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size of the main canopy

 


alberto1980

Apr 5, 2009, 7:12 PM
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size of the main canopy Can't Post

Hi there. Just looking for some advice. I have to buy my own gear and I am undecided on the size. I have 60 jumps, weight 75 kg and I was thinking about a 170 sqft main like a Sabre 2. Then I spoke to many experienced skydiver they say they would go for a 150. I already tried a 170 and it was fine. Do you think a 150 would be safe for my experience? So: 150 or 170? please help..


Gary73  (D 21341)

Apr 5, 2009, 7:20 PM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

At 75 Kg you'll have an exit weight around 190, so even a 170 is smaller than USPA recommends until you have 200 jumps. Never forget that the greatest single cause of fatalities and serious accidents in this sport is excessive downsizing.


GLIDEANGLE  (D 30292)

Apr 5, 2009, 8:04 PM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

Here is some excellent reading for you on this topic by REAL experts.

This will help you evaluate your readiness for a smaller canopy. It is the Downsizing Checklist By Bill von Novak

http://www.dropzone.com/...etail_page.cgi?ID=47

This one is 22 pages long... all of it worth your time! It is the Parachute Downsizing Criterion by Brian Germain
http://www.bigairsportz.com/pdf/bas-sizingchart.pdf

Here is what the manufacturer of the Sabre 2 has to say about wing loading for this canopy.
http://www.performancedesigns.com/products.asp?product=sa


LongWayToFall  (A 52639)

Apr 5, 2009, 8:58 PM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

If you enjoy flying the 170, why do you want to go faster?


councilman24  (D 8631)

Apr 6, 2009, 6:01 AM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

Find some different experienced skydivers to talk to.


Also be sure WHO it is your talking to. We used have a 40 jump wonder with a USPA shirt who gave advice to newbies like he was an I/E but didn't have a clue what he was doing.
Knowing who is giving you advice includes on this forum.Wink

A 150 with your size and experience is asking for a short career. Can you get away with it? Sure. Maybe, Might. But should you? No.


ufk22  (D 16168)

Apr 6, 2009, 6:15 AM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

Consider a 190. It'll get you more safely through the next couple hundred jumps. You can find this size used for a reasonable cost.


AndyMan  (D 25698)

Apr 6, 2009, 6:22 AM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

I would recommend a 190. After quite a few jumps on that, you may find yourself ready for the 170.

Downsizing too fast hurts.

_Am


JanuszPS  (D 568)

Apr 6, 2009, 6:42 AM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

Hi,

It is a little crazy moving to 150.
People tend to advice on safe side here in DZcom as they do not know you and there is responsibility behind written words. From my experience on the dz's usually people act the other way as there is no record what they advised or they know you.

I was about the same level of experience (45 jumps) and weight (73kg w/o rig) and I moved to 170. It was "tricky" at the beginning but nothing crazy. After transitional 10 jumps my level of confidence rose, but at the same time till my first canopy course I was guessing about landings. So first try to get a little couching in canopy flying. If you jumped 170 already you know the feeling.
My first canopy was Cayenne 170 which is of similar class as SA 2 170, Safire 2 169, etc. and I do not regret that.

The decisions is on your side and your choice should be based on good research, knowledge and training. Did you read articles, posts, etc relating to downsizing?

I made my decision consciously knowing that I'm slightly forward the recommendations, but I also spend a lot of time reading articles/posts (including incidents forum) to understand the consequences. I also attended a CP course with the local "canopy wizard" ;-) . But that was 50 jumps after the downsize which I regret!

BTW get a second-hand 170 as you might spend less time than you think on it so a brand new canopy would be lost of money.

good luck
Janusz


alberto1980

Apr 6, 2009, 7:40 PM
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Re: [JanuszPS] size of the main canopy [In reply to] Can't Post

Thanks to everybody for the suggestions. I think I will stick to the safe side. Blue skies


erdnarob  (D 364)

Apr 6, 2009, 8:23 PM
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Re: [alberto1980] size of the main canopy [In reply to] Can't Post

You should try more jumps on a 170 zero porosity canopy say for another 10 jumps or less if you are good at it then get a briefing for a 150 like a Sabre 2. Get a good briefing from an instructor who knows you quite well. The most important is to fly gently without any turns near the ground and to have a lot of clearance ahead of you when landing and flare with toggles very symmetrical.
Equipment is expensive and renting a bit longer to get knowledgeable about canopies will make you bying something you really like and suitable for you.


DrewEckhardt  (D 28461)

Apr 7, 2009, 12:33 AM
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Re: [erdnarob] size of the main canopy [In reply to] Can't Post

In reply to:
You should try more jumps on a 170 zero porosity canopy say for another 10 jumps or less if you are good at it then get a briefing for a 150 like a Sabre 2.

If in 10 jumps your'e making 90 degree turns at roof top level, landing cross-wind, and landing down-wind with the smaller parachute you might want to try the smaller size.

Most people wouldn't intentionally do those things, and if you've had to do those things you have bad judgement and shouldn't be down sizing.

It's not about what happens when everything is going nice. BZ Shaw told me that with less than four years experience and 500 jumps I'd be fine jumping a 104 square foot parachute at 1.8 pounds per square foot. Into a nice wide open field at sea level it was. With more interesting things going on under a 120 with more experience I bruised my heels (it hurt to walk for a few months) and could have done much worse.

You have the potential to be making a roof-top 90 degree turn to avoid obstacles you didn't see when landing out on the sunset load after having a bad spot and opening low ultimately resulting in a down-wind landing. That's the situation you're sizing your canopy for.

If you've seen all those situations in 60 jumps and dealt with them successfully you have bad judgement and shouldn't down-size. If not you have something to learn.

At 60 jumps Brian Germain suggests a 210 with a 177 as a minimum. Brian has jumped more (> 10,000 jumps) than most of us, knows more about parachutes (designed the Jedi series, Samurai, and Lotus), and knows more about teaching parachute flight and sports psychology (there's the lecture series and books).

http://www.bigairsportz.com/pdf/bas-sizingchart.pdf

You'd do well to follow the chart.

When I weighed more than 72.5kg my instructors were uniformly split between a 210 and 190 as being a suitable first canopy. Parachutes are no slower now even though lots of us down size faster and get away with it.

You don't want to bet being unable to walk for three months and skydive for a couple years after a few operations on a 75-90% chance that you'll make it through the downsizing process unscathed.

I ultimately broke myself on landing area debris on a 245 at .7 pounds per square foot with 1500 nice landings. While I avoided a fatal plane crash five weeks later I wouldn't recommend high probabilities of crash landings to any one else without a real bad tarot card reading.


(This post was edited by DrewEckhardt on Apr 7, 2009, 12:46 AM)


erdnarob  (D 364)

Apr 7, 2009, 9:44 PM
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Re: [DrewEckhardt] size of the main canopy [In reply to] Can't Post

Experience has proven me that it depends on the individual. At 60 jumps I wouldn't hesitate to let a jumper use a ZP parachute like a Sabre 2-170 with a loading of 1.0 lbs/sq.ft provided he has shown a good canopy control earlier. The author of this thread did one jump already on such a parachute and need to be briefed for a better landing.
A guy at my DZ at the same level (165 lbs) wanted to buy a 210 or maybe a 190 and after discussion decided to go for a 170. Now the same guy at 110 jumps and after spendind 7000$ for his rig realizes that it's too bad he doesn't have a 150 especially when it's windy. Another jumper with same number of jumps but with weigth of 185 lbs decided to go for a Sabre 2-170 and he did very well. But don't get me wrong, I briefed extensively those jumpers, I had confidence to them because I knew they could honour it. OTOH I would discourage some people to buy a ZP 170 canopy loeaded at 1.0 -1.2 even with 200-300 jumps because they don't have the discipline or/and the skill and good attitude to handle that kind of canopy.
My philosophy is the following: it's not what you tell to a beginner which is important but the amount and quality of time you spend with him/her.


JanuszPS  (D 568)

Apr 8, 2009, 8:48 AM
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Re: [erdnarob] size of the main canopy [In reply to] Can't Post

In reply to:
Experience has proven me that it depends on the individual. [..]
A guy at my DZ at the same level (165 lbs) wanted to buy a 210 or maybe a 190 and after discussion decided to go for a 170. Now the same guy at 110 jumps and after spendind 7000$ for his rig realizes that it's too bad he doesn't have a 150 especially when it's windy.
[..]
OTOH I would discourage some people to buy a ZP 170 canopy loeaded at 1.0 -1.2 even with 200-300 jumps because they don't have the discipline or/and the skill and good attitude to handle that kind of canopy.
My philosophy is the following: it's not what you tell to a beginner which is important but the amount and quality of time you spend with him/her.

I fully agree, the bottom line in my opinion is - everything is related to the individual, his/her abilities and skill level and good knowledge and training.

(I will refer to my example as I dont know somebodies experience and feelings of the problem)

[Edit: in general (not directed to anyone)]

saying this I mean - I had 45 jumps moving to 170 (WL 1.05) and after 70 jumps I was swearing that each time when is windy and I was allowed to jump I had zero wind penetration and lots of dz landings. Believe me, Ireland is quite a windy country ;-) So at 125 jumps mark I moved to SA 2 150 (WL 1.25) but I was already after a canopy class which helped me a LOT to understand the principles. And to be honest I had much better/safer landings than on 170. After another 100 jumps (225 total) and full CP course I moved to Cobalt 135 (WL 1.45) which first time jumping I landed better than friend of mine his canopy with the same WL/canopy but with over 500 total jumps under his belt. This does mean that the jump number very often has nothing/little to do with the ability to fly a particular canopy under particular WL by a particular person.
I am an engineer and going across codes of practice in various disciplines (structural/fire safety, etc) I can see that huge safety factors are build into the recommendations. Usually this is based on experiments, life experience and a significant statistical data. If I good remember this means there is 0.05% chance that something might go wrong in probabilistic approach.
Now, skydiving is not a discipline that we can measure, calculate and predict events/failure etc using simple mathematical formulas with predictable level of confidence. I always was wondering where the canopy sizing charts are coming from. An I come up with conclusion that this is based on an experience which not necessary was build into a statistical data but based on somebodies opinion and skydiving "tradition". When we look at the manufacturers charts there are so conservative that they are so far away from the reality and life and thus mostly ignored. With the better knowledge built on years of experience and mostly available statistical data the charts can be revised but in my opinion at the moment they still are just a guess and that how they should be read. They are only suggestions/recommendations but not the law or Holly Bible to follow with. I'm just saying that if someone is not paying attention to canopy flying could "blindly" follow the recommendations when the need for downsize occur but staying more conservative is the option. In the other situation when a jumper pays attention to canopy flying every time trying improve the landings, putting some effort, etc. the normal chart has little to do, as it covers the "worst case scenario" of a knowledge proofed student/jumper.

the best option would be if the charts were build on statistics, experiments and experience, but I doubt that this is manageable at the moment.

Slightly too long and chaotic, but I'm not a native eng. speaker - so sorry for errors/mistakes.
I also know that my view on things can be verified by life and be much conservative in the future.
I hope nobody will crucify me now. But essentially what I'm saying is that blindly looking into the charts is not always the correct way. However if individual moves slightly forward needs to be fully aware about the consequences of the decision. But who is not aware about that one time bad things can happen? At the end of the day skydiving is a risky adventure and that how I look at it. I think the key is to always try limit the unnecessary risk to the minimum but still give a chance for taking pleasure from doing it - that's the hardest part.

Janusz


(This post was edited by JanuszPS on Apr 8, 2009, 9:52 AM)


Premier skybytch  (D License)

Apr 8, 2009, 9:05 AM
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Re: [erdnarob] size of the main canopy [In reply to] Can't Post

In reply to:
Now the same guy at 110 jumps and after spendind 7000$ for his rig realizes that it's too bad he doesn't have a 150 especially when it's windy.

Yeah, cuz it's so vitally important that he jump as much as possible today, regardless of the conditions. The world could end tomorrow and he'd be so bummed that he didn't get a few more jumps in. Crazy


JanuszPS  (D 568)

Apr 8, 2009, 9:42 AM
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Re: [skybytch] size of the main canopy [In reply to] Can't Post

I disagree,

It depends where you live and where you jump. there are some countries where sight of few clouds on the sky stop people jumping. But there are some countries where a day without wind and clouds is like blessing and miracle.

that's why skydiving and jumpable conditions are so relative depending on the place. Obviously there is some cut of point where regardless the local experience weather permits jumping.

Janusz


Premier skybytch  (D License)

Apr 8, 2009, 10:37 AM
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Re: [JanuszPS] size of the main canopy [In reply to] Can't Post

In reply to:
It depends where you live and where you jump. there are some countries where sight of few clouds on the sky stop people jumping. But there are some countries where a day without wind and clouds is like blessing and miracle.

My view on skydiving is one that encourages longevity in the sport without having titanium implanted in one's body, not piling up jump numbers as fast as one possibly can. One key to longevity in the sport is reducing the risk factors on every skydive you make. Sometimes and in some places, that may mean spending more time at the dz on the ground than in the air.

Jumping in higher winds ups the amount of risk that a jumper is taking, regardless of where that person is jumping, how many jumps they have or how good their training was. There are good reasons we don't take AFF students up in 25 mph winds. Those reasons don't go away when the student gets a license, and yet some people will encourage the newbie to stop being such a pussy and go jump. I think it's a far better thing to encourage the newbie to stand in the landing area and watch the carnage instead of being a part of it. Uninjured newbies tend to come back when the conditions are good. Injured newbies generally don't.

Another issue is travel. If a jumper never leaves their home dz that is located in a windy area, they may be fine with a smaller canopy that allows them to penetrate 25 mph winds. But what happens when they take that canopy to Eloy in July?

There is not now and there will never be a skydive so important that it can't be postponed until conditions are better. Yes, being grounded by wind day after day sucks... but getting hurt or dying sucks far more.


AFFI  (D 25538)

Apr 8, 2009, 12:26 PM
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Re: [skybytch] size of the main canopy [In reply to] Can't Post

Quote:
My view on skydiving is one that encourages longevity in the sport without having titanium implanted in one's body, not piling up jump numbers as fast as one possibly can. One key to longevity in the sport is reducing the risk factors on every skydive you make. Sometimes and in some places, that may mean spending more time at the dz on the ground than in the air.

Jumping in higher winds ups the amount of risk that a jumper is taking, regardless of where that person is jumping, how many jumps they have or how good their training was. There are good reasons we don't take AFF students up in 25 mph winds. Those reasons don't go away when the student gets a license, and yet some people will encourage the newbie to stop being such a pussy and go jump. I think it's a far better thing to encourage the newbie to stand in the landing area and watch the carnage instead of being a part of it. Uninjured newbies tend to come back when the conditions are good. Injured newbies generally don't.

Another issue is travel. If a jumper never leaves their home dz that is located in a windy area, they may be fine with a smaller canopy that allows them to penetrate 25 mph winds. But what happens when they take that canopy to Eloy in July?

There is not now and there will never be a skydive so important that it can't be postponed until conditions are better. Yes, being grounded by wind day after day sucks... but getting hurt or dying sucks far more.
Brilliantly written!


phoenixlpr  (D 3049)

Apr 8, 2009, 1:13 PM
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Re: [skybytch] size of the main canopy [In reply to] Can't Post

There are even more injuries on a 0 wind day. I wonder why....Wink


JanuszPS  (D 568)

Apr 8, 2009, 1:15 PM
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Re: [skybytch] size of the main canopy [In reply to] Can't Post

Agree, but I'm not talking about extremes. I'm talking about a situation which I experienced in the places where 50% of the cloud coverage (above opening altitude) prevented people jumping.
I don't want to go into the discussion about possibilities and safety issues with drowning in a pool/lake, nearby hills and terrain differences and other theoretical problems.
If I was following that way of thinking, I would have 10 jumping weekends (not necessary both days) pear a year. So I do not consider this as an abnormal situation. So in this case we would speak about being grounded week after week after a month, etc.

I did not say that students should be sent up to the air all time!

I know that high altitude lading zones combined with hot temperature create different problems, but an average person does go every July to Eloy for a weekend of jumping. (another extreme). And as you know a very conservative canopy flying is advised in all new places visited by a jumper who is not familiar with.

yet again, I'm not talking about jumping in ridiculously high gusting winds, but on my experience I noticed that level of acceptance depends on the good weather availability per a year not week! And this is equal to training and experience in such conditions.

Best regards
Janusz


Premier skybytch  (D License)

Apr 8, 2009, 2:08 PM
Post #20 of 22 (1652 views)
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Re: [JanuszPS] size of the main canopy [In reply to] Can't Post

In reply to:
Agree, but I'm not talking about extremes.

Sure you are. The majority of dz's in the world get far more than 10 weekends per year with winds of less than 20 mph. So for the majority of skydivers out there, if conditions are sketchy this weekend it's very likely that the weather will be far more cooperative next weekend.

In reply to:
on my experience I noticed that level of acceptance depends on the good weather availability per a year not week! And this is equal to training and experience in such conditions.

If you say so. My experience at the 20-ish dz's throughout the U.S. that I've jumped at over the past almost 20 years has shown me differently.


JanuszPS  (D 568)

Apr 8, 2009, 5:32 PM
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In reply to:
My experience at the 20-ish dz's throughout the U.S. that I've jumped at over the past almost 20 years has shown me differently.

That's why, because you jump in US for past 20 yrs, where the weather is generally very good. Wink
I don't know where the 20mph came from as a threshold in that conversation as I did not refer to any limit. I used expression "strong".

that what is considered as an extreme in one place in another can be just normality. That's what I mean.

BTW, if I don't feel comfortable with the wind, I do not jump even if others try. this is an individual call for anybody.

take care
Janusz
BTW, not everything in the world is based on USPA recommendations/experience.


(This post was edited by JanuszPS on Apr 8, 2009, 5:41 PM)


erdnarob  (D 364)

Apr 10, 2009, 8:44 PM
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Re: [skybytch] size of the main canopy [In reply to] Can't Post

I just said "when it's windy". I didn't say "when winds were too dangerous to jump".

My point is the following. From my experience**, I have found that not landing at the DZ because of a bad spot or because of wind exceeding the capability of the canopy is very dangerous especially at some DZ which are located in town or between the mountains or in the middle of forests. The advantage of having a canopy size at your body size is that a better penetration thru the wind can save your live. You never know what is waiting on the ground for you when landing outside the DZ in the type of DZ named above. Hydro lines, water, road traffic, junk yard, forests...name it. At a DZ there is generally grass and where you land it's free of any obstacles. Elsewhere, you can hurt badly yourself or worse even with a perfect landing. You just don't know. In other words, landing at the DZ is part of the safety because the DZ is designed to do so.
This to illustrate what you can expect at the ground.
** I didn't like the time I had to do accuracy in the forest (in Florida) and pass on purpose at 3 feet from the top of a tree to make sure I would have enough of clear space ahead of me in the 100 ft glade I had chosen for landing with my Katana.
**I didn't like it either when I was over another forest (Canada) and I have landed in a junk yard after passing a road and hydro lines. I just found out after a very nice landing that just beside the place I have landed on there were pieces of concrete with rusted steel bars hidden in the high grass.

You can say that if the wind exceeds your parachute capability, don't jump. Easy to say but it's a bit more unpredictable than that since a wind can pick up after take off and on a Cessna DZ especially, after half an hour of climbing, conditions at the ground can be a bit different than the ones existing at the take off. Landing outside the DZ is very dangerous. A student was lost in 2008 in Canada after he landed in hydro lines not far away from the DZ. OTOH people who hurt themself or die when landing very small canopies (120 or less) are very experienced people, not the beginners. I have produced statistics on this forum showing that students are way less at risk than experienced people.



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