
Unplanned Freefall? Some Survival Tips (2001) - Tomte
http://www.greenharbor.com/fffolder/carkeet.html
======
oska
> You will want a tall tree with an excurrent growth pattern—a single,
> undivided trunk with lateral branches, delicate on top and thicker as you
> cascade downward.

I had not encountered the word _excurrent_ before. They provide a bit of a
definition directly after using it but I was still curious so looked it up.
Turns out it is a general botanical term but when used in the context of tree
shapes (specifically the crown) it contrasts with _decurrent_. I found this
image [1] which illustrates the different shapes of excurrent vs decurrent
trees.

[1] [http://countrysidelandscape.net/files/2018/10/Branch-
pattern...](http://countrysidelandscape.net/files/2018/10/Branch-patterns.jpg)

~~~
efiecho
And to all of you who will soon stumple upon _excurrent_ again, maybe multiple
times, even though you have never heard about it until now. This is called
_Baader-Meinhof Phenomenon_.

~~~
DeRock
To lay down another level of irony, I just learned about Baader-Meinhof
phenomenon an hour ago while watching Stranger Things S03E02. I am now
prepared to read about this all over the place.

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bscphil
I think there's (at least) one important factor this leaves out. Drag doesn't
care what direction you're moving: it will slow you to about 120 mph
regardless of whether you're going straight down or at an angle.

This implies that you want to control your horizontal velocity _not_ just to
decide where you land, but also to build up as much horizontal velocity as
possible. If you can get yourself going at a moderate angle, you can
significantly _decrease_ your vertical velocity, which is by far the most
dangerous part of a freefall!

The most important thing about approaching at an angle is not to tumble. This
strategy would work best if you could slide down or along a loose surface like
snow or small gravel, ideally down a hill. This basic strategy is why high
speed skiers (who are moving _at least_ 120 mph) can survive crashes.

~~~
RSZC
Hmmm...former skydiver here, not sure your point is accurate. I don't
understand why increasing your forward momentum from tracking would decrease
your fall rate.

I think your assumption that drag will slow you to 120mph is inaccurate - for
example, if you fall heads-down your terminal velocity is instead up to
~180mph. Similarly, I'd expect that if you track in a direction your velocity
could increase above 120mph while not lowering the speed at which you approach
the ground.

Apologies - my physics knowledge and terminology is very limited, but do have
some practical experience in the area :)

~~~
nkoren
The trick is that while you can't actually decrease the total amount of energy
in your fall, you can get some of that energy to work in your favour.

Think about when you flare a parachute, shortly before landing. What you're
doing is trading forward momentum for vertical lift, softening your landing.
The more forward momentum you have prior to a flare, the more lift you can get
out of it. This is why you see experienced / foolhardy skydivers doing "hook
turns" to maximise their forward velocity immediately before landing.

(Of course if you just stayed in the flare position continously, you'd have no
forward momentum to trade, and would therefore lose lift entirely, producing
the opposite of the intended effect.)

Anyhow, yeah, I doubt that tracking alone would help with survivability. My
hunch is that you'd be trading 10mph of vertical momentum for about 40mph of
horizontal momentum. Doesn't sound like a good trade. Although maybe -- just
_maybe_ \-- you could execute a "body flare", whereby you kick your legs
forward at exactly the right moment, to kill that forward momentum and trade
it for lift. That might actually work (a bit)! But it sounds like an
extraordinarily difficult manouevre. You'd certainly never get it right on the
first try. Which of course is as many tries as you'll ever get.

------
Someone
_”Look around for a proportionate personal vehicle—some large, flat,
aerodynamically suitable piece of wreckage.”_

Problem: by the time you have dropped from 35,000 to 15,000 feet, such parts
will be thousands of feet above you, way out of reach

⇒ if there are such parts, you’ll have to find them before you lose
consciousness. Alternatively, you’ll have to construct them (rapidly so) from
parts that drop about as fast as you do (could be as easy as opening a
suitcase that’s dropping at your speed, if you’re very, very lucky)

------
dang
Thread from 2017:
[https://news.ycombinator.com/item?id=13839177](https://news.ycombinator.com/item?id=13839177)

------
paulintrognon
Reminds me of that youtube video:
[https://www.youtube.com/watch?v=dy5xLVx2NGY](https://www.youtube.com/watch?v=dy5xLVx2NGY)

~~~
Joakal
There's another video (The Only Way to Survive a Fall Without a Parachute -
Bright Side):
[https://www.youtube.com/watch?v=p5SGdWWu0sI](https://www.youtube.com/watch?v=p5SGdWWu0sI)

Some facts about falling:

\- You don't have oxygen until 6 miles / 10 km left to fall.

\- You have 3 minutes.

\- Some people have survived falling from planes. Most don't. 100% of people
who don't fly never encounter this issue.

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sunnyP
What happens if you are over water? Can you get some horizontal speed and try
to skip across the water?

~~~
NateEag
You hit the water at terminal velocity. Since water is effectively
uncompressible, this is much like hitting concrete, I've read. You are either
instantly killed or knocked out, in which case you slip underwater and drown.

I suppose hypothetically your best bet over water would be vertical entry, as
opposed to the spread-eagle recommended for a land impact, but at the speeds
you'll be going I imagine you're pretty much doomed regardless - even if the
impact doesn't shatter you, I believe water rushes into your internal organs
through your anus and causes massive damage. I've seen that referenced as a
risk for bridge jumps and this is, obviously, as bad a water jump as you can
make. I also imagine you'd go deep enough that you couldn't possibly float
back up to the surface before drowning, and I imagine the impact and pressure
of increasing depth would force all the air from your lungs anyway.

Disclaimer: I am not an expert in any relevant field. I may well have some
facts wrong. Just speculating based on what little I know.

~~~
spqr0a1
By conservation of momentum you won't go much deeper than diving from tamer
heights. Still plenty of other trouble to deal with.

[https://en.wikipedia.org/wiki/Impact_depth](https://en.wikipedia.org/wiki/Impact_depth)

~~~
NateEag
Ah, makes sense. Thanks for the info!

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aptwebapps
So if you immediately went into a face first dive with your mouth wide open,
could you catch enough air to stay conscious?

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stretchwithme
Have thought about this too. I guess a lot of people have, considering how
many people dream about falling.

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pontifier
Any chance you could use the clothes you are (probably) wearing to slow
yourself down?

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andrewstuart
It's so bizarre but I actually want to know this.

You know, just in case.

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mitchtbaum
PaaS

