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billvon

Wake turbulence and the Velocity

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We had another Velocity collapse today at the Cal state record due to a Velocity hitting the wake turbulence of a canopy ahead of him. The canopy collapsed on one side at about 200 feet, spun the person at least 180 degrees, then reinflated at about 30 feet. Jack Gramley was in the process of calling for help when it reinflated and landed the person without injury (fortunately.)

Any canopy can be collapsed by sufficient turbulence, but this is the third Velocity I've seen collapse due to wake turbulence in otherwise smooth air. Might be a good idea to consider whether to use a canopy like the Velo during dives where traffic makes wake turbulence more likely.

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We had another Velocity collapse today at the Cal state record



Why are the organizers allowing such an aggressive canopy on such a large formation?

Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and is tough to fly through traffic (without having to hang in serious brakes or trying to weave through the pattern with speed).

The only time I've ever had problems with a Velo's stability is going through turbulence in moderate to deep brakes or flying one where the trim was going out. And in the case of a high performance canopy, what I consider out of trim is what most jumpers wouldn't even notice on their Sabre2s or Pilots.
--"When I die, may I be surrounded by scattered chrome and burning gasoline."

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>Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and
>is tough to fly through traffic (without having to hang in serious brakes or trying to
>weave through the pattern with speed).

Agreed. And for the "bigger" stuff they are requiring lighter wing loadings and less twitchy canopies. (I know, it's odd that a 200 way is now considered "not that big.")

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Almost identical situation here:

http://www.youtube.com/watch?v=G_MsYQ3GtAg

Thanks for posting that. There's another reason to use an RSL. Funny how people think they're too good to need one. :S

This summer I saw a very experienced jumper jumping a moderately loaded nine cell have a partial collapse, 180 turn and reinflation at low altitude due to wake turbulence. Maybe this is an issue that needs more awareness. The strength of wake turbulence is influenced by several different factors, and so are our canopies' reactions to it. Our modern canopies have little tolerance for many things. Wake turbulence might be one of them.

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>Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and
>is tough to fly through traffic (without having to hang in serious brakes or trying to
>weave through the pattern with speed).

Agreed. And for the "bigger" stuff they are requiring lighter wing loadings and less twitchy canopies. (I know, it's odd that a 200 way is now considered "not that big.")



While it's smaller than 400, there haven't been very many formations >=200 completed.
...

The only sure way to survive a canopy collision is not to have one.

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>While it's smaller than 400, there haven't been very many formations >=200 completed.

I know, which is why it's odd. This was one of the 'tryout' events for the 500 way, so maybe it was seen as more entry-level.

But heck, when I started skydiving they hadn't even built a 200 way yet.

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>While it's smaller than 400, there haven't been very many formations >=200 completed.

I know, which is why it's odd. This was one of the 'tryout' events for the 500 way, so maybe it was seen as more entry-level.

But heck, when I started skydiving they hadn't even built a 200 way yet.



So what was it like being on the first baton pass old man?

:D
--"When I die, may I be surrounded by scattered chrome and burning gasoline."

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>Even at a "light" Velo loading around 2:1, it is still a hyper aggressive canopy and
>is tough to fly through traffic (without having to hang in serious brakes or trying to
>weave through the pattern with speed).

Agreed. And for the "bigger" stuff they are requiring lighter wing loadings and less twitchy canopies.



I thought the wing loadings were requirements too, but I just checked the Dubai 500 application and it says,

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Larger canopies with slower descent rates are highly recommended. Please consider jumping a canopy that puts you in a wingloading between 1.25 and 1.75 for these events.



So, only recommended, not required. Perhaps that should change.
Skydiving Fatalities - Cease not to learn 'til thou cease to live

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Larger canopies with slower descent rates are highly recommended. Please consider jumping a canopy that puts you in a wingloading between 1.25 and 1.75 for these events.

So, only recommended, not required. Perhaps that should change.



Half the organizers exceed that recommendation. They're not going to make it a requirement.


Actually, of the few bigways I've done - having a wide variety of wingloadings helped spread out the landings in time. The higher wingloadings land before the lower ones do. As long as you've got adequate separation at pull-time, having a wide range of wingloadings is one way to reduce the risk of collision.

Even my docile canopies are loaded on the "heavy" side. I was surprised to see all the organizers beat me me down the last time I was at a p3 camp.
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You put the fun in "funnel" - craichead.

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"Maybe this is an issue that needs more awareness."
I'll second that. Pilots are taught about wake turbulence, but skydivers aren't. I'd say that information about wake turbulence should be included in the training along with info about turbulence from wind coming over buildings, etc.
You don't have to outrun the bear.

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>Half the organizers exceed that recommendation. They're not going to make it a requirement.

They're working on that - getting sponsored and semi-sponsored medium performance mains that several team captains will be jumping. The video team is getting bigger canopies as well, since giving them all much larger canopies is a way to "take them out of the equation" so to speak. But I don't think they have a final plan yet.

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I doubt it was a velocity specific problem. Any canopy will collapse under wake turbulence. Smaller canopies do have a higher pressurisation because of higher airspeeds, but loosing 1/4 of a 90 sq/ft canopy is a lot less available wing then loosing 1/4 of a 150 sq/ft canopy. Canopy choice and especially size requires a lot of responsibility, you need to take into account what you are going to do with that canopy. Flying a highly wingloaded canopy on big ways, is probably not the best idea, or if so dont land where everyone else is landing. People now a days downsize without thinking about things fully, just being able to land a small canopy isnt everything to consider. Most dont realise your EP's become more important to have down with a small canopy, Pattern, traffic, ability to put yourself out of traffic ect, ect, ect. Ive heard the excuse I was jumping an 84 I had to land then, too many times. Most dont realise they can stay up, even with a small canopy. Learn your canopy people! learn landing separation, fly a good pattern, and when in doubt land at the alternate landing area. And most of all from this situation everyone should know where not to fly in relation to other canopies. These are all things this person, or anyone that jumps a canopy, let alone a small canopy should know. Especially before someone decides to downsize.
I still dont think its a Velocity problem, Im pretty sure any canopy would have done this.


Ray
Small and fast what every girl dreams of!

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>Any canopy will collapse under wake turbulence.

True, but some are certainly more sensitive than others. (The old Nova was a famous example.) From what I've seen, Velos are unforgiving of wake turbulence, something most other canopies handle without too much trouble.

>I still dont think its a Velocity problem, Im pretty sure any canopy would have done this.

Have you seen other canopies malfunction when flying through wake turbulence?

>Most dont realise they can stay up, even with a small canopy.

True - but when you have 100 other people who are also trying to stay up your options are a lot more limited. If you have a Velocity 84, you're not going to outfloat the guy with a Pilot 150 who is _also_ trying to stay up.

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>Half the organizers exceed that recommendation. They're not going to make it a requirement.

They're working on that - getting sponsored and semi-sponsored medium performance mains that several team captains will be jumping. The video team is getting bigger canopies as well, since giving them all much larger canopies is a way to "take them out of the equation" so to speak. But I don't think they have a final plan yet.



Leaders should lead by example. These are guys working in the sport, it should be no problem for them to obtain more suitable equipment. Especially if they are expecting the guys who are already paying to work their way through the camps, and do the big ways to do the same, who are less likely to have more suitable gear as readily available to them.

Full face helmets and AADs are mandatory for big ways. Why not specified wing loadings? I heard of one guy getting benched at the recent CSR 200-way for having an older rig with poor pin protection. When you get to these sizes everything is about safety and logistics. I don't really buy the separation argument. There's should be enough range between 1.25 to 1.75 without having people outside that. I appreciate there's a risk with unfamiliar gear, but it's easy to get familiar on gear before an event. Is it that much effort? People will argue that their high performance main opens better than anything else, but is it really worth having people at the extreme end of the performance envelope at such high profile, critical events? It seems the only argument for exceeding wing loading guidelines is inconvenience and that shouldn't be a reason.
Skydiving Fatalities - Cease not to learn 'til thou cease to live

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"Maybe this is an issue that needs more awareness."
I'll second that. Pilots are taught about wake turbulence, but skydivers aren't. I'd say that information about wake turbulence should be included in the training along with info about turbulence from wind coming over buildings, etc.



Very true. Back in high school when I was going for my private pilot license (never got it, paying for college took priority), I was learning to fly at Quantico in Virginia. HMX-1 is stationed there which means they've got C-17s and C-130s constantly flying in and out depending on the president's travel schedule.

One day I was returning on a solo flight and entered the pattern behind a C-130. I was about a mile back and at about 1500 feet when all of a sudden the plane got buffeted and thrown into a dive. I quickly recovered and got back into downwind, now probably 1.25mi back. Same thing happened. Took about a second for it to click that his wake was frickin huge and I notified the tower I was heading to the pattern entry point to give my self some space.

Wake turbulence is definitely taught during ground school and the entire PPL progression. It should be included in the AFF program since our wings are susceptible to it and if it occurs it'll most likely be during the pattern where altitude is minimal.

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I doubt it was a velocity specific problem. Any canopy will collapse under wake turbulence. Smaller canopies do have a higher pressurisation because of higher airspeeds, but loosing 1/4 of a 90 sq/ft canopy is a lot less available wing then loosing 1/4 of a 150 sq/ft canopy.



I asked previously if either the lead or trailing canopy were flying in brakes, but nobody answered.

I suspect that the lead canopy in brakes creates an ever larger wake, and equally - the trail canopy in deep brakes is even more susceptible to the effect of the turbulence. The latter may be more true with cross-braced canopies with their very small open cells.

This would create the double-whammy when a canopy pilots first instinct is to slow down.

_Am
__

You put the fun in "funnel" - craichead.

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True, but some are certainly more sensitive than others. (The old Nova was a famous example.) From what I've seen, Velos are unforgiving of wake turbulence, something most other canopies handle without too much trouble.



Are you really comparing a Nova to the velocity? Velocities have a long history of being a good canopy, and yes I have seen many canopies collapse, most of them high enough to reinflate, I see Tandem mains do it all the time, precision, PD and Icarus models. There was a crossfire 1 fatality at the pond national at the ranch where the canopy completely collapsed, yet crossfires continue to safely land skydivers every day.


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True - but when you have 100 other people who are also trying to stay up your options are a lot more limited. If you have a Velocity 84, you're not going to outfloat the guy with a Pilot 150 who is _also_ trying to stay up.



Ill take that challenge, I have a long history of doing video, big ways and 4way, I always made it a priority to have everyone I filmed land before me. Bring your pilot 150 and lets have a lift contest, Ill stay with you all day.


Ray
Small and fast what every girl dreams of!

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