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sillie1111

Vented Canopies?

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In my limted jumping career my blackjack 280 has been awesome. About 20 jumps slider up at Kjerag, the openings were nice and 3 or 4 were more than 30 degrees off heading. Perhaps my body position? Slider down on objects 350' and below with manufacturers DBS and the openings have been on heading every time and seem to burn minimal altitude. Canopy response is crisp as soon as I pop the toggles. I have nothing to really compare it to but I have total confidence in my kit. Manufacturers advice on canopy size and loading seems to work well for brake setings. (You'd hope so!) I'd recomend my blackjack to any beginner.

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I'd recomend my blackjack to any beginner.



How can you "recomend" a canopy to any "beginner" when you your self have limited experience on it?

This is madness...... you may as well say "I have done this a few times so I think you can do it"

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I have nothing to really compare it to but I have total confidence in my kit.



So what? You have confidence in your kit with nothing to compare to it, but you have NO PROBLEM advising newbies on what they should jump.....

[:/]

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another great quote:

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I only have 25 BASE jumps on my BlackJack and 6 skydives, but I would recommend it to any BASE jumper.



Seriously, how can you recommend something you have such limited experience on?

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To play devil's advocate for a second:
Canopy experience numbers are relative. What used to be alot isnt as much these days. In order to be qualified to be a base newbie, that person should have the ability (to think for themself) to qualify to varying degrees the opinions of each person giving recommendations based on how they feel about the recommendor's experience. In other words, who are you or anybody else to decide who can or cannot give recommendations, shouldn't the listener decide for themself who they want to heed and what they want for themselves?
"The evil of the world is made possible by nothing but the sanction you give it. " -John Galt from Atlas Shrugged, 1957

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yet another great quote:

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Wow



Why did you all assume that what Tom posted was the way it happens? Why did none of you question anything he had to say, there were NO QUESTIONS!!!! Just because someone sounds like they know what they are talking about, does not mean they do...... (no disrespect TA, just trying to make a point)....

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To play devil's advocate for a second:
Canopy experience numbers are relative. What used to be alot isnt as much these days. In order to be qualified to be a base newbie, that person should have the ability (to think for themself) to qualify to varying degrees the opinions of each person giving recommendations based on how they feel about the recommendor's experience. In other words, who are you or anybody else to decide who can or cannot give recommendations, shouldn't the listener decide for themself who they want to heed and what they want for themselves?



any BASE jumper that advises to use/do something that they have limited experience in themselves (especially to newbies) is out of order..... thats my thought

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shouldn't the listener decide for themself who they want to heed and what they want for themselves?



sadly the new breed of BASE jumpers (In my opinion) are not the people that make decent choices

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yet another great quote:

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Wow



Why did you all assume that what Tom posted was the way it happens? Why did none of you question anything he had to say, there were NO QUESTIONS!!!! Just because someone sounds like they know what they are talking about, does not mean they do...... (no disrespect TA, just trying to make a point)....



Has it occured to you that possibly there were no questions because Tom's explanation made sense to them?

Rather than slacking others for their alledged ignorance, you would do better to invest that energy into proving their ignorance.

E.g., show them what kind of questions they could have asked.

I guess that goes for me to, rather than slacking the slacker, I should be drinking beers while listening to Dire Straits. Come on Mac, it's time you come visit in Vancouver so we can flick something. Stop breaking your head over the dying noobs around you. As Ray Losli said: "...we're just paying back an overdue loan, who cares about a beginner here and there."

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The Troll MDV already has vents. (forgive me if I'm wrong!)



MDV is an acronym for Mono Directional Valve, so no forgiveness is necessary.



Mono Directional? that suggests only one way? that is completly against the design of what the MDV actually is????

I thought MDV is a Multi directional valve and not mono. This is from the fact that the valve closes in various directions.... compared to the "flaps" that most valves have...

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The Troll MDV already has vents. (forgive me if I'm wrong!)



MDV is an acronym for Mono Directional Valve, so no forgiveness is necessary.



Mono Directional? that suggests only one way? that is completly against the design of what the MDV actually is????

I thought (actually I know) MDV is a Multi directional valve and not mono. This is from the fact that the valve closes in various directions.... compared to the "flaps" that most valves have...



According to the advertisement on Page 12 of this months Skydiving, it stands for Mono Directional Valve (P-MDV is explained parenthetically as Penta-Mono Directional Valve).

I believe that mono directional is meant to refer to the fact that air can flow into the canopy through the bottom skin, but not out. Hence, the valve is mono-directional, where the previous Vtec (no covers) system that had dominated the market initially was a bi-directional (air could flow in and out) system.

See also the Morpheus Web Site which gives this explanation (under the Products: Canopies heading):

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MDV Technology

Stane is on the cutting edge of parachute design in general and this has become very clear with the introduction of MDV technology. The valve system on the Troll is called Mono Directional Valve technology or MDV technology.


-- Tom Aiello

[email protected]
SnakeRiverBASE.com

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touché

:$

I will fuck off and get my coat now.....

:$

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Quote: sadly the new breed of BASE jumpers (In my opinion) are not the people that make decent choices



Hey Mac just a question here but who are you to say that I don't make decent decisions? Just because I'm new to BASE? You don't know much about me or my abilities to make such a statement.
I have been doing a lot or research reading talking with jumpers local and non local jumpers as well as my post here to help me decide what I'm going to get for my new canopy. I chose to get all of the information I could get from many different places to be sure I got the best information I could get and to ensure it is not bias to say jumpers who have jumps on only one canopy. I wanted to make decisions based on many circumstances and view points and not because some jumper with 1000 or 1500 BASE jumps says so. I want to self educate myself. Is that such a bad thing? Should I just do as I'm told and let more experienced jumpers think for me? I agree with tr027here I will and I have decided who's advice am willing to take.
As far as no one questioning Tom's post, I was questioning Toms previous posts on backsurge because from what I read in his old posts didn't make much sense to me and I have never seen it personally during the past year that I have been doing ground crew. He did a great job in explaining where he was coming from in his own eyes. What he said made sense to me and I saw no reason to question him.
Now am I going to make my decision because of one post? No, nor am I going to make my decision based on quifmiester's post. My final decision will be based on my comfort level and knowledge of what is what. I'm not saying I agree that newbees should be giving each other advise I'm certainly going to take comments from more experienced jumpers far more seriously then those from newbees, but I'm not going to discount their post at all I see his advice only as his preference but just because it his preference I'm not going to go out and by myself a blackjack I'm just going to keep in mind there are some who enjoy tat specific canopy. But like I said the people who replied to me giving me concrete explanations on their view point are going to hold more weight when it comes time to pull out my "Credit Card"!;) Yes sadly I must be another skydiver with a credit card (insert sarcasm warning here:o).

Thank you again to all who responded to my thread, although the initial thread was not to ask what canopy I should get it was merely to clear up some confusion about new jumpers and dangers of vented canopies it was none the less helpful in many ways.

Hey look at it this way it could be worse I could go out buy all brand new gear top of the line which I could let the factory decide for me what canopy container ect.. to get. Buy myself a FJC and when I'm done take my proclaimed base jumping self (cause I will know everything) up the local A and throw myself off, but don't worry my accuracy will suck too so I will make sure I only do a go and throw so I'm open high enough to set up a great skydiving like right hand pattern and land right on the big X I'm going to painting in the middle of the landing area!:S Ok so who's with me :) come on it will be fun. We can even dayblaze it so we get cool video B|. Hopefully you don't take me to seriously on that last part :P
~Shelly

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***
sadly the new breed of BASE jumpers (In my opinion) are not the people that make decent choices



Hey Mac just a question here but who are you to say that I don't make decent decisions? Just because I'm new to BASE? You don't know much about me or my abilities to make such a statement.



remember:
"The individual is always the exception.
'Everybody can't...' but anybody can."
- Richard Bach

i.e. Mac may be correct in general, but wrong in regards to you.
DON'T PANIC
The lies in learning how to throw yourself at the ground and miss.
sloppy habits -> sloppy jumps -> injury or worse

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I got one jump on a Unit, best damn canopy I have ever flown, however vented people are right, jumping conventional canopies will kill you and it's just madness, should not be done, you will die, they will open all fucked up and off heading, you will strike things left and right, and you won't be able to free fall anything lower than 150'. All the mojos and aces should be burnt to the ground now, please go and burn those canopies now before you die.

I am hotknifing a the bottom skin of a cruiselight as we speak so I won't die.
You know you have a problem when maggot is the voice of reason at the exit points

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Thanks for those helpful words Mac. Perhaps my 'recommendation' was inappropriate. Just trying to share my experiences as a newby jumper on a vented canopy. I qualified my comments by trying to be humble and stating the limited nature of my experience. I think confidence in your kit is very important. If you have are worried about opening with brake settings set too deep and stalling whilst peering over the edge, your mind is not where it should be.

Should I refrain from passing comment until I have a minium level of experience? Jump numbers? You tell me.

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Shelley, I'd suggest having a look at poster's details when reviewing the advice given. There are some low key posters who have close to a 1000 jumps and others who are critical, frequently passing comment and have very little practical experience (and they are crap jumpers to boot).

With a notable exceptions there seems to be an inverse relationship between the number of posts a person makes and the number of jumps they have.

Good luck

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Cell Inflation: After the bottom skin expands, the cells fill with air. This happens for many reasons, but a prime motivator is that the canopy will slide or hop forward (almost in the same fashion as an old style tracking jumper--by deflecting air off the bottom skin). This forward motion is not strictly "flight" (the cells are not yet inflated and the canopy is not yet formed into an airfoil shape), but rather more "deflection." This motion results in air rushing in through the nose of the canopy, pressurizing the cells (and creating the "wing" that you will fly to the landing area).



Standard disclaimer , etc.

Just trying to clarify :

As I understand the phenomenon the prime motivation of the canopy filling is the depression zone created over the canopy because of the vertical speed (relative to air) towards the ground. This depression expands the upperskin, just like inflating a chewing-gum outside-in (inside your mouth) by sucking air from outside. There would be three steps in an ideal canopy inflation :

*POC = air Pressure Over Canopy
PIC = air Pressure Inside Canopy
PUC = air Pressure Under Canopy


1) The canopy (after expansion) is deflated and act as an aerodynamic deccelerator just like said above. The trajectory is vertical. A depression is created over the canopy, thus sucking the upperskin up, making the canopy suck the air from outside. During this phase, POV < PIC < PUC so any vent will let the air inside the canopy fill the cells quicker but the canopy will inflate even if there's no forward motion and no vents.

2) The canopy is inflated, but the bottom skin is curved inside or just flappy. POC < PIC = PUC. The shape is ready to act as a wing as soon as any horizontal component will occur.

3) As the canopy begins to move forward (because of the "deflection" explained by Tom), a minimal amount of air goes dynamically in the cells from the nose (due to the relative wind). POV < PUD < PIC. As the pressure inside the canopy is greater than the pressure under the canopy the bottom skin inflates towards the outside, making a clean inflated shape of each cells.

so pretty much the same conclusions
head wind -> quicker inflation in 3) and quicker transition to flight mode (less forward speed to build before flying)
vents (any) -> really quicker inflation in phase 1) reducing the loss of altitude during this phase. the inflation also begins earlier when the canopy is still expanding
open vents (no valves) -> maybe slowing down last inflation phase in 3) but probably not noticeable


Anyone could try to evaluate the relative duration of each phase? (probably they arent practically clearly separated, mostly because the forward motion depends on when you pop the brakes and how you set them)

any comment or stupid joke appreciated : )


L.

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To verify the theory of bottom skin expansion, one could make the following experiments on a windy day:

1. Pinch the nose cells and try to kite the canopy. Does it expand?

2. Fold the overhung tops of the nose cells inside and fix with tape to make the nose "straight", with no overhang. Present the canopy perpendicularly to the wind (so that it passes parallel to nose openings). Does it expand?

I think even without doing the above, it's clear that the canopy will just bunch up and flap like an old rag. ;)
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