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yuri_base

Wingsuit research

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yuri_base

I wouldn't even reply to Jarno's useless noise post, but today I learnt (an update was posted in Russian forum about May 24th accident in Kolomna, I missed that thread first time around) about this and that Vasily's (and his mother's) lives are essentially ruined by this guy who even has this hutzpah to post here his nonsense with insults accompanied by a bunch of smilies.

***Any updates on this incident? Seems like the basic rule of "you gotta plan the dive and then dive the plan" was ignored in this case.



Quote

From the Russian forum,

http://www.skycentre.net/topic/23850-270518-клмн-столкновение-во-время-винг-разбежки-тяжелые-травмы/?page=1

(requires registration)

September 12, update from his mother:

"Behind are the 3 weeks in resuscitation unit and 1.5 months in neurosurgery clinic/institute. Now recovering in the hospital of Russian Emergency Ministry. Vasily makes progress: sits in wheelchair, learns to walk and to do day-to-day actions (eat, dress, etc.), takes sessions with speech specialist and neuropsychologist. But there are serious deviations in health caused by severe brain trauma, and Vasily hasn't became yet "himself", he can't live without external help and needs the continuing care and recovery. Taking into account this slow recovery progress, it would take, in the best scenario, at least a half year of care and rehabilitation.

Clinics with decent care charge about $5000/mo. This is the reality. We would appreciate any financial help."

They need to hire a caretaker so that his mother can go back to work to pay for the huge bills.


So, once again, why the name of the person who ruined somebody's life (and mother's) - Jarno Cordia - is kept secret? (it's not secret on the Russian forum)



Dude,

What does this have to do with you coming up with some revolutionary wingsuit equations? It's hard to keep track of the point of this thread with you posting all sorts of nonsense. You fail yet again to answer simple questions?

What is you fastest wingsuit flight?

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I hope Jarno will not only show decency by coming out and saying in the Incidents forum that it was him, but send some of his windtunnel money to Vasily's mother. (https://vk.com/mvkarp) Even if they keep the tunnel shut down for 6.5 hours instead of making this stupid "world record", the saved electricity money would probably pay for a day of Vasily's recovery.
Android+Wear/iOS/Windows apps:
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iOS only: L/D Magic
Windows only: WS Studio

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let's move on to Wingsuit Equations, shall we?

Anyone succeeded in debunking WSE? I see that the initial denial stance of "they are 100% wrong!" changed to "I don't see any significance in them". Does this mean WSE are now accepted even by the stoogiest of the naysayers? We need to be clear on this to proceed.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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yuri_base

Now that we've discovered that "C" is a short for "COWARD", let's move on to Wingsuit Equations, shall we?

Anyone succeeded in debunking WSE? I see that the initial denial stance of "they are 100% wrong!" changed to "I don't see any significance in them". Does this mean WSE are now accepted even by the stoogiest of the naysayers? We need to be clear on this to proceed.



Yuri, you have to prove the WSE are correct. The burden of proof is on you.

I have asked you multiple times what the significance of your "Magic" L/D numbers are and you continue to fail to answer.

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yuri_base

I hope Jarno will not only show decency by coming out and saying in the Incidents forum that it was him, but send some of his windtunnel money to Vasily's mother. (https://vk.com/mvkarp) Even if they keep the tunnel shut down for 6.5 hours instead of making this stupid "world record", the saved electricity money would probably pay for a day of Vasily's recovery.

as apparently thread drift is authorised, and you don’t accept PM’s, do you have anything personal against Jarno ?
scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

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aonsquared

***Anyone succeeded in debunking WSE?



We need to clarify terms. With proving them wrong, do you mean mathematical proof, or physical proof?

Ever heard of proof by contradiction?

We don't even need to do that.

Yuri, came up with the WS equations. The burden is on him to provide the evidence to prove that the equations are mathematically correct and accurately represent the physical aspects he claims they do.

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This is the most impressive and zeroest S/N ratio body of work I've seen in my life. (see quotes below) Asking - dozens of times! - questions that are answered in the OP and links therein. Anyone even read original posts anymore, anywhere these days? Or just jump to the latest reply and make a knee-jerk reaction to that? Complete with unnecessary personification and personal attacks while what we discuss is just equations, numbers, software, instrumentation, articles, and stagnation of innovation in WS industry?

In the recent years I've come up with a radical change in how I post anything in the forums: I never use the word "you" (other than a depersonalized "you", like "If you know of anything not listed, please share."), I never personificate my replies, I only direct them to the subject at hand. (The "C" thing was the only exeption caused by sudden discovery of the situation. I'm done with this.) First of all, it keeps conversations civil. Second, if you don't know the person in real life, it's just a username to you, and it could be even artificial intelligence! (it would be totally stupid to become red-face angry at... a bot!) Now, read all the replies from my opponents and count all "Yuri"s and "you"s and "he"s in them!

Anyway, I hope more folks here and everywhere adopt this approach and we see a lot of interesting things here to read and discuss. This forum in particular has a long history of being a swamp (2010-2018) with nothing interesting in it, let's "Make it great again!" LOL

LeeroyJenkins


You are so full of shit, explaining why would be like talking to a brick wall.



LeeroyJenkins


Literally not how science works, the burden of proof is on you.



LeeroyJenkins


he is laughable on this topic.



aonsquared


And he's just blaming most of the skydiving community for not accepting his genius. What I find laughable is his excuses for not providing proof.



LeeroyJenkins


You are so full of shit. You probably didn't expect to run into an aerospace engineer and a mechanical engineer in here that know more about the mechanics of flight and airfoil design than yourself.



LeeroyJenkins


Did you just use your own equations to prove your equations right?



LeeroyJenkins


“I am very smart👌🏻, so much smarter that’s you🖐🏻, probably the smartest 👌🏻 person ever☝🏻.” - yuri



LeeroyJenkins


In simpler words. Yes he used his own equations to prove that his equations are right.



LeeroyJenkins


Yuri, why don’t you post your equation derivations? Or provide them somehow.



LeeroyJenkins


yuri, where are those derivations I asked for? Why won’t you say what you believe the magic L/D number translates to for wingsuit flight?



LeeroyJenkins


Can you just post your derivations? No more nonsense.

Can you also explain why you think 3.567 is the magic L/D number and what that number translates to in wingsuit performance?



LeeroyJenkins


Are you incapable of answering simple questions?

What does your magical L/D number translate to for wingsuit performance?

Where is the mathematical derivation of your equations?

Where is the physical data to back up your mathematical derivation?



LeeroyJenkins


Still waiting Yuri.....



Skwrl


There's definitely a CoW in this thread, and he's the one avoiding questions. I'm back to my comment about unsubstantiated mathsturbation. Seems like the models aren't substantiated - at least based on the reviews so far. I guess the world still isn't ready for the Yuri Device (remember when it was called that?)



LeeroyJenkins


Nice Dodge, answer these.

What does your magical L/D number translate to for wingsuit performance?

Where is the mathematical derivation of your equations?

Where is the physical data to back up your mathematical derivation?


Can someone repost these questions? I don't know if he is just ignoring me or he blocked me so he doesn't even see my comments.



LeeroyJenkins


As for now Yuris crack pot equations are unproven pshdoacience.



aonsquared


Again, I'm not really seeing anything new or revolutionary?



LeeroyJenkins


Im pretty sure this is how he came up with his equations. They prove what he wants them to and nothing more.



aonsquared


According to your earlier posts, do your wingsuit equations assume that either:

a) L points perpendicular to the trajectory curve? Or
b) L always points "up" opposite the gravity vector? Or
c) perpendicular to the wingsuiter?

Just trying to establish your conventions.



LeeroyJenkins


Whats your wing loading when you include the weight of your ego?


But really, if wingsuit manufactures posted the same nonsense you did, people like aonsquared and I would still criticize them. One thing I do know however, the aerospace engineers that work to design these suits understand aerodynamics way more than you do. You can't even answer simple questions because you know the answer will undo your theories.



LeeroyJenkins


Hey Yuri,

What's your highest performance wingsuit flight. Starting to get the feeling you aren't very good and want to blame the suit instead of the pilot. Your ego is so big you invented equations to make yourself feel better because all those MWS are keeping you down.



LeeroyJenkins


Dude,

What does this have to do with you coming up with some revolutionary wingsuit equations? It's hard to keep track of the point of this thread with you posting all sorts of nonsense. You fail yet again to answer simple questions?

What is you fastest wingsuit flight?



LeeroyJenkins


Dude, are you ok.... like mentally?



BryanCampau


This is a sad attempt at getting the attention off of yourself, Yuri.

You are still ignoring the questions directed at you that are relevant to this thread.



LeeroyJenkins


Yuri, you have to prove the WSE are correct. The burden of proof is on you.

I have asked you multiple times what the significance of your "Magic" L/D numbers are and you continue to fail to answer.



LeeroyJenkins


Yuri, came up with the WS equations. The burden is on him to provide the evidence to prove that the equations are mathematically correct and accurately represent the physical aspects he claims they do.



The full copy of the thread can be found here and in earlier captures:

https://web.archive.org/web/20180927232919/http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=4896302;page=1;mh=-1;;sb=post_latest_reply;so=ASC
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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yuri_base

This is the most impressive and zeroest S/N ratio body of work I've seen in my life. (see quotes below) Asking - dozens of times! - questions that are answered in the OP and links therein. Anyone even read original posts anymore, anywhere these days? Or just jump to the latest reply and make a knee-jerk reaction to that? Complete with unnecessary personification and personal attacks while what we discuss is just equations, numbers, software, instrumentation, articles, and stagnation of innovation in WS industry?

In the recent years I've come up with a radical change in how I post anything in the forums: I never use the word "you" (other than a depersonalized "you", like "If you know of anything not listed, please share."), I never personificate my replies, I only direct them to the subject at hand. (The "C" thing was the only exeption caused by sudden discovery of the situation. I'm done with this.) First of all, it keeps conversations civil. Second, if you don't know the person in real life, it's just a username to you, and it could be even artificial intelligence! (it would be totally stupid to become red-face angry at... a bot!) Now, read all the replies from my opponents and count all "Yuri"s and "you"s and "he"s in them!

Anyway, I hope more folks here and everywhere adopt this approach and we see a lot of interesting things here to read and discuss. This forum in particular has a long history of being a swamp (2010-2018) with nothing interesting in it, let's "Make it great again!" LOL

***
You are so full of shit, explaining why would be like talking to a brick wall.



LeeroyJenkins


Literally not how science works, the burden of proof is on you.



LeeroyJenkins


he is laughable on this topic.



aonsquared


And he's just blaming most of the skydiving community for not accepting his genius. What I find laughable is his excuses for not providing proof.



LeeroyJenkins


You are so full of shit. You probably didn't expect to run into an aerospace engineer and a mechanical engineer in here that know more about the mechanics of flight and airfoil design than yourself.



LeeroyJenkins


Did you just use your own equations to prove your equations right?



LeeroyJenkins


“I am very smart👌🏻, so much smarter that’s you🖐🏻, probably the smartest 👌🏻 person ever☝🏻.” - yuri



LeeroyJenkins


In simpler words. Yes he used his own equations to prove that his equations are right.



LeeroyJenkins


Yuri, why don’t you post your equation derivations? Or provide them somehow.



LeeroyJenkins


yuri, where are those derivations I asked for? Why won’t you say what you believe the magic L/D number translates to for wingsuit flight?



LeeroyJenkins


Can you just post your derivations? No more nonsense.

Can you also explain why you think 3.567 is the magic L/D number and what that number translates to in wingsuit performance?



LeeroyJenkins


Are you incapable of answering simple questions?

What does your magical L/D number translate to for wingsuit performance?

Where is the mathematical derivation of your equations?

Where is the physical data to back up your mathematical derivation?



LeeroyJenkins


Still waiting Yuri.....



Skwrl


There's definitely a CoW in this thread, and he's the one avoiding questions. I'm back to my comment about unsubstantiated mathsturbation. Seems like the models aren't substantiated - at least based on the reviews so far. I guess the world still isn't ready for the Yuri Device (remember when it was called that?)



LeeroyJenkins


Nice Dodge, answer these.

What does your magical L/D number translate to for wingsuit performance?

Where is the mathematical derivation of your equations?

Where is the physical data to back up your mathematical derivation?


Can someone repost these questions? I don't know if he is just ignoring me or he blocked me so he doesn't even see my comments.



LeeroyJenkins


As for now Yuris crack pot equations are unproven pshdoacience.



aonsquared


Again, I'm not really seeing anything new or revolutionary?



LeeroyJenkins


Im pretty sure this is how he came up with his equations. They prove what he wants them to and nothing more.



aonsquared


According to your earlier posts, do your wingsuit equations assume that either:

a) L points perpendicular to the trajectory curve? Or
b) L always points "up" opposite the gravity vector? Or
c) perpendicular to the wingsuiter?

Just trying to establish your conventions.



LeeroyJenkins


Whats your wing loading when you include the weight of your ego?


But really, if wingsuit manufactures posted the same nonsense you did, people like aonsquared and I would still criticize them. One thing I do know however, the aerospace engineers that work to design these suits understand aerodynamics way more than you do. You can't even answer simple questions because you know the answer will undo your theories.



LeeroyJenkins


Hey Yuri,

What's your highest performance wingsuit flight. Starting to get the feeling you aren't very good and want to blame the suit instead of the pilot. Your ego is so big you invented equations to make yourself feel better because all those MWS are keeping you down.



LeeroyJenkins


Dude,

What does this have to do with you coming up with some revolutionary wingsuit equations? It's hard to keep track of the point of this thread with you posting all sorts of nonsense. You fail yet again to answer simple questions?

What is you fastest wingsuit flight?



LeeroyJenkins


Dude, are you ok.... like mentally?



BryanCampau


This is a sad attempt at getting the attention off of yourself, Yuri.

You are still ignoring the questions directed at you that are relevant to this thread.



LeeroyJenkins


Yuri, you have to prove the WSE are correct. The burden of proof is on you.

I have asked you multiple times what the significance of your "Magic" L/D numbers are and you continue to fail to answer.



LeeroyJenkins


Yuri, came up with the WS equations. The burden is on him to provide the evidence to prove that the equations are mathematically correct and accurately represent the physical aspects he claims they do.



The full copy of the thread can be found here and in earlier captures:

https://web.archive.org/web/20180927232919/http://www.dropzone.com/cgi-bin/forum/gforum.cgi?do=post_view_flat;post=4896302;page=1;mh=-1;;sb=post_latest_reply;so=ASC

Yes Yuri, If you would answer simple questions most of those comments wouldn't exist. I'm not going to dig through 50 links looking for an answer to a question you can provide by typing for 15 seconds.

This thread is about your wingsuit equations that you need to prove to the world because you came up with them and you claim they are revolutionary. Yet, you continuously fail to answer simple question.

I am directly asking you, Yuri, the creator of the wingsuit equations about your equations and you refuse to answer the dozens of proposed questions. Here are a couple below. You can even copy paste to make answering them easier.

What is the fastest horizontal speed you have recorded during a wingsuit flight?:

What is the limiting design factor of forced air wingsuits?:

What do your "magic" L/D numbers translate to for wingsuit performance?:

What does the max L/D number translate to for glided flight?:

Did you use Bernoulli's equation or Euler's Formula to derive your wingsuit equations?

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LeeroyJenkins

Attached is my first flight in a freak 2. Also attached is the Raw data. It wasn't the longest flight as I pulled high. It also wasn't a fast flight.



and

LeeroyJenkins

I’ve played with the WS equations and used my GPS data in them and gotten absolute nonsense as an output.



This clearly demonstrates total lack of understanding the basic premise of WSE: they only consider motion relative to air, in the inertial reference frame of the airmass (which is assumed to be moving at constant velocity, or be completely still). In WSE, Vx, Vy, ax, ay are speeds and accelerations relative to air, not the ground!

If one uses GPS data from a skydive, with unknown wind, it's patently ridiculous to "used my GPS data in them and gotten absolute nonsense as an output". It's like recording a GPS track of walking to a restroom in a jet liner and giving it to a running coach asking, "how's my running? looks promising, eh?"

Again, it's like taking the problem of determining the strategy for fastest time from A to B in wingsuit, and applying solution for a completely unrelated problem (bead sliding on frictionless string).

The GPS data from skydives should be considered complete garbage, as the wind can never be reliably subtracted.

The only value of GPS is for windless BASE jumps. Then it's in reasonable agreement with WSE (taking into account inaccuracy of GPS), as platypii's, Hartman Rector's, and multiple mine examples demonstrate.

Use the right tool for the right job.
Android+Wear/iOS/Windows apps:
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iOS only: L/D Magic
Windows only: WS Studio

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yuri_base

***Attached is my first flight in a freak 2. Also attached is the Raw data. It wasn't the longest flight as I pulled high. It also wasn't a fast flight.



and

LeeroyJenkins

I’ve played with the WS equations and used my GPS data in them and gotten absolute nonsense as an output.



This clearly demonstrates total lack of understanding the basic premise of WSE: they only consider motion relative to air, in the inertial reference frame of the airmass (which is assumed to be moving at constant velocity, or be completely still). In WSE, Vx, Vy, ax, ay are speeds and accelerations relative to air, not the ground!

If one uses GPS data from a skydive, with unknown wind, it's patently ridiculous to "used my GPS data in them and gotten absolute nonsense as an output". It's like recording a GPS track of walking to a restroom in a jet liner and giving it to a running coach asking, "how's my running? looks promising, eh?"

Again, it's like taking the problem of determining the strategy for fastest time from A to B in wingsuit, and applying solution for a completely unrelated problem (bead sliding on frictionless string).

The GPS data from skydives should be considered complete garbage, as the wind can never be reliably subtracted.

The only value of GPS is for windless BASE jumps. Then it's in reasonable agreement with WSE (taking into account inaccuracy of GPS), as platypii's, Hartman Rector's, and multiple mine examples demonstrate.

Use the right tool for the right job.

Yuri, answer the questions they are not hard.

What is the fastest horizontal speed you have recorded during a wingsuit flight?:

What is the limiting design factor of forced air wingsuits?:

What do your "magic" L/D numbers translate to for wingsuit performance?:

What does the max L/D number translate to for glided flight?:

Did you use Bernoulli's equation or Euler's Formula to derive your wingsuit equations?



Incase you forgot you posted a link to a spreadsheet where you enter Vx and Vy. It doesn't mater if they are gps or from a vain, as long as they are within a reasonable % of wingsuit ability your equations should produce reasonable results.

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LeeroyJenkins

you posted a link to a spreadsheet where you enter Vx and Vy. It doesn't mater if they are gps or from a vain, as long as they are within a reasonable % of wingsuit ability your equations should produce reasonable results.



Excel solver from this post?

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

It uses initial airspeeds Vx and Vy, as well as a constant flight mode [Vxs, Vys] and then solves WSE for a given length of time (again, relative to air). Not ground Vx and Vy that are from skydive's GPS data. If one uses the latter, of course they would get complete nonsense! Also, one needs to know the flight mode, or try to guess it by trying the fit the theoretical trajectory (or at least, speed profile) to real one; if one just uses default numbers pre-entered in the spreadsheet, they would again get complete nonsense.

I thought this was obvious.

Also, I recommend using Wingsuit Studio instead, since it uses proper altitude density correction, as well as more robust Runge-Kutta (4th order) algorithm to solve WSE (instead of Euler in the simple solver above).

Again, a perfect example of using [this time] a right tool, but for the wrong job. Like using an oscilloscope as a hammer.
Android+Wear/iOS/Windows apps:
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Here is Yuri's WSE spreadsheet for a theoretical base jump.

Now its been awhile since I took control theory but what's with all that overshoot in your graph?

I'd take a 4.6 Glide any day.

Edit 1:

Quote

It uses initial airspeeds Vx and Vy, as well as a constant flight mode [Vxs, Vys] and then solves WSE for a given length of time (again, relative to air). Not ground Vx and Vy that are from skydive's GPS data. If one uses the latter, of course they would get complete nonsense!



False, If you put in values that are well within the range of wingsuit performance you should get valid results back. I put Vx=100 and Vy=40 in the attached spreadsheet. Both numbers that are very reasonable to travel through air.


Edit 2: You still didn't answer the questions.

What is the fastest horizontal speed you have recorded during a wingsuit flight?:

What is the limiting design factor of forced air wingsuits?:

What do your "magic" L/D numbers translate to for wingsuit performance?:

What does the max L/D number translate to for glided flight?:

Did you use Bernoulli's equation or Euler's Formula to derive your wingsuit equations?

WingsuitEquations.xls

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LeeroyJenkins

If you put in values that are well within the range of wingsuit performance you should get valid results back. I put Vx=100 and Vy=40 in the attached spreadsheet. Both numbers that are very reasonable to travel through air.



Correct. Putting in Vxs=100mph and Vys=40mph with initial speeds Vx=0 and Vy=0 would correctly model a WS BASE jump with realistic flight mode (for someone, in some wingsuit with L/D=2.5), provided the flight mode remains constant throughout the flight (i.e. the pilot holds the same AoA and body configuration all the time). Why the results seem to be invalid?
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yuri_base

***If you put in values that are well within the range of wingsuit performance you should get valid results back. I put Vx=100 and Vy=40 in the attached spreadsheet. Both numbers that are very reasonable to travel through air.



Correct. Putting in Vxs=100mph and Vys=40mph with initial speeds Vx=0 and Vy=0 would correctly model a WS BASE jump with realistic flight mode (for someone, in some wingsuit with L/D=2.5), provided the flight mode remains constant throughout the flight (i.e. the pilot holds the same AoA and body configuration all the time). Why the results seem to be invalid?

The most obvious is the overshoot in the graphs for GR. The second thing is the 4.5 mag glide that peaks.

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LeeroyJenkins

The most obvious is the overshoot in the graphs for GR.



What's an "overshoot"? Like, the graph line going out of axis boundary? Just set the automatic min/max axis values.

LeeroyJenkins

The second thing is the 4.5 mag glide that peaks.



And? What's wrong? That's what glide does on a WS BASE jump, it peaks, provided the pilot flies with consistent AoA in flight mode that has at least L/D of approx. 1.0 (as demonstrated in this picture; below L/D=1.0, GR doesn't reach a peak higher than L/D, it just increases monotonically from 0 to L/D).
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LeeroyJenkins

Here is Yuri's WSE spreadsheet for a theoretical base jump.

Now its been awhile since I took control theory but what's with all that overshoot in your graph?

I'd take a 4.6 Glide any day.



Over and over again - a clear demonstration of lack of understanding of difference between GR and L/D. And I'm tired to explain it over and over again, but I do it for other readers who will finally get it.

GR is simply the ratio of current horizontal [air or ground] speed to vertical [air or ground] speed. (thus, different GRs - ground GR, measured by GPS, and air GR, which is equal to ground GR only when there's absolutely no wind and thermals/downdrafts) It can take any value from 0 (first fraction of a second in BASE exit with no forward push) to positive infinity (when pilot transitions from full flight into a flare and flies a concave arc trajectory, and the speed is purely horizontal for a moment) and then flips through negative infinity to some negative number corresponding to steepest climb angle during the flare.

L/D is NOT a ratio of speeds, L/D is literally a lift-to-drag ratio, at any moment in time, and in general is not equal to GR. For example, 1-2s after BASE exit, GR is essentially zero (jumper is mostly just falling down), but L/D is equal to that of the flight mode he's currently in; for example, if pilot managed to "nail" the AoA and body position after 2 seconds, to that of his best L/D (say, 3.0), then L/D is 3.0 at that moment! So, GR~0, while L/D=3 at that moment.

L/D has hard top boundary (the bottom is, of course, 0 - no lift, pure drag) that is determined by aerodynamic "finesse" of the gliding apparatus, in our case, wingsuit and its pilot. And at current state of the art of wingsuiting, max L/D across all pilots, rich and poor, of any skin color, big ego or small - is approx. 3.0, give or take maybe +/-0.1, for an average body build and average bulk rig. (of course, superlean pilots - possibly just released from Guantanamo Bay - with superthin rigs have a slight advantage over the average builds, probably by 0.1-0.2)

Is this explanation of the difference between GR and L/D enough?
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I will continue, because there's never enough times to hammer the differences between L/D and GR.

Imagine you're standing on a sand surf board on a sand dune. (Suppose) the board has a coefficient of friction 0.4 with sand. (This means that if total weight of person+board is 100kg, and it's on level sand surface, it will take 40kg of force to move it horizontally at constant speed.) If you stand on a slope with the angle arctan(0.4)=21.8 degrees to horizon, the board will juuust start sliding on sand, because at this angle the component of weight parallel to slope becomes equal to friction force. But if you make a half-pipe from steel to first fall straight down, gain a lot of speed, and then start surfing the sand, then you for some time can slide on a more shallow slope, like angled at only arctan(1/4.6)=12.3 degrees. Of course, you will start slowing down and you can't sustain sliding on 12.3 degrees indefinitely, only on 21.8 degrees you can slide indefinitely! Also, given enough gained speed, you can even temporarily go up on the upward sand slope!

As I explained in some previous posts, L/D is analogous to the inverse of the coefficient of friction, so in this example L/D = 1/0.4 = 2.5 and sustained glide slope is 21.8 degrees to horizon. The "glide ratio" in this case is simply the inverse of the tangent of the slope to horizon. So, it was zero on the top of the half-pipe (sliding on steel straight down), then the pipe increased it, and you peaked "GR" at 4.6 (you overshot "L/D" of 2.5!), but it decreases after that and you can only sustain, of course, 2.5 in the long run. But if you have enough gained energy from a "dive", you can even temporarily go up - "flare".

Note that at all times the coefficient of friction remained 0.4 (L/D remained 2.5), while "GR" increased from 0, peaked at 4.6, and then fell to 2.5 in the long run.

Have I hammered the diff between GR and L/D, L/D and GR, hard enough? Or it's still not enough?
Android+Wear/iOS/Windows apps:
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iOS only: L/D Magic
Windows only: WS Studio

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Overshoot is what your equations are doing. Look up Gibbs phenomenon if you want the fancy math version.

Yuri, I know the difference between L/D and GR. I pointed out the fact that your spreadsheet said after 30 seconds there would be a GR of ~4.5 You claim that Yuri, your equations say that.


You still didn't answer the questions.

What is the fastest horizontal speed you have recorded during a wingsuit flight?:

What is the limiting design factor of forced air wingsuits?:

What do your "magic" L/D numbers translate to for wingsuit performance?:

What does the max L/D number translate to for glided flight?:

Did you use Bernoulli's equation or Euler's Formula to derive your wingsuit equations?:

How do you personally calculate the coefficient of lift?:

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LeeroyJenkins

Overshoot is what your equations are doing. Look up Gibbs phenomenon if you want the fancy math version.



https://en.wikipedia.org/wiki/Gibbs_phenomenon#Explanation

Wikipedia

Explanation

Informally, the Gibbs phenomenon reflects the difficulty inherent in approximating a discontinuous function by a finite series of continuous sine and cosine waves.



Has absolutely nothing to do with WSE. A better analogy would be a pendulum in viscous liquid where it will swing and overshoot the equilibrium state due to initial energy. And the less viscosity, the more it will overshoot (like the higher L/D, the higher peak GR will be achieved; with L/D = 3.567, the peak will be equal to infinity).

Just like that cycloid example mentioned above. Totally irrelevant.


LeeroyJenkins

I made a statement off the fact that your spreadsheet said after 30 seconds there would be a GR of ~4.5



After 18 seconds, not 30. And what is wrong with that? I personally have experienced this "overshooting" on all BASE jumps when starting to fly quickly (i.e. using mushy, high-lift flight mode with AoA ~ 45 degrees) was not necessary and I could dive at constant L/D. The time of onset of this planeout and its duration depend on wingloading - shorter for light jumpers and longer for heavier ones. It's all in the same post as with the Excel solver.

[inline PlaneoutTheoryVsExperiment.gif]

[inline PlaneoutVsLD.gif]

[inline PlaneoutVsWingloadingAndLD.gif]
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

PlaneoutTheoryVsExperiment.gif

PlaneoutVsLD.gif

PlaneoutVsWingloadingAndLD.gif

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Yuri, you honestly don't see whats wrong with you GR v. Time graph with the various L/D plots on it?

After all you have said about L/D and GR being different you don't find it weird that the steady state GR=L/D?

You don't think it's weird that your equation overshoot steady state?



*this is not my professional opinion. This is a question of Yuri's consistency and understanding.

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LeeroyJenkins

Yuri, you honestly don't see whats wrong with you GR v. Time graph with the various L/D plots on it?



No.

LeeroyJenkins

After all you have said about L/D and GR being different you don't find it weird that the steady state GR=L/D?



No.

LeeroyJenkins

You don't think it's weird that your equation overshoot steady state?



No.
Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

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