Basejumper.com - archive

 

What discussions....
What were the arguments suggesting Vents are outdated technology ?

 

Just wondering, but why did many old school hardcore accuracy canopies have slots on the bottom ? (aka Parafoil) I believe it was for deep brake approaches.

Perrine bridge is not a lab environmental (in other words the only variables you could control were canopy type and jumper weight, deployment method - all others no matter how much you want to think that they stayed the same - did not), a fixed number of 6ft for the opening differential sounds like a number that cannot be proven statistically, unless of course your margin of error is about 99% :)

 

Who were you talking too? If your nose is closed off by a wall, you want the pressure that holds the valves closed to let them open, not so that air spills out, but so that more air can get in to keep the pressure in the canopy, so you can still control it.

Simple:
Vents will become a 'thing of the past' no sooner than object strikes and dirty low freefalls become a 'thing of the past'.

Hey tr, i was thinking about posting the video of me doing a roll over with your Ace off the udistB, and then my BJ off it to show that it's a lot more than 6 feet, but decided it was too embarrassing Watching the video I can hear you giggle as I'm swinging under that shit and falling on my ass

Not spilling the air out, but pumping the air inside choked canopy. Vents saved my life in cliffstrike (video). With vents, the canopy stays fully inflated and greatly reduces the rate of descent, helping you fight.

Jumping low cliffs is already semi-suicidal, but jumping them without vents eliminates the "semi" part.

Probably been hanging around Sonic, world famous base guy.

 

I am still waiting to hear someone say
why vents might be a Bad idea... other
than the extra cost and pack volume.

I've had two object strikes in my day. Both times I was jumping a blackjack with vents and valves. I believed that if I didn't have the vents and vales the canopy wouldn't have stayed inflated and the canopy probably would have collapesd and caused me to fall to my death. Both were slider off jumps.

Word of advise, take it low of low cliffs so you don't have time to have 3 strikes.

Well said...

 

There's another very very important advantage of vents. You gain directional control much sooner in the pressurisation process of an inflating canopy. This is particularly useful in off headings on slider-down jumps.

Another advantage. I have seen some seriously low pulls in my time. 6ft can make all the difference between a twisted ankle and a broken femur.

Another disadvantage I just remembered. They're supposedly prone to fall backwards with a tailwind over 15mph, when in deep breaks. I've seen footage of it happening, where the person had good clearance from a freestanding A, but on opening the canopy slid backwards hard and put the person into the tower. The way it was explained to me is, some of the air that would be pressurizing the tail is blowing through the vents and out the nose, which also makes it harder for air to come in the nose, and the bitch slides backwards.

 

Me neither...hehe

Tom A showed me the video and told me about the phenomenon. Hopefully he'll see this and give us some more info on his thoughts.

<=== many jumps with very high tail wind. No issues except needing to turn around quick. 15 is pretty normal for open tower jumps. Around here, higher is very common.

How in the world will a canopy fall backwards in a 15+ MPH tail wind and hit the object? Even if it does stall a little, it's going to go forward relative to the ground in that much wind.

i don't know about the flying backwards part, but i've definitely experienced opening stalls in tailwinds in very deep brake settings.

but i don't think that's a flaw of vents, i think it's a flaw of brake settings... (especially for the conditions) and is prone to any canopy vented or not.

Where I come from - 6 ft can mean a lot.

this is a good point about them staying open better when you smack something. makes perfect sense. however, lots of people hit stuff with non vented and there parachutes have stayed open too. what we need to do is have a bunch of object strikes, like eveyone goes out and has 3 or 4, with and without vents, and then we can get to the bottom of it.

seems our base wants and needs are moving on from vents for some, but really we just have lots of choices. its great. Aylum has a new ultra cool bad ass check this out its really expensive and great canopy coming out and it is not vented.

APex is offerring/ soon to be offerring all their canopies with the option of superlightweight material that lasts and it too is expensive and great, but it is offerred with or without the vents, just like all APex canopies save the dagger.

The trango is very popular and it is not vented. many of my friends were all about vents and now they jump trangos. go figure

not sure where i stand on it. one thing i've learned about vents is that they will help a canopy work better if the canopy has big logos on it.

i have on a windless night done 3 HH freefall loads off of an antenna 12 miles west of SLC international airport named "the substitute tower" or more commonly "the 220"

each time my canopy ride was somewhere more than 6 less, than a full 7 seconds and my ground rush was very similiar and for all i could tell i opened at the same height. those 3 parachutes were Flik 4/7 VTEC, Raven IV (no vents), Fox 265 (no vents). one the same 223ft tower in the same week, we loaded 8 dip shits on the tower and most everyone freefell. there was a variety of canopies and after going among the first, i watched everyone. the only kids who had higher openings were the ones with smaller canopies. fill volume is less, it fills quicker regardless of vents.

this post is long sorry, i type fast.

by the way, there is nothing like sunlight shining on green california steel beams to get you back to being fired up on base jumping again. so much fun

correct!!! vents has nothing w this

i have a video of a good friend jumping a low object and while the canopy pressurizes he is flying backwards but i dont think it was his vents pushing air out the nose it was more he selected wrong brake settings ,

we watched it over and over and its insane how far back he goes nearly hitting the B but after blowing the brakes it surges forward very quickly

If you check with him, i believe his opinion on this has changed. I believe it had something to do with early vent designs w/o covers.

That looks unforgiving.
How tall is that?

 

Haha wow I'm retarted. Guess that's what happens when you look at this shit in the middle of class.

Thanks

Just imagine what you are missing in class...

I bet at least one thing that will be on a test

Thanks mom.
Haha I'm in good ol phsics as I post this.
And yes i'm sure I'm missing plenty of info that's gona be on my final

I am 100% definitely not a parent!!
The wife and I are NOT having kids.

We are taking our fucked up genes to
the grave with us, as a service to all
of humanity...

But I am a college professor and you
are proving my point: cell phones and
computers in class are a distraction.

I also bust Jake's balls for this too

Lastly, it is spelled: P H Y S I C S

haha i would definetly have to agree that they are a major distraction but its also the cure for boredom...no offense to teachers

and im gona have to blame the poor spelling on the touch screen phone

I'm sure everyone here would agree that being a good student in physics is unnecessary as your familiarity and understanding of physics will never be tested or of any use in parachuting. Attention to detail and risk management are also bundled in with physics as worthless skills that will never be useful in this sport so party on!

Haha I'm glad you agree with my decision to surf this site instead of paying attention in my physics class.

What I didn't say before but probably should have is that I have the highest grade avg in the class with a test avg of 92. Honestly I'm not trying to brag but if I can sleep in class and surf this site and still do good in the class then why not do it

But I do enjoy applying kinematics and freefall equations to skydiving and base.

have you covered the difference between relative scales and absolute scales?

i.e.
are you trying to be fast, or just faster than the guy beside you?

Nope I was asleep for that lesson

Haha I'm jk uhhhh I don't think we are covering that. I'm taking algebra based physics and I'm in high school. Sooo it's no suprise that we didn't cover that.

Guess that's why it's so easy. God knows I couldn't do it if it was calc based.

If the nose is closed off against an object, you are right air cannot get in. But air can't cat out as well

 same thing happened to me only i didn't hit the a.
i'm pretty sure my deeply set brakes were the main contributing factor, but i'm not going to rule out the vents contribution.

If air isn't being ram'd the wing won't be able to fly. And air can still get in and out with f111 material, just not effectively enough.

But I am a college professor and....

Really?

Do you use Green white board markers? Green chalk? Green fuckin' handouts.

Intolerable!

John

I use a whiteboard and whatever markers aren't dry.

Ease up dude, it should be the least of your worries.

I do have to say that it is a bit annoying. Especially when you constantly point out the fact that you are an educator, and yet do something as juvenile as insisting on making your posts all green.

Naturally it helps to ease off your case knowing that you teach in a community college :)

kisses and hugs.

Vents have made BASE safer.
A vented canopy will open more consistently regardless of wind direction. A non-vented canopy opening with a tail wind will take longer to pressurize.
Someone in this thread mentioned a vented canopy backing up. We saw the same thing in the early days of Vtec testing. We had vented 6 cells (with no valve) and done long no slider delays. The Vtec pressurization was so powerful the excess air had to excape through the nose thus created a back slide. After we added the Vtec cover (valve) and reduced the vent to 4 of 7 we've never experienced this again.
Remember all vents are not created equal. One example is some canopies use a larger inlet than others. This is great for ultra low jumps. And is one of the difference we use in our FOX xs canopy. But the FOX xs is built for those who want to free fall in the ultra low category.
Regarding the post that spoke about the test jumps at the Perrine- What was the wind speed and direction? If you have a head wind you will notice a much better pressurization, with non-vented, than with a tail wind. A vented canopy will notice very little difference if any.
Vents work.
Vents work well. They provide consistent pressurization from the only consistent relative wind, the falling jumper.

"Vents work well. They provide consistent pressurization from the only consistent relative wind, the falling jumper. "...........................................................................................enough said!


ps great post.

Definitely great post. Thanks Todd.

After seeing a 180 freefall.... and making numerous jumps in the 150 -180 range... i am a believer

well put.

I recently had a canopy retro fitted with vents.

I think that that saved my ass on a recent unintentionally very low pull with a wingsuit in which i was going more down, than forward (after front flips)

I have slowly come around to agree with Todd entirely.