Basejumper.com - archive

As a very new guy in the sport (less than 25 jumps), can somebody explain what a VENTED pilot-chute is and what it buys you versus a non-vented PC? Also, what's this I hear about directions of mesh, etc...
Probably needs to be a new thread...?

Rich

a zp(i never saw them in F-111 but i could be wrong) pc whith a hole in the top.in that hole theres mesh like the buttom of the pc.

A vented pc should be more stabel,which means it should help keeping an onheadding to the canopy.

other can sure describe this better than me

http://www.dropzone.com/..._latest_reply;so=ASC

And so it is...

Vented PC's have a mesh vent on the topskin. Different vent configurations have been tried (my personal favorite is the configuration currently used by Morpheus). The idea is that air is vented out the top, instead of the sides, so that the PC is more stable. Orbiting PC's can cause off headings, by switching extraction directions during deployment.

Do you have 25 BASE jumps, or 25 skydives? I hope it is skydives.

I believe he is talking about BASE jumps. His profile lists that has been in sport parachuting for 9 years with about 800 airplane jumps.

nic

I was wondering that - surely this is the sort of thing you should know about before you start huckin your carcass off stuff relying on equipment being made correctly?

or am I being too harsh?

Here is a pic of my morpheus tech vented pc. You can see the mesh venting around the black cap at the apex. I am not sure but I believe all other vented pc's by other companies are completely vented (meaning that the entire apex is vented without a cap).

That's pretty much what the Bounce Proof pilot chute vents look like. Ray has been venting pilot chutes for years before they became mainstream.

When I first started asking questions, some people were dicks and others were generous with their replies or at least informative.

No one starts this game knowing alot about alot. At this stage of the game, I still know very little. I have vowed to, whenever possible, try and be helpful to those who ask rather than judge them by a simple question.

Hope that helps.
....

I'm curious to see the construction methods used on the Morpheus vented pilot chute since I've only seen one in pictures. I have several AV pilot chutes made by Asylum and they work rather well but have nothing to compare to.

Agreed. Someone can either ask a question and get help, or keep jumping and not gain knowledge.

Ideally, a new jumper will hang out with a more experienced BASE jumper who can't stop talking about BASE gear and techniques.

I talk and think about BASE all day. If you want to share ideas, come hang out with me.

That's a reasonable question from a new BASE jumper.
In the beginning you rely on mentors and manufacturer QC.
Sometimes you rely on the next clown in line, as if he knows anything.
Believe me, there are some hot-shots who don't even know what bias is....
Eventually, we all realize we need to be our own rigger,
then the little details become important.

Edited to add:
Vented PC's are not the end-all in PC mfg.
An assymetrically loaded vented PC could oscilate.
A poorly constructed PC of any type could be deadly.
If everything is perfect, you could still have a bad day.
The only way to be sure you will not get hurt on a BASE jump: don't do it.

In my opinion, assymetric attachment will overcome venting. I think that venting is only going to matter when everything else is done correctly (i.e. PC is attached symmetrically, constructed correctly, etc.).

looking forward to

by the way are there F-111 vented pcs out there? im thinking of the smaller range to slider up which i ofcourse dont know sh#t about

Tom you for got the pic

Maybe (we) I was too harsh whit that comment, but if someone with 25 base jumps don't know what is vented PC, he should be VERY scare, and maybe he should consider changing base crew or mentor.

that may have been harsh, and yes I know that I am still learning and I dont really know shit, and that asking questions is a good thing, but surely there is something wrong with someone who is hucking themselves off objects (with 25 jumps its not unheard to not have a mentor or to be going out soloing) and not to have a basic understanding of equipment available to you (I agree that perhaps the bias thing is not something that a great deal of people are fully knowledgable about).

Sorry if my tone seemed harsh and I appeared to be one of those "dicks" but shouldnt one want to know as much as possible before they start experimenting with Low Alitiude Parachute Deployment Science?

Sorry for being a dick

just dont let it happen again,or ill show you which kind of dick you are(intern joke about some video i will keep to the day i can sell it to mac for the right amount of mony,nahh fuck that having it using it against you all the time is much more fun than mony)

Now claim your right:
Pink hat wearing mincer BASE#1

I some how agree that a person whith 25 jumps should have the knowlegde of this kind of gear,then i look back and onto myself,i guess i wasnt better at that pointHell i still sucks but whos give a Sh#t

Ahhh... this forum never gets dull, I love it! It's like pushing people's buttons just to be vicious and get a laugh! In my case, ask 2 simple questions and get 17 vehement responses... only a couple of which attempted to answer my questions, which I sincerely appreciate.

Anyhooooo... now that I've been soundly chastised for not being an expert on all facets of the sport at the scant number of 25 basejumps, I'd like to ask again... is my brand-new (ok...18 jumps) non-vented PC unsafe? Am I setting myself up for something detrimental when statistics finally kick in?

Second question: What is bias? And what does it mean to me as a low-time basejumper?

Please don't stop the attitude, hollering and jeering... I really do get a kick out of it. Just try and teach me something at the end of your post. That's all!

Rich

Also, why are vented PC's only offered up to a 42 on this website? Why not a 46?

http://www.baserigs.com/docs/products/accessories/pilot_chutes.html
(haven't figured out the link thingy yet...)

non vented pcs has been used for a long time whith ok results. I think your in no more danger than the rest of us.
That said i didnt belived it and my only unvented pc as today is a 48´and a old 45´

Why Morpheus dont make em? hmm i dunno if the do or not but try mail them theyre really kind people,just dont say you spoke to Faber or they will laugh all over

i dont know but it sounds cool dosnt it?
did i write that?? he he(psst i cant spell my own name so if so,sorry)

This is just what I remember from a couple of years ago. So I may not remember it correctly. Morph. was doing some testing on the vented pc's and I think that they felt the venting didn't have as much benifit when you started getting into that size pc (short delays). Like Faber mentions though... you should email them/call them. Then try to post the answer here. Or have them pop in and answer themselves.

I didn't know what a vented canopy is for a long time, there flame me too. how goes the journey for jumps out there man? lucrative I hope. If you ever get to Denver, remember, fun to be had.
Adam

Hey.....Vented Mesh-Apex on your Pilot-chute sure beats
burning Holes in the top with Lit Cigarettes.

is my brand-new (ok...18 jumps) non-vented PC unsafe? Am I setting myself up for something detrimental when statistics finally kick in?

* No ...as long as you are using proper size in relation to your delay of free-fall and it is properly constructed.
.....................................................

Also, why are vented PC's only offered up to a 42 on this website? Why not a 46?

* Your delay being very short it is more likely will be affected More by other things like:
body positioning and out side interference like wind etc.

* A 46 or 48 is not hanging like a Anchor long enough to start oscillating.
You pitch it out / It's ripping your canopy out of container.
If it is Not... You have a Container Lock or a Severe PC Hesitation.
........................................................................


What is bias? And what does it mean to me as a low-time basejumper?

* Are we talking about the way the Taping is sewn on the Rip-stop material ?
The cross hatching design of the reinforcement (those little squares) ?
or
* Are we talking about the Mesh material on a PC.. ? Which way it is turned because
it has a directional stretch to it to.
Depending on which way it is turned. On the Square / or On the Bias. ?
Taping on the mesh is what gives it an even or balanced shape.

* Those little squares of reinforcement in the Rip-stop Nylon.
If you turn them 45 deg. from square to diamond.
Its changing them from being square to the Bias.
Tapering done on the Bias is much stronger than being sewn on the square.

* Your attitude of BASE Jumpers on this Forum is Bias.
Thinking that we are all Ass-Holes... (most are not)
Some of us actually take great Pride in being an Ass-Hole when we Post hear.
.
.

just a side note,you earlyer told that you use your 48 stowed,for how long delays?

If you pop your pc no matter the size it will need the time to fill up the pc whith air before having a pull force.It dont takes much time to fill it up whith air but you actualy have slightly longer time on your 48 than on a 46,which is why some people use a 46 rather than a 48 as it inflates faster it will pull faster...theoretic at least

Personally i only jumped a 48 once and it were a SL jump so it wont tell a thing. But i have freefalled sub 200ft whith a vented 46´

It's probably going to get you to linestretch at the same time.

The 46 will pressurize faster but will have less drag than the 48. The PC will pressurize faster and pop the pins, but get the canopy to linestretch slower than the 48.

The 48 has more drag. It will pressurize and pop the pins slightly slower but once it's pressurized it will take the canopy from the packtray to linestretch faster than the 46.

So, the 46 will start doing the work earlier than the 48 (probably) but in the end, at this delay range, the result is probably going to be nearly identicle. From the outside, it's going to be hard to tell the difference.

What will be easy to notice, will be the jumper with the 48 opening really low because he stowed a PC that was too large and it hesitated for a second before pressurizing and popping the pins. He could have just went stowed with a 46 and reduced the chances of a hesitation. If it was 300 feet to impact, he could have used a 42" PC and taken a 1.5 to 2 second delay and been just fine.

"If it was 300 feet to impact, he could have used a 42" PC and taken a 1.5 to 2 second delay and been just fine."

Dude, speaking of all this, I did a jump from our 300' B, it has that "alternate" landing to the right of the corner we jumped. That makes it 240' to landing, I took a 1/2 second or so off the corner, had a 50 degree right and landed on the 240' landing. It was reasonable, too, I didn't even bat an eye. I was really surprised that on a half second hand held jump with a 42" PC, I was fine at 240' (inadvertantly, but it sure answered a lot of questions I had on accident).

In Reply To
just a side note,you earlier told that you use your 48'' stowed,for how long delays?
................................

I usually don't delay more than a 2 sec. with no slider.
I believe people were talking about not using a 48 PC stowed because it not safe.
Just because I used a 48'' stowed for years on every no slider jump does not mean
I go stowed on low & shitty jumps.

Dude Pilot-Chutes are a HUGE subject.

I personally believe that "Air Speed" is the factor that does not mater as much on
46'' - 48'' inch pilot chutes. As far as.. bad-time Oscillation.

When you start cruzing over the 4 sec. mark in free-fall... That's the "Judge" of a balanced PC.
....................................

In Reply To
Personally I only jumped a 48 once and it were a SL jump so it wont tell a thing. But I have freefall sub 200 ft with a vented 46''

I have jumped every sub-200' with a 48'' PC.

** Pilot-Chute hesitation can happen to... Any PC & Any SIZE PC.

** Pilot Chutes are all subject to:... The way they were CONSTRUCTED & The Jumper that is " THROWING" it out.

Weight of PC, also Balance....but..... " DESIGN of Efficiency".... is a Big-One.
that is bigger than efficiency ....It's Design of efficiency.
Every manufactures builds them different & has his own design and thought of design efficiency.
An extremely well Designed 42" PC is a lot better than a fucked up 48" PC and visa-versa.

* Jumper
There is a proper way to * "PRESENT" * a PC to the air when you Pitch a pilot-chute to the air.
both... Hand -Held & going... Stowed.

I don't want to get into all that fucked-up argument of the Mushroom & Super-Mushroom CRAP.
* Lets just say..." There is a proper way to fold a Pilot-Chute."... (enough said) on this over talked about subject

The way a Jumper throws a PC out to the air is BIG.... There is a different way to throw a PC out. For different jump situations.
There is ....TECHNIQUE.....In How & when to pitch a Pilot-Chute.
There is also Technique involved in Knowing.... "Which"...technique to use in Different Jumps.
Different pitches for Different Jumps.

* this can all be... Summed-Up.... in 3 Words.......Design, Technique, Timing .

>- A.Well Built Pilot-Chute.....> - Knowing, How to Throw it out..... >- Knowing, When to throw it out.
.
.

Probably best to ask the owner of the website that, don't you think?

I'd guess that they've found the advantages of the venting minimal on larger PC's/shorter delays, or that they've found some problems (increased hesitation rate, maybe?) on the larger vented PC's. You'll note that the other manufacturers of vented PC's _do_ offer vented PC's in the larger sizes, so it's obviously not something that everyone agrees on.



To make a link clicky, put {url} before it and {/url} after it, but use "["
where I'm using "{" here.

No. As long as it's manufactured correctly, it'll be fine. People used them for years. A vented PC is probably better, but not so much that I'd throw out the brand new unvented one. Before the vents make a difference, everything else needs to be done correctly, so you may as well use that one to learn everything else. Once it's worn out, you'll have the other stuff down, and you can buy a shiny, new vented PC to use with your new skills.


Ray did a pretty good job explaining. If that's not clear, post a follow up and I'll try to find diagrams. It's _very_ important that your PC be constructed properly, and tapes sewn on the block of the ZP means it is _not_. In my opinion, a poorly constructed PC is a much bigger deal than the apex vents (or lack of them).



Most of the attitude is done with your best interests in mind. Although it may not come across that way in this form, most of those folks are genuinely concerned to not see you end up as a statistic.

Ray i do agree in what you say,but as you know trimming is important then i still belive that my 46´is one of the most used tools of my pc´s(well 42 and 46 to say),i also usaly use a 45-46´for my SL jumps.
I know serval people in Europe jump this way aswell.

Ray

"Different techniques for different jumps"

You talked of pilot chute presentation by the jumper (pitching, throwing, placing) for both stowed and hand held jumps. I would be very keen to hear yours (and other experienced jumpers) techniques for folding and presenting the pilot chute to the air in these different situations.

This is definitely something i need to brush up on and i'm sure i'm not alone.


If you're happy to share, i'd be delighted to listen.

ian

Just out of curiosity, if you are going for a jump with 300" to impact, why go with 42" PC when planning to delay max. 2 secs ? Especially I'm interested why you chose a 42" PC on a 1/2 sec delay ? Wouldn't it be more appropriate to use a 46" ? Since all major manufacturers recommend a 45-48" when delaying under 2 seconds and the way I feel it in PC's (as in probably everything in BASE) you should always err on the bigger size. I'm very interested in this 'cause I've done a ~300" A several times with delays of 1-2 secs and my choice has always been 46" (hand held).

too big pc can cause centercell stripping if you overdelay that PC.

a 46´wont harm you on a 1-2 sec delay,but neither will a 42´off 300ft.
I before saw people freefall aprox 1 sec delay off 230ft whith a vented 42´ on a unvented canopy,serval times whith out any problems...

NOTE: isure recomend a 45 or bigger sub 250 ft for sure...

Rich,

To help you understand, let's go back to the beginning . . .

There were many skydiving and BASE gear manufacturers (and still are) who build pilot chutes improperly. When all pilot chutes were made from F-111 these design problems didn't matter much, but when Zero-P material came into use the problems of bad pilot chute design became apparent.

Picture in your mind a very early round parachute with no modifications (no apex or steering vents). The problem with these parachutes is they would oscillate. The reason for this is the great amount of air trapped inside the parachute had no where to go, so it would spill out from under the skirt. This caused the canopy to tip one way and then the other, hence the oscillations.

On a smaller scale the same thing happens to pilot chutes. The F-111 material in the top of the PC negated this effect somewhat because air can actually pass through this fabric and this has a stabilizing effect. The problem began when Zero-P replaced F-111. We then began to see wildly oscillating pilot chutes. (Check out the Radix video page for Bridge Day 2004, in one of the teaser videos you can see a good example of this, and the effect it has on the canopy).

The underlying problem is really not the Zero-P material itself, it's the way the PC is manufactured. If the trim of the pilot chute is incorrect when manufactured then when inflated the upper surface forms a perfect circle. This will cause the oscillations. A better design will make an inflated pilot chute looked lobed (the trim tapes break up this circle and forms channels down the side of the PC.) These channels allow air to pass by the pilot chute and at the same time stabilize it. There's much more to pilot chute trim, but in simple form that's it.

I'm not convinced, at this point, that vented pilot chutes aren't just a quick fix for badly designed pilot chutes.

NickD
BASE 194

In my experience, the problem, 9 times out of 10, isn't the PC manufacture. Almost everyone is getting their PC's from a handful of (generally good quality) manufacturers. There are still some "garage specials" floating around, but fewer and fewer all the time.

What I've seen, more often than not, as the cause of orbiting or oscillation is asymmetric attachment, not manufacture. Even a perfectly made PC can oscillate if you attach it assymetrically, and most of the modern designs allow assymetric attachment (I have some Paratech PC's that will not, and Marty made me some custom that won't either--I heard a rumor that this is standard for Asylum now, but I'm not certain).


I'm actually fairly convinced that they are a fix for poor attachment. So most of the gains from this gear advancement have gone to allowing us (jumpers) to get away with sloppiness.


Back to the original question: I think that if you learn to attach the PC symmetrically, it's not going to be much of an issue, the vast majority of the time. If you attach the PC wrong, then the vents aren't going to save you (they'll help, though). If you have a properly constructed (most PC's) and symmetrically attached (unfortunately, not most jumpers), PC, then you may see some improvement from vents, but the improvement will be at the margin, and not noticeable on the majority of your jumps.

BASE311 was kind enough to give me this diagram of block and bias.

Sure thing that overdelaying with too big PC is not recommended but neither is underdelaying with too small PC. Of course you can get away just fine with 42" PC on a 300 footer with 1-2 sec delay but my main question was kinda why choose a 42" instead of 46" if you are planning a delay that is inside 46" PC's recommendations ? Do you see any considerable pros in using the smaller PC ?

This is starting to slide offtopic, feel free Tom to edit this or start new thread.

did you read Dexters comment?
http://www.dropzone.com/..._reply;so=ASC;mh=25;
it kind of sums it up.

a 42 will inflate faster than a 46,and pop the pins.
It still need to pull out the canopy through..

I prefer the 42 on anything over 300 feet because it's a lighter PC. When you throw a pilot chute out to the side, the added inertia of a heavier PC will take more time and airspeed to overcome and inflate.

I prefer the 42 for anything over 300 feet but once I'm under 300 feet, I use the 46" PC in a handheld configuration. Remember, my personal hard deck for going stowed is 300 feet. I've gone stowed plenty of times just over 300 feet with a 42 and I'm very comfortable with it. Step under 300 feet though and the 46 goes on and the PC goes into my hand.

There's nothing wrong with using a 46 for this same 300+ foot jump, I just don't think you'll gain anything over the 42 at this airspeed. Go out to a friendly object and do a bunch of go and throws with a 46, then do a bunch with a 42. Decide for yourself.

Remember, all of my opinions are exactly that, opinions. I do what I feel comfortable with. I'm offering this information because we're discussing this topic. In no way do I recommend you take your 42" PC and go stowed from 300 feet. There are many things that need to be done after the canopy opens and just physically getting the parachute open over your head is just the start of the dangers of a BASE jump. I feel comfortable that the height my canopy will be open above the ground after taking a one second delay (stowed) from 300 feet will give me the time I need to land the parachute with some degree of safety. Based on your individual experience, opening 300 feet above the ground may give you the same degree of confidence. Others are more comfortable exiting and opening much lower than I am. To each his own in this sport. Remember, no information on this forum is going to keep you alive unless you have the experience to make it work, and have the patience to gradually up the ante.

That's pretty much the way I've thought about it too.


That is an important point and point indeed worth of making. Still I'm glad that this discussion took place cause I mainly got the opinions I looked for. I've always thought about PC decisions on delays near 2 secs and on objects round the 300 ft mark.

>>What I've seen, more often than not, as the cause of orbiting or oscillation is asymmetric attachment<<

And that too . . .

Thanks Tom.

NickD
BASE 194

I actually know people who prefer smaller PC's at lower altitudes. The general feeling is that a smaller PC inflates more quickly, so that in the end it cancels out the greater extraction force of the larger PC.

In my experience, the real killer at low altitude is not slow inflation. It is PC hesitation. Larger PC's are marginally more prone to weird hesitations. Stowing big PC's, in my opinion, greatly increases the risk of hesitation.

So, I think DexterBASE is on the right track here. Downsizing the PC when you stow is definitely a good idea. Keeping the big PC's in your hand helps reduce the chance of a hesitation.

There's definitely something to the "smaller = less hesitation" school of thought. I know people who take this as far as using 42's on 200' freefalls. I'm not quite all aboard for that, but I can definitely see the logic.

I think in ten years, a 46" Pilot chute will be considered the "Big One." The trend seems to show that more jumpers are using pilot chute sizes that were considered (just a few years ago) inappropriate for short delays.

Who knows?

 
one thing that seems not to be mentioned (i dont think by looking over the thread) is the canopy size. It maybe ok to take a 42 for certain freefalls with a 240 canopy but this does not mean that someone with a 280 should be doing it.

a jumper borrowed my vented 42´attached it to his unvented canopy,fitting in a velcro rig.
we went to 230ftwere he made 1 sec delay on this each time.i made aprox 1,5 sec delay on my 46´vented in a pin rig containing my vented canopy. we ended up under flying canopy arround same hight(70-100ft)each time,both of us.

I know that the Basedudes(Belgium)use an unvented 46(or45) as their biggest pc.

Personaly i have serval ff off 180ft whith my vented 46 pc,that i choose to use a 48 from that alti after my last jump is another thing..

You might want to ask Tom on PM who made the lowest ff whith a 42 on i think it were one from CR jumping off 180 or so,quiet insane but it were done...

From your posts i see i think alot like you in gear.(after a pc hessi on a 180ft ff) i usaly also use a 46 below 300ft now,if i rember.but am ok if needed to jump off 250ft whith my 42´.

I know that Tom has been thinking alot about this as we were asked not to speak up about this as we dont really want to undersize pc´s for jumps,but its interesting.

A jumper once made a pc drag tabel(i cant find it any more which teoretic showed how much pull force a given pc would have at a given time(weight and wing load considdered

its werry interesting stuff

Any way
did you make any of thouse carry on SL´s? i might want to ask you to build some for me.if you havnt i can tell you how to do.
My local beforeBASEfreindly has become unBASEfreindly.
i need some in different lenghts,and the one i have is pretty mush worn out(not that i do alot of them SL jumps he he,i just love it..)

Happy safe new year mate..
besides i think i found a place that sells tickets to that tampac(tampax?)place you want me to go

edit: by request of poster

I've got all the stuff to build the SL setups. Just send me a PM with the lengths you want and I'll throw a few together for you. I've been using them a lot and they work great. I'm building them out of 900 pound dacron.

Tampax??? Seatac!!!!! Crazy Dane...

Nice, I was wondering when someone was going to point this out. I'm just getting off work but hopefully I'll be able to post more on this topic later.

As for length, what would you propose? I would suspect that it should be about the same length as your bridal unless the object needed a different length?

What situtations have you ran into where you have needed a different or special length "Carrywithyou SL"

So when you say length, do you mean anything longer than the normal bridal length?

Another point/ issue: What benifit does using the "Carrywithyou SL" have over using a basket SL? (basket: where the circular SL goes around the object looking much like a horseshoe) (also noted that the basket ?doubles? the breaking strength or point)

a carry on sl as long as your bridal will probaly snag as the break cord breaks.
it should only be so long that it can go arround the rail plus some slag,but not long enough to snag an rail below or so..

Thanks Tom for edit my post.(to others i some how mistakenly thourght i made a pm),which i later realiced i didnt

hey faber - the PC drag table is here:

http://www.blincmagazine.com/cms/deployment.shtml

and a post from Andrea on the calculations:

http://www.blincmagazine.com/...highlight=drag+table

and some more info from Andrea:

http://www.dropzone.com/...drag%20table;#738161