actual size of reserve

[fireemt97 0]

I was talking with a very experienced and respected skydiver the other day about actual reserve size. He told me something I had never heard. He explained that a PD reserve is actually 15-20 percent bigger then the size they say it is. I was wondering if that is true. It concerns me because If I use this reserve I think it will be too small. But, If you add the 15-20 percent it will be a good size for me. Any thoughts

SUCK IT UP BUTTERCUP

[MB38 0]

The second question here is more important than the first: if you think it's too small, it's too small. Ask your instructors what they think.

To me, I don't care if a PD143 is actually 143 feet or if it's 171 feet. If it's really 171 feet, it should be safe, right? I jump a 169 main, so I should be able to handle it, right? To me, wrong. They wouldn't have called it a 143 if somebody who needs a 170 could safely jump it.

I, too, have heard that PDRs are bigger than their numbers would reveal. That said, square footage of a canopy is a subjective measurement. There are many ways to measure a canopy's square footage and different ways will often produce different results.

It is my understanding that these differences often come from the difficulty in accurately measuring an elliptical planform. With reserves being square, perhaps the measurements are more accurate.

Or perhaps I'm full of it. Wait for more knowledgeable posters.

I really don't know what I'm talking about.

[mjosparky 4]

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He explained that a PD reserve is actually 15-20 percent bigger then the size they say it is.

Either that or a manufacture that measures by a different method has canopies15-20 percent smaller than they say it is.

And I would say that this "very experienced and respected skydiver" is a little over the top with 20 percent. That would make a PD-176R almost as big as a Raven II.

As has already been posted, it is a numbers game and the numbers are just a starting point. What does the manufacture of a given canopy have to say about the weight limit of it? That is your best source.

P.S. This skydiver is not trying to sell you a canopy is he?

My idea of a fair fight is clubbing baby seals

[jojo0815 0]

look in the back of the paragear catalog. it has a pack volume chart that also states the PD reserve sizes and PIA sizes. I think it's measuring the top vs the bottom skin...

[fireemt97 0]

According to the manufacture I would be within the weight limit of the canopy but the wing loading would be a lot more then I'm used too. Yes he was trying to sell it to me, but I could have got a new one of any size through him also. This particular one is used but has no jumps on it.

SUCK IT UP BUTTERCUP

[fireemt97 0]

I'm not sure what PIA means but I did look in the paragear catalog. The reserve is a PD 176 and the catalog indicated the sq. ft. is 189. So would I calculate the wing loading with 176 or 189? I like 189 better just because I will be jumping a 210 main with this container. Should I scratch this all together and go with a larger reserve?

SUCK IT UP BUTTERCUP

[jojo0815 0]

I would calculate the WL by the actual square footage. since this is how all the other manufacturers measure their reserves. be careful though, reserve WL is not like main WL. a reserve loaded at 1.4 is already heavily loaded and will be tricky to land. in your case i'd rather to with a 193 reserve. because even with the 176 it will still be 20 square feet less than your main. you don't want to be stacking odds against you by default. think about it... you have to chop, ergo you are probably low. add a bad spot to that and you are most likely to land off. now you don't have any wind indicators, uneven terrain and probably some obstacles too. do you really want to be downsizing right then? :)

[fireemt97 0]

good point, thanks

SUCK IT UP BUTTERCUP

[MB38 0]

You don't want to find out that you're uncomfortable with your reserve wingloading at the wrong time. Finding out at a low altitude, potentially outside the dropzone and pumping full of adreneline with no backup? Wrong time. Better safe than broken.

I really don't know what I'm talking about.

[ryoder 1,590]

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look in the back of the paragear catalog. it has a pack volume chart that also states the PD reserve sizes and PIA sizes. I think it's measuring the top vs the bottom skin...

There has long been a PIA standard for measuring span and chord. Look in this document:

http://www.pia.com/piapubs/TSDocuments/ts-100.pdf

For a rectangular planform, (which includes all current reserves): Area = Span x Chord.

Now will someone 'splain to me why it is so damn difficult for all mfgrs to follow such a simple standard???

"There are only three things of value: younger women, faster airplanes, and bigger crocodiles" - Arthur Jones.

[riggerrob 643]

There are more than a dozen different methods for measuring canopy area, but I will limit my comments to the two most popular methods: PIA and PD.

The Parachute Industry measures span across the top skin, a short distance aft of the top leading edge. The PIA standard was written by Manley Butler when he worked for Para-Flite. Since Parachute Industries of Southern Africa used to build canopies under license form Para-Flite, they used the Para-Flite/PIA method for many years.

Performance Designs measures span across the boototm skin.

To further confuse the issue, in 2001, Icarus changed from the PIA method to the PD method, so a old Icarus "150" canopy (pre 2001) would be about the same size as a new "135" canopy (post 2001).
Similarly, when Aerodyne owned PISA, they quoted canopy sizes via the PD method, so that a new Aerodyne Solo 270 is about the same size as an old PISA Skymaster 290 canopy.

[mjosparky 4]

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Yes he was trying to sell it to me

Boy was that a lucky guess or what.

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So would I calculate the wing loading with 176 or 189?

Calculate your wing loading by the sq. ft. given by the manufacture. I can show you a third way to measure canopies but it won’t change the canopy’s size.

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Should I scratch this all together and go with a larger reserve?

First of all, how much do you weigh?

My idea of a fair fight is clubbing baby seals

[caspar 0]

"To further confuse the issue, in 2001, Icarus changed from the PIA method to the PD method, so a old Icarus "150" canopy (pre 2001) would be about the same size as a new "135" canopy (post 2001). "

is it me or does that sound like a dumb thing to do? what if someone buys a second hand canopy mfg before 2001 and doesnt know about this? if they've been jumping PD canopies and downsize to an old icarus they'll be going down two sizes, right?

"When I read about the evils of drinking, I gave up reading."

[dragon2 2]

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"To further confuse the issue, in 2001, Icarus changed from the PIA method to the PD method, so a old Icarus "150" canopy (pre 2001) would be about the same size as a new "135" canopy (post 2001). "

is it me or does that sound like a dumb thing to do? what if someone buys a second hand canopy mfg before 2001 and doesnt know about this? if they've been jumping PD canopies and downsize to an old icarus they'll be going down two sizes, right?

Yep. That was what was happening before. Now that they changed it, everybody should know (it's been published a fair number of times) that all Safire 1 and Omega's are affected and all other Icarus canopies are not. Do your homework.

ciel bleu,
Saskia

[fireemt97 0]

I weigh 205 normally and about 225 out the door with gear, give or take a pound or two. If my calculation was correct on my main I would have a loading of 1.09 and with a 189 sq. ft. reserve that para-gears says the square footage is, it would be 1.2. If I used the 176 from PD the WL would be 1.3. I rounded up to 230 lbs when doing the calc just for a little safety factor. Just of my minimum knowledge I can see I'm starting to get into WL past my skill level.

SUCK IT UP BUTTERCUP

[mjosparky 4]

At 225 out the door a PD-176R is too small for you with your experience. A wing loading of 1.3 on a 7 cell reserve is somewhere you don’t want to go. Hell you don’t want to be on a main at that loading for awhile.

I notice from your profile that you jump in Northern California. I would suggest that you go to Bay Area Skydiving in Byron and talk to Bonnie at Gravity Gear. This sort of thing is always easier to handle face to face.

Bonnie is with Gravity Gear. She is very knowledgeable and will not try to sell you something you can’t use or is not safe for you. In any case, with 50 jumps and a weight of 225 out the door stay away from a PD-176. jmo
I hope this helps.

My idea of a fair fight is clubbing baby seals

[Cloudi 0]

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Bonnie is with Gravity Gear. She is very knowledgeable and will not try to sell you something you can’t use or is not safe for you. In any case, with 50 jumps and a weight of 225 out the door stay away from a PD-176.

Solid advice.

Kim
Watch as I attempt, with no slight of hand, to apply logic and reason.

[mjosparky 4]

Does your avatar have a sister, I know a guy that would like to take her out?

My idea of a fair fight is clubbing baby seals

[Cloudi 0]

She already knows all about him. She had this friend who was a pig.

The pig died tragically when he pushed her off a cliff so she wouldn't "squeal" on him.

Kim
Watch as I attempt, with no slight of hand, to apply logic and reason.