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http://www.youtube.com/...amp;feature=youtu.be

Someone finally posted this to Youtube.

Nice delay... Throw and go. No shame in a PCA if u are only taking a .25 second delay anyway, I mean seriously. I've been guilty of it too of low A's, the ground if fucking scary, but so is the object!

Chronologically, I think this was cliff strike #3 during the boogie...

are any of these recent cliff strikes under canopies with properly tuned DBS??? They all seem to be going forward on opening QUITE fast.

It's good that we can see these and possibly learn from it.

However, I can't help but think that all of these videos of people posting their cliff strikes is harming credibility of our sport. Let's face it, the masses are pretty ignorant to the actual risks of BASE jumping. Epic TV: Wingsuiter crashes parachute malfunction is going to get a hell of a lot more views than "BASE jumper successfully flies 6,000 ft wingsuit flight and has tip toe landing". Thus people have it ingrained in their mind and it makes it harder for me to convince superintendents what we are doing is practical and manageable.

Seems to me we are only shooting ourselves in the foot with letting all these carnage videos go viral.

Just a thought, keep it unserious as possible

Probably not, people that take toms course are about the only people I know that get them done.
I never bothered to change mine and neither does anyone I jump with. Probably dumb but just what Ive noticed.

There seem to be people that don't care and a group that thinks DBS don't matter. I've personally seen low off headings with short delays turn away with them, but those same delays have always resulted in object strike without them.

Freeze the frame at :40 then again at :41. Check out how the PC swings left (jumper's right) from the PC toss, then swing back hard right (jumper's left) throughout extraction, line stretch and spanwise expansion.

I have to wonder whether PC oscillation had something to do with the off-heading since his body position looked pretty solid. I also wonder what the winds were doing.

As for the carnage vids, you're right Mitch. But on the other hand maybe they'll help prevent prospective jumpers from joining our mongoloid air force.

Agreed, and the canopy was a full 180 before any body position could effect it. There was also a tail first inflation, but the tail gate looks like it was working.

Your comments seem insane to me.

Why would you NOT take the time to tune brakes and possibly slow down (OR AVOID) a possible cliff strike. It could happen to you TOMORROW.

Ive had 180's turned it around maybe they are already pretty good or maybe I am... jk

I wish you well!

I've probably had more experience customizing DBS than anyone else at this point.

Tuning DBS is not simple or easy. And if you make a mistake and overshoot the canopy will stall out at deployment. Overly deep brakes are definitely more dangerous than overly shallow brakes (because they effect you on every opening--not just the relatively rare off headings toward close solid objects).

A custom DBS needs to be carefully set and the jumper needs to be vigilant about watching and maintaining it (especially if they lose substantial body weight, or set the brakes in winter with lots of heavy clothing on).

The first time I tried to set DBS (my own, more than a decade ago), it took me more than 25 jumps, and I'd bet the result was worse than what I can manage now in 3-7 jumps. Experience setting DBS helps a lot, but having a relatively forgiving object and access to a bar tacker are even more important--and most people lack all three.

I'd much rather jump with a (relatively shallow) factory brake setting than a poorly done "custom" setting that was overly deep. I'd rather have a good custom setting than either, of course.

I think that is just from the short delay. Jumper pitches out (obviously to the right) and then the pilot chute swings out and then back left. I see it a lot on short delays where there isn't enough air pulling the PC hard into a vertical alignment behind the jumper. I noticed it a lot when I would go handheld and use to really throw the pc to the side. Got at least a 90 every time. I try to throw it "up" more now to keep the PC directly above me through deployment.

Short stowed delays are scary- there is a lot of time between pitch and inflation for things to get screwy!

I think if you go for your front risers instead of rears the canopy will go forward fast :-)

He didn't pull the fronts--it's just the initial opening surge which happens pretty consistently without DBS.

From the outside view you can tell it happens instantly.

I can clearly see his hand on the right front riser. I can't tell if he pulls it at all before he repositions it, but either way it costs him valuable fractions of a second.

The part where you see the canopy from the outside doesn't look like a front reaction to me. I also heard him say he didn't use fronts when that was brought up after the rescue, but I'm not 100% on that.

There seems to always be a desire to find something egregious enough to write off such incidents. I just don't think these recent two are those. I saw a lot of weak pushes and short delays last week--myself included on a bumpy exit.

Because you don't need Uber Deep brake settings to avoid an object strike. Just turn the fucking parachute around. I have seen a multitude of object strikes over the years, the number of those that could be attributed to shallow brakes are very very few. Even in this video I counted 3 seconds before any obvious canopy input. Uber Deep brakes may make people feel safe but in the end it's your canopy control you will need to rely on.
Secondly, the "Uber Deep Brakes" have a whole range of flaws people rarely ever consider, like fluctuating wing loadings or drastic elevation changes.
I personally leave mine at the factory setting as I jump a very wide range of objects with wing loading variances of up to 30lbs or more. I also hate the way canopies respond to riser inputs when the brakes are set on Uber Deep.

This is the first resonable response I have seen as to why you may not want to use DBS

How close to a stall is the canopy in DBS? If you yanked on the risers after a 180 before letting one up to turn the canopy is there a real risk of stalling the canopy.
Or with DBS would you rather just pull one riser because it is closer to stall and flying slow already?

Two similarities between both of these recent cliff strike videos I noticed: Both jumpers fumbled reaching their controls wasting all valuable working time and both jumpers had not one but two cameras on their heads.

Deep, shallow, risers, toggles, PC oscillations, delay, body position, whothefuckcaresflyyourparachute! 180's will happen. Location of toggles/risers should be more natural to you than the damn record button on your gopro.

Just to make sure I am very clear here. I do still use "Factory" deep brakes for slider off (normally). I do not bother customizing the "Super Deep" brake setting that some people advocate.
To answer your questions:
1. How close to the stall a DBS is depends on how you would set it (Ultimately there is too many other variables for internet speculation).
2. There is always a risk of stalling when yanking risers with the brakes set, unset for that matter too. Even pulling one riser can cause the canopy to stall and spin. This is why I prefer a slightly higher airspeed because I know I can be heavy handed with my riser control.
3. For object avoidance I would still pull both risers before letting up on one. You would expect to not have to pull them as far though.

Good points Fledgling...

I have settings that allow some forward flight and by goal (practiced in 10-15 drills off potato) has been to get my canopy backing up first (altitude provided) before turning the canopy away from the object.

Pretty close, it should stall one side causing the forward motion to arrest. It should not completely stall or stop you from turning. Different combinations of gear, weight, canopy size will change the performance and stall point.


I'm sure Tom will chime in, but his theory is that you use one riser with DBS. The reason this is possible is the forward motion should stop with a single riser input but still turn away.


I don't understand this logic. With 30 extra pounds you'd be going even faster and DBS would do nothing but help. 30 less lbs is a different matter, and I'd use factory in that case too.


I think a 1 second or less delay with a weak push and a 180 will result in an object strike no matter how quick you are. Popping your toggles increases the forward speed and degree of injury when you do hit it. I think it helps to know what causes 180s and to know there is nothing you can do about it before jumping solid slider down.

My logic is that the "Uber Deep" brake setting is a specialized setting that can only be confidently used under similar conditions as it was set. By nature it simply can not be viable for all the possible jump scenarios available to a BASE jumper. So I choose not to fuck with it and instead take a more standardized approach. If you do insist on an extremely deep brake setting then you better also know when it could bite you in the ass (variable wingloading, wind conditions at opening, changes in MSL).

Are you sure about that? Or could the extremely deep brake setting you have been using at lighter loadings now be too deep when the wingloading has been increased by that much.

More weight requires deeper brakes, and less weight shallower to achieve the effect discussed.

Adding more weight makes the one riser technique less effective because the forward speed will not stop as it should with a perfectly tuned setting. Removing weight risks a stall and will prevent you from turning unless you pop the toggles. This is discussed in detail for almost a whole day in Tom's course for those that choose to use DBS.

I actually used DBS before I fully understood all the effects or took Tom's course. I did it largely to prevent that initial opening surge you see in the above video.

I think it's possible that your "uber" deep settings are too deep (i.e. deeper than a good custom setting).



You should always leave the factory settings on your lines. A good custom deep setting can cause deployment stall in tailwind conditions, so you need to have the factory settings for those jumps (like slider down antennas) where this is likely to occur.



Can you explain what difference you're seeing?

In general, the goal of custom DBS is to reduce the forward speed of the offside of the wing (the one you're not touching the riser for) to below the rearward speed of the parachutal side, so that the overall flight path moves backward.

If you go beyond this point, you end up with a canopy that doesn't turn on a riser input because the drag from the parachutal slows down the unbraked side so much that you have a full stall. And a brake setting that yields a canopy that can't be turned on a riser is more or less completely useless.

As far as possible while still allowing the canopy to move backward in the riser correction.

This is why it's critical to set DBS by doing a series of test jumps--not just by sticking in an "uber deep" setting on the line and going with it. Randomly placing a deeper than factory setting runs the risk of creating a stalled canopy or one that is not responsive to riser input at opening, both of which are very bad things to have over your head on a BASE jump.




If you are yanking on both risers, you are trying to stall the canopy (to move it backward away from the cliff).

If your goal is not to stall part or all of the canopy, why would you grab the risers? The toggles are a far more efficient control mechanism in that case.



One riser cannot be guaranteed to move the canopy backward without a good custom DBS. Which is the primary reason to customize DBS--to allow the overall flight path to move backward on a one riser turn.

If you aren't using custom DBS, there are many situations in which I think you're going to be far better off to go with toggles (and in that case I'd recommend routing the control lines through the keeper rings and using line release toggles, to avoid a fumble-and-drop on the toggle).

But I think we're getting a little beyond the scope of this thread here.

No saying that we shouldn't look into what causes 180's or how to avoid them. Either way they will happen to all of us at some point. Whichever way you decide to get yourself out of a bad situation reaching/fumbling for your controls should not be a factor in the outcome. I've had a few 180's in Moab. I've used both toggles and risers in different situations to get off. (Hell I've even had a cliff strike and was stuck on the wall (180 with line twists off a 300' object.) How I managed that I have no idea).

I wasn't there and I'm glad both these guys are ok. I just couldn't help but feel that hitting the wall was avoidable in both of these videos with whatever setup they had going. I've seen videos of way worse 180's in Moab where the jumper avoided impact due to nothin more than fast fumble-free reaction on the risers/toggles.

just for the sake of argument, i would like to point out that I am in agreement with Fledgling's position on DBS.

I know many others that have at least told me at one point that they agreed when this topic was discussed.

not sure there is a definite "right" answer, but as is BASE jumping, you make your own decisions.


also, just to add... i have jumped a low bridge in the past with a light tailwind and had the canopy open in a stall while set in "factory" DBS, i surely didn't need a deeper setting after that, especially since most of my jumping then was low As almost always having some tailwind.
that being said, i think there is a significant different analysis needed when going to a solid object like a cliff or building as well as a solid understanding of the weather conditions and wind.

As was pointed out, You don't use the deeper setting on A's only slider down E jumps.

I think you may be getting confused somewhere.
More weight equals more airspeed by necessity ie. higher stall speeds. Or another way of saying it, you can fly much slower at lighter loadings than heavier ones. So while I can agree with your statement it is beside the point. The point I was making is that if you set an extremely deep brake setting on a lightly loaded canopy it could well be too deep for that same canopy at a higher wingloading.

I'll take your word on that. It is a good example of configuring your gear to your technique. I personally use both risers to stop forward movement, but that may just be me.

See above. Reducing wingloading will actually reduce the chances of a wing stalling. I have also found my canopies to turn around just fine without releasing the toggles.

Right, so what I should have said was to customize a DBS for two of the same size canopies, the one at a higher wingload will be deeper past the factory setting.


Every technique has pros and cons. It's up to the jumper to decide what types of jumps and techniques they use, but understanding all of them is important so you can make an educated decision.

Different manufacturers have chosen different "depth" for their factory brake settings. I've seen factory settings that were right at a "custom" setting before (which seems too deep to me, because of the tailwind stall phenomenon), and I've also seen factory settings that were 7 inches shallower than a good custom setting.

If I saw a canopy stall in a tailwind like that, I'd want to put in a shallower setting. In fact, I've had to do this (twice now) on student canopies when tuning DBS.

Lots of people use a 2 riser technique. And if you're one of them, customizing DBS has fewer advantages for you. There are still a couple advantages (more reaction time because the canopy flies slower, lower impact speed during a strike), but the primary advantage (backward movement on one riser input) isn't something that you'll take advantage of.

The increased altitude loss on a double riser input makes me uncomfortable with that technique in many situations.

Thanks for clearing that up. I thought it went without saying.

Simple, If your parachute is not flying you cannot fly it. I feel that the extremely deep brake settings bring your canopy too close to its stall point which could render it fucked when you try to turn around. (It is becoming apparent that maybe my avoidance techniques are different to what is being taught these days).

Mine seem to have worked fine on all the 180s I have had.

To be honest I am surprised that simply pulling one rear risers is being taught as a response for object avoidance. That being said I can see how the settings you condone would be better suited for the techniques your are teaching.
I still maintain that an extremely deep setting has many issues that people are not aware of and will most likely stick with my factory settings and the avoidance techniques that accompany that choice.

I actually teach three different techniques (1 riser, 2 risers, toggles) and encourage students to try all three and select the one that works best for them, on their gear.

The "best" technique for one jumper (and set of gear) may not be the "best" for a different jumper with different gear.

I've seen people with very short arms (for example) have a lot of trouble hitting the stall point on a riser correction (so the canopy continues forward toward the cliff) while they are very effective on toggles.

The bottom line is that you should be familiar with many techniques, and spend some time trying them out, and then make a decision for yourself about what technique works best for you, on your gear.

To achieve the same ground speed yes. Where as I was trying to say that you could set the brakes far deeper on the lighter loaded canopy and achieve a much slower ground speed than would be physically possible on the same canopy at a higher loading.
So back to my original point, If you set extremely deep brakes at a light wingloading and then decide to jump with a shit ton of climbing gear or some other shit then you could be in for a surprise.

Unless you learned from someone that goes over it for an entire day and are fully aware of it.

Like I said, "I didn't realize anybody was teaching a 1 riser option. Consequently I can see how your brake settings would need to evolve to that.

I've got these big fucking knuckle draggers so that I can man handle the shit outta my canopy.

Didn't you just question why I would jump a factory setting at a higher loading? Sorry but it doesn't give me the impression that you were "fully aware".

No, I stated that I don't understand this anti-DBS argument: I won't use DBS because I may jump in a configuration with faster airspeed, when DBS would only slow you down giving you more time, no matter how much weight you add. The one riser technique may not be as effective in that case, but that's a separate argument.

Like I said, many moons ago I jumped DBS without having a full understanding. My technique then was DBS on slider down with toggles because I was primarily trying to prevent the opening surge. I took Tom's course recently and modified my technique for the reasons outlined above.

I personally don't see it consuming more altitude than your deep brake one riser thingy. If performed correctly of course.

Edited: Not worth the argument.

Will you not be going slower than you would if it was factory deep?

The rate of injury will be less at least.

If you set a custom DBS and then add too much weight you could risk stalling. This would obviously not be as good as factory deep.
In any given year my body weight alone will fluctuate 10-20 lbs, depending on jump gear I could vary another 10lb, then depending on jump site I have carried over 30lbs of extra gear. I have also jumped in numerous places with MSL variances of 5000ft. What custom DBS do you suggest I use? Cos I definitely ain't installing one for every jump I do.
My original point on custom DBS (extremely deep) is that it would be too much of a fuck around for me to do it safely and effectively for the variety of jumps that I do.

The nice thing about custom DBS is that it's not mandatory that you use them on every jump.

I think the idea is to use them only when appropriate, and then use normal DB or SB for all of your other jumps.

I think arguing against custom DBS by saying they don't apply to every jump is a strange stance to take. Of course they don't always apply...so just use them when they do.

Is it just me who doesn't "get" this? I always thought that if you add weight under custom DBS there's less chance of stalling the canopy.

Page 86 of The Great Book of BASE:
"The canopy will have more of a tendency to surge at the same brake setting with the heavier jumper, and more of a tendency to stall at the same brake setting with the lighter jumper"

This is true.

Well I obviously feel that Uber Deep brakes are a lot less useful than you do. Wingloading is but one example.
Also for the record I don't urge or argue for people not to use them. Their choice, their preference, their responsibility. Just providing points for thoughts and discussion.

I've never read this before. I didn't learn to fly a parachute from a book
Not exactly sure what they are referencing here as in, where did they get their info and what part of the opening sequence they are applying it too.
Maybe we should all go back to jumping 150s so no one has to worry about stalling ever again

Can we call them balls dbs instead of uber dbs? :)

Fledgling, I think you're forgetting that with parachutes, the payload is also the thrust mechanism, so to speak. More payload = more thrust. Hence, on any given canopy, at any given brake setting, it will naturally fly faster with a greater payload. The fact that the wing's speed changes is what prevents the stall under heavier load.

~ Chris

I'm also confused by the more weight = more stall hypothesis.

My understanding is in-line with yours. To think of it another way, the heavier the jumper the deeper your custom DBS will be in order to achieve the same reduction in forward speed. So if you can take the brakes deeper with a heavier jumper, doesn't that imply that a canopy is less prone to stall with more weight?

A lighter jumper will need a shallower DBS setting, and may even be fine with factory DBS. I think Tom even said above that he's had to install custom DBS between the factory deep and factory shallow because a jumper was very light.

I haven't dialied in my deep brakes yet, but I plan to to it with Tom after the snow melts up in Twin. Seems to me that you have everything to gain and nothing to lose by spending the time and energy to learn about the pros/cons while installing them on your gear. After all is said and done if you decide that you hate them you don't have to use them.

True but only until you reach its stall point which will have an earlier and more violent onset at the higher wing loading.

True. But this should be your indicator that it is taking more effort for you to slow down, not that it is possible to slow down more.

No. You can't take the brakes deeper with a heavier jumper. You can fly much much slower ie deeper brakes at lighter loadings (why do you think 300ft parachutes are so good for accuracy?)
Parachutes 101 boys. A parachute will stall earlier and more violently at higher wing loadings.
Edit: Again I'm not exactly sure what they are referencing as to lighter jumpers causing it to stall. But lighter loadings equal slower flight potential.

You aren't considering the size of the wing. That also has something to do with it. Different wings have different stall speeds. For the purpose of this discussion we've kept the wing size constant and talked about the load of the jumper and equipment in relation to the brake stall point.

That's 2 excellent cliff strike videos! I'd like to see a couple rescue scenes as well!

Might have been mentioned already.

Reaching directly back over the shoulders is a common habit. The people who are quickest on the controls generally don't do that. Keeping the arms more neutral boxman or just putting them up where the controls are during opening can indicate a heading issue before the canopy is even open.

As you set up, put your arms up with your thumbs out and hands wide open and let the risers hit you in the hands all the way up where the toggles are. If the canopy is turned, you can often feel if the risers are uneven. Take em as soon as you feel them. If you're quick you already have them, as it slams open. Heading issue, no hesitation.

If your hands are over your shoulders right over the 3 rings, it's slower to grab the controls because you need to reach up for them and you may even miss.

The only reason I mention thumbs out and hands open is... I've seen quite a few bloody knuckles from not opening them up.

Also, reaching back like that sometimes leads to head low body position.

Practice catching the risers where they'll actually do you some good. Taking them at the 3 ring, then reaching up is not as quick. If the jumper in the video had reached up instead of so far back, he might have already found the controls and had more time to yard down on the risers.

Another thing, JUMP the fuck away from the object. If you can run, then run. If you do a standing jump, plant both your feet, lean forward, then push out like a kangaroo. If you happen to jump bridges like the perrine, practice jumping away from the object like you can actually hit it.

Lastly ... good luck!

Just to add some fuel to this fire...

Keep in mind that there are different types of stalls, despite all stalls fundamentally having the same definition.

It is true that a "heavy" gliding airfoil will fly faster along the exact same glideslope compared to an equally-shaped gliding foil of lighter weight. More weight = faster glide speed.

It is true that a lighter airfoil will stall at a lower speed than a heavier airfoil, all else being equal. More weight = higher stall speed. The catch is that such a stall speed is secretly based on certain assumptions of flight. You can literally stall an airfoil at any speed if you know what you are doing (or more likely, don't have a clue)

You can take the brakes deeper (i.e. on landing) with a heavier jumper, because you are coming in at a faster speed (assuming more wingloading). That does not mean you are slowing to a lower absolute speed than the lightly-loaded configuration in partial brakes.

Also: the approach-to-flare phase of flight, that precedes landing, is much different than the initial flying moments after deployment.

In your approach-to-flare, you start with significant forward speed, which you convert into lift. In a deep brake setting on opening, when the canopy is trying to inflate and has no forward airspeed (or maybe negative forward airspeed), the angle of attack is totally different. So is the entire energy state for that matter.

Keep this in mind when trying to translate the rules of landing a canopy to the rules for your DBS. Because a stall always comes down to angle of attack. Any relationships to wing loading, weight, and airspeed are based on certain assumptions which may not translate from one phase of flight to another. And using a collapsible nylon wing does not simplify things.

Ok now that i have tried to sound like a smarty pants, i will remind everyone that i am a mediocre, ill-experienced canopy pilot at best. I am going to run away from this shitstorm now. have fun people

Are you basing that on practical results? Have you altered the brake settings with a variety of different jumper weights? Can you give us an idea of what your experimental results have been?

When you say it will stall earlier, you have to be explicit with what you're saying. That's where the confusion is coming from. At higher wing loadings, the stall speed increases. At higher wing loadings, the stall will be more pronounced once it's reached. True, true.

BUT, if you take a particular canopy, and set a balls DBS on it, and that DBS is slightly above a stall for a 175-pound jumper, it will be further above the stall for a 185-pound jumper. And the reason is that the canopy's forward speed will be slightly greater under the 185-pound jumper.

So while the stall speed increases with increased payload, within the range of aerodynamic effects we are discussing, the additional "thrust" from a heavier jumper keeps the wing above the stall.

Now, there are other performance consequences to loading a BASE canopy at higher wingloadings, and those have been mentioned here.

~ Chris

I don't understand this. It sounds like you are trying to say that you will be able to slow down more because you will be flying faster even though you can't slow down as much because a higher airspeed needs to be maintained.

Incorrect. If the 175 pound jumper is on the stall limit a 185 pound jumper on the exact same canopy with the exact same DBS will stall.

Since weight opposes lift, a light loaded wing (parachute) will have a lower stalling speed than a heavier loaded wing(parachute).

Due to the extra weight the canopy would not be able to create sufficient lift and a stall would develop.



There is no thrust or lift or any extra force generated by the heavier jumper. The airspeed of the heavier jumper will be greater than the lighter jumper on the same wing at same brake settings. However the excess weight will not increase the horizontal to vertical speed ratio. Meaning that the "A parachute will stall earlier and more violently at higher wing loadings" will come into effect. Thus a identical parachute will stall with a heavier jumper at the same DBS as a lighter jumper.



"A parachute will stall earlier and more violently at higher wing loadings."

More proper would be: On a heavier loaded wing (parachute in this case) a stall will occur at higher airspeed than on a lightly loaded identical wing. The stall will be more violent and abrupt on the heavier loaded wing.

Do you have experimental evidence for this?

My real world experience altering brake settings and putting different jumpers under them suggests the opposite.

I would honestly love to have a discussion about what testing you've done to arrive at this conclusion.

+1
I was just talking about this the other week.
I agree with you Hookit about hand placement being open and ready right where the toggles should be on opening. Unfortunately, missed grabs, fumbles and excessive time getting on toggles or risers seems to be pretty common among jumpers and not just on 180's or other off headings, it happens frequently with on-heading openings as well.
I also think that putting your hands over the shoulders above the 3 rings can potentially cause off headings in addition to possible head low orientation like you mentioned.

Nobody is contesting this fact. It is true.

However, parachutes do not have a powerplant. They rely upon a payload accelerated by gravity for their "thrust". The heavier the payload, the faster the parachute will travel.

Now, I'm specifically restricting this discussion to reasonable payloads. That is to say, you cannot extend my argument linearly ad-infinitum. We can't load a Blackjack 200 with a 5000-pound man and expect it to "fly". So please don't use reductio ad absurdum when analyzing this.

If you take your canopy and finely tune your balls DBS to the point where it opens just above stall speed, you may confidently let (somewhat) heavier friends jump that canopy in DBS without fear of it opening in a stall, for the simple reason that the canopy will be flying faster when it opens. Its horizontal and vertical speeds will be higher, and its increase in horizontal speed will be sufficient to prevent a stall.

Just don't lend it out to a ham planet. And note I don't say anything about how well that wing will perform in a BASE environment; it will stall earlier in the flare stroke, and at a higher speed than a lighter payload will in the flare stroke. I'm simply saying it won't stall on opening.

~ Chris

Edited to add: Another way to look at this is -
When you load a canopy with a heavier payload, its stall speed will increase. BUT, its natural forward speed will increase enough to keep it above the stall.

Completely hypothetical example of what I'm saying:
Let's pretend a canopy loaded with a 175-pound payload in DBS flies at 3mph and its stall speed is 2.25 mph.
If you load this canopy at 185-pounds, its stall speed may increase to 3mph, but its forward speed will increase to 3.5 mph. (Note the difference between flight speed and stall speed has shrunk. And this is what will happen in nature. If you continue to load the canopy with heavier and heavier payloads, you'll eventually find a failure point. But within the realm of properly-loaded BASE canopies, you won't likely produce these failure conditions.)

I have no experience dealing with the exact same deep brake settings on the same canopy and varying the jumper/jumpers weight.

I would like to see tests that prove otherwise. I am intrigued and curious. :D


I do have a lot of experience with both airplanes and gliders and varying their weight/loading. My experience tends to prove having the same AoA and increasing the weight will induce a stall (with no power adjustments) and the vice versa. Dumping weight/reducing loading and maintaining the same AoA (with no power adjustments) can prohibit a stall.

Im sure there are differences between A/C and parachutes but I do have experience under canopies and cant imagine its that drastically different.

That's the ticket, right there!

~ Chris

Ya i was keeping the wing loadings within reason and not imagining crazy out of this world scenarios. I was more thinking the ultra balls DBS wont permit a friend of 5-10lbs more jump without stalling on opening.

Kind of renders my point mute I guess. Maybe 15-20lbs of a heavier jumper is more my scenario.

The problem I see with the "heavier jumper stalls on same brakes" hypothesis, is that the implied corollary would be "same weight jumper stalls on shallower brakes."

Which would mean that if I had a canopy that was stalling out on deployment, the correct response would be to _deepen_ the brake settings?

Is that really what your experience suggests?

That makes no sense to me. In the real world, if the canopy is stalling during deployment, the fix is to lighten the brakes--not deepen them.

Put another way, if a canopy is stalling on deployment, would you suggest the fix is to lighten or deepen the brakes?

 

I believe this is incorrect.

On an A about 265ft I reached back for some reason, natural reaction I guess, and felt my bridle hit my arm, scared the poop out of me. I cringe everytime I see a vid of the early reach back. Boxman!

It is just me or does the jumper grab the right front riser at :19 sec. Seems he/she is going to grab toggle at beginning of frame then at very end has right hand on front riser. Left is already on rear at this point. Not being critical (I personally know what 180s w/ object strike are like....they suck) just wondering if there is a benefit to this or if it was just a misgrab in the "oh shit moment"?

So Moab strikes again (no pun intended).......

It certainly looks that way. I can't tell if they actually pull on it, or just reposition their hand a moment later.

Shoot me an email. I can upload some video and we can dissect it together and try to figure it out.

Tom this is not a logical conclusion. I tend to agree with you about the DBS argument. However, saying that "heavier jumper stalls on same brakes" DOES NOT IMPLY "same weight jumper stalls on shallower brakes."

In one case the weight is varying, in the other case the brake setting is varying. No one is questioning the effect of adjusting the brake line for a constant weight. The real question is: what is the effect of changing the weight of the jumper with a constant deep brake setting?

I think it is generally accepted that, all else being equal, higher weight implies more forward speed, and also a higher stall speed. So the question really comes down to which of those factors dominates in practice.

Tom you probably have more empirical evidence for this than most. But please don't use invalid logical arguments to defend your points

Stalling on deployment you would want to lighten/shorten the brake settings to avoid the stall.

I think there is just a misunderstanding of the wording on my end. This last post I come to agree with.

I'm not really trying to argue any point. More trying to understand the logic you're following.

Well, that and avoid doing test jumps where I attempt to stall the canopy, since it was 12 degrees here when I jumped this morning, and I don't want to end up on the water right now (since I'm not sure if I'd break through or not).

Regardless, it should be relatively easy to test and get some video, assuming we're willing to face a water landing.

http://www.youtube.com/watch?v=w9Ljp3tlVK4

Here´s one of my old jumps. 60m jump with slight tailwind and my deepest breakes. I have 3 brake settings and i use these ones when i jump objects where i have altitude to spare after opening. The jump on the video was a test to see how much I actually loose altitude. And i like when it stalls a little. Makes me (maby wrongly) feel safer if I have an 180. Im a toggle guy. My factory settings are my shallow ones. If I pack not knowing what Im going to jump I pack the middle settings.

PS. Haven´t read the whole thread yet so not commenting on anything particular....

-
You are Correct & I can not express how much this upsets me when reading this Thread . I have never heard of this ????
The pulling of a single ( Single Rear Riser ) technique is NOT a valid option and is far to passive for an imminent 180 deg. slider-Down opening on a sheer-face object strike . ( Both Rear Riser ) or ( Both Toggles ) is the only thing that should be taught for recovery . A Technique of pulling only a Single-Rear Riser is NOT even a option & I don't know anyone personally that believes that is correct information to passed down for anyone that you actually care about surviving jumping sheer-face .

Also the argument of losing Altitude from Both Rear Risers being aggressively pulled for a 180 deg. recovery of Cliff Strike is not valid either . As The Talus below is NOT the primary the second your Canopy opens @ 180 .
Your Primary is NOT to kiss that shear-face with your Canopy-Nose and your Body & drag down both to the Talus below facing that Cliff . If you Cant ' SLAM BOTH ' , Risers or Toggles down hard, in a technique to stall and then next to' PIVOT/Turn' your canopy before Slamming the Object then your not ready to jump a sheer-face object .

I believe that everyone should practice multiple techniques and then make a decision for themselves about which to use.

For what it's worth, I have two good pieces of video from Object Avoidance courses with students correcting serious off headings (pointed toward a strike) on a single riser successfully.

Single riser in DBS does not use as much altitude. Personally I've seen single riser technique successfully turn around on a particular 280 ft cliff. I've seen double riser technique on the same cliff cause the jumper to almost lose both his legs.

Hypothesis: Single deep riser with custom DBS will back up the canopy just like double riser without losing as much altitude.

I personally believe it based on video evidence and anecdotal personal evidence.

When you start talking about sub. 300 ft. impact point that is low with having a 180 into the face . What ever a jumper decides to use he/she better have made the best choice .
But Any jumper who is under the impression that when you grab both Rear-Risers and slam them both down and then release on one Riser to snap a Canopy around is faster than using a Single Riser to save his/her life is sadly mistaken .
.

All I am saying is that on ( personal experienced ) all the 180's and full recovery on heading that I have had . I have had the majority been used, Rear Risers (plural) . with also some using Toggles (plural) .
Will ( singular) Riser work to turn a canopy around when pulled down on a 180 off heading . ( YES ) . but it will not serve you as fast or with as much canopy control like using ( Plural ) both Risers or Toggles .

Also 'Both Risers' with there stopping power of forward canopy movement gives the pilot ( Choice ) . Choice of going either Right or Left on with your correcting pivot turn .
Besides being slower with less canopy control ' A panic Grab for a Single Riser' will be with your dominant hand in your bodies muscle memory . When time is precious with that Single Riser grab. You are married to that directional recovery change . Hopefully there is no Buttress or other cliff or Talus features and your second choice LZ or other outs are in that inferior, singular directional commitment to recovery .
.
edit to add :
Reality Check to please Keep that Single Riser turn shit as a Drop Zone technique . For when you open after break-off and canopy collision avoidance . Not for BASE & sheer Face .
.

Also :
this Vid. is TombStone , Right . SO WTF ???? .
It does NOT GET any easier and forgiving than Tombstone as a smooth sheer-face object to have a 180 & turn around with time to spare .
Last Time I had a Full clean-Snapping 180 looking right back on that Cliff Face . It was so easy . I did a Riser Grab (plural) stopped canopy and was fucking LAUGHING so loud my Buddy on top heard me as I turned around and flew away . I had that much clearance .
A very relaxing learning experience that object is . I have Several 180's off that cliff & that is By Far the cakewalk of object to learn or fuckup on . Still I have seen & also see Vids. of people eating rock on this fucker . WTF ????? is going on .
.

 


+1 to your +1. Have had this conversation before, many have a problem understanding it.

several 180's on tombstone? how many 180's have you had? Seems like a lot
Out of my 600 jumps Ive had 1 slider down 180 and maybe 5 slider up.

Please go back and read prior messages in thread. Single riser methodology is only advocated in situations with custom DBS where forward speed is slowed on opening, thus allowing for more time for choice and correction before striking the object.

Stall is defined strictly as exceeding the critical angle of attack. The critical AOA is not related to weight. If you are flying a plane whose wing dimensions change in correlation with weight, I would like to learn about this please :)

The default response to your claim is that you are probably, in actuality, at a higher AOA in the heavier scenario. And that is why you are stalling. Do you use an AOA vane to make your judgement? Or are you relying on a pitch indicator, or artificial horizon?

-
I never even had my 1st true hard snapping 180 till over 300 BASE jumps .
.
edit add :
I have had a few off that object and I am about as guilty as any of them for playing and fucking around and not respecting an easy object like tombstone . But I had the advantage on most with a under-hung, gnarly faced, buttressed talus local cliff for practice before I ever went to Moab .
If people cant Keep off TS Cliff Face they probably should go back and assess the basics of what they believe to be a solid foundation of there 180 recovery techniques or if they have low jump numbers on cliff . sprint off the exit with more respect .

Everybody started out the same with low jump #'s & needing experience . I hate to say it but Tombstone for a sheer Face object it is still about the best place for learning & honing the skills for other cliffs that are more Technical, Gnarly or lower . I wish people would be better armed before them going out and off TS though .

Hey ??? . even though I never heard of it till today . Did I fail to mention how I really hate the suggestion that Single Riser pull for a 180 turn-around technique for a collision avoidance of a sheer-face object be used or taught or even thought as anything but weak anemic fluff ?
.

You don't seem to understand--It's not just single riser. It's single riser on a canopy with custom deep brake setting for that jumper. The canopy moves backwards with one riser input.

Tom,with respect to your greater knowledge and experience can you explain what margin of "safety" you advocate be built into custom deep brake settings (to avoid a stall on opening) to allow for changes in body weight, altitude, atmospheric/climatic change, line stretch etc, or do you have multiple settings on your lines and use accordingly?
I know that this is starting to get off subject but would appreciate a greater understanding of your philosophy.
NB. I am not requesting that you explain how to set deep brakes, in this forum I would take it as "given" everyone knows how to make that adjustment from factory settings.

I tend to set the shallowest possible brakes that will still perform the basic function (backing up on one riser) that I am trying to add to the canopies flight capabilities.

I think a lot of people want "deep brakes" that are right at the stall point. I personally find such a setting a lot less useful, and even potentially dangerous if it results in stalls (and consequent loss of altitude) at opening.

I've found the "sweet spot" for custom DBS is about a 1.5 inch range for most canopies/jumpers, and putting it as shallow as possible while still being in that range gives us a good margin for error. In my experience, set that way, the DBS usually don't start misbehaving unless the jumper loses 15 or more pounds of body weight.

Regardless, any time you are using deep brakes (custom or even some manufacturers factory brakes), it's critical that you manage and maintain your settings by periodically rechecking them in a safer environment (and being alert to problems on any other jumps). If you discover that a setting is causing stall/sink issues at opening, I recommend immediately discontinuing use of that setting until you have time to re-check it with test jumps from a safer slider down object (like the bridge here, but there are many others).

Thanks Tom, pretty much sums that up in my mind.

-
I do understand and I do have a total grasp of the mechanics of Single Riser pull when combined with a 'very Deep Aggressive Brake setting' . The pulling of only 'One Side' of the canopies C & D line-set, as apposed to Pulling of 'Both sides' C & D line-set of the canopy simultaneously with a custom DBS setting . I totally understand . And I understand the thought of it having less sink from start to finish over the pulling of both sides C & D line-sets .

You may also have the mechanics grasp of it also as well as practice this . I Dont do it . I especially don't agree of it being pushing to Beginners or low jump #'s to be used as one of your 'Go To' moves for sheer-face object & 180 correction . It is going to be a rarity for the low time or beginner to even be proficient in use and tune mechanics of just there personal custom DBS setting of there canopies for Double Riser & Toggles to fit there own bodies .
From what I am seeing, a lot people can't even proficiently use the ( Traditional Go-To methods ) of both Risers or Toggles Combined with doing there own custom DBS . & that makes me believe they have not the rigging mechanic knowledge, let alone the knowledge and commitment of canopy mechanics for a choice to commit for life to the Single Riser Pull combined with 'Real' indepth knowledge of DBS matching there canopy & body .
.

Food for thought- When finger trapping 900 lb. Dacron line, the line will shrink approximately ¼” per 2 inches of finger trap. This means if you modify existing lower control lines by installing a DBS, you’ll effectively be making the 2 factory settings (and fixed toggle loop) deeper by ¾ to 1 inch (depending on the amount of finger trap used).

Not surprisingly, Apex BASE does not endorse nor recommend modifying its products in any way.

You can avoid this by replacing the entire lower control line, and building the factory brake settings back into their original locations after compensating for the new setting.

seems like all the cliffstrike videos i see are of people fumbling for toggles or attempting some weird pull both let up one pump the other proceedure. I think ill just stick to the panic pull of a singular rear riser.

do you think that people who customise their settings don't allow for that?

I have personally seen it more times than not where people don't account for it.

Me too.

Didnt work for Dwain.....1:40- I got on a Fuckin riser not a toggle

http://www.youtube.com/watch?v=H47X7e8W8OE

Listen to DW

Were you friends with Dwain, Huck? Or are you just in "old youtube videos as evidence mode"?

This is one of the most misunderstood pieces of video of Dwain that is circulating.

Dwain says "I should have got on the toggles and not the risers, because the risers sunk the canopy out. I didn't have any lift, which I needed..."

He should have used the toggles because he would have flown over the ledge and tree he ended up hanging from. Toggles would have given him a better glide angle to clear them.

This is not an object avoidance (risers v. toggles) situation.

His point was that he needed better glide--not that he needed to correct heading to avoid the strike.

I had a long discussion about this with him before he died.

I really wish people would stop misinterpreting that video.

I personally favour risers.

Good response at 9.23 in this vid - http://youtu.be/y-6ZSLL_SpA

and this has probably been posted before but this guy has some good reactions on the toggles.

http://vimeo.com/29058707

Write up

http://www.watchthybridle.com/2011/09/strike-n-go/

Worth a watch

Everything I kno comes from youtube


( wasnt directed at you Hank)

Just my opinion.

My post is not directed to Spiderbaby. It is directed to all.
DBS is a tool. same as SBS. Apply to the jump, the style.
Bottom line is know how to fly your canopy in certain predicaments before you are forced in those predicaments.
JUmping a solid object SD, is riskiest on the scale.
In general, one should know how to do object avoidance with one riser IMHO.
Why? because there are 2 types of 180s. Flying 180 and deployment 180. The diff being that the deployment 180 will result in a crossed riser scenario.
Trying to figure out which riser to put your grip on while the wall is approaching is time consuming.
While I prefer DBS, wherein the canopy stalls on one r-riser input. I can launch as hard as i can to get separation from the object outside of the arc of a stall turn losing more altitude than the other option.

The other option. SBS, Dont launch agressive. One would be very close to the wall in a 180 situ but the canopy will be flying mode faster than DBS. distance from the object will be close so one's canopy has not the chance to build up speed.
SBS, Shallow exit, DBS, Deep exit for a rule of thumb.
It may seem counter intuitive, but one still needs the ability to stall the canopy with one input to be a conservative jumper on SD solids. The ideal canopy would be the one like backing out of a parking space. Left riser or toggle, canopy stalls and backs up, left side starts flying backwards while right is flying fwd..
If you do not have a canopy and the skill to do this,....I wish you luck.
Take care, and thanks to Andycal229 for his input.
space

I wonder what he would be saying if he had fumbled for toggles and hit the wall? Simething like man i wish i had gone for risers sunk out and hit the tree. I know he def wasnt saying "i should have used the majic combination of risers and toggles stalled it out to give me time and options then let up one pump the other bla bla float over the tree land on my tippie toes after front risering all my extra altitude.

two good examples - starts at 5:20

https://vimeo.com/58211243

No. I'm basing that on the most basic of parachuting principles. The heavier the wingloading the higher the stall speed will be.
Take 2 identical parachutes. One loaded lightly and one heavy. Now incrementally deepen the brakes on each canopy. The heavier loaded canopy will stop flying first.

Are you assuming that the two differently loaded canopies have the same forward speed in the beginning?

I think we need some experimental results here. Simply asserting that something will happen doesn't make it so.

Hey Todd,
I was always taught that a shrinkage rate of 1 in 10 was an approximate rule of thumb. Which is probably close to your numbers if I could bother to convert them to proper (metric) measurements :-) I also believe that the shrinkage rate remains fairly constant regardless of line type or size as long as the finger trapped line is the same type as the full length line. Care to confirm or deny?

I'm pretty sure that it has already been determined that higher wingloading equals higher stall speeds (square parachutes have been around 30+ years). Would you agree with this?
You cannot fly the same parachute as slowly at higher wingloadings as you can at lighter loadings due to its higher stall speeds. Would you agree with this?
If you agree with the two statements above (which I have always taken for granted as basic parachuting principals) regarding basic canopy flight then I fail to see how you think you could flip the rules for slowing a parachute down more for opening.
But you are right. Without empirical evidence this is a wasted argument. Even with evidence the internet world will still argue

Higher wing loading equals higher flight speed, too, though. We're gliders. Gravity is our only engine. More weight means we go faster, which means we need more brakes to slow down to the same speed.

My daughter is on christmas break so I won't be jumping until Saturday. I'll try to throw a weight vest on a jumper with tuned DBS and see what I can determine.

Correct. Never argued this point. Actually mentioned earlier that this should be your indication that it will not be possible to ultimately slow down as much in the end.
Remember at higher loadings the parachute doesn't just fly faster. It flies faster because it needs to fly faster. Thus while your forward speed will be higher, by default your slowest speed needs to be higher.
Can you slow it down to the same speed as a lighter loaded parachute? To some extent, sure. Can you slow it down as slow as you could slow down a lighter loaded parachute? No chance.
So way back to my original statement. You can set an extremely deep brake setting on a lightly loaded parachute that can fly nice and slow due to its light loading and low stall speed. But if you take that extremely deep/slow flight setting and then increase the wingloading you will reach a point at which the canopy will stall due to its increasing need to maintain a higher minimum airspeed.

Stall speed and brake setting are not one in the same.
Stall speed and toggle stroke are not one in the same.

At different wingloadings, the same brake settings and/or same toggle stroke will not produce the same result. Therefore, we have to stop equating these things in our discussion.

Any particular wing at a fixed brake setting will fly faster under a heavier load. Therefore, even though the stall speed increases with heavier wingloadings, it would take a deeper brake setting to produce the necessary stall profile/AOA.

So yes, heavier wings will stall at higher speeds. But it takes a deeper brake setting and/or toggle stroke to produce the stall condition.

So, when you say the wing needs to fly faster to remain in flight, you can only say this is true with respect to stall speed, not brake setting or toggle stroke.

~ Chris

I was never much of a BASE jumper but I did at one point set up a DBS on my Mojo.

As a rigger this was pretty much a non event. Simply figure out your DBS point (I did the "take a pen with me on a skyjump thing") and then, before you do any finger trapping or sewing, measure that mark against a fixed point of reference (say from the control line cascade or something).

As a rigger I had some rough idea of how much the finger trap would shrink the line, so I simply experimented a couple times with where I would actually insert the finger traps, then measured against the fixed point of reference.

Once I had the basic position down, I made a little bit of allowance for the zig-zag stitching shrinking the line a bit more (not very much though) and sewed it up.

Basically, you can experiment a bit; take your bit of dacron you'll be fingertrapping in to create the setting - finger trap it in below the factory setting; see how much that shrink the line; since you'll be fingertrapping in the exact same amount of line, just in a different position, the shrinkage will be constant, and you can take that amount of shrinkage into consideration when you do the finger traps for reals.

I suppose if you wanted to be 100% anal about it you should then adjust the factory setting it came with (since it will be a bit out of whack now) but I just left it as it was.

It's also possible that different wings respond differently--that the relation between wing loading, stall point and forward speed vary from one canopy to another.

Take two parachutes, with the same DBS, but one is high wing loading and the other is low wing loading. You are saying the heavier wing loaded one is more likely to stall than the other one, on opening.

This comes back to angle of attack. You are fixating on the relationship between forward airspeed and stall, which is irrelevant in this scenario. The angle of attack immediately after opening is determined by factors unrelated to static stall conditions such as those found in steady-state flight. You must forget about the relationship between airspeed and stall here.

Back to our two parachutes with different wing loadings. Both have the same AOA in the immediate moments after opening, assuming both the jumpers were falling straight down. Assuming the wing fully pressurizes and begins flying at this AOA, the higher-loaded canopy will accelerate to a faster speed than the lower-loaded canopy. It will be descending at a faster rate, however, and the difference could indeed be dramatic. This is not a stall and must not be confused with a stall state.

If you propose that the heavier-loaded canopy will stall first, you must show how it has a higher AOA.

I guess by that defenition both canopies will stall at the same brake setting regardless of wingloading or airspeed as both canopies achieve the same aoa for the same stroke of toggle regardless of wingloading or airspeed?

a. The AOA is set by the lines, not by the w/l or speed.
b. The stall speed is determined by how fast the canopy must fly to support the payload. this means a canopy opening with a the deepest DBS (without stalling opening) for a heavy jumper will stall on opening with a lighter jumper.
c. Dacron take up. with 600lb Dacron is -13% for a given length fingertrapping.
d. My calcs for my style of installing DBS (5cm trapped on the ends) with a 10cm SBS vs DBS diff is equal to a take up of 3.6cm of overall brake line length. less than 1% of apprx 5m. the DBS setting would be half of that shrinkage. My control stroke is a bit over a meter meaning 25%. The <0.5% of fingertrapping will be unnoticeable in the opening performance. Air density and harness symmetry plays a bigger role than that.
Note: it doesnt mean you should discount it in rigging. only in the canopy flight.
take care,
space

No.
Take care,
space

This thread is brilliant.

i think he was alluding to this statement,

a given airplane will always stall at the same angle of attack regardless of airspeed, weight, load factor, or density altitude.
which does kinda make sense. i cant imagine a canopy with brakes fixed/set a whatever (below stall) changing its critical angle with weight to being above that of stall or vice versa.

Space, allow me to echo Tom A here. "Do you have data to support that?" I get what you are trying to say, I think: weight drives your forward glide speed, and you need a minimum speed to not stall, therefore a heavier jumper goes faster and is less likely to stall.

If I have mis-read your train of thought, please forgive me!

Otherwise, the flaw with your line of thinking is the part about "you need a minimum speed not to stall," which, in this setting, is not true. Stall speed is dependent on a great many things. But it is not "determined" by how fast a wing must fly to support a load. That is simply not the definition of stall, and it is highly misleading.

First off, you are not in a stall just because the force of weight has exceeded your wing's ability to provide lift. Totally different things. In fact, weight can exceed lift by a factor of infinity -- literally -- and you can be nowhere close to a stall. Many folks here seem to misunderstand this.

Second of all, Space, your prediction is only valid if it can explain why the lighter jumper's canopy, which you say would stall, would have a higher AOA than the heavier jumper's canopy. I am very eager to hear your thoughts on this.

I think Space actually agrees with you, because he says,


Therefore if the heavy jumper and the light jumper both are at the same point directly under the canopy upon opening, then both canopies will start out at the same AOA, because the lineset is presumably the same. Keeping in mind we are talking strictly about the first few moments of flight.. but I speculate in my sleep deprived post-call state that it is generalizable to many other modes of canopy flight. In reality, the heavier jumper will stretch the lines somewhat more overall, and, certain lines would be stretched more than others, having multiple effects on the trim. It would take some data to convince me it was relevant to our scenario.

I propose a mod break off this excellent discussion of canopy stalling into its own thread in the technical section.

Using weight to calculate stall speed, is like using "time of fall" to calculate the force of gravity. You can mathematically do it, because you know the other variables in the equation. And of course pilots and flight engineers do it all the time. But the time of fall is not the cause of the gravitational attraction, any more than the weight of an airplane causes you to stall at stall speed. It leads to a "cargo cult science" misunderstanding of how a canopy stalls, as people don't truly understand what a stall is.

This is worth its own thread, beyond the great learning points of the original cliff strike topic.

I see this quite often when we overshoot DBS (make them too deep) during testing. The wing still turns on the riser, but it sinks out immediately at opening.

Fortunately, I've never had to leave the brakes that deep to achieve a good DBS.

“Space, allow me to echo Tom A here. "Do you have data to support that?"”
Other than watching friends pound in in a stall on Piney Creek. No. Shattered heels and such. These were the result of a heavier jumper lending his canopy in DBS to a lighter jumper. Also some of my jobs working research in canopies with W/L, 8lbs/1sq2 and my rigging with Skydiving, BASE and Paragliding canopies. I am not saying this to brag, but only to point out my experience range in ramair tech. My experience does not exclude me from being wrong though.


I get what you are trying to say, I think: weight drives your forward glide speed, and you need a minimum speed to not stall, therefore a heavier jumper goes faster and is less likely to stall.

I will explain differently. All wings have a minimum speed below which there is insufficient airflow for it to fly (create enough lift to support the payload). Wingloading is the determinator of that speed.

“If I have mis-read your train of thought, please forgive me! “
I think you have the causes and results backwards.

you need a minimum weight not to stall, Stall speed is dependent on a great many things. If a wing cant fly fast enough to provide enough lift to support a load, it is in a stall.

“First off, you are not in a stall just because the force of weight has exceeded your wing's ability to provide lift. Totally different things. In fact, weight can exceed lift by a factor of infinity – literally -- and you can be nowhere close to a stall.”
Look the other direction. Weight can be decreased by only a finite amount.

Second of all, Space, your prediction is only valid if it can explain why the lighter jumper's canopy, which you say would stall, would have a higher AOA than the heavier jumper's canopy. I am very eager to hear your thoughts on this.

Miscomm here.
The AOA is set by the line trim and DBS.
AOA is not related to weight for a flying airfoil.
The hypothetical situation involves one canopy with a DBS for a heavy jumper compared with a lighter jumper jumping the same canopy.


I hope this helps, feel free every one to dissect my post.
Take care,
space

I totally disagree with Imsparticus.We are talking about velocity and mass. This is a quadratic equation. it isnt linear i.e. one to one.
If weight was the only diff. everything else will be diff except for the AOA. this discussion is not about the effect of the control stroke. it is about DBS.
Wingloading creates airspeed. they are dependent on each other. Brake setting will determine speed at wingloading. Canopy will determine if it is enough to fly.
Take care,
space

you are not disagreeing with me you are disagreeing with a basic aerodynamic principal and sometimes even yourself, like you said aoa is not affected by weight and set by lines and dbs or whatever brake or toggle setting.
How can a canopy be flying at one weight and stalled at another (aoa is fixed in this case dbs is set) given that a given airplane will always stall at the same angle of attack regardless of airspeed, weight, load factor, or density altitude?
as for dbs not being a control stroke, cuckoo.

When you say "all wings" are you talking only about ram-air wings? Or wings in the general aerodynamic sense? Are you saying, in other words, that all ram-air canopies need a minimum wing-loading to stay pressurized? That I would agree with, but that's different than a stall.

Your arguments make more sense to me if I assume you are using "stall" interchangeably with "depressurized state."


That is not a stall. If a wing is not supporting the load, you merely have an increase in sink rate. see below.


I think the other miscomm is the common assumption that canopy depressurization (or failure to pressurize) is the same as a stall. Several things can cause depressurization, stall merely being one of them. Insufficient wing loading, another. Also windshear, turbulence, tailwinds on opening, etc etc

Real question for you, to glean from your experience with ram air design-- Do you find a correlation between the overall AOA that your line trim (all line sets, not just the break depth) gives you, and the required wing loading for that configuration?

Just out of curiosity, have you thought about differential line stretch effecting differently-weighted jumpers?

I am envisioning a heavy jumper stretching lines more than a light jumper. And center lines and A & B lines bear more weight or so I am told, and therefore wouldn't they stretch more? If the A&B lines stretch more than the rear lines, would that affect the AOA of the canopy? Just a thought experiment.

@ Imsparticus.
I understand the confusion in my post now. I dont believe I ever said "airplane" in my previous posts.
airspeed, weight are not independent but dependent. More weight gives you more speed and vice versa.
Dealing with ramairs, the canopy needs to create a aeroprofile by ramming the air. The given profile needs a given weight (remember it's gravity powered) to achieve enough speed to apply enough lift thrust to support the pilot through flight. A simple calc of the imagined Bottom surface chordwise as a ratio to the imagined top surface will give you the lift coefficient in 2D. Or you can just google and learn about it at this link http://virtualskies.arc.nasa.gov/aeronautics/2.html
I am trying to not complicate things with numbers so peeps can understand.
The bottomline is that on a gravity powered airfoil with a set AOA 'weight' is the determinator.
Please explain your DBS vs cuckoo control stroke. I dont know if you are being sarcastic. Please let us keep this discussion technical and not personal. I find your "cuckoo" interesting but we can take that outside this thread.
Take care,
space

@ Colm.
"All wings" as answer to question mark one.
I am not including unpressurized in the scenario.
AOA of canopy design is dependent on how you want the canopy to perform in certain flight sequences and inputs. In Skyfalling you need to do it for landing. "it" meaning moving the highest point of the topskin in realationship to the cg (jumper). An accuracy jumper canopy would pull it back from 25% of the chord. whereas a CRW or swooper would move it forward. This has little to do with opening in a stall.
wing loading has nothing to do AOA on a flying airfoil.
Ask me more or tell me more.
Take care,
space

edit to add..
To answer your question about line stretch.
The BASE canopies we jump are like trucks. Not highend sportcars. As long as the line diff is under 3 inches for a 260ft2 it shouldnt be a prob as long as it is symm. Polishing a 18-wheeler with the slippiest silicon gel will help it to be more efficient airflow wise. but one would need to drive cross country to earn a cup of real coffee with that efficiency.

The use of the word airplane in the statement was used to encompas all airfoils weather under power or in a glide in regards to stall. Thankyou for your patronising link that didnt once mension ram airs or how different laws of physics apply to them or airfoils in a glide (actually it might have but i didnt actually bother to read just looked at the pictures), for that i think ill just keep the cuckoo explanation to myself thankyouverymuchfornothing.

love and hugs,
Sparticus

Colm, I'm not replying to you directly, I just mashed on your reply button.

In general, I think I have another way of looking at this:

When a ram-air canopy is in full flight, and the pilot flares the canopy, the toggle stroke does not directly change the pitch of the wing. The toggle stroke mostly increases drag. The wing slows down dramatically while the pilot's (payload's) momentum continues inertially. It is the pilot/payload moving out "in front" of the wing that causes the change in pitch (AOA).

Contrast this with the deployment of a BASE canopy in a braked configuration. Because the canopy is not yet flying forward, but rather, behaving parachutally, the brake setting does not have the effect of inducing a pitch change during deployment. To the point made by Space, the AOA is set by the line trim, regardless of payload. The brake setting at deployment merely sets the drag profile for the wing as it begins trying to fly. More brakes, more drag. If the wing does not fly forward fast enough, but rather sinks disproportionately, it will achieve a stall-worthy AOA.

HOWEVER, more brakes, more drag cannot be taken on its own without considering the effect of payload. At any given brake setting, a heavier payload will induce more airspeed. Too little payload and the airspeed may not overcome the set drag profile to produce flight-worthy airspeed.

~ Chris

Dude, if you have a prob with me, lets take it outside to the exit point :-) All are wrong at points in life. It doesnt mean you have to ride it into the ground. One could always back off and say "hey, I was wrong, thanks for enlightening me" rather than attacking the poster.

So i play your cuckoo game to discredit you.
and it ends here.
Tip: There are no different laws of physics.
Thank you for bringing up intelligent topics in this thread.
Take care,
space

Spot on Dude.
Take care,
space.

Since all the lines on a BASE canopy are not made from the same material, there will always be differential stretch, to a greater or lesser degree.

Any thing less than 2 inches wont matter on a 240sq2ft.
It's a freakin truck...

A couple of kgs in the wrong direction though and she balls up and drops out of the sky

i was talkling more like 10kg. And the canopy will do the stall/surge scenario.
If you want to fight, bring it to PM, no one else cares.
If you actually have ever posted something positive, post it again on this thread.
Here is my lame attempt at poetry for you.
"If you gonna diss me, display yo history"
14 jumps on 1 object in 1 year. according to your profile.
This would lead me to be almost certain that I have been BASE jumping before you were born. You have no credentials other than "havingnothingtoadd". I took a lot of time to re-explain things to you. You have no idea how much energy this takes for me.
But I will still share the same exit point with you willingly.
Take care,
Space

I think that's a great description too, Chris. One little point-- when you say opening in DBS is the same AOA as opening in SBS. Technically it is a different wing, if it is configured in DBS, than if it is in SBS, than if it is in full flight. Just like an airplane wing with flaps up is actually a "different wing" than the same wing with flaps down. Different camber, maybe even different chord length. And when pulling the trailing edge downward, it changes the direction of the chord line and thus the AOA. And technically the critical AOA will change minutely depending on where your tail is pulled to, but that is enough to make one's head explode, and probably completely negligible for practical purposes. (Like Space says, it is a truck)

Maybe what is going on, immediately after your canopy inflates, your canopy has a straight downward vector, and an initially very high AOA (90 degrees for the sake of argument) beyond the critical AOA. i.e. we all open into stalls every single time. But parachutes being highly stable, a heavy jumper accelerates out of the stall rapidly, as the relative wind begins to come from ahead and not below. Whereas, a light jumper will not accelerate enough to overcome drag, and will stay in the stall. Their parachute is just an inflated (maybe) drag device. If they start sliding backwards, it will become a deflated drag device. I wonder then, if a lightweight jumper opened up, and was faced with a persistent stall, if they could fix it by pulling down on the front risers thus changing the AOA.

That whole concept makes more sense if every canopy deployment initially pressurizes into a momentary stall, that must be broken for flight to occur. Thoughts people?

I didnt want to fight but right after your it ends now statement you began taunting me via pm. Actually nothing i have said in statement has been factually incorrect and i dont belive once i have dissed you so to speak (though you have dissed me neumerous time and made plenty of faulse accusations) not even the toggle stroke if you actaully read what i was trying to say than what you want to think i said the rest were all just valid questions to your own statements that right or wrong contradict basic aerodynamic principal rebuke me if you can. I will say though it is now obvious that your the one that has a problem with me and is looking for a fight. Anyone with the ability to read and understand whats really being said instead of just running with what try think is being said will see that the rest i dont care for.

Could it be the canopies physical colapse and aerodynamic stall are not the same event and dont happen at the same time? Ie the canopy is in stall and acting as someone put it parachutically well before it colapses?

Yes sir! We're thinking the same...

~ Chris

PS - everyone in this thread should get a t-shirt
"I survived the Cliff Strike #2 Thread"

So in a headwind you are flying sooner? And in a tailwind it takes longer to "catch up" to the wind speed?

How does that change things in PCA v. free fall?

I think yes. In a headwind the transition to flight would occur more quickly, and in a tailwind the transition would take more time. I think this effect is brief, however. (And I'm assuming we're talking about short delays / low airspeed deployments.)

My thoughts on this particular question are purely theoretical, though. I have a tendency to climb down off the low stuff when it's windy. But I've ventured a few go-n-throws in stiff tailwinds (while in deep brakes), and I've always had more problems with heading performance than the transition to flight. That said, I'm also jumping factory deeps.

~ Chris

Ok. Then I think I can agree with what you're saying. My real world experience on that stuff is actually pretty large, and it definitely says the same thing.

I'm still interested in the PCA v. Freefall issue. I've noticed some interesting things there, especially on vented v. unvented canopies, and especially especially on OSPs.

Tom,
Agree with Chris, that you summarized it correctly. Groundspeed doesn't matter, airspeed matters. In a tailwind, you must account for the fact that your canopy feels like it has a slower, possibly even negative, airspeed.

As far as PCA vs freefall-- Hypothetically here... The faster your downward vector, the relatively less influence your tailwind has on the overall relative wind vector. A PCA would have your canopy open sooner, and therefore your downward velocity would be slower. For argument sake, suppose 20 mph downward velocity and a 20mph tailwind. The net relative wind vector is 45 degrees from below and behind you. If you freefell, and your downward velocity during deployment was 40mph, the relative wind angle would be more directly below and behind you at an angle of ~63 degrees below the horizon. Obviously keep in mind that during opening you are going to be decelerating, so 40mph and 20mph are probably not the numbers you need to use. But the more-rearward the angle is (i.e. the PCA), the deeper your stall could be, and it could take longer to achieve stable flight. Edit to add- and also, once you have slowed down significantly, a 20 mph tailwind is still a 20 mph tailwind!

That's a pretty rough analysis and I can think of a dozen other possible factors that might influence differences between PCA and short freefall openings. But this analysis suggests a mechanism that might make PCA more vulnerable to tailwind effect.

Imsparticus- Yes, I would argue that depressurization and stall are different things and definitely not interchangeable. To test this would require wind tunnel analysis or installing numerous air pressure sensors on your canopy. Both would be fascinating experiments.

ok now im a little freaked out how did you figure out my date of birth from that information?

I think: I love the way you backed out of this shit storm...

Get your butt over here ASAP, to jump in the North Island...C'mon brother...

"I survived the Cliff Strike #2 Thread" - Quote by Seekfun (Chris).

Frank.

My opinion (based on real world experience) regarding this subject is a cliff strike could have been avoided by double rapping the tail gate and by using a small chest strap instead of a wide chest strap.

Well, how could I... I was actually learning something from everybody's posts :)

Next year, dude! And hopefully you will have your new gear by then too.

I would agree to momentarily parachutal. Not a stall. If everyone was opening into any type of stall they would know about it. Out of curiosity have you ever opened in a stall?

I don't recommend rappelling off a tailgate, even with a double-rope setup. Dangerous.



~ Chris

Numbers are magic ;-) so is knowledge.
Take care,
space

I survived to this point! Great read with lots of information. Where can I get one of those T-shirts?

PCA is way diff than FF in a wind. Example; 90deg wind to exit direction. In A PCA scenario,the leading and trailing edges will be on the downwindside. with FF or DB on SD, there is none of this. only the lateral of the position of the canopy and your body position. This will cause the canopy to tend to turn into the wind at < one with the wind.
Boil it down to windvector and harness angle (?) to the wind vector for FF and DB for heading tendencies. In a PCA, the opening gets quite complicated in theory in other than a headwind or downwind.
I have to go, now but want to continue this thread in the tech forum.
take care,
space

Of course I have, I fly a dagger :)

But seriously yes I have- tailwinds, and while adjusting DBS.

I think it's more proper to say that all of us open in a stall, every single time. The question is whether the canopy spontaneously recovers from it and starts flying. Or if not, do you just sink down, or does it depressurize.

Can you elaborate on what you've noticed? I'd be interested to hear more of your observations, especially the OSP

I have. Jumping a prototype canopy that had brakes set for a guy who outweighed me by a good 35 pounds. The canopy surged backward and down hard--I was on my back looking up at the sky. When I popped the toggles it recovered, surged and dove fast and I was leaning forward at something like a 45 degree angle as it recovered.

 
This two cliff strike threads are good source of information, and i've read somewhere here (or on the other thread) that "body position does not affect the heading until the shit is out" ... at least i understood it that way...

Can you elaborate it a bit ? Did I understand it correctly ?

I've always been under impression that bodyposition always have an effect on the openings...

Not necessarily a question to Tom...

Elaborations.
in the ideal scenario, one should have the shoulders equally spaced from the thighs, perpendicular to the wind vector. Not the Horizon.

DEfine "bodyposition in relation" and go from there. what is the position relative to.
Does that make sense?
take care,
space

Body position usually only changes heading as the lines tension. Before the lines go tight it's very unusual to see body position effect opening heading.

If there is no tension between the jumper and the canopy, the only way for body position to change heading is through physical interaction (i.e. a body part or container flap actually touching and rotating the pack job as it extracts). Body position has to be very bad for this to happen.

Exactly my point. So I don't understand when Colm says "Every one opens in a stall every single time". For me opening but not yet flying isn't the same as opening stalled. I would reserve the phrase "stalled" for exactly what you described.

I'm not sure he is asserting that so much as throwing it out for discussion.

Also, as a pilot his technical knowledge and terminology may be more scientifically accurate than ours.

Tom with the DBS single riser method, do you teach to go with the turn, or stop the turn and go back the way you came, with 1 riser? and a 180.

Just food for thought and from my exp. How could you grip double rear risers or toggles to back off quickly if the risers are crossed in a 180ish deployment situ?
Take care,
space

I think it hinges on that some people are using "stall" equivalently to "depressurizing." Whereas I am not, according to the strict definition of an airfoil stall.

My explanation is, in the instant after your canopy has fully pressurized, it is still momentarily in a stall (every single time). The wind vector is still coming straight up from underneath, i.e. close to 90 degrees AOA. A properly loaded canopy will accelerate out of this immediately. An improperly loaded canopy, on the other hand, fails to stay pressurized once the g-forces of deployment stop forcing air into it, because it couldn't accelerate and reach a flying AOA. In other words:

Step 1, during inflation, the canopy uses the energy from your deceleration to inflate itself.

After step 1 is done, the canopy needs something else to keep it inflated. That is step 2.

Step 2, it stays inflated by ram air from its forward travel.

(You already know this of course, I'm just going through methodically)

If you do not weigh enough, you do not have enough "thrust" to overcome your drag, and the canopy never gets to step 2. It collapses because it can't stay pressurized, not because the airfoil is in an aerodynamic stall. If you have bottomskin vents, it stays pressurized because there is an alternate means of keeping it inflated.

It's not that being lightweight is directly causing a stall. You were already stalled. But being lightweight prevents you from flying out of the stall. If my theory is valid, a lightweight jumper could break the stall by pulling down the front risers and decreasing the AOA. But with the tail deeply distorted by the DBS this might be futile, causing a highly-warped wing (which stays inflated but isn't performing well at all). This is my theory, not my experience.

The other limitation to my theory is that my intuitive grasp of airfoil performance relies on higher airspeeds (i.e. airplanes) than you see with parafoils. But a stall is a stall is a stall.

But you know, you and Space could both be right, at the same time, about the lightweight vs. heavyweight effect on DBS. I haven't really analysed the other side of the envelope that closely yet. Ediit to add: And I'm definitely not contesting anybody's experience. I think the explanations need examining though (including mine).

Edit again to add: "opening but not yet flying" is the key here... it is not flying because it is in a pressurized stall.

Just a quick theory that popped into mind, while I really should be leaving to do something else.

When a very heavy jumper jumps the canopy that is properly tuned for a lighter person in DBS: The forces on the system are heavier, obviously, and air is being forced against the bottom skin of the canopy more aggressively. All this air has to go somewhere.

Shallow break settings limit some of the air going out backwards. Deeper break settings limit lots of air going out backwards. In this stage of flight it's not quite the same as saying "more drag" because you aren't moving forward yet.

In a properly loaded canopy, the air spills out backwards, canopy goes forward, wing starts flying.

In a heavily loaded canopy, with all the extra wind that needs to go somewhere, maybe there is some fluid effect where extra air now spills out from under the FRONT of the canopy. Air spills out frontwards, canopy goes backwards. Canopy goes backwards, jumper feels like they are swinging forward, looking 45 degrees up into the sky.

Pop the brakes, canopy corrects itself and surges forward, past overhead the jumper, dives at ground as it rotates you face-to-earth.

Just a theory. Thoughts?

Edit to add: I'm not saying the heavier jumper is falling faster. I'm saying the aerodynamic and mechanical forces are stronger. I have no idea if there is any validity to this theory whatsoever.

I teach "turn the shorter direction" so, go whichever way requires fewer degrees of correction.

In a pure 180, I usually advise the students to turn toward the landing area.

That's not necessarily true. On a short delay in a strong headwind, the wind vector can be coming into the nose of the canopy.

Excellent point!

edit to add:
in a PCA, falling straight down, this would be particularly true. In a go-and-throw, would we have to consider that the PC would be getting blown behind the vertical plane of the jumper... pulling the canopy in that direction and changing the angle... and the parachute could be opening up a bit aft and nose-high relative to the normal no-wind situation? I wonder what angle the lines would have to be pulled to, to be relevant. and how strong a wind that would take.

can you take this to technical please: 'how to properly youtube each stage of an incident'.

tut. and we have to surf this stuff.

p.s. great discussions re dbs' btw.

thks for the posts....re the guy above....it looked to me like a right turn was the quickest/best option out of that, was that dominant hand bias in action or was it a 50/50?

perhaps LZ condition played a part also? does everyone plan outs for a cliff strike?

because you post like you may have gone to higher education - which i confess doesnt specify your exact birth date, merely your star sign - virgo?

keep the banter public pls, thks.

ah so thats how he did it. I just thaught he didnt have a clue and was just looking for another oppportunity to thump his chest. No not a virgo btw.

Nah, he is a Scorpio. or something asstrological to do with goats.
Take care, ;-)

space

Then I don't think your exact definition of a stall works as well with parachutes as it does with solid wings. Sure an airfoil is either flying or stalled, or working and not working. But with a parachute we do have that middle ground where our inflated wing stops being an airfoil and becomes a parachute (ie. something that slows our descent) before it finally stalls (depressurizes). While not your strict definition maybe its more suitable.

While I am finally starting to understand your theory I still find myself wanting to argue with it :-) I would say that the lighter loading has less need to begin it's drive and when it does it would actually need to drive less. Not to mention it's lighter loading would give it superior slow flight capabilities as well as a greater safety margin for the onset of a stall (depressuriztion). Maybe this is why I would consider a lighter loaded canopy to be more stable in deep brakes.
I am also starting to think your overcoming drag theory may be flawed in that drag is a product of airspeed. The higher the airspeed the higher the drag. Right? So wouldn't that mean that the lighter loading that requires less airspeed to fly would also create less drag and therefore have less drag to overcome? Wouldn't this render the lighter loading not enough thrust argument void? No clue here, just discussion.

But i tell ya man, you fuck one goat!

I think there are good reasons to stick with the standard aerodynamic definition:
1. every other sub-discipline of aviation uses it
2. all the relevant scientific work revolves around that definition-- if we start re-defining stall, we have to completely re-invent the wheel if we want to mathematically analyze a parachute. That is a lot of work!
3. what is aerodynamically called a "stall" reflects a distinct physical phenomenon that happens to parachutes, independent of them collapsing, and now we have to come up with a new name for that process.
4. that "middle ground" which you describe is already addressed by current aerodynamic theories of drag
5. stall does not mean a wing suddenly falls out of the sky as some assume (although that CAN happen.. i.e. Air France 447). It doesn't even mean you will get any tactile indication whatsoever of a stall. Stall means your wing is producing less lift (instead of more) as you steepen its AOA. In an airplane with tail section, this is bad for reasons I don't need to get into here. In a parachute, we can tolerate it because parachutes act as drag devices, not just lift devices.
6. It confuses what we are really trying to avoid in BASE life: depressurization!

On the other hand, the vast majority of parachute pilots out there colloquially use "stall" exactly the way you use it. So you have already won that battle :) And it's fine for people to do that day-to-day. But when we start getting into technical discussions of brake settings, limits of the flight envelope, stall speeds etc, we can use established aerodynamic theory to predict outcomes. But to take advantage of all the hard work that aero engineers have done for us in the past, I think it behooves us to at least know what the standard definitions are and what physics each definition represents. Just my opinion though!


Check out this graph of speed vs. total drag found here on page 34. Here is a screenshot, but note that the speeds on the x-axis are arbitrary and generalized for gliders. Our speeds would be much slower:



Note, there is a realm at low speed where drag actually decreases as you go faster. And it's not that "lighter wingloading requires less airspeed to fly," its more correct to say "lighter wingloading will seek a slower equilibrium speed, all else being equal." If that equilibrium speed happens to be lower than the speed you need to stay pressurized, you have a problem.

Regarding your final 2-3 sentences, you are absolutely correct in identifying that a dynamic equilibrium exists between drag and airspeed. But note how it is not linear. Ultimately drag and airspeed become balanced, they have to neutralize out somewhere in the middle. Lighter gliders neutralize out at a lower airspeed than heavier ones, at the same angle of attack. Not because they "need to" to keep flying, but because that's where the physical equilibrium happens to be found.

Aerodynamics is all about "the sweet spot"... travel too far in one direction or the other, with regards to weight, center of gravity, line trim, etc etc etc... and you often paradoxically find that the explanation for one phenomenon is now oppositely true! Eager to hear your thoughts on these proposed theories.

Do you think a canopy with dbs set but inflated is in an aerodynamic stall?

Depends where your DBS is set. The only way to truly answer your question, that I can think of, is with pressure sensors or a wind tunnel.

if your canopy, in deep brakes, sinks straight down at a 90 degree angle, in calm air, the wing is stalled. (Yet that is the "ideal" custom DBS by some schools of thought) no meaningful wing can maintain upper boundary layer flow at that AOA.

Your canopy at that point is functioning as a drag device, not a wing. But how often is your canopy truly going straight down at 90 degrees. Our perceptions can be deceiving, what one really needs is an AOA vane on the canopy


Here are some images that illustrate air flow at high AOAs. In the bottom right frame, the wing is about 45 degrees. Just for fun, imagine what the slipstream would look like at AOA of 90.



(from here)

A fun experiment you could do in your backyard, is take your canopy out on a strong, windy day (steady winds). Put on your harness, or anchor the risers somehow. Measure the wind speed and see if that force of wind can inflate the canopy. Fly it like a kite using the toggles. See what angle your canopy lines make with the ground. See what angle it has to reach before it deflates.

Maybe you are properly tuned and don't have the deer in the headlights effect!!!!

The profile will not be matured if there is not some air ramming going on. Vented canopies are diff in aspect of the maturation of the airfoil over a timeline as it is not dependent upon the canopy flying forward and to produce the airfoilprofile. Colm is the Dude to listen to on aero.
Take care,
space

As long as we have matured ramming going on I think we will all be ok!

maybe hear is a 180 from this morning

https://www.youtube.com/watch?v=W1ANi66b36U

It's a shitty push because of the snow, slider up on a small positive cliff and still have time to turn it around on toggles.

Hell yeah!!!!!! You got that shit turnt round. Nice.

Which schools of thought are those? I'm really not familiar with anyone who thinks that would be an ideal DBS.

It was just a side reference to how you can hear people say, their goal in tuning their DBS is to get their canopy to fly as slow as safely possible on opening. Take that to the logical "idealized" extreme, and you have a DBS that gives no forward airspeed. edit to add: i admit to twisting words a bit there (Obviously in real life, each canopy is going to have a limit as to how slow it can actually go.) Idealized... hence the quotes.

I don't know all the philosophies out there about tuning one's brakes. I'm just taking a common reason and (somewhat sarcastically) extending it to the extreme. I wasn't trying to make a strong point, but if it gets people thinking about why they are actually tuning their brakes, that's worth it.

I'm not a 180 ninja like Heath (nice job btw), so if my 180 faces me at a cliff, I'm totally happy with as slow a forward speed as "safely" possible, even if I know "zero" is unrealistic.

Nice work turning that around Heath. Just curious- why are you guys jumping that SU? Between the short delay and positive cliff face, seems like a spicy SU jump!

Side note- I love jumping in the snow

Yeah its a terrible idea... We were packed slider up for a ski base across the way and there was not enough snow.

Not an excuse we like to do stupid shit just the reason we came up with this idea...

Colm, you should "back out" more often.

You talk sense and you have a nice, thoughtful style of writing.

Frank

Every now and then, I see a type of incident that has been hanging around BASE for thirty years. A lot of stuff was happening, such as the line release mod, better pack jobs, and the tail-pocket were in use after the first few manic years, but nobody could figure out a way to get rid of the dreaded 180 on a slider down jump. We did what we could to lessen the risk of hitting the object in the event of a 180, which happened a lot more often back then.

It is a combination of unrelated factors. So what do you do? Well, every jump should be approached with a 180 off in the back of your mind anyway. We went for the rear risers instantly, and would stall back and let up on one if you could...but this maneuver does gobble some altitude.

One of the simplest things is to push off HARD on exit. If you have room for a couple of steps, darn near run off of the exit.

The other was a longer delay than the one showed in the original post. If you push off hard and have room for three seconds, that forward motion vector will have you tens of feet away from the object when you open.

Yep. Some of us would open lower. Not so much as to risk a PC hesitation, but pretty low compared to a lot of the modern strikes that I see.

The main thing was the push off. There is no reason for a limp push off and an instant pilot chute toss. No reason on this type of object.

I will go through my old logbooks and see my notes. I wrote down the object, delay, and degrees off heading on every jump.

Here is an old school pic showing how to jump out like a mofo.

Edit: I looked back at my few posts, and I've said this before with less detail. Robin Heid also mentioned pulling lower. We would do this.

nice shorts!!

Separation is life.

I've actually said this so many times during courses that I'm having t-shirts made up with it.

I think that as the gear has advanced over the years, we've lost sight of a lot of the basics.

Booth's skydiving rule hard at work.