Anyone been hit by a hook knife or other debris in freefall?

[jont 0]

Was filming an 8-way last weekend that went into a funnel. Just as they were starting to regroup, I saw something red flash by me. Turns out one of the team lost his hook knife.

Looking at the video in stop-frame later, you can see it appear near his armpit, and pass fairly close to two others coming down to him (he was low man on the funnel at the time) before passing about 15/20 foot away from me and out of the top of the frame. Good thing I wasn't steeper on the formation at the time!

Started me thinking. How much would that have hurt or done damage if it had hit me or one of the others? Particularly if it had hit me in the face - while the rest of the team were all wearing full-face, I was of course in open-face camera helmet.

Anyone any experience of this, or any other debris hitting them?

jont
p.s. sorry for cross-post, but jsut realised this could go in camera forum too

[pringles 0]

I had a tandem students glasses hit my hand one time (I was the instructor). His goggles had shifted and he started fussing with them. He made matters worse and lost his glasses. It didn't hurt that bad. But I was very aware of it. Im sure if there was more seperation from the object it would hurt quite a bit.

Matt Davies

[Fast 0]

I was high and comming down when a formation funnel'd all to hell. People kinda ended up flying every which way and for whatever reason one person grabed anothers leg and the result was me getting hit with a shoe. Didn't really hurt.

~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

[ScottishJohn 25]

I've seen (the video) of a camera man catching a wrist mounted alti that someone on a 4 way RW dive lost.

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If you think my attitude stinks you should smell my fingers

[jose 0]

Dude at my DZ had his knife flapping all over the place off his chest strap. He thought no big deal, until he went to go pack his rig. He walked up the lines to start flaking and there was a nicely cut D line, about 3/4 the way up. Seems that the hook part of the knife caught the line as it came out of the rig and sliced it clean. What amazes me is that the dummy never knew it until he packed? How do you miss that under canopy?

Oh well, what doesn't kill you, only shows how clueless you are.

[councilman24 37]

I've had a few new swoopers who hit me that I'd consider debris.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[airtwardo 7]

I got hit in the face with a crushed flat beer can once...

(length wise, not stomped on straight up & down)

It was spinning frisbee like but slower

As a joke one guy had put it in the container of
another guy thinking it would fall on / past him
under canopy when he opened...

We were in a separate 4 way group from those clowns,
when at about 2500' I'm reaching to pull after tracking
and just caught a glimpse of it before it hit me.
(I hit it?)

Mr. Idiot was joking to his buddy about
'did ya see something from last night'
under the packing tent, and went into details....

I walked over and explained how happy I was
about the bleeding cut under my eye!

(No video...but still have the scar!)

~ If you choke a Smurf, what color does it turn? ~

[FrogNog 1]

Quote

a nicely cut D line, about 3/4 the way up. ... How do you miss that under canopy?

There's a lot of lines up there and I don't check them all under canopy most jumps. If it were hanging down on my face or otherwise in my way, sure I'd notice it. But if it were just one out of the "mess in the middle" that was hanging behind me out of sight, and my "squarish, turns, flares, yellow cables" test showed nothing abnormal, I probably wouldn't notice until I got to the ground and started packing.

-=-=-=-=-
Pull.

[airtwardo 7]

Quote

Seems that the hook part of the knife caught the line as it came out of the rig and sliced it clean

Quote

Trying to picture that...

Was the knife still on the chest strap when it cut..?


or had it come out and gone up into the deploying canopy?
(what I'm thinking / hoping)

~ If you choke a Smurf, what color does it turn? ~

[Keith 0]

I know a guy who's hook knife came loose on opening and sliced several of his suspension lines resluting in a cutaway. There's video floating around somewhere.

Keith

Don't Fuck with me Keith - J. Mandeville

[darkwing 5]

a guy at our DZ got hit by the altimeter he accidentally packed up in his main.

-- Jeff
My Skydiving History

[Vertifly 0]

Aren't they kinda shaped to avoid getting cut unless it's used on purpose?

[cvfd1399 0]

A result of murphy's law. My translation-If can be done, and it makes things worse it will happen at the exact moment you think it could never happen

[jose 0]

yeah, but if the hook catches a set of stowed lines, it will slice anything that goes near the blade.

[jose 0]

yeah, still attached to the end of its strapt that was connected to the chest strap. So it was flappin around behind him.

Duh.

[sweep 0]

Just a theory, but I reckon something light and flat like a hook knife is going to hurt more than something heavier like a shoe or an alti. Especially if you're a bit away from it.

Reason being I imagine shoes and the like will fall quite a bit faster than a hook knife / glasses / goggles etc and the speed it hits you will actually be lower the faster it falls (until it starts falling faster than you).

So I reckon something like a hook knife could really sting. Just a theory though, I've lost my shoe once (on deployment) but it never hit me or anyone else.

Blue ones

Sweep

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Yay! I'm now a 200 jump wonder.... Still a know-it-all tho..

[airgord 1]

Hook knife, Teva, helmet, pilotchute, target fixated late diver x2, other than that not really.

[jheadley 0]

slightly OT but when I was doing my 2nd tandem, during the climbout, the camera guy's camera fell off and it ended up landing about 20 feet away from the packing area.

[jose 0]

I wouldn't really subscribe to that train of thought. Here's why. The energy transfer between 2 objects that collide will depend on mass and speed. The more the mass, the more energy transfer. The higher the speed, the more kinetic energy there is.

So, with that, think of a feather. Its flat and light, but does not possess the energy and mass to have any effect. Now think of a feather that has been bronzed. It has the same shape as a feather, but it weighs much more. There is more mass to it, has more kinetic energy. It also falls faster, but that is not nearly as relative as its mass and the effect it has on energy transfer.

[mr2mk1g 10]

Sure?

I thought Force = Mass X Velocity. (Force of course being the thing that hurts/damages you)

In that equation, Mass and Velocity have an equal impact on force. Double Mass, you double the force. Double Velocity, you double the force.

Or is it more complicated than that?

[Vallerina 2]

I thought it was F=ma, but it's been years since I've had a physics class!

There's a thin line between Saturday night and Sunday morning

[Dougiefresh 0]

Momentum=mass x velocity. And you have to keep in mind relative velocity, too. You're falling, it's just falling faster. If you were on the ground and got hit by a falling hook knife you'd be seriously hurt or killed.

Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so. --Douglas Adams

[mr2mk1g 10]

Yeah your right it's f=ma... I think in this instance acceleration is physics speak for what the knife's doing relative to you... or something It's a little beyond my recollection.

My head's far too full of stupid things like movie quotes and what has happened in the Simpsons for me to be able to remember inconsequential little things like the laws of physics.

[droidicus 0]

For kinetic energy KE = ½ * m * v^2 where m = mass in grams, v = velocity in meters per second, and KE is energy in Joules. The velocity is squared, so there is twice the energy in a 100 gram object going 20 meters/second as there is in a 200 gram object going 10 meters/second.

Having said that I don’t know if a hook knife or an altimeter would hurt more since I don’t know there weights or fall rates ;-)

[RogerRamjet 0]

Quote

I wouldn't really subscribe to that train of thought. Here's why. The energy transfer between 2 objects that collide will depend on mass and speed. The more the mass, the more energy transfer. The higher the speed, the more kinetic energy there is.

So, with that, think of a feather. Its flat and light, but does not possess the energy and mass to have any effect. Now think of a feather that has been bronzed. It has the same shape as a feather, but it weighs much more. There is more mass to it, has more kinetic energy. It also falls faster, but that is not nearly as relative as its mass and the effect it has on energy transfer.

Hmmm, with enough volocity relative to the object being struck, the light weight object can still do damage. Ever seen the picture of the piece of straw driven partway through a tree by a hurricane?

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Roger "Ramjet" Clark
FB# 271, SCR 3245, SCS 1519