canopy construction question

[sfzombie13 307]

i have been interested in designing a main canopy for myself for a while now and i have a couple of questions from riggers/knowledgeable people.
1. is it legal to jump it? i have read that you don't have to be a rigger to alter/repair canopies if you are the one jumping it. would canopy construction be covered here?
2. how would it be tested to be airworthy? i can get the material tested, and some of the seams tested i think, but how would i be able to tell what it would do when i jumped it, unless i jumped it?
3. would it be a good starting point to take a canopy that i own and use it for a pattern, just changing sizes of panels/cells/crossbracing? or would this infringe on the manufacturer's patent/copyright?
i suppose that as long as i had a reserve that was properly packed and airworthy, and opened at about 8k to test out the flight/handling characteristics, it would be ok, i would have plenty of time to ditch it.
has anyone tried this, or know anyone who tried this before? maybe someone has access to a cad program for use in canopy design that i may be able to borrow for a couple of months? thanx,

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Si hoc legere scis nimium eruditionis habes

[tdog 0]

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i suppose that as long as i had a reserve that was properly packed and airworthy, and opened at about 8k to test out the flight/handling characteristics, it would be ok, i would have plenty of time to ditch it.

Unless it spun up with such Gforces you pass out and.... http://www.dropzone.com/fatalities/Detailed/71.shtml

Sorry to be the first to be so negative.

I wish you the best of luck, even the PD designers and Brian Germain had to make their first canopy some point in their path to success.

[skybytch 259]

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1. is it legal to jump it?

Yes. As long as you have one more parachute than you are intending to use you can legally jump a bedsheet as a main.

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2. how would it be tested to be airworthy?

Jump it. You could drop test it with a dummy or tow it behind a vehicle if you don't want to risk jumping it.

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3. would it be a good starting point to take a canopy that i own and use it for a pattern

Yes.

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i suppose that as long as i had a reserve that was properly packed and airworthy, and opened at about 8k to test out the flight/handling characteristics, it would be ok, i would have plenty of time to ditch it.

If you don't intend to land it you will need to jump it in a tertiary system in the US anyway (a tertiary system is a rig set up with three canopies).

Would be a great learning experience if you have the time and patience to attempt it.

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[mjosparky 3]

First thing you want to do is get PPM Vols. I & II. Study the sections on materials, manufacturing procedures and design and construction. You should thoroughly understand how a parachute functions before you attempt to build one. And remember there is no perfect canopy, each design element is a trade off.

Next buy or get access to a number of sewing machines. Double needle with a french seam folder, single needle walking foot, a zigzag and a bartac.

Spend countless hours with scrap material learning the various stitches that will be used.

It is legal for you to make and jump your own main canopy. Drop testing is the safest way to see if it works but at some point it has to be live jumped. This is best left to someone with experience doing such things.

Be prepared for some failures.

Good Luck.

Sparky

My idea of a fair fight is clubbing baby seals

[darkwing 4]

I have built a few dozen canopies. My STRONG recommendation is that you first make sure you have some sewing skills. Second, you want a double needle machine. Third, and this is the most important one - COPY a canopy that you know works. You can become a designer after you become a builder, not before.

You can make the seams differently, since you will likely use a hot knife to cut out the pieces. I'll gladly give you construction tips when you get far enough to need them.

Your first canopy should be a mellow one, nothing more than a Spectre-class canopy. Preferable to that would be a rectangular canopy, i.e., nothing tapered or elliptical, but the real choice is yours.

It is "interesting" to jump the first canopy that you built.

-- Jeff
My Skydiving History

[ryoder 1,394]

1. You can design, build, and jump your own canopy with no legal restrictions. As long as you don't sell it, patents should not be an issue.

2. Test it by using a cutaway rig. Used an old Wonderhog with front-mounted D-rings to which the test canopy attached with a custom-made front-mount container.

3. My first canopy was a 7-cell copy of a 9-cell canopy whose designer gave me a rib pattern. I had previously bought one of his canopies, so I had an assembled canopy to examine for constructions techniques. If you try to make patterns from an existing canopy, bear in mind that even on a rectangular canopy:
- Loaded ribs might be shaped differently from unloaded ribs.
- The topskins will probably not be the same width as bottom skins.
- Top and bottom skins of a cell may not even be rectangular.

Learn to identify the symptoms of an out-of-trim canopy:
- A canopy trimmed too nose-up will oscillate side-to-side. It will stall abruptly with very little flare.
- A canopy trimmed too nose-down will fly stable and fast with a poor glide ratio. It will be VERY unforgiving of poor flare timing.
- Do some practice flares. If you aren't confident you can safely land the canopy, then chop it.

I built my canopies on a Singer 31-15 straight stitch machine. If I was going to do it again, I would definitely buy a bartack machine. It is difficult to get enough stitches in high-stress points with a simple straight stitch machine.

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

[sfzombie13 307]

thanx to everyone for all the tips. i do have some sewing skills, but nothing i would trust my life with yet. the canopy i was going to copy first was a raider 220. i was going to make it out of zero p and maybe a 190-200. i really like how it handles, do you think it will change the flight characteristics radically by switching material? i definately need to get those books that were mentioned, a friend showed them to me years ago. he taught me some tricks on stitching patterns and making line loops. i figure i've got a long way to go, skill-wise.

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Si hoc legere scis nimium eruditionis habes

[mjosparky 3]

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thanx to everyone for all the tips. i do have some sewing skills, but nothing i would trust my life with yet. the canopy i was going to copy first was a raider 220. i was going to make it out of zero p and maybe a 190-200. i really like how it handles, do you think it will change the flight characteristics radically by switching material? i definately need to get those books that were mentioned, a friend showed them to me years ago. he taught me some tricks on stitching patterns and making line loops. i figure i've got a long way to go, skill-wise.

Don't look for the material change to change the way a given canopy handles. ZP just allows it to have the same flight characteristics longer then with a lopo material.

Sparky

My idea of a fair fight is clubbing baby seals

[sfzombie13 307]

actually, that's what i was hoping for. same characteristics, just lasting longer.

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Si hoc legere scis nimium eruditionis habes

[johnny1488 1]

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i have read that you don't have to be a rigger to alter/repair canopies if you are the one jumping it. would canopy construction be covered here?

From what I was told at my riggers course, thats not entirely true. You can make whatever the hell you want. You as a non-rigger can not alter/repair the canopy once it is made BUT, you as a manufacturer can.

Also you as a non-rigger can not repair any canopy (like an Icarus/PD/Aerodyne) but there are no records required to be kept for main canopy repairs.

Its pretty weird, but we pretty much came to the conclusion that it wasntnecassary to understand the ins and outs of conflicting rules like this since they very rarely come into play.

I would think you're best bet would be to try and build a conventional 7 cell canopy of decent size (around 170-210) to keep the risk factors lower.

Good luck, sounds like fun (if your into that sort of thing!)

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[mjosparky 3]

Part 65.111

(b) No person may pack, maintain, or alter any main parachute of a dual-parachute system to be used for intentional parachute jumping in connection with civil aircraft of the United States unless that person—
(1) Has an appropriate current certificate issued under this subpart;
(2) Is under the supervision of a current certificated parachute rigger;
(3) Is the person making the next parachute jump with that parachute in accordance with §105.43(a) of this chapter; or

Sparky

My idea of a fair fight is clubbing baby seals

[johnny1488 1]

Like they say, something new everyday!

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[kaerock 1]

Isn't the stipulation that if you indeed intend to cut away your main canopy you must be a USPA C license holder as well to do such intentional cut-aways?

-R

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Part 65.111

(b) No person may pack, maintain, or alter any main parachute of a dual-parachute system to be used for intentional parachute jumping in connection with civil aircraft of the United States unless that person—
(1) Has an appropriate current certificate issued under this subpart;
(2) Is under the supervision of a current certificated parachute rigger;
(3) Is the person making the next parachute jump with that parachute in accordance with §105.43(a) of this chapter; or

Sparky

You be the king and I'll overthrow your government. --KRS-ONE

[mark 102]

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Isn't the stipulation that if you indeed intend to cut away your main canopy you must be a USPA C license holder as well to do such intentional cut-aways?

Except for tandems, the FARs are silent about USPA's role in skydiving. USPA BSRs require a C license or better, but BSRs are not legally binding even though they are good ideas, having been written mostly in blood.

Mark