Ground rush

[Zep 0]

I was remembering the days when sometimes we'ed take it down low enough to experience GR
Anyone able to explain why it happens


No wise cracks it's a serious question

Gone fishing

[DrewEckhardt 0]

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I was remembering the days when sometimes we'ed take it down low enough to experience GR
Anyone able to explain why it happens

The ground fills your entire field of vision (there's no horizon) and is spreading out _fast_. It's pretty good arround 1000 feet at terminal, a few hundred feet sub-terminal.

[davedlg 0]

Yeah, It's called paralax. When you are far away from an object (the ground) the angle between points is fairly constant as you move. The closer you get to an object, the angles change faster as you move.

Think of driving between two telephone poles in the distance. At a mile they will appear to be in about the same location and angle relative to each other. As you get closer they will quickly change angles and eventually be at 180 degrees to each other as you pass them. The same thing happens with ground rush.

[Zep 0]

My ground rush occurs at around 1800 - 1600ft I can't ever remember taking it down to 1000ft
So with different people can it occur at different hights?

Gone fishing

[sunshine 2]

I've noticed it with clouds also.

___________________________________________
meow

I get a Mike hug! I get a Mike hug!

[XOsunnydaysXO 0]

Hate to ask a silly question...but I'm new! What's groundrush???

[JohnMitchell 16]

It's what you see as your Cypress is firing.

Seriously, it's the "rushing up" appearance of the ground when you're in freefall a lot lower than you should be.

IMHO, I think it occurs when you go lower than your brain is used to seeing. When I used to open low a lot, I didn't get it as much as I do now. I think that's why some people get it higher or lower than others. If you do get ground rush, you're probably screwing up. PULL.

[bch7773 0]

I've always heard that ground rush is actually caused by how your eyes work. that you can't focus on things farther then 3000-4000 feet. (you can see them, but your eyes just tell your brain that object is "far")
so once the ground gets closer then that distance, your brain can actually see it getting closer. and of course this effect seems scarier the lower you get.

thats the explanation i've heard anwyays

MB 3528, RB 1182

[crotalus01 0]

hmmmm, i dont know about that. i almost always pull at 5 grand, and ever since i lost my tunnel vision i see ground rush on every jump that i look at the ground for more than five seconds or so.

As for me and my house, we will serve the LORD...

[firstime 0]

you guys are making my heart palpatate. I would be
in the "kiss my ass goodby mode" I am not coming
back to this thread till this one is over...whoa

[flyangel2 2]

Balloon jumps. Just look right at the ground, that will give you ground rush.

May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds. - Edward Abbey

[skybill 22]

Hi zep,
Dave says it quite eloquently a post or two below yours. Ground rush you say? That's a trip. But you havn't been low till you're still in freefall and see your shadow on the ground!! That's low!! Had a friend who survived a very low opening and after he quit shaking and settled down said that he saw his shadow right afer he pulled his ripcord and knew he was going to DIE!!!!!!!!! He said he then saw his shadow expand out really fast and thought this was the end but his reserve opened with him just barely feet above the ground. What he saw expand was his chute opening!!! One Lucky Dude he was>>>>>>>>>
PS, Saw a picture at old Elsinore I think Tom Sanders took it but I don't know of a LA cop named Jerry who had a really low reserve opening. The picture shows Jerry with about 1/2 his chute open and his shadow distinctly on the ground below him! He was lucky in that he lived! His canopy had just finished opening when he hit and he sill broke his leg.

SCR-2034, SCS-680

III%,
Deli-out

[slug 1]

from what i heard

When your at a good altitude your visual references on the ground, roads, RR tracks, cars, people, bldgs are very small.

The closer you get to the ground the faster those visual references will get bigger, roads get wider, RR tracks you can see indivdual rails, house look bigger etc. you can start seeing individual hay bales and there getting bigger and bigger very fast and look very big.

A easy way to experience Ground rush is from the ground and watch people in FF. When they exit their little black dot's and don't look like their falling very fast. The closer they get to the ground the easier their to identify as humans.

Then you can see arms and legs, some times you'll see fingers and feet. As they get closer to the ground they look like their falling faster and getting big very fast. Thats the safe way to experience ground rush.

Don't recomend doing it from the top down.

R.I.P.

[tdog 0]

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IMHO, I think it occurs when you go lower than your brain is used to seeing.

I agree - in my last jump I pulled higher than required as a student - but lower than I had ever before.

Even though I was pulling higher than anyone else on the plane as a novice - I thought, "shit that ground is getting close and it is getting closer much quicker than before."

[davedlg 0]

Okay, yes I am bored right now but I thought I'd do up a quick graphic. This shows a skydiver at 10,000 feet and at 1,500 feet Three seconds later in both cases he is 500 feet lower. There are two points on the ground 500 feet apart. The points could be anything: the edges of two buildings, the sides of a field, two cars, etc. I have shown the visual angle between the two points in all cases. In the first example, the points remain at relatively the same angle apart, "moving" at only about 0.025 degrees per second. In the second example, the points are moving apart relatively quickly at 1.5 degrees per second. So, when you look at a 500-foot long object on the ground from terminal velocity at 1500 feet versus 10,000 feet, it will appear to be getting bigger at 60 times the rate.

(Can you tell I used to tutor physics?)

[slug 1]

Quote

Okay, yes I am bored right now but I thought I'd do up a quick graphic. This shows a skydiver at 10,000 feet and at 1,500 feet Three seconds later in both cases he is 500 feet lower. There are two points on the ground 500 feet apart. The points could be anything: the edges of two buildings, the sides of a field, two cars, etc. I have shown the visual angle between the two points in all cases. In the first example, the points remain at relatively the same angle apart, "moving" at only about 0.025 degrees per second. In the second example, the points are moving apart relatively quickly at 1.5 degrees per second. So, when you look at a 500-foot long object on the ground from terminal velocity at 1500 feet versus 10,000 feet, it will appear to be getting bigger at 60 times the rate.

(Can you tell I used to tutor physics?)

You got it
I hear that some people have gone down to the mid 100's at terminal before opening. Ground rush was faster than brain could compute. Or so I heard.

Don't try this dumb shit on purpose even with computer stuff (AAD) shit happens you could get seriously hurt for a nano second. Not worth the risk.

R.I.P.

BTW if your watching someone in freefall and you start getting ground rush because their getting that big that fast turn around and take a walk

[Zep 0]

Great graphical explination Thanks.

By the way I loved the sensation of groundrush but along came ZP

Gone fishing

[jas8472 0]

Quote

I've always heard that ground rush is actually caused by how your eyes work. that you can't focus on things farther then 3000-4000 feet. (you can see them, but your eyes just tell your brain that object is "far")
so once the ground gets closer then that distance, your brain can actually see it getting closer. and of course this effect seems scarier the lower you get.

thats the explanation i've heard anwyays

This is what I thought too, It's different for different people too, if I'm just falling down the tube I get ground rush about 5k if I'm looking at it, but I don't get it at all if I'm tracking, not that I notice anyway.

[slug 1]

Quote

Great graphical explination Thanks.

By the way I loved the sensation of groundrush but along came ZP

Hi ZEP

ZP no problem you want ground rush you can get it. Skydiver's aren't dumb they have invented a whole new type of "ground rush"

Open canopy at safe altitude (before old fart ground rush) fly around under a perfectly good canopy botch a high performance landing or do a panic turn to low to the ground and I think you got the new wave type of ground rush. Cypress won't do squat.

Anyone experience the new wave type of ground rush? What you think?

R.I.P.



I think that might qualify as ground rush

[DanglesOZQld 0]

Yeah 1,000 feet terminal is DEFINITELY a rush!!

I was *STUPID!!* enough to go there once chasing a student who had gone unstable on stage 4 AFF. You feel helpless when you cannot get to them but then feel like a complete tosser when you know that they have a cypres to save them and (in my case!) do not!!

The thing that got me most was the fact that your whole peripheral view is taken up by ground all of a sudden. It is like a weird and MASSIVE change visual wise and not one I will forget quickly. Fortunately I dumped with plenty of height to spare and have learnt from that one!!!

Most old timers I think would have a story or two about close calls but I think I have had more than enough to last me a long time to come!!

Some basic rules I live by are -
1) No matter how many jumps you have you NEVER EVER know everything, You should always strive to learn.

2) Be Self critical as much as possible but in a healthy way to learn more. IE- A jump funneled on exit / mid air collision with a team mate in a four way etc etc....how can I avoid this in future and what caused it in the first place??

If you THINK you were not in the wrong let the other person describe what they saw/felt/heard before saying anything and if it turns out that you were in the right don't be afraid of being humble and not just crapping on the person at fault.

SORRY!! Once again rambled on way too much!! ;)
-BSBD! -Mark.

"A Scar is just a Tattoo with a story!!!"

[j3zz 0]

New wave ground rush a thing or stupidity and beauty.

I have experienced it twice, and no I am not intentionally doing HP landing one was many years ago with about 60 jumps thought a nice fat hook turn would be cool, did it too high so did a front riser s-turns, had to dig so hard I landed hands first, and got away with it.

Second time was even more stupid, it was about 30 jumps ago, I thought I looked a bit low but decided i could carve a 180 front safely(should have flat turned based on sight picture) anyway that one I did not have to dig out but was lower than I am ready for,

Before anyone goes off on one, I am not intentionally doing HP landings yet and when I do start it will be with 90's not 180's. I just have a brain fart every now and again.

Jezz

"Now I know why the birds fly"
Hinton Skydivers

[Remster 30]

For me, the only time I experienced ground rush was at Empuria, while tracking over the town. Still was above 2K, but the visuals were awsome....

Remster

[Zep 0]

Quote

Quote

Great graphical explination Thanks.

By the way I loved the sensation of groundrush but along came ZP

Hi ZEP

ZP no problem you want ground rush you can get it. Skydiver's aren't dumb they have invented a whole new type of "ground rush"

Open canopy at safe altitude (before old fart ground rush) fly around under a perfectly good canopy botch a high performance landing or do a panic turn to low to the ground and I think you got the new wave type of ground rush. Cypress won't do squat.

Anyone experience the new wave type of ground rush? What you think?

R.I.P.



I think that might qualify as ground rush

I think ya fucking crazy

I'll go for the new wave GR the nexy time I'm up Under my Safire2 loaded at 1.6 I'll go for a 270 front riser at 400
If it works I'll let you know. If it dosen't ..................Arggggggg

Gone fishing

[slug 1]

Zep

>>I think that might qualify as ground rush

[skypuppy 1]

My ground rush occurs at around 1800 - 1600ft I can't ever remember taking it down to 1000ft
So with different people can it occur at different hights?
__________________________________________________

I don't think a lot of you people have really seen ground rush... I know I didn't understand it for the longest time... People said it was when you lose the horizon from your peripheral vision - when the ground fills your entire view - when it looks like you're falling into a bowl...

I got news for you. That's not Groundrush!!! Someone said it right when they explained it's about the changing angles, and the diagram is really cool to explain how it happens in a technical sort of way, but, in layman's terms, when you're really low at terminal, the ground looks like the surface of a pond after you've thrown a pebble into it - directly below you is the centre, and around it are concentric circles of waves radiating out rapidly from the centre, as if there was a weird wind blowing out 360 degrees from that one spot. I wouldn't have believed it if I hadn't seen it for myself....

You won't see this at 2000 feet, or even at 1000 feet. Maybe at 500 feet, definitely once you get below that having pulled every handle you got and waiting to see if something's going to open (at that moment you'll be sure it won't), you have nothing else to do but watch the ground....

After seeing it, you'll understand what groundrush is...

Most of the people that see it probably don't live to tell anyone elsewhat it is, and that's why so many people think it means the ground just starts to look big. Groundrush is not just fear or a feeling, it's an optical illusion caused by the rapid rate of descent in close proximity to the ground, and will never be mistaken for anything else once you've seen it.

I remember Mike Swain talked about trying to film groundrush in his book 'Endless Fall', but I think his camera malfunctioned and he didn't try it again. I wonder if anyone has ever managed to film it?

If some old guy can do it then obviously it can't be very extreme. Otherwise he'd already be dead.
Bruce McConkey 'I thought we were gonna die, and I couldn't think of anyone