0
yuri_base

Wingsuit research

Recommended Posts

Here are some resources about wingsuit research in the last 12 years or so for those interested. If you know of anything not listed, please share. Let's keep this up-to-date as a central "What's new in wingsuit research?" reference.


1. Geo Robson:

http://www.idsc.ethz.ch/research-dandrea/research-projects/archive/actuated-wingsuits.html

2. Israel Institute of Technology:

https://aerospace.technion.ac.il/projects/aerodynamic-design-of-a-wingsuit/

(can't find the paper though, probably, was sent to me by email and is lost now)

3. Karl Nyberg:

https://mdx2.plm.automation.siemens.com/sites/default/files/thesis/pdf/Examensarbete_Karl_Nyberg.pdf

4. Icarus Project:

http://generic.wordpress.soton.ac.uk/icarus/

(no papers)

5. Hartman Rector:

The Excel spreadsheet (3D Wingsuit Equations solver) was sent in an email to me, don't know if he wants to publish it or not. A simple 2D Wingsuit Equations Excel solver can be found here:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2563142#2563142

3D WSE in fixed frame of reference can be found above "FUCK YEAH!!!" in my notebook here:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=4825693#4825693

6. MIT:

https://www.researchgate.net/publication/245481528_Wind_Tunnel_Testing_of_a_Novel_Wingsuit_Design

7. Maria Ferguson:

https://openscholarship.wustl.edu/cgi/viewcontent.cgi?article=1000&context=engr310

8. Timothy Sestak:

https://commons.erau.edu/edt/355/



I'll throw in some of my stuff as well:

YB1 - "Superterminal" wingsuit idea:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2084537#2084537

YB2 - Wingsuit Equations, 2D:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2563135#2563135

3D:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=148684;

YB3 - Accelerometer on a vane as L/D meter principle:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2563139#2563139

YB4 - "magic" L/D's

- 1st, for maximum horizontal speed:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2253168#2253168

- 2nd, for level planeout after headdown dive:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3148124;#3148124

- 3rd, for level planeout after BASE exit:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3145335;#3145335

YB5 - wingsuit hysteresis:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2532192

YB6 - Wingsuit Studio, WSE-2D solver, L/D Calculator, World BASE Race simulator:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3626009

(download at http://www.pureflyingmagic.com)

YB7 - flying with just a leg wing and like Superman:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=2264543#2264543

(additional experiments with top above waistline removed for Phantom-1 and Vampire-2, circa 2012-ish and with arm wings cutoff completely on Vampire-4 and flying like a Superman, with arm(s) stretched forward, circa 2015-ish)

YB8 - Z-Device, with accelerometer and Pitot Tube on a vane:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3069522#3069522

YB9 - Analog L/D Meter (laser-cut bubble level with mathematically calculated curve):

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_attachment;postatt_id=120198;

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3796788#3796788

YB10 - Smartdevices on a vane as real time wingsuit instrumentation:

Links to the apps (L/D Vario and L/D Magic) can be found at http://www.pureflyingmagic.com

Examples of flights with smartphones or smartwatches on a vane can be found here:
https://www.youtube.com/channel/UCFaKavzIFhlKuFp40l4osIQ
https://vimeo.com/pureflyingmagic

Some examples of data and discussion of challenges: http://www.basejumper.com/cgi-bin/forum/gforum.cgi?post=2982476

YB11 - Fast, Accelerated Proximity principle:

http://www.basejumper.com/cgi-bin/forum/gforum.cgi?post=2991086;#2991086

(for Wingsuit FAP app links, see http://www.pureflyingmagic.com)
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
YB12 - The Great Confusion:

http://www.dropzone.com/cgi-bin/forum/gforum.cgi?post=3112987

I just started to read #8, the big dissertation (1000 pages!), The Effect of Surface Materials and Morphology on Wingsuit Aerodynamics. And immediately was SHOCKED to find that it falls into the same fallacy as Geo did - applying the math for powered level flight to wingsuit flight!

I pointed about this confusion many times in wingsuit forum. Hopeless. In 2009, Geo wrote this post:

http://www.basejumper.com/cgi-bin/forum/gforum.cgi?post=2911547#2911547

which clearly showed his wrong approach, and a couple of posts below, I explained it to him. Hopeless. He continued doing it the wrong way.

Then, he posted about his study on effects of altitude on start arc:

http://www.basejumper.com/cgi-bin/forum/gforum.cgi?post=2923164;#2923164

- apparently, this was part of his preparation for that fatal jump. And it's quite possible, that this Great Confusion cost him life, if there was an error in his calculations (BFL #146).

Cf. pages 47-49 in the Sestak's dissertation. As Geo, he separates total drag into two parts: induced drag and parasite drag. As I explained in "The Great Confusion" post and in reply to Geo, this is an artificial math trick designed to make life a bit easier when doing calculations related to powered level flight, but they are useless and even harmful, when applied to non-powered gliding flight!

[inline Fallacy.png]

Wingsuit's drag does not go to infinity as the speed approaches zero, otherwise, we'll be like a fly that flew into honey, after a BASE exit, since the enormous drag will stop us right away! Drag is always (with high Reynolds number) proportional to the square of airspeed!

Unfortunately, the way they teach aerodynamics to aeronautical students, pounds this fallacy into their brain. From my observations over the years, aeronautical students and engineers do not have a solid grasp of fundamental physics concepts to recognize this fallacy. They fall into this pothole every. single. time.


Finally, both Sestak's and Robson's work fail to mention the prior art - Wingsuit Equations (ca. 2006) and L/D Meter principle (i.e., the possibility of precise measurements of wingsuit flight characteristics) - in their work. (Robson learned about WSE and Wingsuit Studio in 2009.) Wingsuit Equations are like Newton's F=ma in wingsuit dynamics. For an aeronautics researcher who is also a wingsuit pilot, to not know about them in 2017 is laughable, they are easily googled by "wingsuit dynamics", etc. It's like writing a doctoral dissertation on mechanics and not knowing F=ma. Or like a Ph.D. candidate in electrical engineering doesn't know Ohm's Law. You can run, but you can't hide from the Wingsuit Equations!
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Fallacy.png

Share this post


Link to post
Share on other sites
I’m really curious if all of this extensive research has ever been applied to wingsuit performance? I mean, given this information, shouldn’t you be able to figure out a mode of flight that out-performs everyone? How do your flights compare to typical performance suit fliers?
Skwrl Productions - Wingsuit Photography

Northeast Bird School - Chief Logistics Guy and Video Dork

Share this post


Link to post
Share on other sites
Skwrl

I’m really curious if all of this extensive research has ever been applied to wingsuit performance? I mean, given this information, shouldn’t you be able to figure out a mode of flight that out-performs everyone? How do your flights compare to typical performance suit fliers?



To the best of my knowledge, true L/D and polar measuring devices I invented have never been used by anyone in Solar System other than the author.

[inline Vane.jpg]

Smartphones and smartwatches are available. Apps (even free) are available. Telescopic poles are available. Simple materials are available. But no one has ever been interested in spending an evening or two to build a vane. 12 years since the idea publication, about 10 since Z-Device and Analog L/D Meter, 5 years since L/D Magic launch in Apple appstore, 3 years since free L/D Vario app, available on 4 platforms. Nothing. Nada.

Imagine similar situation in any hi-tech industry (aerospace, cars, etc.) if someone invents the theory and devices to measure critically important performance parameters, and for 12 years they do this (and will continue for X more years):

[inline Cow.gif]

Hartman Rector is the only one who "gets it". Using polar curve deduced either from GPS data with wind correction, or from L/D Magic and L/D Vario, one can not only model their flights with arbitrary conditions and control inputs (to evaluate a prospective WS BASE jump, for example), but also model competitions for speed, distance, time to find the winning strategy (and it's all can be simply done in Excel, like Hartman does, no special software needed! although Wingsuit Studio can be used for piece-wise modeling since it only supports constant flight modes).

Even when I mention 1.4=sqrt(2) (recently corrected to 1.3) as the best L/D for max horizontal speed and ask the competition champions what's their glide on speed runs and get ~1.6 (which is, more or less, 1.4 + wind push), I get a blank stare. They can't fathom that these things can be determined by scientific research, without leaving the couch even, and has been done 10 years ago!

As I said before, unfortunately, despite all the guerrilla/gorilla/Godzilla marketing BS we get to eat these days, the wingsuit industry has been, essentially, in a coma since its birth 20 years ago. No wingsuit manufacturer knows the most important flight characteristic of their products - max L/D - or how to precisely measure it.

And a lot of the research listed above is also just BS, the vehicle for students (or even professors!) to get their diploma/get funding and be out the door:

[inline DoneWithWingsuitScience.jpg]

Some research is genuine (Geo's, who was also a WS BASE jumper), but has errors or fallacies in it, stemming from aeronautical educational background, which puts emphasis on powered airplanes, not gliders. These fallacies get perpetuated and we get dangerous errors unintentionally disguised as scientific nuggets.

As far as my performance numbers, I precisely measured my max L/D in Phantom-1 (2.15), Vampire-4 (2.75), and Aura-2 (2.9). I'm not fit, so for the same suits I would expect 5-10% higher numbers for athletic body build.

[inline Brento.png]

[inline Sputnik.png]


PS. For PF tracksuit, I got 1.4, and for V-4 with cut armwings, in traditional tracking position/arms along the body, or in "Superman mode", with arms stretched forward, I get about 1.5-1.6 (but much faster than tracksuit). Unfortunately, I didn't have time or energy to pursue Superman flying more, because I always skydive my BASE canopy, and openings after Superman are really hard; and I don't have a physical strength to hold Superman position for long - the forces that try to bend you like a banana are incredibly strong! If anyone sees me at their dropzone, ask me, I can give you the leg wings of Phantom-1, V-2, or V-4 to try this "superterminal" flying.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Cow.gif

DoneWithWingsuitScience.jpg

Vane.jpg

Brento.png

Sputnik.png

Share this post


Link to post
Share on other sites
yuri_base

***I’m really curious if all of this extensive research has ever been applied to wingsuit performance? I mean, given this information, shouldn’t you be able to figure out a mode of flight that out-performs everyone? How do your flights compare to typical performance suit fliers?



To the best of my knowledge, true L/D and polar measuring devices I invented have never been used by anyone in Solar System other than the author.



Smartphones and smartwatches are available. Apps (even free) are available. Telescopic poles are available. Simple materials are available. But no one has ever been interested in spending an evening or two to build a vane. 12 years since the idea publication, about 10 since Z-Device and Analog L/D Meter, 5 years since L/D Magic launch in Apple appstore, 3 years since free L/D Vario app, available on 4 platforms. Nothing. Nada.

Imagine similar situation in any hi-tech industry (aerospace, cars, etc.) if someone invents the theory and devices to measure critically important performance parameters, and for 12 years they do this (and will continue for X more years):



Hartman Rector is the only one who "gets it". Using polar curve deduced either from GPS data with wind correction, or from L/D Magic and L/D Vario, one can not only model their flights with arbitrary conditions and control inputs (to evaluate a prospective WS BASE jump, for example), but also model competitions for speed, distance, time to find the winning strategy (and it's all can be simply done in Excel, like Hartman does, no special software needed! although Wingsuit Studio can be used for piece-wise modeling since it only supports constant flight modes).

Even when I mention 1.4=sqrt(2) (recently corrected to 1.3) as the best L/D for max horizontal speed and ask the competition champions what's their glide on speed runs and get ~1.6 (which is, more or less, 1.4 + wind push), I get a blank stare. They can't fathom that these things can be determined by scientific research, without leaving the couch even, and has been done 10 years ago!

As I said before, unfortunately, despite all the guerrilla/gorilla/Godzilla marketing BS we get to eat these days, the wingsuit industry has been, essentially, in a coma since its birth 20 years ago. No wingsuit manufacturer knows the most important flight characteristic of their products - max L/D - or how to precisely measure it.

And a lot of the research listed above is also just BS, the vehicle for students (or even professors!) to get their diploma/get funding and be out the door:



Some research is genuine (Geo's, who was also a WS BASE jumper), but has errors or fallacies in it, stemming from aeronautical educational background, which puts emphasis on powered airplanes, not gliders. These fallacies get perpetuated and we get dangerous errors unintentionally disguised as scientific nuggets.

As far as my performance numbers, I precisely measured my max L/D in Phantom-1 (2.15), Vampire-4 (2.75), and Aura-2 (2.9). I'm not fit, so for the same suits I would expect 5-10% higher numbers for athletic body build.






PS. For PF tracksuit, I got 1.4, and for V-4 with cut armwings, in traditional tracking position/arms along the body, or in "Superman mode", with arms stretched forward, I get about 1.5-1.6 (but much faster than tracksuit). Unfortunately, I didn't have time or energy to pursue Superman flying more, because I always skydive my BASE canopy, and openings after Superman are really hard; and I don't have a physical strength to hold Superman position for long - the forces that try to bend you like a banana are incredibly strong! If anyone sees me at their dropzone, ask me, I can give you the leg wings of Phantom-1, V-2, or V-4 to try this "superterminal" flying.

Where is your 3D flow simulations and modeling?

Share this post


Link to post
Share on other sites
LeeroyJenkins

Where is your 3D flow simulations and modeling?



CFD for now, as applied to wingsuits, is just a toy producing pretty colorful flow pictures. (See #2, 4, 7, 8.) They miss the most important first step: validation of simulations vs. real wingsuits. They get unrealistic max L/D (I've seen 4.0 and higher), which shows that their results have unknown (possibly no) relevance to real wingsuits.

Their main purpose is to make pretty pictures.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
yuri_base

***Where is your 3D flow simulations and modeling?



CFD for now, as applied to wingsuits, is just a toy producing pretty colorful flow pictures. (See #2, 4, 7, 8.) They miss the most important first step: validation of simulations vs. real wingsuits. They get unrealistic max L/D (I've seen 4.0 and higher), which shows that their results have unknown (possibly no) relevance to real wingsuits.

Their main purpose is to make pretty pictures.

Give me a break, are you at least a mechanical engineer or aerospace engineer?

So how long till you start selling your product/data? You marketing campaign seems to be off to an aggressive start?

Share this post


Link to post
Share on other sites
Everyone is most welcome to compile their work in a post here. Your thoughtful posts here on dz.com, bj.com, or elsewhere, articles you wrote, calculations you've done - share the love, don't be shy! It will be a very interesting read. Everyone remembers what they've done over the years; but not what others had done. It's like a ton of needles thrown from a plane onto a field of haystacks. Who can find them all?! Collect all your needles from your haystack and give it to us!

If you have any critical thought on any material in this thread, go ahead, shred it!

True science does not know "politics", little talk, tact, pretty lies... True science is the pure truth, it's fucking straightforward!
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
Quote

Unfortunately, the way they teach aerodynamics to aeronautical students, pounds this fallacy into their brain. From my observations over the years, aeronautical students and engineers do not have a solid grasp of fundamental physics concepts to recognize this fallacy. They fall into this pothole every. single. time.



I'm an aerospace engineer, and I don't know anyone who actually takes that plot as no more than a rough approximation of drag. The drag increase towards zero does not actually go to infinity, as it levels off at stall speed.

You say that drag is proportional to just the square of airspeed ( D~=v^2) but you've probably measured that drag with a constant angle of attack. The reason why the induced drag in the graph increases with decreasing speed is that you need to increase the angle of attack to maintain straight and level flight as you get slower. So yes, this graph is usually meant for powered aircraft in straight and level flight rather than gliding flight.

However, in gliding flight you still need to take this graph seriously. Why? Because your lift must still equal your weight! If you are flying your best glide angle, and your lift is not equal to your weight, then your speed will not be constant. You will be accelerating. As you yourself said, F = ma.

So, if lift is not equal to your weight, L - W = ma, which will accelerate you towards the ground. So if your definition of a good wingsuit flight is a parabolic trajectory towards the ground, I'm not sure how many people would agree with you.

On the other hand, I do agree with you that CFD in wingsuit situations needs to be taken with a large grain of salt. Low Reynolds numbers, large amounts of turbulence and large aeroelastic effects are not easy to simulate accurately even with the latest CFD algorithms.

Share this post


Link to post
Share on other sites
aonsquared

You say that drag is proportional to just the square of airspeed ( D~=v^2) but you've probably measured that drag with a constant angle of attack. The reason why the induced drag in the graph increases with decreasing speed is that you need to increase the angle of attack to maintain straight and level flight as you get slower. So yes, this graph is usually meant for powered aircraft in straight and level flight rather than gliding flight.



Exactly. The aircraft has to change its AoA to maintain level flight if it wants to fly slower or faster, so that graph and formulas for induced and parasitic drag reflect that.

A simple numeric illustration. We have a 1000kg plane flying level at 200km/h, with AoA=4 degrees and L/D = 10. We have a simple "cross" force diagram: weight W = 1000kg is down, lift L = 1000kg is up, drag D = L/(L/D) = 100kg back, and thrust T = D = 100kg forward.

Now the plane wants to fly level at 141km/h (200 deviced by sqrt(2)). If it doesn't change AoA, the lift (and drag, too!) will decrease by a factor of 2, since aerodynamic force is proportional to V^2. Now the lift is only 500kg - half the weight, the plane can't fly level! (the drag will be 50kg) We need to increase the lift by 2x. So we increase AoA to 8 degrees, since for thin wings the lift is proportional to AoA in a range of about 0-10 degrees. Now lift is 2x (1000kg), but drag is roughly proportional to the square of AoA (there's an offset to parabola - non-zero drag at zero AoA, but let's ignore it for the purpose of illustration), so the drag now is 50*4 = 200kg! So the airspeed decreased by sqrt(2), but the drag increased by 2x.

This illustrates why for powered aircraft flying level at constant speed, drag increases as the plane tries to fly slower. This is because they have to increase AoA to maintain level flight, which leads to sharply increasing drag.

This is not applicable to non-powered aircraft.

aonsquared

However, in gliding flight you still need to take this graph seriously. Why? Because your lift must still equal your weight! If you are flying your best glide angle, and your lift is not equal to your weight, then your speed will not be constant. You will be accelerating. As you yourself said, F = ma.



No, even for sustained flight, lift is not equal weight, this is because the force diagram is different, there are only 3 forces, and L and D are angled to W (all this is explained in The Great Confusion post).

For sustained non-powered flight,

L = W*(L/D)/sqrt(1 + (L/D)^2)
D = W/sqrt(1 + (L/D)^2)

For non-constant speed, Wingsuit Equations are needed. The calculated lift and drag vs. time can be seen in the graphs of my jumps above. How these calculations are done, is explained in the article How L/D Magic Works: once the "magic" coefficients of lift and drag Kl and Kd are found, lift and drag can be calculated as:

L = W·Kl·V^2
D = W·Kd·V^2
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
Quote

No, even for sustained flight, lift is not equal weight, this is because the force diagram is different



All the forces need to balance to zero if it's moving at a constant speed (either straight and level, or a straight-line unpowered glide).

The only difference between powered and unpowered is that unpowered, you're using a bit of your weight vector (W*sin(theta)) to push against whatever drag you're experiencing. Your wing won't generate a force perpendicular to the earth, but the component of that force vector perpendicular to the ground (L*cos(theta)) needs to be equal to your weight, otherwise you will be accelerating rather than staying at a constant descent velocity.

I don't think you've explained very well WHY the standard drag polar is not applicable to unpowered flight.

Unpowered flight has been around for way, way longer than wingsuits have. Unpowered gliding flight has even been around for longer than powered flight.

I hate to break this to you but, your equations are wrong.

Share this post


Link to post
Share on other sites
aonsquared

I don't think you've explained very well WHY the standard drag polar is not applicable to unpowered flight.



Because wingsuits (and any nonpowered AC) do not have the goal (and means) to maintain the level flight. So we do not change AoA to maintain LF at different speeds; we change our AoA to do, for example, a flare, or to do a fast start in BASE, or adjust it to find some sweet spot, whether it's distance, time, or speed; or to stay in formation; etc. etc. We cannot fly level at constant speed like planes do!

aonsquared

I hate to break this to you but, your equations are wrong.



No, they are correct. Prove mathematically that they are wrong!
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
Quote

Because wingsuits (and any nonpowered AC) do not have the goal (and means) to maintain the level flight



I never said it was. I said the goal was constant velocity, not constant altitude.

So if your force diagram does not balance to zero then your equations are already wrong. Because F = ma.

Again, I'm sorry for saying it like this. You seem fairly good at maths, but it's really quite unlikely that you've found a groundbreaking new equation. Wingsuiters, as well as any other form of gliding flight, are probably better off using standard aerodynamics equations. Blue skies!

Share this post


Link to post
Share on other sites
aonsquared

So if your force diagram does not balance to zero then your equations are already wrong. Because F = ma.



Which equations? I wrote several above,

Quote

For sustained non-powered flight,

L = W*(L/D)/sqrt(1 + (L/D)^2)
D = W/sqrt(1 + (L/D)^2)



For both sustained or non-sustained, non-powered:

Quote

L = W·Kl·V^2
D = W·Kd·V^2



And then Wingsuit Equations - they are simply F=ma in expanded form for non-powered flight, for any velocity, sustained or changing.

So, which equations are wrong in their respective conditions and where is the math to show it?

aonsquared

Again, I'm sorry for saying it like this. You seem fairly good at maths, but it's really quite unlikely that you've found a groundbreaking new equation.



Yes, I did find groundbreaking equations - Wingsuit Equations, in 2006. I also invented the ways of measuring L/D and other aerodynamic parameters by using accelerometer and other sensors on a vane in undisturbed airflow.

aonsquared

Wingsuiters, as well as any other form of gliding flight, are probably better off using standard aerodynamics equations.



In my opinion, it's quite possible that this is what killed Geo Robson. He used "standard aerodynamics equations" and grossly overestimated his flight path. He didn't "get" WSE (the only person in Solar System other than me who gets them, is Hartman Rector).

It almost seems that aerospace engineers hit a wall when one talks physics and math. They often lack even basics.

A very clear example of this is #8, a 1000-page dissertation for "Ph.D. in Aviation" (!) - not only it has this wrong drag plot and [unnecessary for wingsuits] separation of drag into induced and parasitic, but the whole method of studying effects of fabric roughness on wingsuits is grossly wrong, because taking a high-L/D section of a wing and covering it in fabric and seeing L/D dramatically decrease by half, has little relevance to wingsuits as our L/D is much much lower to begin with, so the effect of rough fabric will be probably within 5%.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
Quote

L = W*(L/D)/sqrt(1 + (L/D)^2)
D = W/sqrt(1 + (L/D)^2)



Those are not equations. That's like saying 1=2.

Quote

I also invented the ways of measuring L/D and other aerodynamic parameters by using accelerometer and other sensors on a vane in undisturbed airflow.



I'd strongly suggest you publish your wingsuit equations in a reputable academic journal then, it would be good to see full methodology and get it through peer review.

I'd also recommend using Microsoft Equation or LaTeX when you typeset your equations to make the equations easier to read in your PDF.

Share this post


Link to post
Share on other sites
aonsquared

Quote

L = W*(L/D)/sqrt(1 + (L/D)^2)
D = W/sqrt(1 + (L/D)^2)



Those are not equations. That's like saying 1=2.



These are equations. They allow one to calculate lift and drag, given L/D and weight, for sustained flight. Yes, they are simple Pythagorean cathetuses from right triangle force diagram (W is hypothenuse, L and D are sides). That doesn't make them "not equations".

aonsquared

I'd strongly suggest you publish your wingsuit equations in a reputable academic journal then, it would be good to see full methodology and get it through peer review.



I feel no need. I'm not affiliated with any academic institution, so don't think this is even possible for a person "from the street" to publish articles in academic journals.

For me, it's sufficient to do the way I do it.

For those writing academic articles and even Ph.D. dissertations, it's an academic shame not to mention (either intentionally, or genuinely not knowing it and not simply googling around a little) the prior art that has been developed 12 years ago. Other than Hartman #5, none from the list #1-#8 mention it. It's pure ridiculousness.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
You can't have L isolated on one side of the equation then have it on the other side too. Same with D. Equations need to be equal (that's why they're called equations).

Quote

I feel no need.



Well, the burden of proof is really to prove that your "equations" are correct, as you haven't provided any proof that the prevailing academic thought on aerodynamics is wrong. And please stop using a dead person as proof. Anecdotes are not data.

The burden of proof should be on you as you're using them to instruct other wingsuiters and if they change their behaviour according to your possibly incorrect formulas, you should have the experimental data to back it up.

I don't have time to fully review your experimental methods, but without wind tunnel tests and only relying on wingsuit jumps with variable weather data (you did record all wind conditions, temperatures, pressures, and humidity, right?), with noisy instruments that have not been calibrated against laboratory references, and of course a very variable and very human test model, lack of convergence testing and instrument parameters, lack of error bars in your final graphs - there's a lot to work on.

Share this post


Link to post
Share on other sites
aonsquared

You can't have L isolated on one side of the equation then have it on the other side too. Same with D. Equations need to be equal (that's why they're called equations).



(L/D) on the right side is used as a notation for a number, not as literal lift devided by drag. I can denote it by some letter, e.g. greek gamma. In the absence of rich formatting here, I get around this limitation by enclosing the number L/D in parenthesis: (L/D). For example, if L/D=2.5, just substitute 2.5 wherever there's (L/D).

Same for drag in sustained level flight:

D = L/(L/D).

It's not literal (otherwise, it's like D=D). It's "take the lift (1000kg), devide by L/D of the plane (10), you get drag 1000/10=100kg".

I thought this was pretty obvious.

aonsquared

Well, the burden of proof is really to prove that your "equations" are correct, as you haven't provided any proof that the prevailing academic thought on aerodynamics is wrong.



I proved that they are correct by deriving them using proven physics (I'm Ph.D. in Physics) and aerodynamics laws. The derivation is here:

http://www.pureflyingmagic.com/Content/Knowledge/Resources/Articles/en/WingsuitEquations.pdf

I have no further "burden". If anyone scientifically proves them wrong, not just saying they are wrong, then I will have a burden to confirm my mistake. This hasn't happened yet. (And I strongly think, it never will.)

aonsquared

The burden of proof should be on you as you're using them to instruct other wingsuiters and if they change their behaviour according to your possibly incorrect formulas, you should have the experimental data to back it up.



I've done it many times, both deriving my aerodynamic parameters from my flights, and using this data to model flight. Hartman does this even in 3D!

aonsquared

I don't have time to fully review your experimental methods, but without wind tunnel tests and only relying on wingsuit jumps with variable weather data (you did record all wind conditions, temperatures, pressures, and humidity, right?), with noisy instruments that have not been calibrated against laboratory references, and of course a very variable and very human test model, lack of convergence testing and instrument parameters, lack of error bars in your final graphs - there's a lot to work on.



Yes, there's a lot to work on, but a lot of work is done already. I collected some of my work in OP, the burden to study it is not on me.

Actually, using jumps as a personal research windtunnel is way more superior to lab windtunnels, because 1) it's you, and in your suit tailored for you, not some other guy in a different suit or build; 2) laying on a measurement platform, waiting to get strapped, the blower motors to reach their speed, etc. is tiring, so the test pilot in windtunnel may have a body position not reproducing the real one in flight; when jumping, one has their real body position and can measure true aerodynamic parameters of it; 3) platform itself can introduce errors in measured lift and drag since it is big and interferes with the flow and can't be just subtracted (unlike thin mounting hardware for wing sections).

Re: wind conditions. L/D Magic and L/D Vario on a vane completely exclude wind, since the vane points into relative wind. They measure the motion relative to air, no ground (like GPS).

Altitude pressure is taken into account, of course. Effects of humidity and temperature are relatively minor and are ignored for now (but now that Nixon Mission smartwatch has a humidity and temperature sensors, it can be done).

"a very variable and very human test model" - yes, and it's yourself, which is the best. I'm not fit and very heavy, so, for example, Hartman's data will have little relevance to me. What I need for me is my data.

Instrument noise is taken into account by L/D Magic's Kalman filters.

Calibration is a big issue, need to, for example, put the pole with L/D Magic/Vario on a car in clean airflow and drive on a level road to calibrate 0.0.

There's a lot of work to do, unfortunately, other than me jumping with vanes and Hartman using GPS data, no one has done any meaningful work in deducing the real aerodynamic parameters of wingsuits and applying them to modeling. In 12 years. In the whole Solar System.

That's the state of the wingsuit industry today. 20-year long coma. And continuing indefinitely, it seems.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
We use subscripts, e.g. C_L and C_d to denote lift and drag coefficients.

If you're a PhD then you should know how the peer review process works! (And if you're a PhD then you would also have published a few academic papers - so you're not really 'outside' the system are you?)

Quote

(And I strongly think, it never will.)

um...

Quote

Instrument noise is taken into account by L/D Magic's Kalman filters.


That's not how noise works...did you do any experiments during your Physics PhD?

Quote

In the whole Solar System.


Right... I'm done here. Good luck!

Share this post


Link to post
Share on other sites
aonsquared

And if you're a PhD then you would also have published a few academic papers - so you're not really 'outside' the system are you?



After my PhD in 2005, I'm not in academia and not doing physics professionally. It remains my hobby as applied to wingsuits and whatever other interesting for me areas I find it useful and fun to apply to.

http://www.pureflyingmagic.com/About/

aonsquared

Quote

(And I strongly think, it never will.)

um...



Other than "um", any rigor proof?
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
Based on this conversation with "altimeter designer at AO(N²)" (per signature), I would not recommend the products from

https://www.aon2.co.uk

since they are "black boxes" (we don't know what they do inside) and as obvious from above, the lack of knowledge of physics and aerodynamics can result in errors in outputs. I wouldn't trust it!
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites
Quote

The solution of these is:

Kl = Vxs/Vs^3
Kd = Vys/Vs^3

With these adjusted coefficients, the wingsuit equations are

dVx/dt = g*V*(Kl*Vy - Kd*Vx)
dVy/dt = g*(1 - V*(Kl*Vx + Kd*Vy))

Now the unknown wingsuit parameters (wingloading mg/S and aerodynamic properties Cl, Cd) are "hidden" inside coefficients Kl and Kd, which can be easily calculated from sustained horizontal and vertical speeds.



Sigh. You treated C_l and C_d as constants. Which means if you use the equations that you used in the beginning:

D = 1/2 rho * V^2* S *C_d

Then yes, setting V to 0 will result in D = 0. Is this why you think the drag polar is invalid? Because of D = qSC_d?

Also, you said in the post:
Quote

We have 2 equations for 3 unknowns (k and Cl, Cd). But note that if we combine k with the Cl and Cd into "adjusted" lift and drag coefficients (no longer nondimensional)



Which is incorrect. k is known - it's 0.5*rho*S/m which is constant (rho = approximately 1.225 kg/m^3). So I'm not sure why you had to condense them to yet another set of coefficients.

It's understandable why D = 0 if V = 0 when you use that equation, but this drag term is not a constant - it's a condensed set of coefficients itself and is itself calculated with another equation. The drag polar was not derived from the equation you started with, which is why you got a different result. The equation you started with has been extremely simplified.

The V in this equation also denotes airspeed, and GPS measurements only measure ground speed.

Please refrain from personal attacks.

Share this post


Link to post
Share on other sites
aonsquared

Quote

The solution of these is:

Kl = Vxs/Vs^3
Kd = Vys/Vs^3

With these adjusted coefficients, the wingsuit equations are

dVx/dt = g*V*(Kl*Vy - Kd*Vx)
dVy/dt = g*(1 - V*(Kl*Vx + Kd*Vy))

Now the unknown wingsuit parameters (wingloading mg/S and aerodynamic properties Cl, Cd) are "hidden" inside coefficients Kl and Kd, which can be easily calculated from sustained horizontal and vertical speeds.



Sigh. You treated C_l and C_d as constants. Which means if you use the equations that you used in the beginning:

D = 1/2 rho * V^2* S *C_d

Then yes, setting V to 0 will result in D = 0. Is this why you think the drag polar is invalid? Because of D = qSC_d?



The equation for D is "the whole pie", as I explained in my reply to Geo. Splitting the drag "pie" into two parts, while can be done, is totally unnecessary for wingsuits. We still have to eat the whole pie. Split is useful for powered aircraft flying level at constant speed. Does not apply to us.

aonsquared

Also, you said in the post:

Quote

We have 2 equations for 3 unknowns (k and Cl, Cd). But note that if we combine k with the Cl and Cd into "adjusted" lift and drag coefficients (no longer nondimensional)



Which is incorrect. k is known - it's 0.5*rho*S/m which is constant (rho = approximately 1.225 kg/m^3). So I'm not sure why you had to condense them to yet another set of coefficients.



Because,

Quote

With these adjusted coefficients, the wingsuit equations are

dVx/dt = g*V*(Kl*Vy - Kd*Vx)
dVy/dt = g*(1 - V*(Kl*Vx + Kd*Vy))

Now the unknown wingsuit parameters (wingloading mg/S and aerodynamic properties Cl, Cd) are "hidden" inside coefficients Kl and Kd, which can be easily calculated from sustained horizontal and vertical speeds.



aonsquared

It's understandable why D = 0 if V = 0 when you use that equation, but this drag term is not a constant - it's a condensed set of coefficients itself and is itself calculated with another equation. The drag polar was not derived from the equation you started with, which is why you got a different result. The equation you started with has been extremely simplified.



Yes, Kl and Kd vary with angle of attack, and they form a polar curve in [Kl, Kd] space. This curve can be obtained from "natural research windtunnel" - your own flights. And can be subsequently used in modeling, for example, answering questions: what sequence of flight modes (Kl, Kd pairs) would be a winning strategy for competition in speed? in distance? in time? etc.

I strongly recommend contacting Hartman, may be he will share his brilliant spreadsheet that uses 3D WSE. (maybe he already posted it somewhere on social media, idk)

aonsquared

The V in this equation also denotes airspeed, and GPS measurements only measure ground speed.



Yes, I only operate with airspeed. GPS measurements cannot be trusted since the wind is never known with sufficient for us accuracy. L/D Vario and L/D Magic with the first two Kalman Filter models (with accelerometer and accelerometer+gyro when iphone is mounted on a vane) are completely independent from wind influence since the vane always point into relative wind, not apparent ground impact point.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account. It's free!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
0