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Airlocks would theoretically help keep the air inside the canopy in case of object strike. Why is there no such design, as far as I know? Would the openings be too unpredictable/slow?

Several prototypes have been built. None has yet reached production.

The problems appear to fall into 2 major categories:

1) Inflation
2) Deflation

By "inflation" I mean their are difficulties with subterminal inflation. I do not believe these are insurmountable.

By "deflation" I mean that it is hard to get the canopy bagged after the jump in a timely fashion. This is a fairly big negative when landing a less than legal jump, especially when faced with active pursuit.

lucky to mee i never hit an object for reall,but from what i saw i think the vented canopyes(no matter which manufactor)does a great job keeping the canopy as in flated as posible...

i think the cons of airlocks overweigh the pros on vented canopyes as its now...

I see. I suspected something along these lines.


I am not saying this is not a real con, but it's more of a conveniency issue as opposed to safety/keeping you alive. (Better be busted than dead?)


Well, nobody says there can't be vents AND airlocks.

Thanks for the replies!

maybe some sort of valve you could release immediatley upon landing?...

That sounds complicated. Wear and tear on attachment points notwithstanding, what if you forgot to put a valve back on a cell? That would be quite an opening I guess.. :)

When would airlocks be a good thing?

Turbulance
Object Strike

Turbulance: Equals windy conditions where rotors can come into affect. Also thermals can be a factor as well.

Thermals are not much of a issue in BASE. Wind can be but how much wind are you willing to jump in? Obviously the answer is mostly object dependent.

Object Strike: The main objective of a BASE canopy is to inflate and pressurize quickly. It needs be responsive to control inputs right away. If you can control the canopy as fast as you can grab toggles or risers, you lesson the chance of object strike if the canopy opens facing it.

Would airlocks be of use for an object strike? Probably.. but at what cost to performance?

Landing in the middle of a city street requires the abilty to leave the area rapidly. Deflating the canopy and stuffing it away, or just holding the bundle and walking away to another area is necessary.

Airlocks have proven themselves in the Skydiving environment but only Airtime uses them regularily. The Vengeance by PD is the only other one I'm aware of. (that canopy is a dog anyway). How usefull are they? I don't have an answer for that as I've never owned an airlocked canopy.

So in short, there may be a specialized market for airlocked BASE canopies at some point. In this area, it doesn't seem feasible yet to have them, simply because the objects are generally low and expeditious evacuation is required for many of them.

Hope that helps

Tim,

Can you elaborate on when airlocks would help with turbulence?

This may be something of a leading question, as I had a conversation with Scott Miller about it, and I'm not convinced that the airlocks would actually yield better performance in turbulent conditions.

Actually, no I can't. I didn't proof read so I missed adding a clarification to that.

Additionally, Scott is much more qualified to answer that properly so I'd be inclined to believe him.

===
Turbulence... at least in theory: <== that's the missing part.

I've jumped for a few years now and so far haven't seen enough, nor flown enough air locked canopies to make a proper determination.

Airlocks have proven themselves at least in the sense that they don't seem to have detrimental effects. Brian Germaine would be best to answer that since he's the designer.

Most skydiving parachutes don't have them and have little trouble staying inflated. (There were exceptions to that though... for example the occasional collapse of the pintail, conquest, nova...)

Most of my jumps have been with Stilettos. I've flown in high amounts of turbulence, followed many a canopy through their wake zone without troubles ... sometimes had closed end cells but was expecting it. A quick pop of the toggles fixed it.

In short, I haven't seen enough data to incorporate them.

Air locked design is not the new concept. It was first seen in Paragliding and soon after was also abandoned because theoretical concept was not proved in practice.
Actually, in skydiving the same thing happened. In short, there is no single good thing why this design should be used in BASE canopy design.

I was going to say the same thing. Looking at the video, and at the damage to my canopy, I'd say that the vents managed to keep all but the front foot or so inflated the entire time I was nose-in to the object. Furthermore, they kept enough canopy inflated that the thing pulled back from the wall within a second of my applying the correct input.

What more could one ask by adding airlocks? Factor in the thought that the same cliff that was dragging at the nose of the canopy would have been clawing at said airlocks, opening them and closing them...

I'm quite certain that airlocks would offer no advantage at all in the event of object strike. I'm also quite certain that they would add complexity to the system.

from your video i think it shows alot about the vents,i just didnt want to bring it up whith out your acsept.
i think your video prove good that vents CAN ceep the pressure in the canopy,even facing the object as you did

good job by the way i like your last comet he he good work

I agree with Tim that Brian Germain is the best one to ask, but I do have a fair amount of time under airlocked canopies (PD Vengeance, BAS Jedei & Samurai) to say that the definitely DO make a big difference in turbulence.

I've flown through turbulence that gave me maybe a minor bump or two and was wreaking all sorts of havoc for folks under non-airlocked canopies.

Turbulence is turbulence, and all airfoils will experience the negative lift effects from it. The difference, I think is how negative the impact is.

With non-airlocked canopies, in addition to the straight loss of lift caused by turbulent air, you also have the side effect of cell depressurization... end cell closures in particular. Thus, in addition to losing lift, you also lose part of the flying surface.

Airlocks prevent the de-pressurization side effect, and thus all you have to deal with is the temporary loss of lift. Non-airlocked canopies have to deal with the loss of lift, PLUS the loss of part of the airfoil and then recovery of the airfoil and normal flight.

That said, airlocked canopies are a ROYAL pain in the ass to gather up... especially on windy days. On particlarly bad days I literally had to stand on the bridle and then walk up up it just to get TO the canopy to gather it up and deflate it. The airlocks definitely do what they're supposed to do.

I tend to agree that the primary benefit of airlocks in the BASE environment... maintenence of cell pressurization in the event of an object strike, is adequately addressed through bottom skin inlets. I have video of a wall strike by a person flying a vented Fox and the canopy stayed pressurized during the entire episode... thus allowing him to turn around away from the wall and land (though the landing, given the terrain, was almost as scary, if not scarier, than the strike itself).

One problem I've had on all Germain Style Airlocks are hard openings. They snivel for a while but presurization is very firm. (Vengance, Jedi, Samuri)

One thing we talked about a while back was something that interested me alot. The openings and presurization carachteristics of THIS (<--Clicky) canopy were great. It could have use a re-trim in my opinion, but it's interesting technology.

They were, I assume, canopies of similar size and performance? I remember flying my Velocity 96 (before I sold it for a BASE trip) through some pretty choppy conditions, and watching other canopies (mostly larger and slower -- which, I'm certain, was the key) breathe big. The Velocity, meanwhile, behaved like I was running over small speedbumps or something. All speed and pressurization, in that case.

I recall reading an article (perhaps even by Brian, though I'm not certain that makes sense) which claimed that the "temporary loss of lift" which you noted was, in fact, the more important part of why a canopy becomes dangerous in poor conditions, and that the breathing itself was a comparatively minor issue. Perhaps somebody else remembers it and can link to it?

While I'm no expert, this theory made a good deal of sense to me -- some of my scariest moments flying a BASE canopy in turbulence corresponded to nothing more than a 5-10% change in surface area in the canopy, and (unless I'm horribly mistaken) not enough deformation to account for the "oh sh*t" feeling.

Also look at Brian Germain's site.

http://www.bigairsportz.com/airlocks.php

I usually set my canopies down sideways so they fold-up spanwise like a flat pack. While my Samurai 105 doesn't loose as much air as my other parachutes it still wads up into a helmet sized bundle.

If I let it land in land behind me with a head wind or in front with a tail-wind it takes some shaking and probably doesn't get back to that size until I pack it .