Terminal Height??

[guest]

I was wondering, when it comes to cliff jumping, what is the maximum height which will not kill a person? In other words, how heigh does the jump have to be before the water "becomes concrete"?

-Jesse P.

[BASE359]

I heard somewhere years ago, that the highest anyone had "INTENTIONALLY*" jumped/dove into water without sustaining injury, was 125 feet. I think that is probably about right and would prefer not to hear from the guys who "remember when" while in high school, they used to jump into/off of, the quarry, RR bridge or what have you, that was "at least 200 feet high." Sorry, didn't happen.
Acapulco cliff divers? In the range of 60 to 90 feet.
Butch Cassidy and the Sundance Kid? Watch it again.
I went face first through a Para Commander in 1975, after having been in a no-lift dive for about 10 seconds. I was wearing a motorcycle helmet and still lost 6 teeth and my right eye socket. Not to mention a cracked skull, broken nose, broken jaw and surgery which left several very nasty scars on my otherwise very handsome face. My point? Even a fluffy parachute can hurt you pretty bad at a buck sixty.
Water? A whole lot more dense, therefore...

BASE359

* On purpose. Didn't fall or wasn't pushed.

[feral]

Someone work out the height of the walman falls jump that dwain did took in at line stretch the speed he was travelling and then the speed you would reach off different heights he lived with some brain damage some say 100kmph 60mph to much thinking I'm going to sleep pass the needle and the smack

[petterekman]

Well, if you would search the internet, you would eventually come up with a man named Harry Arias Froboess. But, since I'm a kind person, let me tell you a little about Harry.

Harry was a german stuntman, born 1899. From being an infant, his mother taught him to be a "jumping fish" and his father taught him gymnastics. This gave him all the skill he needed to become something out of the ordinary!

In 1918 Harry broke the world record in high diving, by diving (head first) from 75 meters! Which, for you english people (divide 75 with 0.305) is 245.9 ft!




And as if that wasn't enough for dear Harry, on June 22 1936, he jumps (not quite sure if he just jumped or dove...) from 110 meters! Now, that is 360.7 ft!

would prefer not to hear from the guys who "remember when" while in high school, they used to jump into/off of, the quarry, RR bridge or what have you, that was "at least 200 feet high." Sorry, didn't happen.

Now, dear BASE359, you see, since this is in the Guinness Book Of World Records, it DID in fact happen. And seeing that 360 feet is quite alot higher than your "at least 200 feet high", I feel like having the right to say: You're wrong.

Now, my thoughts on this matter are:
-This record has stood solid for nearly 70 years now, do any of you think it will be beaten?
-How long does this fall take? Assuming that he is in an upright position, with very little air-resistance, how fast will he be travelling? What are the forces on impact?
I've been very interested about this world-record jump since I was a kid and first read about it, and also being an experienced cliff-jumper myself, it would be pretty cool to find out the answers to my second question. Could anyone contribute?

Well, that's about all I had to say, so cheers!

[Tom Aiello]

You realize you've dredged up a 3 year old thread, right?

[petterekman]

Well, after I posted I realised it... But I don't really see any harm in it, do you?

And also, by posting in this thread, you contribute to keeping it alive...

[wolfman]

Hi there,

great to get these informations about the highdiving record! Thanks!

BTW: You might be interested in other records of cliff-diving (Sport):

High-Diving and Cliff-Diving records

Highest Dive Women
In 1985, the American Lucy Wardle dove at Ocean Park in Hongkong from 120ft / 36.80 meters.

Highest Dive Men
In 1987, the Swiss Oliver Favre performed a double back somersault from 177ft / 53.90 meters in Villers-le-Lac, France (see www.olivershow.com)

Most spectacular Dive
In 1998, the Swiss athlete and WHDF foundation member Frederic Weill performed from a helicopter an armstand double somersault pike with split and head first entry into Lake Verbano, Italy from 86 ft / 26 meters. pictures see whdf photo gallery

Highest scored Dive
In 2000, during the WHDF Cliff-Diving World Championships in Kaunolu, Hawaii, the Colombian Orlando Duque performed a double back sommersault with 4 twists from 80 ft / 24.40 meters. For this dive he earned a perfect 10 from all seven judges and scored 159.00 points. short video see whdf video section

from www.whdf.com

@Jesse P.: The Water will become very dangerous for your Health over 20 meter, unless youre are not very well trained in Platform Diving. Below 20 Meters Feetfirst entries won´t kill you (uhmm well,anything is possible).
The Problem is, that your fallingspeed will be extremely stopped by entering the water. On every HighDive you wont get much deeper than 4 metres, but the deceleration will increase with every meter you go higher.

[justfyi]

In 1918 Harry broke the world record in high diving, by diving (head first) from 75 meters! Which, for you english people (divide 75 with 0.305) is 245.9 ft!




And as if that wasn't enough for dear Harry, on June 22 1936, he jumps (not quite sure if he just jumped or dove...) from 110 meters! Now, that is 360.7 ft!




Now, my thoughts on this matter are:
-This record has stood solid for nearly 70 years now, do any of you think it will be beaten?
-How long does this fall take? Assuming that he is in an upright position, with very little air-resistance, how fast will he be travelling? What are the forces on impact?

Acceleration due to gravity on earth without any air resistance equals 9.8m/s/s or 32ft/s/s. if there is higher humidity, the air will be more dense, resulting in more friction which reduces the nominal rate of acceleration. For simplicity, assume that Harry jumped at sea level with low relative humidity. The idiot's guide to physics of acceleration and speed gives us this tool to calculate speed and distance and time, since 9.8 is pretty close to 10:

10+20+30+40 = 100m/s after 4 seconds of freefall

an 8 second freefall would equal the following distance:
10+20+30+40+50+60+70+80 = 360 meters

The speed a person would be traveling at the end of a 450 meter jump would equal 90m/s

The conversions between metrics and ft and miles are as follows:

10m/s/s = 32ft/s/s
100ft/s = 68mph
10m/s = 36km/h

[Tom Aiello]

The speed a person would be traveling at the end of a 450 meter jump would equal 90m/s

I think that may be oversimplifying.

A human body falling in air has multiple forces acting on it.

The acceleration due to gravity is slowed by air resistance. The air resistance is determined by a combination of factors including air density, density of the falling body, shape of the falling body, position and stability of the falling body, etc, etc, etc.

These systems are so complex that even university researchers using supercomputers can only approximate solutions.

[Cosmos]

Well, if you would search the internet, you would eventually come up with a man named Harry Arias Froboess. But, since I'm a kind person, let me tell you a little about Harry.

Harry was a german stuntman, born 1899. From being an infant, his mother taught him to be a "jumping fish" and his father taught him gymnastics. This gave him all the skill he needed to become something out of the ordinary!

In 1918 Harry broke the world record in high diving, by diving (head first) from 75 meters! Which, for you english people (divide 75 with 0.305) is 245.9 ft!



And as if that wasn't enough for dear Harry, on June 22 1936, he jumps (not quite sure if he just jumped or dove...) from 110 meters! Now, that is 360.7 ft!




Now, dear BASE359, you see, since this is in the Guinness Book Of World Records, it DID in fact happen. And seeing that 360 feet is quite alot higher than your "at least 200 feet high", I feel like having the right to say: You're wrong.

Now, my thoughts on this matter are:
-This record has stood solid for nearly 70 years now, do any of you think it will be beaten?

Harry Arias Froboess was an amazing person. He was perhaps the best stuntman that ever lived. Anyone who could accomplish the same would shock the world.

-How long does this fall take? Assuming that he is in an upright position, with very little air-resistance, how fast will he be travelling? What are the forces on impact?
I've been very interested about this world-record jump since I was a kid and first read about it, and also being an experienced cliff-jumper myself, it would be pretty cool to find out the answers to my second question. Could anyone contribute?

Well, that's about all I had to say, so cheers!

I'll do my best.


Assumptions:

• Height of Harry Arias Froboess: 1.77800m (5' 10")
• Weight of Harry Arias Froboess: 80kg (176lbs)
• Surface Area of Harry Arias Froboess: 1.99362713 m^2 (A = 0.204 * H^0.725 * m^0.425) where A...surface area [m^2], H...height [m], m...mass [kg]
• Drag Coefficient (rough estimate): 1.0 (man in typical upright position = 1.0-1.3 / streamlined man on bicycle = 0.9)

• Fall Distance: 110 meters
• Release Height: 110 meters
• Density of Air: .075 (lbs/ft^3)
(Density of Air assumes a temperature of 15°C (59°F) and a density of .07608 lbs per cubic foot at sea level)



Results:

With these assumptions, Harry Arias Froboess hit the water at 25.17m/s (56.30 mph) and survived.
He took about 6.1 seconds to fall and had a slowdown factor of 1.28259.


Note: These results vary greatly depending on what degree of Drag Coefficient is assumed.
With the current assumed drag coefficient, Harry has nearly reached his terminal velocity by the end of his fall.

So I decided to play around with the drag coefficient.
Many writers peg a skydiver's typical terminal velocity around 55m/s (123mph) - under conditions where there is no attempt at streamlining the diver's body shape or angle of attack.
So I decided to drop Harry from 10,000 feet.
Keeping all other assumptions the same (except density of air which I dropped to .055 to correct for altitude), I located a drag coefficient that would result in a 55m/s terminal velocity for Harry.
The result was 0.35 (somewhere between a bullet 0.295, and a sphere 0.47)


Using this new drag coefficient (Harry the bullet) with all the other original assumptions (including .075 air density) I again dropped Harry from 110 meters.
This time Harry Arias Froboess hit the water at 35.82m/s (80.13 mph) and survived.
He took about 5.2 seconds to fall and had a slowdown factor of 1.0977.
In this case he would not be reaching terminal velocity for another 6.5 seconds.

Images and Equations:






Summary:

Ultimately drag, air density, air temperature, body shape, and body position are not constant during the fall / dive. Also we are not certain of Harry's exact height and weight.
Nonetheless, the inaccuracies in the majority of the variables (surface area, air density, etc..) appear to be too small to have any significant impact on the result relative to the most significant unknown: Drag.

***********************************************
Assuming Harry fell as something between a "typical stiff upright human shaped robot" and a "semi-spherical bullet" he would have taken between 5.2 and 6.1 seconds to reach the water.
He would have hit at a velocity of between 25 and 35 meters per second (56-80mph).
In neither case would he have reached terminal velocity.
************************************************** **********

To answer the original post question, there is no specific "terminal height." Not only does survival depend on the diver and the conditions during the descent, but also water conditions and the manner of entry.

Cheers.

Sources:

Surface area of the human body: What is the skins surface area of an average human being? | Answerbag
Drag Coefficient Examples: Drag coefficient - Wikipedia, the free encyclopedia
Density of Air: Aeronautical Engineering and Airplane Design - By Alexander Klemin, Thomas Henri Huff - Chapter 2 - page 23
Aeronautical engineering and ... - Google Book Search
Also: WikiAnswers - How much does a cubic foot of air weigh in pounds
Skydiver Terminal Velocity: http://hypertextbook.com/facts/JianHuang.shtml

[Johnny Utah]

Well, if you would search the internet, you would eventually come up with a man named Harry Arias Froboess. But, since I'm a kind person, let me tell you a little about Harry.

Harry was a german stuntman, born 1899. From being an infant, his mother taught him to be a "jumping fish" and his father taught him gymnastics. This gave him all the skill he needed to become something out of the ordinary!

In 1918 Harry broke the world record in high diving, by diving (head first) from 75 meters! Which, for you english people (divide 75 with 0.305) is 245.9 ft!




And as if that wasn't enough for dear Harry, on June 22 1936, he jumps (not quite sure if he just jumped or dove...) from 110 meters! Now, that is 360.7 ft!

amazing!
seems unbreakable... but who knows

if there is higher humidity, the air will be more dense, resulting in more friction which reduces the nominal rate of acceleration.

I realize this is an old thread.....
but as a pilot I need to disagree with this point.

one of the basics is:
as humidity increases, air density decreases and density altitude increases (assuming temp and pressure remaining the same).

moisture in the air weighs less than the same volume of dry air and therefore if there is higher humidity the air will be less dense.

every pilot should know this:
high, hot , and humid = high density altitude (which means less dense air... which affects the performance of an airfoil...longer takeoff rolls, slower climb rate, etc)

[Flying_Mike_D]

Johnny nailed it, but what do I know. I just fly airplanes for a living.

Think of it this way...humid air takes up more space. The water molecules push air molecules out of the way making the air less dense. Don't believe it? Go for a run in a desert area then go run in a humid climate at the same altitude and the same temp as the desert and tell me which climate makes your cardiovascular system work harder.