reply 14):
I noticed the *one* synergy not being applied in this design: A shrouded propeller. I noticed there was a concept in the 2nd video Planmaker supplied...

The prop won't be shrouded because it will function more like an impeller than a prop (and the flying prototype prop will have at least 4 blades).

Quoting lightsaber (Reply 14):
However, some of the boundary layer claims make no sense. Boundary layer sucking and blowing is old technology (that still needs a lot of work).

From the FAQs page:

Q: How can you predict 100% laminar flow over wing and fuselage surfaces?

A: By analyzing the pressure and velocity distributions required to maintain an attached boundary layer. Pioneering work by August Raspet in the 1960s showed that 100% laminar flow is surprisingly easy to achieve at general aviation speeds, using power. Suction applied to perforated wing skins at a rate of 0.0137 horsepower per square foot of wing area provided laminar flow on turbulent airfoils, and very high maximum lift coefficients, on full scale aircraft.

Our 'natural laminar flow' airfoils have a very flat pressure and velocity distribution, easily maintaining laminar flow up to 60% of the wing 'chord length'. Suction is applied beyond this point, which not only stabilizes the boundary layer for 100% laminar flow, but creates pressure thrust for extremely low drag. (We use a number of commercial grade airfoil analysis codes to compare similar airfoils having flight test data.)

In addition to issues of safety (see FAQ), there are several reasons why boundary layer control failed commercially. First, some aspects, such as contamination, water entry, maintenance, and so forth, require serious effort to address. Second, aero research at the time was all about high speed and supersonic flight, where it was hard to achieve and not helpful.

Third, BLC is seldom seen as the easy recipe that it is. Much emphasis is given to using specific 'proven' details of hole size, pattern, placement, and so on, without insightful consideration of the dirt-simple mechanism (pressure gradient) that we're using. Fourth, airplanes that could use it really weren't changing, and it didn't adapt well to old designs. Finally, a push toward blowing, rather than suction, goofed up the ability for designers to know what they're doing in physical terms. Thus the attitude: active laminar flow is complicated and expensive. Probably not worth it!!!


Quoting lightsaber (Reply 14):
I'd also like to know more about the laminar flow cross sections. My employer is spending a fortune on flaps and leading edge treatments as the latest laminar flow cross sections are *very* efficient, but with *nasty* stall characteristics.

I saw a picture of some early iterations somewhere. I'll try and find the link to them. First off, McGinnis says that the stall characteristics are very benign somewhat similar to the ICON A5 (see this video of an ICON A5 and a 152 stalling side by side and see the result as both aircraft try to enter spins at the same time! Really great stuff! Also the A5 vs a sky diver under open canopy!)

Second, the Synergy wing is very clean with BLC and no ailerons but it does have split flaps which McGinnis says worked better than fowler since they are simpler, lighter and create more drag (which he says is what you need in a aircraft this "slippery").

Quoting lightsaber (Reply 14):
Occasionally, the industry produces mavericks that 'break the rules' by figuring out the new rules.

You might like to take a look at this 7 min TEDxNASA video of Al Bowers from NASA Dryden (there since 1982) who is an aerodynamicist. He is the Associate Director of Research, has 30 research publications, and has contributed to seven books. The title is Toward More Bird-Like Flight: Thinking Outside the Box

Quoting lightsaber (Reply 14):
That is a long flight without a bathroom... Single engine plane range is ultimately limited by the bladder. However, I'm not seeing where that fuel volume would be stored... I looked at the videos and I noted the presented said there was a tremendous amount of fuel volume. I'm just not seeing where the fuel tanks are put.

The design reference aircraft is a Velocity and it has a 1000 nm range @ 65% power with a Lycoming IO-360 200HP. The exact same Velocity with a DeltaHawk diesel burns 3 gal/hr less @ 65% power (4.8 gal/hr less @ 100% power). Velocity/DeltaHawk endurance with 50 gal @ 65% power with 45 min reserve is 6.4 hrs. Given that the Synergy is a much more efficient design aerodynamically, is lighter and that the wings are "fatter", depending upon power setting and load, +1500nm range looks feasible (with a pee bottle.)

Quoting lightsaber (Reply 14):
Huh? CFD software certainly can 'cut it', it is the complications of the detailed application. I suspect no small shop could economically do the CFD. Since UTC could do CFD on a configuration such as this a decade ago, I refuse to believe the knowledge was somehow lost.
Quoting Jetlagged (Reply 15):
I recognise his experience, but he dismisses CFD and tunnel testing as "not really cutting it." Why exactly don't they? He doesn't explain and but cites unnamed people in support.

There is a more detailed explanation somewhere why he says what he says that I'll try to find. In the meantime this is from the FAQs page:

Q: Are your predictions based on CFD?

A: No, they're consistent and flow from classic methods including 2-D flow solvers, spreadsheets, proprietary analysis, and panel codes. Computational Fluid Dynamics is an attempt to solve Newtonian models of fluid particle interaction, based usually upon the Navier-Stokes and Barnette equations. While solutions to these equations typically DO NOT exist, and their approximations difficult, CFD has been empirically refined to the point where a reasonable degree of accuracy can be obtained for well-known geometries and flow conditions. However, the fundamental liabilities hidden in today's level of affordable CFD are many for an 'open thermodynamic' configuration. Foremost is that process simplifications and sensitivities to initial condition assumptions are amplified in an unsteady manner, such that the results one gets are a product of the expectations one expects to be reasonable. This need to input the expected result in advance, in order to get the "solution" to converge, cannot be described as rigorous or even scientific. The term "Reynolds-averaged" betrays another hidden liability capable of destroying useful data.

In the surprisingly candid opinion of many who use it daily, CFD makes pretty pictures for the marketing department. It would take a full workup, non-simplified LES study, or flight testing, to reveal data we haven't already worked out the hard way.

Computers do hold the key to accurate realtime prediction of fluid dynamics. A completely different mathematical basis is required, however. Stay tuned.


Quoting lightsaber (Reply 14):
IMHO, cheaper for a small shop to build a demonstrator than a wind tunnel model. But CFD would allow further optimization of the demonstrator and a wind tunnel allows measurements that are horrendously expensive in flight. I've spent my career with even more complex 3-D aerodynamics. So its possible, just a question of cost.

I will find his comments about why wind tunnels don't work for Synergy... if I recall correctly McGinnis said something about Synergy requiring a 1,000 ft long wind tunnel... I think.

Quoting Jetlagged (Reply 15):
Anyway, tip vortices always act in that direction, it's just with his configuration there's a shortage of tail moment arm so he need all the help he can get. The picture envisions a magnified vortex, surely the opposite of what would be desirable to reduce drag.

In a conventional design there would be a "shortage of tail moment arm"... but not in Synergy. BTW, he isn't magnifying.



[Edited 2012-06-02 01:24:01]
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Mon Jun 04, 2012 5:15 am

Quoting planemaker (Reply 17):
and the flying prototype prop will have at least 4 blades

Always a good outcome. More blades add cost, but I've yet to meet anyone who upgraded their prop to more blades regret the more efficient and more flexible performance on the GA planes.

Quoting planemaker (Reply 17):
without insightful consideration of the dirt-simple mechanism (pressure gradient) that we're using.

I'd like to know more. This is boundary layer 101 though... (Recall, I'm a fluids specialist.) So I'm waiting to see his trick. The discussions on what he didn't like is the practical limits of low cost BLC.

Quoting planemaker (Reply 17):
the Synergy wing is very clean with BLC and no ailerons but it does have split flaps which McGinnis says worked better than fowler since they are simpler, lighter and create more drag (which he says is what you need in a aircraft this "slippery").

I like the flap idea. I agree 'slippery' designs need more drag on landing. The Rockwell commander is a great plane that more than a few people I know have bought used. But oh boy does it take a little time to understand how to land it. A nice 'sticky flap' system will simplify the training (or eliminate the need). So a less 'efficient' flap design is perfect for the pilots who will fly this plane.

Quoting planemaker (Reply 17):
However, the fundamental liabilities hidden in today's level of affordable CFD are many for an 'open thermodynamic' configuration.

And there is the catch. However, there are ways to use the models more effectively. However, I'm not familiar with the limitations of the 'affordable' CFD codes. I'm used to high power codes that have better turbulence models that switch on which regime the turbulence is in. But as I noted, it is a small shop. I doubt they have a $10 to $20 million CFD simulation budget.   So I agree that CFD isn't applicable for their project. My issue is the wording. On a big project (e.g. MAX or NEO), its worth spending $20 to $50 million on the CFD and the results are very enlightening.

Quoting planemaker (Reply 17):
In the surprisingly candid opinion of many who use it daily, CFD makes pretty pictures for the marketing department. It would take a full workup, non-simplified LES study, or flight testing, to reveal data we haven't already worked out the hard way.

Some companies do better with CFD than others. This sounds like a team who came from a company whose CFD was sloppy. I've seen companies flail with CFD in areas that GE and UTC excel. I've seen journal papers by large teams of CFD work that was worse than what UTC (or GE) expects out of a CFD Jockey with only two years of experience should be able to complete in a week. e.g., ex-McDonnel engineers often have a negative opinion of CFD as they made some major mistakes. But I can point to their competitors who have done far better. But this is out of scope for this project due to the budgets required. For this size of project, good 'old-school' 2-D analysis would be good enough. They'll miss some 3-D effects, but it shouldn't really matter.

Overall, it will be very interesting to see how this plane does in the market. I appreciate you taking the time to answer my questions. It looks like the fundamentals are well done. Just don't go on a long flight without a Pringles can...

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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Wed Jun 06, 2012 7:18 pm

Quoting planemaker (Reply 17):
In a conventional design there would be a "shortage of tail moment arm"... but not in Synergy. BTW, he isn't magnifying.

Now you're being as inscrutable as Mr McGinnis (you aren't him are you?). Why isn't the short tail arm a problem for his design? Clearly he has two very large elevons, which would help things, but aren't they also rather draggy?

BTW, I didn't say his design was magnifying the vortex, but using that picture makes it look as if that's the idea. The picture doesn't explain anything, but puts too "cool" concepts together for effect.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Thu Jun 07, 2012 3:34 am

Quoting lightsaber (Reply 14):
I'd also like to know more about the laminar flow cross sections. My employer is spending a fortune on flaps and leading edge treatments as the latest laminar flow cross sections are *very* efficient,

I am still looking for a recent cross section to post (the one below is an iteration from 2008)...

http://www.oshkosh365.org/userimages/37433/3acbcc68-bcd6-4657-9cf3-3d4daed8740f.jpg

Quoting lightsaber (Reply 18):
I'd like to know more. This is boundary layer 101 though... (Recall, I'm a fluids specialist.) So I'm waiting to see his trick. The discussions on what he didn't like is the practical limits of low cost BLC.

He writes that he "allows the NLF to work as long as possible and confine BLC to the aft backwater portion" and that keeping the BLC "holes clean are easy when they are big and are on removable panels".

Quoting lightsaber (Reply 18):
I like the flap idea. I agree 'slippery' designs need more drag on landing. The Rockwell commander is a great plane that more than a few people I know have bought used. But oh boy does it take a little time to understand how to land it.

The aircraft has a 30% chord split flap in the inboard wing section. BTW, I flew both the 112 and the 114 way back in 1979. As an aside, I really liked their stance on the ramp compared to all the other singles.

Quoting Jetlagged (Reply 19):
Why isn't the short tail arm a problem for his design?

Due to the integration of many of the design features including things such as having the rear engine mount closer to the CG, wing design with less pitching motion, elevon located above the wing down wash but taking advantage of the tip wortex, etc, etc.

Quoting Jetlagged (Reply 19):
Clearly he has two very large elevons, which would help things, but aren't they also rather draggy?

The elevons are not actually very large though they do have a high aspect ratio so are "less draggy" than having ailerons and a conventional horizontal stabilizer and elevators.

Quoting Jetlagged (Reply 19):
BTW, I didn't say his design was magnifying the vortex, but using that picture makes it look as if that's the idea. The picture doesn't explain anything, but puts too "cool" concepts together for effect.

Not from an aerodynamic point of view.
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RE: 1st Aircraft To "synergize" 6 Six Aero Principles

Tue Jul 10, 2012 4:38 pm

Quoting planemaker (Reply 20):
The elevons are not actually very large though they do have a high aspect ratio so are "less draggy" than having ailerons and a conventional horizontal stabilizer and elevators.

The elevons do not have high aspect ratio compared to conventional control surfaces, in fact probably less than is conventional. However, the area of the elevons relative to the area of the main wing is certainly much larger than on a conventional wing. At a rough estimate from the image on the website the elevon area is one about third of the area of the fixed part of the wing, in other words elevon area represents about 25% of the total wing area. That's a surprisingly high ratio.

Quoting planemaker (Reply 20):
Not from an aerodynamic point of view.

A superimposed image of a breaking wave tells you nothing about the aerodynamics of this, or any other, wing. The physics is completely different for a start. He could have used an image of an actual wing tip vortex to illustrate it, but he chose a breaking wave, which happens to look "cool" because of the association with surfing.

Sorry for the delay in responding to your post but I've been away from this forum for a while.
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