Canopy Loading

[skydude2000 3]

Hi all,

I asked my DZO this and he wasn't quite sure, so he suggested I try this. I'm a student and I fly a
Tutor-288, but I wondered if there is a formula for proper loading of your canopy? I know it depends on body weight, canopy size and type, but I thought there was a way to calculate the optimum loading for different canopies.

Thanks,

Skydude

[ianmdrennan 2]

It's the jumpers exit weight (clothing, gear - including main and reserve, etc) added up and then divided by the canopy size.

ie: 180 Pound Jumper
25 pounds of gear
205 Exit Weight.

Canopy size 288, therefore wingloading is:
205/288 = 0.71

Blues,
Ian

Performance Designs Factory Team

[JohnMitchell 16]

I'm gonna go with this not being a troll, but a serious question. Take your weight, geared up with rig on and ready to jump, and divide that weight by the square footage of the canopy. If you've never weighed yourself with gear, just use naked weight + 30-35 pounds for geared up weight. Until you get more experience, my advice is to not jump any canopy with fewer square feet than your weight with gear. I'd prefer to see you jump .9 loading or less. High wing loadings are popular these days. Some people will say that up to 1.3 loading is okay for under a hundred jumps. The canopy manufacturers still call that an "expert" loading. If you do everything right under a highly loaded canopy, you'll survive. The chances of you not making canopy mistakes the next hundred jumps are pretty slim. A lighter wing loading is less likely to hurt or kill you when you screw up close to the ground. A lot of people will disagree with me, but that's the truth.

As far as what is the best loading for a particular canopy, it depends on what you want from that canopy. Each canopy flies differently for each loading. Lighter means slower, softer landings, and higher loading means faster speeds and landings, and more radical flight characteristics. The crossed brace ellipticals are designed for high speed, low drag, and efficient airfoils, but could be jumped at .9 wing loadings if made big enough or a jumper was light enough. They would work just fine.

[jerry81 10]

Most canopies have a minimum and maximum suggested exit weight, meaning they'll fly normally within these limits, although they will behave differently depending on what the wl is. I suggest you talk to a person with a solid knowledge of aerodynamics, preferrably a canopy designer, or research the subject yourself if you'd like to learn more.

Now, the best formula for proper loading is your knowledge of canopy piloting and experience, which can be roughly represented by your jump numbers. I believe Brian Germain suggests wl can be increased by .1lbs/sq.ft. for every hundred jumps (so 1.1 at 100, 1.2 at 200 and so on). Me, I've been pushing these limits for the last 150 jumps, but that was a personal decision based on what I hope was a fair understanding of the risks and my own abilities. I don't think I'd suggest it to anyone who'd turn to me for advice.

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[DrewEckhardt 0]

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I believe Brian Germain suggests wl can be increased by .1lbs/sq.ft. for every hundred jumps (so 1.1 at 100, 1.2 at 200 and so on).

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It's a never exceed chart that reads 1.0 + .1 / 100 jumps up to a 2.0 maximum for 1000+.

Foot notes include manufacturer's maximums may be lower, -.1 per 2000 feet of density altitude, and -.2 for canopies under 150 square feet.

[kelpdiver 2]

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Foot notes include manufacturer's maximums may be lower, -.1 per 2000 feet of density altitude, and -.2 for canopies under 150 square feet.

Any adjustment for ZP versus F111? Or would it be too simplistic to make it into a single value?

I think that may have been the question the OP was pointing to: how to compare WL for different canopy makes.

[grega 0]

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I know it depends on body weight, canopy size and type, but I thought there was a way to calculate the optimum loading for different canopies.

There sure is a way to calculate it, but the formula is not that easy. I won't go into details, because it would need too much explanation (it involves calulating the Cl - Lift Coeficient which is fairly difficult). But in general for most HP 9-cell eliptical canopies optimum wingloading is somewhere between 1.6 - 2.0 and for most crossbraced canopies 2.0 - 2.4. depends a lot on canopy design.

I didn't calculate that, i assumed it because most pro canopy pilots say they get best results with those wingloadings...

The best way to find that out is to ask the canopy designer of the canopy you're interested in, which WL is best for that canopy and its size?

"George just lucky i guess!"

[DrewEckhardt 0]

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Foot notes include manufacturer's maximums may be lower, -.1 per 2000 feet of density altitude, and -.2 for canopies under 150 square feet.

Any adjustment for ZP versus F111? Or would it be too simplistic to make it into a single value?

The chart is based on human performance.

Specific canopies have their own limitations from the handling characteristics that result from airfoil, nose configuration, planform, etc. - past some point the stall speed becomes unreasonably high, swoops get shorter, etc. I think PD's current recomendations are reasonable.

[CSpenceFLY 1]

Quote

Hi all,

I asked my DZO this and he wasn't quite sure, so he suggested I try this. I'm a student and I fly a
Tutor-288, but I wondered if there is a formula for proper loading of your canopy? I know it depends on body weight, canopy size and type, but I thought there was a way to calculate the optimum loading for different canopies.


The key word here is optimum.I think he or the DZO could figure out wind loading.As for me helping,I was out of school the day they talked about advanced aerodynamics.

Chris
Thanks,

Skydude

[jaaska 0]

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I believe Brian Germain suggests wl can be increased by .1lbs/sq.ft. for every hundred jumps (so 1.1 at 100, 1.2 at 200 and so on).

---

It's a never exceed chart that reads 1.0 + .1 / 100 jumps up to a 2.0 maximum for 1000+.

Foot notes include manufacturer's maximums may be lower, -.1 per 2000 feet of density altitude, and -.2 for canopies under 150 square feet.

So, to jump Sabre (1) 135 square feet with 1.3 WL would require 500 jumps (if jumping at the sea level)?

[JohnMitchell 16]

Looks like Brian's formula would recommend 300 jumps, right? Loading 1.0 + 0.3 (for 300 jumps). I know that sounds like dinosaur talk to be that conservative, but I've done a lot of first aid and been to a lot of funerals. I like that formula.

[jaaska 0]

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-.2 for canopies under 150 square feet

[FrogNog 1]

Quote

Quote

I believe Brian Germain suggests wl can be increased by .1lbs/sq.ft. for every hundred jumps (so 1.1 at 100, 1.2 at 200 and so on).

---

It's a never exceed chart that reads 1.0 + .1 / 100 jumps up to a 2.0 maximum for 1000+.

Foot notes include manufacturer's maximums may be lower, -.1 per 2000 feet of density altitude, and -.2 for canopies under 150 square feet.

Practically, wouldn't that be "up to a 2.0 maximum for 1200+"? Unless the 2.0 lb / sf jumper was at least 300 OTD...

-=-=-=-=-
Pull.

[DrewEckhardt 0]

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Practically, wouldn't that be "up to a 2.0 maximum for 1200+"? Unless the 2.0 lb / sf jumper was at least 300 OTD...

It translates into a 1.8 maximum at sea level unless the jumper + gear are over 285 pounds (1.9) or 300 (2.0).

Disregarding professionals and elite athletes I think it's pretty close to right. The tail end of the chart might be spaced a bit close (completely adjusting to a new canopy before down-sizing 10-15% is a good idea, and it takes more jumps to do that than you get from the chart) and limit may be low at higher density elevations (there's definately a size component - a 105 @ 1.7 is more of a handful than a 120 at the same loading).