FTP - Neck injuries vs type of setup

[cj1150gs 0]

Hi,


I am in the proccess of setting up my new FTP (2.nd hand, acctually
From my own limited experience and by listening several other recent threads I have already realized that neck problems are hard to avoid for people jumping SLR's.

In what concerns the FTP, people talk about a good, balanced setup, but that's where consensus ends. For some this means everything top mounted, for others a front mounted stills is a good thing.

I am by no means a biomechanics expert, and physics classes are something very blurred in a distant past but it seems obvious that, when in a deployment position, facing down, the furthest the added weight is in relation to the neck joints, the worst. I mean, the leverage of the added weight would increase, right? This would point to an advantage of the front stills configuration. After all, your forehead is closest to your neck joints than the top of your skull.

For both configurations I have drawn a little diagram which tries to represent the Centers of Mass (CoM) of the head+FTP (orange), of a stills camera (green) and of a video cam (blue). I have then graphically calculated where the resulting overall CoM (red) will be and measured the distance from this one to each of the cervical joints on a human neck. The result is the table I am also attaching. Yeah, I know I could have been jumping instead, but the subject really matters to me and besides we're short of turbines here

Anyway, this exercise points to an effective advantage of the front mount, but some people complain about unbalance. I wonder if these complaints will result from the effective unbalance one feels when holding heads vertical while standing up on the ground or plane.???

Although these diagrams were made by aproximation I tried to draw them to scale. I have used the following figures for mass representation:

Human head: 4.5 kg
Bonehead FTP: 1.1 kg
Canon D20 with 15mm 2.8 EF lens and QR: 1.1 kg
Sony PC106: 0.55 kg

FTP users comments would be welcome, as well as from anyone that could help with the physics of this (as I prolly missed some important physical law!).

One thing is sure: by adding all this to our heads (and I am neglecting sight, cameye, wiring, extra mechanical hardware, (let alone flashes, batteries wireless mics...) we're increasing overall "head weight" by 60% and significantly moving the correspondent center of mass away from the neck joints!

Blue skies,

Carlos

Carlos Martins
Portugal www.cj.smugmug.com

[AndyMan 7]

That's an interesting analysis, and presents some aspects I haven't thought about. Thanks!

For me, though - I'm not worried about the weight while in a deployment position, (ie, looking at the ground) - but the position I'm in when the slider comes down. I worry about the position when I've already been stood up, and that last slam comes as the canopy fully opens. The forces are straight down your spine.

That means that I want the weight centered directly ontop of the spine, which I've always figured having both on top accomplishes. Your pictures illustrate this nicely.

With a downward force, having a front mounted still would strain the muscles in the back of your neck and may dip your chin forward, a position I understand to be one of weakness.

_Am (not an MD, PT, or really anything relevant...)

__

You put the fun in "funnel" - craichead.

[piisfish 135]

and this is when having a "slow" opening canopy comes into account.. And also Bill Booth's advice on the type of lines you should use for the occasional slammer. I know "it's not cool" to jump dacron lines...but we are all educated, and we have to pick our poison...

scissors beat paper, paper beat rock, rock beat wingsuit - KarlM

[BlueSBDeath 2]

Try these parameters with a side mount and a nice lite Canon XT on top and PC-330 on the side (FF2).

I know it sure does feel better, I suspect the math is better for the neck too.

Just my 2 cents,

Arvel

BSBD...........Its all about Respect,

USPA#-7062, FB-2197, Outlaw 499

[ltdiver 3]

AndyMan,

You have the concept correct.

It's not the balance, per se, when you're in flight that matters the most but when you're in the position of risk with opening.

I'd much rather have the weight straight down through my spine than in front, pulling my head to my chest.

ltdiver

Don't tell me the sky's the limit when there are footprints on the moon

[The111 0]

I have DV and SLR on top of an Optik Illusion which probably is worse than on an FTP, because the helmet has an inferior grip on my head compared to the FTP. My setup weighs 6.5 lbs and is very tall. (In the process of building my own rear-entry system)

I fly wingsuit only and usually have great painless openings, like others pointed out just get it over your spine for that last little opening shock. The snivel is when you line everything up.

Yesterday I got lazy after a very high forward speed flight over clouds, and pulled from full flight without slowing down. It's possible to do smoothly but riskier. I didn't nail it just right and got SLAMMED, chin knocked into breastbone, neck felt like rubber. Funny thing is it didn't hurt and today I am pretty sore but no more so than after a lot of situps. I think for once I got lucky. I have a real shitty lower back, maybe my neck makes up for it? Just got done reading Joe Jennings' article where he mentioned genetics giving him a good neck, and that's all I can think about.

www.WingsuitPhotos.com

[lewmonst 0]

I feel the weight on the ground and occasionally on opening. I think the key is having a reliable soft opening canopy. You probably aren't ready for it yet, but my XAOS-21 opens like a dream. I never worry about openings with it.

peace
karen lewis

http://www.exitshot.com

[Brains 2]

I am in agreement with the others who say they are not worried too much about the snivel, only the end of the opening. I mounted my 20D and TRV19 on top to keep everything over the spine. However, when you have bad openings, it doesn't make a damn bit of difference. I think it will only save you on the normal wear and tear over a weekend of jumping.

Never look down on someone, unless they are going down on you.

[cj1150gs 0]

Thanks all! This is great input!!

I once got slammed big time - opened in a rush after a great track away. I was wearing only video on a side mount on a Vertigo-X, but got pulled so hard I thought I had no slider at all!! Chin hit sternum pretty hard, I compressed the front ribs and distended the back ones. Took me 4 weeks to jump again. That's why I was basing all my reasoning around the first instants of deployment when the snatch force will pull you to the vertical position.

I was not considering the last part of deployment, and that's what seems to worry most of you...

I guess Brains summed it up well - if you got a slammer with 2.5 extra kg on your head, you're done anyway. That's a good reason to try to keep the weight as low as possible. But in a "regular" opening all on top makes sense...

I'll have to discipline myself to pack properly and allow extra altitude for slowing down. I don't want to change canopy now, but I'll consider the softer alternatives when time comes.

Thanks again for all your comments!

Carlos Martins
Portugal www.cj.smugmug.com

[Winznut 0]

Quote

I once got slammed big time - opened in a rush after a great track away. I was wearing only video on a side mount on a Vertigo-X, but got pulled so hard I thought I had no slider at all!! Chin hit sternum pretty hard, I compressed the front ribs and distended the back ones. Took me 4 weeks to jump again.

Still suffering from one of those.
Had a slammer about a week ago and since then, I have numb fingertips in my left hand.
Visited the doctor yesterday and he was talking about the possibility that I maybe have to stop jumping to not end up paralyzed at one day...

I "only" wore a RAWA with a PC100 side mounted...

[davelepka 4]

I've been behind this concept for a long time. Keep the weight as low as possible, keep the weight as close in to your head as possible, and keep your head square on your shoulders on opening (meaning don't look at your canopy).

This also ties into the 'keeping it simple' principle. The fewer parts and components on your helemt, the fewer parts there are to break or mal. The bonus is that fewer parts usually leads to a lighter helmet.

Newer camera flyers need to embrace this stuff and realize that a camera helmet is 100% function. Too many of them go for fashion, or the latest gizmo, and most of it is crap, and is just going to work against them in the long run.

[The111 0]

What is an example of a fashion gizmo that somebody is mounting on his camera helmet? You lost me with that comment.

www.WingsuitPhotos.com

[Jumpnfun2 0]

Hey,
Check out the thread about the XT. It has some interesting stuff about which setup to use.
BS,
Sue

[Zee 0]

Quote

What is an example of a fashion gizmo that somebody is mounting on his camera helmet? You lost me with that comment.

I jumped with a talking monkey humping my TRV at the WFFC - does that count?

Action©Sports

[The111 0]

Quote

Quote

What is an example of a fashion gizmo that somebody is mounting on his camera helmet? You lost me with that comment.

I jumped with a talking monkey humping my TRV at the WFFC - does that count?

Hey, stay on topic!

Seriously, was the monkey's weight centered?

www.WingsuitPhotos.com

[davelepka 4]

Situations like a guy using a stroboframe (or two) when he doesn't need to remove cameras, or maybe isn't even a working camera flyer who's just making fun jumps. The strobo's add weight, and their added height moves the cameras further from your skull.

How about the guys with one small PC cam on an FTP. They buy the FTP just because it the top of the line, regardless of what their application really requires.

In the early days of the PC cams, I knew a few guys who bucked up and were jumping VX1000s for the three chip quality, when they were just fun jumping. Even worse was the guys who bought the VX700 (single-chip) becasue they couldn't afford the 1000, but wanted to look like 'one of the guys'.

It's the same theory as every 500 jump wonder who thinks he needs a Velo or a VX to be a big shot on the DZ. Put your ego aside, and realize that real results will come from making smart equipment choices, and that in the end, real respect comes from what you do with your equipment, not what equipment you have.

[ltdiver 3]

Quote

real respect comes from what you do with your equipment, not what equipment you have.

Must....not....hijack.....

ltdiver

Don't tell me the sky's the limit when there are footprints on the moon

[The111 0]

Quote

How about the guys with one small PC cam on an FTP. They buy the FTP just because it the top of the line, regardless of what their application really requires.

Good point, but on the flipside I chose not to get an FTP when I started shooting video only, just so I wouldn't look like "that guy". Then when I needed to add stills I had no good top plate real estate left and am left with a ridiculously crowded Optik Illusion.

So maybe sometimes "that guy" is smart and has a reason for doing what he's doing (like using a helmet he can expand on later).

In my case it turns out ok since I don't want an FTP anymore, since my Wes CCM copy will be much better, if I can ever freaking finish it.

www.WingsuitPhotos.com

[cj1150gs 0]

Quote

I jumped with a talking monkey humping my TRV at the WFFC - does that count?

Typical Talking Monkey: 240 gr

Runing center of mass dislocation... check drawing attached

Carlos Martins
Portugal www.cj.smugmug.com

[cj1150gs 0]

Quote

Hey,
Check out the thread about the XT. It has some interesting stuff about which setup to use.

Thanks,

(acctually it was that thread and somehow diverging opinions on front/top mount that had me thinking about this.)

Carlos Martins
Portugal www.cj.smugmug.com

[Zee 0]

Quote

Quote

I jumped with a talking monkey humping my TRV at the WFFC - does that count?

Typical Talking Monkey: 240 gr

Runing center of mass dislocation... check drawing attached

I have to admit, that's a stunning rendition

Action©Sports

[airborne82nd 0]

i jump a Hc 40 side mount with a small elph on top for stills no site use non dominent eye site in the googles.

i use th small battery in the hc40 and the helmet is a hawkeye.

now i am one of those guys who did a lot of football, 16 years of karate, airborne specail opps, and moto-cross

now when i was say till 32 i was still made out of solid steel, now 38 i am in good shape but years of hardcore has stressed my neck. my neck is in great shape.
I had line dump 2 months ago and i am in the medical field, i just knew i broke my neck i sevearly hyperflexed it. my chin slamed my chest and my canopy went boom!!!

so i went to my hospital and went to nerosurgeon i know and they did a CT scan. nothing wrong at all, i have some arthritic changes consistant with age and years of neck stress activity. he told me that my big chin cup hit my chest and prevented any further flexion. he saw the video of it he said its good you dont have one of those mailboxes on you head and you have a little camcorder on the side. he said with the chin cup and the side mount i was lucky, i thought i was still tough as nails but if i was wearing some of the top mounts i see, i dont knwo if i would have broke my neck, fractuure vertabre???

your graph is very interesting, can it calculate the stress of side mount camera helmet set ups???

thanks for sharing the info

[cj1150gs 0]

Quote

i jump a Hc 40 side mount with a small elph on top for stills...

i use th small battery in the hc40 and the helmet is a hawkeye.
...
your graph is very interesting, can it calculate the stress of side mount camera helmet set ups???

Hi,

I haven't calculated (because I don't know how to) the stress on the neck joints of any of the FTP configurations (front / top mount) . I just tried to represent (to the best of my intuition) the dislocation of the Center of Mass and the overall weight increase.

It seems that I considered only the explosive deployments and not the problem of "regular" openings, in which most of the forces apply when you're already in a vertical position and the decceleration exerts a force aligned with your spine and not perpendicular to it.

Anyway, if you consider the first case, (caused by line dump, improper slowing down, lousy packing) one thing is sure, the lesser the weight, the lesser the damage. And, yes, a side mount on a small helmet will keep the overall center of mass in a less damaging position than an FTP (this in the jumpers longitudinal plane... acctually there's a dislocation to the side that could induce torsional stress on the neck - but my experience , and yours, shows that this in not the problem with explosive openings - the problem is hyper-extension). I remember seeing a pic here in dropzone.com of a guy who acctually broke the jawpiece of an integral helmet with his chestbone.

As a conclusion, I think we must avoid THE SLAMMER at all cost. Change those loose/old rubber bands, pack properly, choose a slow opening canopy, allow extra altitude for slowing down and assume a good balanced position before dumping that PC!

Oh, and please remember i am just an aspiring freefall photographer and by no means a biomechanical engineer

Carlos Martins
Portugal www.cj.smugmug.com