MINIMAL wingload

[CheshireCat 0]

Although most of wingload-related discussions are concentrating on wing overloading, I'd like to ask a different question: what MINIMAL wingload is safe to fly?
Our club offers 270 student canopies, regardless of student weight.
If I am doing the math right, 114lbs girl under such canopy is about 0.42. Seems she can flight up catching thermals Another 60kg guy had slider up mal few weeks ago which resulted in an uneventful cutaway; could it be related to sub 0.5 WL?

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52kg = 114 pounds
60kg = 133

[quade 3]

What does the canopy manufacturer recommend?

quade -
The World's Most Boring Skydiver

[Fast 0]

I just listened to a seminar of sorts about canopy selection. The main jist of what he (scott miller) had to say was that unless the manufacturer has a minimum listed, then there really isn't.

One of the things that he had stressed on was that often light people end up on canopys that are much smaller than what they should because there is alot more to selection than wingloading. I won't go into the long discussion of it, but uhh yeah what quade said,... manufacturer recomendations.

~D
Where troubles melt like lemon drops Away above the chimney tops That's where you'll find me.
Swooping is taking one last poke at the bear before escaping it's cave - davelepka

[CheshireCat 0]

manufacturer recomendations you say.
VLC - is what most of manufacturer charts recommend for minimal weight

So, a questions to experienced folks: is it safe to put a 120lbs person under 280sqft canopy?
From my observations, landing a canopy that goes backward even in light winds could be really upleasant and harmful.
In crosswind it could be even worse.

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*VLC - Varies with Landing Conditions

[wmw999 2,166]

Quote

landing a canopy that goes backward even in light winds could be really upleasant and harmful.

What is unpleasant and harmful about it? Going backwards? Then PLF. Used to happen under rounds all the time.

It's not ideal by a long shot. Certainly not for trying to learn good stand-up landing technique. But I really can't see dangerous. Going backwards or sideways, you still can anticipate where you're going to land, steer for open areas, etc.

Wendy W.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[quade 3]

Ok, then let's get specific.

What canopy is this?

quade -
The World's Most Boring Skydiver

[Beachbum 0]

I did that (land going backward) a couple of times on the student gear while going thru AFF ... 2nd time danged near ran it out backward ... LOL!! Same sort of thing ... no small student gear, and I only weigh about 145 (the dz had an 18 mph waiver because it is WIDE open). I agree that it sucks, but also agree that it doesn't have to be all that dangerous ... just inconvenient unless the wind is really strong, in which case students shouldn't be in the air anyway. I'm not so sure about trying to plf backward ... I did that on the first one, and found it is not easy to do backward even if you're planning on it from plenty high up.

As long as you are happy with yourself ... who cares what the rest of the world thinks?

[skycat 0]

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I'm not so sure about trying to plf backward ... I did that on the first one, and found it is not easy to do backward even if you're planning on it from plenty high up.

Only thing that saved me (I jumped those exact same really huge student rigs you did) was that I was a gymnast and it was actually easier for me to PLF backwards than forwards. On the other hand only was able to have 1 stand up landing on those silly huge ass things cause I was never going forward.

Ofcourse you never lived till your rig slips off both shoulders when you go to track, which made those rigs extremely dangerous for really small people to jump. I mean not learning canopy control due to the size is one thing, gear coming off is another.

Fly it like you stole it!

[billvon 2,456]

>So, a questions to experienced folks: is it safe to put a 120lbs person under 280sqft canopy?

Depends on conditions. In light winds, no problem as long as you meet the mfr's minimums. In stronger winds, you want to make sure you're not going backwards too rapidly. Sure, you can barely steer the thing at those loadings, but I've never underloaded a canopy enough to make it uncontrollable or unstable - and that includes an 11 cell F111 canopy loaded .38 to 1.

[pilotdave 0]

I jumped a manta 288 a couple times when I weighed under 110 lbs (without gear). They weren't windy days so I didn't have a problem with backing up. The problem I had was a 360 degree turn must have taken like 20 or 30 seconds to complete (at least it felt that way). Every turn was a flat turn. I COULD NOT get that canopy to dive at all in a turn. I was coming in high, so I did full-toggle s-turns all the way down to about 50 feet. The flare was very weak too. The problem was probably just the length of the brake lines more than anything, but I don't know if it would have been more responsive at a higher loading.

Dave

[petetheladd 0]

Under extremely lightly loaded canopys, would'nt cell pressurisation be less ?

Would this not make a canopy more susceptable to turbulence/canopy collapse?

Certainly the prevailing wisdom is a more heavily loaded/zippy canopy can 'cut through' the turbulence

Spare me the 'You shouldnt be jumping arguments' and play along with my thought experiment.

No, Not without incident

[CheshireCat 0]

Another story about low WL:
A tiny (~100lbs) girl was jumping a 280.
During deployment the PC stuck in front. One or two middle cells did not inflated normally and after she tried to pull the brakes - the canopy collapsed in middle. Cutaway, good landing.
Do not know what canopy it was.

[bch7773 0]

I've seen a really small girl do her first jump class, and when they put the big ol' student rig on her and had her hard arch, she kept falling over backwards because of the weight. I can't remember how her actual jump went, but she didn't get injured.

MB 3528, RB 1182

[billvon 2,456]

>Under extremely lightly loaded canopys, would'nt cell pressurisation be less ?

Yes.

>Would this not make a canopy more susceptable to
>turbulence/canopy collapse?

Yes; however, you could lose half a Manta momentarily to turbulence, and as long as it reinflated before impact you're generally going to be OK. If you lose half a heavily loaded Velocity as you're starting to flare, you're going to be seriously injured.

One of the reasons everyone hates lightly loaded Mantas is that they don't turn very quickly even if you really hammer on them. Mantas show this same reluctance to turn in turbulence, even when they're getting bumped around quite a bit.

>Certainly the prevailing wisdom is a more heavily loaded/zippy
>canopy can 'cut through' the turbulence

Turbulence can collapse any canopy, although higher loadings are slighlty more immune than lower loadings. I don't think the "cut through" thing makes much sense, any more than you can "cut through" waves more easily in a boat if you go really, really fast. But the increased cell pressures do help a little. Nothing in the world will keep your canopy flying if it is loaded by a gust from above, though, no matter what sort of cell pressures you have.

The other side is - what happens when you do have a collapse? In such a case, a large canopy will recover more quickly - and if it doesn't recover in time, the results will be far less painful.

[skycat 0]

Quote

Another story about low WL:
A tiny (~100lbs) girl was jumping a 280.
During deployment the PC stuck in front. One or two middle cells did not inflated normally and after she tried to pull the brakes - the canopy collapsed in middle. Cutaway, good landing.
Do not know what canopy it was.

Actually this is really common with spring loaded pilot chutes and really under loaded canopies. Since there isn't enough weight to get the canopy moving forward during the opening sequence the canopy in effect stalls and the pilot chute lands on the top skin then rolls down the front to inflate and wrap around lines. I had it happen 4 times, but luckly I was able to counter the turn and have a nice PLR, I do know one girl though that did have to cutaway because she couldn't control the turn it caused.

Now a collapsible throw out pilot chute would have fixed this, except that the rig I jumped was so large I couldn't have reached the BOC if I wanted to.

Fly it like you stole it!

[PhillyKev 0]

Quote

Under extremely lightly loaded canopys, would'nt cell pressurisation be less ?

Yes.

>Would this not make a canopy more susceptable to
>turbulence/canopy collapse?

Yes; however, you could lose half a Manta momentarily to turbulence, and as long as it reinflated before impact you're generally going to be OK.

Exactly what happened to me on AFF 3, except it didn't reinflate in time. Lost pressurization just as I was about to start my flare, and came straight down on my back and ass. Thought I broke my back, but was ok after a couple weeks.