yuri_base

rscott

A true heads up display would be nice, but is overly complex and not needed. With the display and electronics so small today the whole thing could mount on the helmet with a small display in view.

HUD does not need to be complex, it can be just a semitransparent mirror or two mirrors reflecting the smartwatch's screen which is mounted on the helmet out of the way. There are cheap products ($3-10) for smartphones that do the same:

[inline HUD1.jpg]

[inline HUD2.jpg]

For a smartwatch with 1.4" screen, the whole thing can be quite compact.

I use the 99 cents grippy gloves from Home Depot. They're thin, so maybe not enough for real winter, but enough for the temperatures when your hands get pain from cold. Can't find exact model, but similar to this:



https://www.homedepot.com/p/2XL-Black-NiteGrip-6001-2XL/302952136

They provide excellent grip and precise feel-through.

Imho, Neumann's are way overhyped. Way overpriced ($45 LOL); not warm for real winter, either; weak, tear easily; not enough precision feel to make things like collapsing slider easy.

I recommend to everyone when needing peripheral gear, to look elsewhere, not skydiving shops. Gloves, helmets, goggles, even altimeters - there are excellent alternatives available that work well and are not outrageously priced.

SMBowen

I have been thinking about buying the Garmin Varia and having it display my watch information. I recognize that my watch doesn't have the same refresh rate as my skydive altimeter, but it would at least give me the rough number.

https://buy.garmin.com/en-US/US/p/530536

Buyer beware: Garmin Fenix 3 does not update altitude in freefall fast enough, some skydivers reported that it stops updating after exiting the aircraft and resumes only after opening, some see 1000ft delay:

https://www.youtube.com/watch?v=KacXA8OJ4fo

This is a perfect illustration of my point that hardware is "game over", meaning that it doesn't make sense anymore to make specialized hardware to measure altitude - "generic", affordable hardware (like Moto 360 Sport, $50) already exists (and will only get better with time) with excellent barometric sensors, the game is software. It's software that can make an expensive hardware a piece of junk; or can make an inexpensive hardware shine. And with Android/Wear, anyone can start writing their own altimeter app.

Let's Make Altimeters Great Again!

Here's the diagram I promised. I didn't find the pressure distribution around a cone, but by analogy with the pressure distribution on the bottom surface of an airfoil -

[inline AirfoilPressureDistribution.gif]

- pressure is nearly perpendicular to the surface of the cocoon, so it tries to compress the cocoon, not to "skin" it. Fresh ZP is happy to unwrap itself as it's so slippery and springy, but used ZP's friction can keep the cocoon closed for an extra fraction of a second and cause the slider to slide down the lines as it encounters no resistance from the wind - it's inside the "cabin" of the cocoon. With wingsuit, due to sagging, the air mostly hits the bottom of the cocoon which is a smooth surface and it's just happy to stay closed and trailing behind.

[inline MechanismOfCocoonHesitation.jpg]

Anyway, I feel I said everything I wanted to say, tested the ground 5 years after first sharing this (after about 4 years of testing it), and it's still infertile. Oh well, not the first time, not the last. I'll revisit the topic in a few years to see if it's a good time to plant the seed. Bye bye now!

>>> BASE pack jobs. (Neither of which, of course, having "slow comfortable deployment" as a goal.) <<<

Exactly - when saving life is paramount, having "slow comfortable deployment" is not a goal. But deploying main in skydiving *is* an act of saving life, too. So, having "slow comfortable deployment" should not be a goal, neither. Having comfortable, but not slow, opening should be a goal. ES method provides perfect middle ground between slow opening wasting too much of our most valuable asset - altitude - and hard opening that consumes little altitude but makes us unable to have fun due to pain. Its speed of opening is an optimal balance between comfort and safety.

https://www.youtube.com/watch?v=Bg8O5-6fDz0

This is a tracking jump pulling from full flight, and since I'm heavy (260lbs out the door), the speed is "superterminal" for sure, perhaps, ~140-150mph? Not a problem for Exposed Slider method. The opening is not "falling into pillows", but is not hard either. Yes, I've got an offheading 90 degrees, but taking into account that I rarely jump my tracksuit (almost 100% - wingsuit), it's not too shabby.

**Insults removed** Try it in 2-3 jumps moving the mouth of the cocoon down 1 inch at a time. When the logic of presenting the slider to relative wind as #1 stage in the openings sequence (after D-bag opens) becomes obvious and tried, stand in the middle of the hangar and loudly proclaim: "Guys, I just had my FIRST properly staged opening! Beeeeeeeeeeeeerrrrrrrr!!!"

PhreeZone

In that photo the grommets are not exposed, they just did not cocoon it as tight as some jumpers do for the photos.

The reason that in the reserve manual they are shown that way is since you need to stack the grommets on top of each other for each side while creating an and at no point are you wrapping the tail all the way around the canopy. Reserve openings from terminal are rarely described as "Soft and gentle" - the method we use to pack reserves is to give the canopy the best chances of opening on heading in the fastest possible way while consuming the least amount of altitude while not causing openings that are excessively hard. We leave the nose exposed and don't wrap anything.

These are just weak excuses, once it's admitted that it's "officially" (from PD) OK to just "lay" the mouth on top of the grommets (there's no tension, no resistance there), or make them even barely visible through the hole, one might as well just "go big" and expose them fully. The way it's done in my photo actually keeps the bulk of the slider under some tension of the "neck", there's no tension whatsoever in the PD Horizon photo.





It's fascinating to watch how resistance to any deviation from habits and dogmas works. "This is PD, this is OK, but not even an inch lower! Once even 1 millimeter of the shiny grommets becomes visible, bad things will happen catastrophically!" Hard to believe, but it proves to be true - very experienced jumpers with many thousands of jumps are scared to do 2-3 jumps with gradually lowering the cocoon.

And it's not about "Soft and gentle", it's about priorities, it's about doing things right, it's about staging the opening properly. And to stage it properly, slider must be numero uno thing that is presented to the wind. Not the cocoon... slider. Period! The openings become more immediate, without wasting altitude to "Soft and gentle". How many times we've read in fatality reports, that "after cutaway, the reserve was activated but didn't have enough altitude to fully inflate"? (extra 100-200ft would make a huge difference.) That's because of wasting altitude to "falling into pillows", "Soft and gentle". We're not jellyfish, we don't need to fall into pillows, we can take an opening that starts immediately, but is not hard by any measure.

>>> That looks similar to what PD recommends for packing the Horizon. They state to leave a small mouth open at the tip of the cocoon. <<<

Leaving small mouth open didn't work for me when I had troubles with my Spectre. I started opening it more and more over 2-3 jumps, until got brave enough to "go big" and expose the grommets fully. BOOM, problem solved. Apparently, the air pressure near the tip of the cocoon in angled deployment works in such a way that it can close the small mouth. (probably, works better for belly deployment) When grommets are exposed, that doesn't matter, because slider starts inflating immediately and pushes the cocoon open.

>>> Why dont you just email John LeBlanc and ask him what he thinks?

I feel zero need. The "authorities"*, from my experience, are virtually always dismissive. For example, I've tried to talk to wingsuit manufacturers back in 2005-2010 about ideas like leg wing-only half-wingsuit, angle of incidence, balance, instrumentation, flight analysis and modeling, etc. - they've always been dismissive, ridiculing sometimes even. "This won't work, you're wrong, you don't know what you're talking about, ..." etc. etc.

Besides, it's funnier when the revolution comes from within, from the "masses". When manufacturers are late to the party. Just shows how little fresh thinking they do, they just sit on their throne for decades. I'm just that little spark that ignites the fire under their throne.


* no disrespect to anyone in particular

Android+Wear/iOS/Windows apps:
L/D Vario, Smart Altimeter, Rockdrop Pro, Wingsuit FAP
iOS only: L/D Magic
Windows only: WS Studio

dgw

I think the physics of what you say is difficult to refute. I agree with the idea. Safe implementation might be a practical issue, but implementation of the 'standard' method is also potentially a practical problem.

Out of curiosity, I downloaded a PD reserve manual to see what the practice is on (a) reserve parachute. It's a TR-375, which was just the first manual that I happened upon.

The attached photograph shows the slider packing method to be ES

Haha, this is awesome, thanks!

[inline ReserveWithExposedSlider.jpg]

>>> https://www.youtube.com/watch?v=cVAoiLl2B6M
What's interesting that in the old illustrations of PRO pack we've all seen in the manuals, it shows slider grommets exposed, with a big "mouth" of the cocoon making grommets visible:

[inline OldPROPackIllustration.gif]

(is this John LeBlanc, a sketch made from a photo?)

So, maybe it was taught like this in the beginning (1970's?), but people just started wrapping the cocoon tightly above the grommets, and it just stuck, and exposed grommets became a "no-no"?

But in the video, we see a tightly closed cocoon with no hole in the apex and no slider grommets visible.

INCORRECT:

[inline PDIncorrect1.jpg]

INCORRECT:

[inline PDIncorrect2.jpg]

INCORRECT:

[inline PDIncorrect3.jpg]

CORRECT:



(Forgot: yet another benefit of the ES method is it makes squeezing air out much much easier.)


According to USPA, about 3 million jumps are made every year. Worldwide, probably about 5 million? Every jumper experiences a hard opening once in a while. Let's be conservative and say that on average, hard opening occurs only once in 1000 jumps. That's ~5000 hard openings a year. Some of them are hard enough to cause at least some injury (spine, neck). And some of them are hard enough to kill. (probably, an average of 1 per year? some deaths that are chalked up to "medical condition" may have been caused by a hard opening as a trigger of that medical condition)

If we can develop a method that reduces hard openings by at least some factor - 10, 100, whatever - that's a great achievement, there will be many thousands of people (over the years) without back/neck problems, and dozens of people (over the years) alive today. Imagine they're alive and knew that they were destined to be killed by a hard opening - you could organize a boogie and invite these "dead men walking" and celebrate life!

I - very strongly - believe that Exposed Slider is such a method.*

Don't hide the slider from the blast of fresh air it likes so much! Free the nipple slider!



* I'm only a human, so might be wrong. Only widespread courage of experienced jumpers willing to test it, can prove it right or wrong. I've done 400 tests, I'm done with this. The ball is in YOUR court now.

Westerly

***https://www.youtube.com/watch?v=hVJjN-O6EG0


For wingsuiters, I recommend dropping all this collapsing PC BS and getting a non-collapsing PC. With big wingsuits (this is V-4 in the video, that's not very big) the burble is massive, even when pulling from full flight. The burble causes the lines go all over the place. Non-collapsible PC will keep the lines straight throughout the deployment.

How does a non-collapsible PC keep the lines straight? Both a collapsible and non-collapsible PC will be fully inflated until the canopy is completely out of the bag. The lines in your video dident look any more 'all over the place' any more than a standard belly jump. Slowing down the video, the lines were most chaotic right after a stow released them, suggesting a semi-stowless bag would be of greater benefit to prevent that.

Quote

Non-collapsible PC will keep the lines straight throughout the deployment.

https://www.youtube.com/watch?v=hVJjN-O6EG0

I found an example at 120fps, but not sure if Youtube retains 120 or downconverts it to 60fps. Anyway, try setting 720p60 in Quality and 0.25 in Speed. If you view frame by frame, you'll see that the slider got a bit "confused" in the first moments probably because it was not quartered well, it took a few moments to quarter itself.

Presenting more videos like this won't show anything new, the openings become 1:1, carbon copy of each other. Immediate and on heading. Boring, no variability. Those who crave the excitement of "panoramic linetwists" and cutaways, can always hide the slider under the cocoon.

For wingsuiters, I recommend dropping all this collapsing PC BS and getting a non-collapsing PC. With big wingsuits (this is V-4 in the video, that's not very big) the burble is massive, even when pulling from full flight. The burble causes the lines go all over the place. Non-collapsible PC will keep the lines straight throughout the deployment.

My "burden of proof" is officially furnished. It's now up to you, ma chickenz, to multiply and lay more eggs!

sundevil777

The pics you provided aren't enough to convince. The number of jumps you've done with ES is quite significant, but it is reasonable to want better visual proof.

I posted both before and after videos (they're small to fit under 1MB limit, but enough to show the gist). They are 30fps, can be examined frame by frame. Doing more fps won't produce more evidence, just more of fabric flapping in the wind. But everyone is welcome to, it won't be coming from me anymore!

>>> Why do you recommend this method for WS jumps but not standard terminal jumps? If the cone hiding the slider from the wind is the issue, the cone is still wrapped around the slider on belly jumps too you know. <<<

Quote

I fully recommend it for any environment. This is simply how parachute deployment should work!

>>> I think I know what equation you're going for but you're leaving out just every real world concept and confusing statics, dynamics and fluid dynamics. <<<

These are just empty words, no value. Diagrams, equations, argumentation to back this up?

>>> And yes that's what my degree is in. <<<

Ph.D. in Physics here. Worked in both experimental and theoretical physics. (Currently a programmer.)

>>> What you're trying to say is that there's a relationship between friction, force and the angle of the fabric against each other. That's not something that can be modeled by back of the napkin math or really any mathematical equation as it applies to fabric at those wind speeds. <<<

Sure, exact modeling is complex. But as an illustration of the concept, it is sufficient.

>>> Please continue with your experiments in the air and we'll be happy to learn from the results. <<<

Nope, not gonna happen. I quit jumping skydiving canopy (Spectre) several years ago. Skydiving my BASE canopy ever since, and totally love it always jumping the same canopy in any environment. So, packing is very different, and Exposed Slider method does not apply... actually, in BASE packjob slider is always exposed, there's no cocoon. The ~400 jumps I did on the ES packjob in 2009-2013 are final.

If anyone wants to collect statistical data, they'll have to do it themselves.

>>> He's also missing a lot of the forces involved, like acceleration during deployment. Indeed he explicitly ignores it - "Slider in this case is like a pilot in the cabin" - as if there are no acceleration forces on the slider. <<<

True, there are some acceleration forces acting on the slider once linestretch is achieved and canopy is out of the D-bag: because the whole system "jumper-canopy" is decelerating due to extra drag, slider is experiencing extra force, besides gravity of the grommets, that pulls it down the lines. Adding insult to the injury, so to speak. But the shake of the dancing cocoon, I think, is the dominating factor in shaking the slider down the lines under the cover of the cocoon-"cabin". Slider that is exposed and experiencing 100lbs+ force from the wind pushing it against the stops, is not going anywhere, neither by deceleration not the shake.

>>> As a side note, what many people experience during their packing careers goes something like this:

They try to learn to pack. Their new ZP goes everywhere. They get hard, inconsistent, off heading openings.

Someone tells them to try psycho packing. They try it for 30 pack jobs or so. ZP goes everywhere. They get hard, inconsistent, off heading openings.

Someone tells them to try putting the top of the canopy in the bag first before the S-fold. They try it for 30 pack jobs or so. ZP goes everywhere. They get hard, inconsistent, off heading openings.

Someone tells them to use a hook. They try it for 30 pack jobs or so. ZP goes everywhere. They get hard, inconsistent, off heading openings.

Someone tells them to turn sideways while they are packing. They try it for 30 pack jobs or so. ZP goes everywhere. They get hard, inconsistent, off heading openings.

Someone tells them to pack on concrete instead of grass. They try it for 30 pack jobs or so. ZP goes everywhere. Their openings start to get better!

Their conclusion - packing on grass causes hard openings. They post on S+T to tell everyone the wonderful news, but lament that until someone like John LeBlanc tells everyone this obvious truth, people will still suffer hard openings.

What has really happened, of course, is they just did 150 pack jobs and got to be better packers. But packing is so complex, and so hard to learn - and improvement comes so slowly - that they chalk the improvement up to the last thing they tried.

I have a feeling the same thing is going on here. But everyone has to learn that for themselves. <<<

This is a perfect example of dynamics of acceptance of new things in skydiving world. All these examples, "psycho packing", "putting the top of the canopy in the bag first", "use a hook", "turn sideways while they are packing", "pack on concrete instead of grass" are things that someone tried before and maybe in their particular situation (there are many variables) it helped. And these things got at least some acceptance, they're not considered to be "What Yuri described can indeed be deadly". But since nobody tried (except me, with good results) exposing the slider and is not something we hear at DZs as one of the advices on how to eliminate hard oepnings, it is perceived as "deadly". Chicken and egg. We're so scared to try new things (even fully backed up by problem identification, logical analysis, solution finding, and testing for hundreds of jumps) that we start justifying our unsubstantiated fear by calling it "deadly", "this is a bad thing to teach students", etc.

By the way, I didn't arrive at fully exposed slider at once, I did it gradually over several jumps, making a 1-inch hole in the apex, 2-inch, 3-inch... (with slider still hidden by the cone; and of course, the wraps were very light, barely enough to keep the packjob from falling apart) And when I found that nothing bad happens, but the problem still persists, I finally fully exposed the slider grommets, and BOOM! problem's gone. So, anyone who wants to try, but scared, just do it gradually over several jumps. And then maybe we'll have enough chickens to start multiplying.

Exposed Slider method will be more noticeable by wingsuiters with aging ZP canopies who are experiencing frequent delayed openings, linetwists, and sometimes hard-ish or hard openings. The improvement of proper staging the opening thanks to ES method, will be less noticeable for fresh ZP and belly-down deployments.

However, I'm claiming something bigger, and it's not only possible solution for problems when they start: I'm claiming that exposing the slider, i.e. presenting it to the wind as the very 1st thing in opening sequence, is THE right way of staging the deployment, it is THE right way to pack, while hiding it is THE wrong way to pack and may occasionally stage the opening incorrectly and lead to injury or even death from extremely hard opening.

Very hard openings are relatively rare and impossible to predict, so the improvement in reducing their occurrence may not be immediately noticeable; but in the long run, the effect should be noticeable by not reading anymore in Incidents forum that someone died of hard opening. For this to happen, the method should be widely accepted, taught to students, included in packing videos, etc. But it won't happen anytime soon... Maybe, Bill Booth will come and say, "Yuri has the valid point. I tried it and I think this is the way to proper stage the opening. I recommend it." And everyone will throw their hats in the air, "Hooray! Genius! Bill does it again! Bill reinvents the properly staged opening! And doesn't even patent it! Hallelujah!" Unfortunately, this is how things work, widespread acceptance needs The Authority to endorse it. Not some unknown dude Yuri.

Further argumentation of the discovered mechanism of hard openings due to cocoon hesitation and of proper use of slider.

The packed canopy cocoon is like a cone, with some angle at the apex. The wind force tries to push the center cell tail surface forming the cocoon "up" this slope. The aerodynamic force acting on the angled surface of the cocoon is at some angle to the surface, and due to relatively high lift-to-drag ratio of the angled surface, this angle is actually close to perpendicular to the surface. (I'll draw a force diagram later.) Let's call this angle between perpendicular to the surface and aerodynamic force alpha.

We know from basic physics that for an object to slide on an inclined surface, tangent of the angle to horizon must be greater than the coefficient of friction k:

tan(alpha) > k

So for the tail to start sliding off the rest of the canopy, while experiencing friction against it, k must be below certain value as per formula above (read from right to left).

If for fresh ZP k is less than this value, it will slide off easily; if ZP is no longer fresh after few hundred jumps, k might exceed this value and then cocoon hesitations will start to happen.

This is the physical mechanism for cocoon hesitations (CH).

Now, let's consider what happens during the CH. When the cone stays closed for some extra tenths of a second (on WS jumps sometimes even one or two seconds, due to slower speed and angled deployment), the slider experiences zero force from the air, and its heavy grommets start sliding down under the cover of the cone. The apex of the cone itself cannot stop this, since it simply moves with the grommets pulled by gravity. Slider in this case is like a pilot in the cabin: there's no wind to push him against the seat, and if the plane is falling straight down nose first, the pilot will fall out of the seat forward on the dashboard. Slider moved a few inches down the lines - boom, a hard opening.

If slider is exposed, it's like a pilot with no cabin - he's pushed by the wind into the seat. Same with slider - it's pushed against the stops with significant force - probably, ~100lbs. It's not going anywhere and starts doing its primary function - reefing - immediately. When canopy starts inflating, it resists the expansion and slows down the opening.

This is the proper opening sequence - slider is inflated immediately and starts working. This is the proper way of packing. Slider MUST be exposed, not hidden.

>>> This technique might work for the slower environments of Wingsuiting but it is not recommended to do it in a terminal environment. <<<

Not recommended by who? Anyone actually tried? I've done many, many deployments with Exposed Slider method on non-WS jumps as well, pulling from full track without even slowing down (and I'm 260lbs out the door, my track speed, especially in tracksuit, is way more than standard 120mph belly speed), and always got good openings. I fully recommend it for any environment. This is simply how parachute deployment should work!

Also, deleted effort from the Incidents thread:

"Two worst things one can do to the slider: hide it from the deployment airflow, and hide it from sight when packing.

With decades and millions of packjobs, we have this tattooed in our brains that exposed slider is bad. While if we were taught the other way, with the understanding of how deployment actually works, hiding the slider would be considered as a no-no. And many jumpers who died from hard openings would be alive today."

"If we were taught this, "the slider MUST be the very 1st thing that is blasted by the wind" for 40+ years, the thought of hiding the slider by cocoon would sound totally bizarre and sketchy today! It's all about our perceptions... We took a wrong turn in the fork."

"As I said, if students were taught to pack like this in the first place, and exposing the slider was a dogma instead of hiding the slider, people would have the same arguments if one proposed to hide the slider. It's all just resistance to a new thing. New is always scary. We like to do what we're taught and what others are doing. We don't deviate from dogmas hammered in our brains until some Authority like John le Blanc tells us."

The blue thing looks like a retractable conical vane, that automatically extends on exit and retracts into the helmet before deployment. That would be totally magical.

>>> Also, even in non-steady state, AGR is actually ~1% (depends on Vy) higher than L/D, because of increasing density going down <<<

Correction: "Also, even in steady state".

platypii

Cool application of WSE: Roll Angle from GPS data!

Basically, by finding the angle of the Lift vector relative to flight path, you can compute the roll angle of the suit.

Here's an example of pitch, roll, and yaw reconstructed from FlySight data:
[.image]https://thumbs.gfycat.com/ReadyMatureGilamonster-size_restricted.gif[/image]
This shows initial steep exit from a cliff, followed by leveling out, a slight right turn, a corkscrew (!), then a long commute before deploying.

Note that the visualization assume AoA = 0. Credit to Hartman for the roll angle calc, and DFR for the corkscrew line.

That. is. so. cool! Kudos! And this is just the beginning... I'm not kidding when saying that WSE are like Pandora box!

An example of Cocoon Hesitation was posted above; here is an example of an opening (same canopy, Spectre 190) with the Exposed Slider method. The opening is more immediate, with stronger initial jolt on the shoulders due to towing the inflated slider in the first moments, but the openings are comfortable, just not wasteful of altitude. And I've had ~400 of such openings like this one, 1:1, virtually exact replica. Openings become very consistent, and with very good heading performance (thanks to inflated slider anchoring the heading). It feels like it even 'corrects' your body position! (because the inflated slider is hard to turn, it turns your body is you drop one shoulder; with cocoon-cigar, dropped shoulder spins the cigar very easily, besides its own dance)

And...

ZERO line twists.

(before, linetwists were like 1 in 3-4 jumps, that would be >100 linetwisted openings out of 400 jumps!)

I'm no longer jumping my skydiving canopy, so if anyone asks to take a video of packing or opening, I can't do this. If nobody jumps this pack job, the idea will be buried, but I'll remind again in 5 years, since in skydiving world any fresh idea takes decades to pick up.

OpeningWithSliderExposed.m4v

>>> Anyway, on my first Swift 3 jump I had a hard opening which lead to massive line twists putting my canopy into a spin with me trying to fix it on my back.
It opens off heading 50%+ of the time on WS jumps and when it does open in serious twists it spins up. <<<

I recommend trying the Exposed Slider method that solved similar problems I had with my Spectre, including hard openings. Before buying a new canopy, it may not be needed.

>>> With the chaos of openings your sample size it not enough to prove anything. <<<

Yes, this is a classic chicken and egg problem. If out of 100,000,000 jumps 50M were done with slider hidden and 50M with slider exposed, we would have solid stats of which causes more of catastrophic hard openings. With only one jumper having done ~400 jumps with slider exposed (BTW, I no longer skydive my Spectre, only freepacked BASE canopy, so no longer pack like this), sample size is negligibly small.

But if nobody tries or doesn't continue jumping slider exposed, we'll never know!

Free the slider, everyone! Try it! Trust me, it won't hurt.