Basejumper.com - archive

i am considering the purchase of a vented canopy. i currently jump a non-vented dagger. my question is this is there much differance in the vents between the differant companys producing them. and if so what are the pros and cons of those particular vents.

I'm no rigger, but I have seen and jumped CR's vented canopy (Blackjack) and Atair's vented canopy (Troll MDV)......there is a MAJOR difference in the vent/valve system, although I 'believe' they are meant to serve the same purpose. Other than that, I recommend you contact the appropriate manufacturer with your specific questions, and/or hopefully someone with much more experience will chime in.......
cue TOM A.....

Or Skin if you like, add your .02, I could use the laugh, its a Monday and its too windy to jump.....

Later
Blair

PS FWIW, I own one vented and one non-vented canopy, and I just ordered another VENTED one.....UMMV

you still pack so slow that you´ll need 3 rigs to hang on to the other jumpers of the crew(thats why i have 2)

Long time no see bro.

to the main thing. i dunno about diff in the vents,but sure vents is the way to go..

As you alreaddy jump a Troll you might want to ask people like Mac/BASE813 what his oppinion is on this. he first jumped an unvented Dagger(if i rember correct?) and now flyes a Troll MVD.

dont forget a harness to that 2.nd canopy

thanks i had ben thinking about the troll but i did not no of anybody personally who jumped one. i no that any vent is better than none since most of my jumps here are under 200' kind of pushing it for no vents.

Different valve systems are definitely different. Basically, it's a trade off between inflow and seal, with some better valves doing better in both areas.

In my opinion, Stane's MDV design is the best one going right now. I like it significantly better than either the Apex or CR valves. Those two are fairly close, although I do like the Apex valve a little better. (Go figure, because I like the CR canopy best).

I'm about to have dinner, but I'll try to post more later. There's actually a lot to the differences in valve systems.

thanks tom i look forward to any more info that you may have.

Does anybody have some close-up pictures of all the different designs in vents? It's one thing to be told about the differences but to see what they are helps a lot too.

are you talking sub 200ft or sub 200m/yards?
I do agree that jumping below 200ft unvented is pushing the limits not a kind but ALOT...

personaly i wouldnt take a unvented canopy below 250ft/76m/yards(rughly).but we´re all different people

I'm with Faber on that one. I did take unvented canopies as low as 175', but that was before vents (of any kind) were available. Nowadays, with better options out there, I wouldn't do it.

This isn't as much base related as general skydiving canopy related, but base jumpers have more experience with vented canopies, here I go. Does a canopy with nose airlocks, and bottom vents exist. I realize that with base, nose air locks might hurt inflation, but with skydiving canopies, I was wondering if the combination would work. If the forward nose pressure was greater, it would close off the bottom valves, and the air would enter through the nose airlocks, but if the air pressure was greater from the bottom vents they would open and close the nose air locks. That way there is two ways for air to enter the canopy and keep it in a state of positive pressure and rigid, In my theory that is?

tom i agree with both you and faber 200 ft. is getting low for no vent. but tall sites here do not exists and i am still looking to find out what type of a vent i would like; thus the purpose of this thread!

i am not sure as to why you would want the canopy to pressurize from the bottom if you were skydiving. the only time that i could see this as an advantage would be if you were in very turbulent air, in which case you would probably not want to be skydiving. just my .02 maybe you could elaborate on the reasoning behind the question

Not yet. But I heard a rumor that one is in the works.

As we all know the ram air works best when rigid and pressurized. I was just thinking of a way to keep it that way. Like you said, I was thinking that the air locks would keep it pressurized in normal conditions, and would close like they normally do when the air pressure outside is greater. I assume that most of the pressure loss come from the top of the canopy. At that time the bottom vents would sense that the parachute is not being pressurized through the air locks, and open up to provide the pressure from the bottom. In my mind I believe that as the glide ratio shows most canopies could attain a 3:1 glide ratio. To me that means that the canopy should see air pressure at a the front and the botom. with the front seeing more pressure than the bottom. This could be in normal conditions, but I would think that it would be most effective in turbulant conditions, or might work well as a accuracy canopy as you can stall the canopy almost totally where the nose is not receiving any more pressure, but is closed off to prevent pressure evacuation as the bottom vents have opened to provide the pressure. I dont think that this would be effective enough to be able to fly all the time with the nose air locks closed off at all, but it should help out for the length of time needed to recover from something like turbulance, or the last 10-15-20-25(who knows) feet of a stall on an accuracy jump

Vertigo tested an airlocked BASE canopy several years ago. They abandoned the project for a variety of reasons.

Adding bottom skin valves (not available at that time) may be a way to revive the idea.

One of the reasons that BASE canopies do so well in turbulence is that they have a lot of "give". When they hit dirty air, they tend to wiggle around on themselves, effectively absorbing the impact of the turbulence without transferring it to the pilot. If you create a perfectly rigid wing, you are going to be getting every bit of the turbulence yourself.

I'm not saying this (airlocks and vents) is a bad idea, but I don't think that turbulence is necessarily going to be the best application for it.

There are lots of other potential advantages: deeper stall point, maintained pressurization during object strike, wider control range, maintained pressurization during double riser stall (object avoidance), etc.

Have you considered how to deflate the canopy after landing from a "need to get away quick" jump? That's a question that occupies my mind.

I can think of several reasons why airlocks with bottom skin vents would rock, and the only downside would be stashing your gear after a hot jump.

- Having a fully inflated canopy after an object strike, from the inability of the air to escape from the nose, and the vents/valves allowing the airflow to pressurize the canopy from below, which is pretty much where the canopy is going. Canopies don't develop much lift when they are collapsing.

- Rapid inflation. If you've seen more than 5 openings, you've noticed that some canopies will inflate, and then collapse, and cycle less and less until it is flying. Jellyfishing. When a airlocked nose/vented/valved canopy opens, it would slam the nose shut, not allowing the air to rush out, and hopefully giving you a rigid, flying wing sooner...

- Increasing range of control. With the same idea that a collapsed wing won't develop lift, the airlocked/bottom valved and vented canopy could allow the canopy to fly, and develop some lift, well past where the canopy's AOA will not support lift, but instead won't collapse and take valuable time to reinflate...

- If you run into crazy, canopy collapsing turbulence from wind rotors and wind gusts, it shouldn't collapse, but then again, the canopy probably didn't open very well in the windstorm you jumped the cliff in.

There are more advantages that I can think of, but imagine a canopy that would inflate quickly and solidly, and would remain rigid and developing lift despite a number of potentially sucky situations we can often times find ourselves jumping.
Etc, etc, etc...

For those that would love to demonstrate how easy it is to post on dz.com, please note that this idea has been tried and worked well. Certain factors stopped the project, but it will be reevaluated in the future, I am sure. Send me a PM if you want to discuss this idea in more detail, I would love to hear other people's ideas and comments. I have three CRs now, I promise if I have to build it myself, my fourth will have an airlocked nose with bottom skin vents and valves...

I was thinking, just in case you HAD to take this bad boy off the super hot site, if you stuck your hand into a couple nose cells, or lined them up and deformed them, it would lose all of its superpower and air would rush out as if they weren't there.

But with all the ways that this would kick ass, I would or could bring my Zero-p Blackjack to the places that give style points for quick getaways... I also think that this airlocked canopy would be more ideal for short-delay, slider-down, solid object jumping. (Bs and Es)

i beleive that the original question regarding such a canopy was for skydiving application, not base. i definately see some advantage in a base app. but not so much in a skydiving atmosphere.

I am not sure if you have ever jumped an air locked canopy. I have owned two Jedei's (150, 136). The idea of grabbing the nose and deforming it does not work well. They could be alot of work to get deflated. I could not imagine having one that was 240 square ft or above. If you were in any sort of hurry better have a cargo van or box truck. Does anyone know why airlocks never developed in the paragliding. It also seems to be slowly dropping out in the skydiving community as well.

There are a few paragliding wings that were made with airlocks. I'm not sure if they're still made. PG wings have very small cells (compared to skydiving/BASE canopies). PG wings also tend to collapse. Airlocks made the wings slower to re-inflate after a collapse. Although you would think with airlocks it wouldn't collapse as ealsiy. It seems it's just like the skydiving/BASE world. Airlocks were tried but just not deemed worth it.