0
udder

Canopy for turbulence

Recommended Posts

Howdy

I landed out on the weekend under a huge ass student canopy and had a pretty hard landing. I think this was caused by the field with cut wheat, some patches are dark earth with the light coloured wheat... It felt strange as soon as I flew over the field. That may be full of shit cause im just a very unknowledgable newbie but im wondering what canopies are more resistant to turbulence?
peder
"In one way or the other, I'm a bad brother. Word to the motherf**ker." Eazy-E

Share this post


Link to post
Share on other sites
I own a Samurai, but I wouldnt recommend a airlock canopy for its turbulance resistance.
Buy one because you like the way it flies, and get some extra insurance for turbulance as a side effect. If you dont feel confortable jumping in turbulant winds, dont jump regardless of canopy type.
Remster

Share this post


Link to post
Share on other sites
Quote

You've been sucked in by marketing hype. Airlocked canopies don't offer any protection whatsoever against the dangers of jumping in turbulent conditions.



I never said they gave protection against the dangers of flying in turbulent conditions. I simply answered udder's question. The inflated canopy wing seems to stay more rigid in turbulence, which in my mind means that the canopy itself is more resistant to the effects of turbulence.

A couple weeks ago I was watching people land in bumpy/choppy/gusty 30+mph winds. There were a lot of heavily-breathing canopies that looked really scary and on the verge of collapse, and then there were a few airlocked ones that looked quite solid.

Yes, I'm well aware that both canopy and pilot are still susceptible to turbulence and still get jostled around in the air when flying through the turbulence, but the wing pretty much stays inflated. Just my observation that day.

I also understand that if a dust devil or similar comes ripping through and whips yer butt near the ground, you're screwed with or without airlocks. So obviously the best course of action is to avoid jumping in turbulent conditions, which is what I do.

I'm just throwing the information about airlocks out there...he's a newbie who wants to learn, so why not give him the information and let him decide for himself? The more you know... :P ;)

_Pm

Edited to add: For udder--I recommend doing a forum search on the words "airlocks and turbulence" or "airlocks and collapse." You'll find a lot of opinions (pro and con) and experiences on the subject.
__
"Scared of love, love and aeroplanes...falling out, I said takes no brains." -- Andy Partridge (XTC)

Share this post


Link to post
Share on other sites
Essentially, jumping a smaller canopy will make you feel the bumpiness more because of hte increased speed, but on a different note, smaller canopies have been known to do better in turbulence because they are faster and can sort of "cut through" the air quicker. Dont downsize for this reason, but in all reality, the faster the parachute, the less suceptable it is to turbulence. The speed is also directly related to lift, and therefore you would have more lift when the wind is suddenly changed or taken away (like in turbulence).


Cheers,
Travis

Share this post


Link to post
Share on other sites
>can sort of "cut through" the air quicker.

No parachute in the world can "cut through" a downdraft. They will all collapse instantly. Lines have no strength at all in compression.

>but in all reality, the faster the parachute, the less suceptable it
>is to turbulence.

Not really. The faster it is, the more likely it is to _encounter_ turbulence.

There's no such thing as 'turbulence' the way most skydivers talk about it. There are no 'pockets' of bad air that drift around. All turbulence is, in the final analysis, is moving air. If all the air moves the same way we call that steady wind. If all the air moves differently we call that turbulence.

That means that if you transition an area of changing winds more quickly you will experience more turbulence. If you go from a 10kt wind in front to a 10kt wind from the side in 5 seconds, it will seem like a sudden change in wind direction, and the canopy will weathervane due to the change. If it happens in 1 second, then you're likely to see a collapse. The faster you go, the faster you see those changes.

On the plus side, if you're doing 30kts, the _apparent_ change in wind direction will not be as great, since the new relative wind is a vector sum of your previous speed and the new wind. So:

Pluses for small canopies in turbulence:
-More speed to overcome small losses in airspeed

Minuses for small canopies in turbulence:
-You will see more turbulence
-You need every bit of control to pull off a safe landing
-If you have a collapse you will hit the ground harder

>The speed is also directly related to lift . . .

Nope. If a skydiver has a 190lb exit weight, their canopy generates 190lbs of lift over the course of their canopy flight, whether it's a 3:1 elliptical or a Manta.

(A good reference for all of this is "understanding the sky" by Dennis Pagen. It's written for paragliders but is very applicable to skydiving canopies.)

Share this post


Link to post
Share on other sites
Quote

A 7 cell...



actually, my triathlon becomes a pretty wild ride when there is a lot of thermals. I'm starting to believe its bark is much worse than its bite, but it's definitely distracted me up at 2 or 3 grand. Thankfully it rarely seems as bad close to the ground, though the occasional dive or surge can get the heart beating.

Add: when I rented spectres, it never seemed as crazy, but in truth most of my rental jumps were at Hollister when I've rarely found thermal activity to be very noticeable.

Share this post


Link to post
Share on other sites
Quote

You've been sucked in by marketing hype. Airlocked canopies don't offer any protection whatsoever against the dangers of jumping in turbulent conditions.



Which is exactly what I would expect to hear from someone who makes his living selling open-nosed breather canopies (which, in fairness, you neglected to mention).:|

I, on the other hand have NO hat in this ring, and I have come to the exact opposite conclusion to yours. I have direct experience flying through turbulence that caused a similarly loaded Spectre to collapse. My airlocked Lotus buffeted like a big hand smacked my canopy, but for the moments that I needed it most, I did not lose pressure, nor did the canopy deform noticeably.

I'd venture to say that if PD invented airlocks, or if there was no patent on it, very few canopies on today's market would be without airlocks.

mike

Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills.

Share this post


Link to post
Share on other sites
Quote

I'd venture to say that if PD invented airlocks, or if there was no patent on it, very few canopies on today's market would be without airlocks.



Isn't the Vengeance airlocked? Or is your point that it isn't as good of a design as the Big Air Sportz canopies?

Share this post


Link to post
Share on other sites
Yes, the Vengance is airlocked. No, that wasn't my point.

The airlock was not invented by PD, but it did buy the license to build airlocked canopies. All theories as to why aside, PD only incorporated airlocks into the Vengance and nothing more.

mike

Girls only want boyfriends who have great skills--You know, like nunchuk skills, bow-hunting skills, computer-hacking skills.

Share this post


Link to post
Share on other sites
>The airlock was not invented by PD . . .

I would point out that they were not invented by Brian Germain either. One of Domina Jalbert's original patents on the parafoil contained "a normally open flexible valve for the opening closeable by the air pressure to seal the opening when pressurized air is admitted to the wing."

Share this post


Link to post
Share on other sites
Here's something to chew on. I have a Velocity a Vengeance and a Katana. All are loaded about the same give or take and without a question my Velocity handles the winds better then all. The Vengeance is a great canopy but on a day that has turbulance chances are you have some nice ground winds as well. Just imagine who always make it onto the year end video when they don't get the canopy with airlocks collapsed fast enough once on the ground. It's quite a show and not always enjoyable. I believe the Velocity does well only because it's such a stiff wing. I think my Katana does very good also considering no cross braces and the Vengeance is great but nothing better then any other canopy I have flown in the conditions you are asking about. Just my humble opinion and from the experiences I have had.


There are 3 kinds of people in this world, those that know how to count, and those who don't.

Share this post


Link to post
Share on other sites
So for a newer jumper, such as the thread author, who is looking for equipment that can provide extra safety in bad conditions, and who obviously can't fly a Velocity, there are no canopies out there that would help (like a Lotus or a 7-cell, or any other)?
"The evil of the world is made possible by nothing but the sanction you give it. " -John Galt from Atlas Shrugged, 1957

Share this post


Link to post
Share on other sites
>I believe the Velocity does well only because it's such a stiff wing.

Well, no canopy is stiff in any conventional sense. They are all at the mercy of aerodynamic forces. That being said, I agree that some canopies handle turbulence much better than others - and it's not always obvious which ones will do better and which ones will do worse.

Share this post


Link to post
Share on other sites
Turbulence can bring a 747 out of the sky. [:/]

Original poster describes conditions that sound like a thermal but doesn't really tell us about the winds conditions that day. How do you know it was turbulence? Maybe it was an over all lack of piloting skill?

19 jumps under a huge ass student canopy doesn't sound like a formula for a bad landing due to turbulence unless you were caught in a dust devil (australia).

There is no parachute out there that is turbulence resistant. Just pilots who feel comfortable jumping their parachute in higher tubulent winds. All bets are off on high wind days and flying thru turbulence. You may have a great landing one jump, or 5, and then a landing that dropped you hard on your ass. It has nothing to do with airlocks, flying faster thru turbulence, or any other theory. If you jump enough in high winds and turbulence you will have some good landings and some bad landings but you'll never know which landing you're going to get until the very end.




Ken
"Buttons aren't toys." - Trillian
Ken

Share this post


Link to post
Share on other sites
Quote

Turbulence can bring a 747 out of the sky.



It wouldn't if the 747 had a more rigid wing or went faster, right?

That's what most of the misconceptions in canopy flight sound like, unfortunately. The best way to make it through turblance is to NOT JUMP in those conditions, and if you do find yourself in those conditions, do your absolute best to fly around areas that tend to create opportunities for turbulance to develop.

It may seem like highly loaded canopies fly through it with no problems, if that was true, apparently 1.9-2.0 isn't a high enough wingloading.

Its like potholes in the road, you go through the pothole faster if you're moving faster, you go through slower if you're driving slower. When going faster you sometimes have less of a reaction from your car, sometimes, when slower you get more of a reaction...sometimes. The bummer is when going faster, you have much less time to react and correct.
--"When I die, may I be surrounded by scattered chrome and burning gasoline."

Share this post


Link to post
Share on other sites
In my experience, the most dangerous type of "turbulance" is gusting winds, when your canopy is surging forward and dropping as the relative airspeed drops. That got me once, and there wasn't a thing I could do. I'd say an airlocked canopy is superior in that type of conditions since you don't get as severe depressurization, but it's not a cure-all for gusts or rotors. I started sitting out days when the wind is "gusting and quitting", it's too risky and all the experience in the world won't remove the risk if it happens when you're low on final.

Share this post


Link to post
Share on other sites
Not exactly.

Flying thru a body of air is similar to surfing in a body of water. If you surf in relatively calm waters that is similar to "normal" parachuting conditions. You're generally working with a consistent and predictable current.

Turbulence is like big wave surfing. It will carry you as far as it can while you are caught in that current. A big wave or an undertow can hold you on the bottom. If you're caught in a mass of air that is moving straight down, you will ride that mass of air straight down until you fly out of it or hit the ground. Unfortunately, its difficult to look at the air an determine exactly how large that turbulence will be or when exactly it is occuring.

There are good rules of thumb for predicting turbulence in any landing area but you can never know what conditions you'll land in until you are in them. The faster wing theory works if the turbulence is relatively smaller/ shorter in duration and you have some altitude to work with.



Ken
"Buttons aren't toys." - Trillian
Ken

Share this post


Link to post
Share on other sites
Quote

>The speed is also directly related to lift . . .

Nope. If a skydiver has a 190lb exit weight, their canopy generates 190lbs of lift over the course of their canopy flight, whether it's a 3:1 elliptical or a Manta.



I do not claim to have the knowledge to argue any skydiving related point with you, but this comment is in complete contrast to any thing I have read about wings, weather it be a ram-air wing or an airplane wing.

Lift is increased by the square of the speed. That is pretty much directly I thought

Gravity pulls an object towards the ground at 32ft\s\s with no consideration to drag/air resistance until said object reaches terminal velocity which is dertermined by density and air resistance. Now if a skydiver is falling feet first with a terminal velocity of about 180mi/hour then consider the drag of a parachute which would slow that terminal down to about (hell I dont know) lets say 40mi/hr then consider the lift generated by the air foil of the wing that causes a low pressure above the wing and high below the wing which would slow terminal down to about 20mi/hr. This lift would be acting on system during the intire canopy ride and total lift of the ride would have to be dependant apon the length of the ride since the lift is constant during the ride, that is with out considering change in wind and pressure ofcourse.(my explaination of lift with out walking to the bookshelf to get the physics book)

Again, I have no idea as to the answer to this thread as I do not have that kind of experience, nor do I offer my explanation of lift for any other reason than to get feed back from the more knowledeable


Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

0