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woodpecker

Terminal velocity

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First, I did a forum search on this topic and there are over 200 pages of posts.....and call me lazy but I am not going through each post. :)

How long does it take to hit terminal on a B.A.S.E. jump?
SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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First, I did a forum search on this topic and there are over 200 pages of posts.....and call me lazy but I am not going through each post. :)

How long does it take to hit terminal on a B.A.S.E. jump?



How long does it take to hit terminal when jumping from an airplane?
My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

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I thought of this too, but dont you hit terminal faster since you are exiting the aircraft at the same speed its flying. You not in dead air, so it would seem to me that you would take longer on a base jump to hit terminal then exiting an aircraft. And I could be wrong, just really curiouse.

Thanks in advance,
SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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I thought of this too, but dont you hit terminal faster since you are exiting the aircraft at the same speed its flying. You not in dead air, so it would seem to me that you would take longer on a base jump to hit terminal then exiting an aircraft. And I could be wrong, just really curiouse.



aircraft speed tends to be horizontal and is NOT a factor in standard terminal velocity (which is vertical).
DON'T PANIC
The lies in learning how to throw yourself at the ground and miss.
sloppy habits -> sloppy jumps -> injury or worse

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Typically it takes about 11 seconds to go the first 1000 feet either from an object or from an airplane so in that aspect they do compare.

The difference is you have horizontal speed when exiting an aircraft so there's relative wind on which to fly.

Hope that helps
My grammar sometimes resembles that of magnetic refrigerator poetry... Ghetto

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I actually didnt know that either (shocking huh). But without all the variables, what is an average time?

Lets make it easy, If I was to jump the balloon at WFFC with a base rig (sorry couln't resist) from 5000ft, how long would it take to hit terminal.
SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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that explains it purfectly and thanks hookit. Wasnt thinking of the speed from an aircraft as horizontal, but now I got it.

thanks again.
SONIC WOODY #146

There is a fine line between cockiness and confidence -- which side of the line are you on?

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I actually didnt know that either (shocking huh). But without all the variables, what is an average time?

Lets make it easy, If I was to jump the balloon at WFFC with a base rig (sorry couln't resist) from 5000ft, how long would it take to hit terminal.



well odds are the bas rig would be reserve free, so ya would be lighter.....

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would depend on the height of the cliff

surely if it was 4000 feet it would technically be faster then a 1200 foot cliff

due to the thicker air




Are you basing that on experience jumping big cliffs at various altitudes?

I haven't noticed an appreciable difference from similar sized (terminal) cliffs with landing areas at sea level and 4000' above sea level.

I'm curious if your experience has been different.
-- Tom Aiello

Tom@SnakeRiverBASE.com
SnakeRiverBASE.com

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Are you basing that on experience jumping big cliffs at various altitudes?

I haven't noticed an appreciable difference from similar sized (terminal) cliffs with landing areas at sea level and 4000' above sea level.

I'm curious if your experience has been different.



Tom you know my experience.
if it was like 1 billionth of a second later it would still be a difference.

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What if you were to consider the difference between summer and winter air? Based on the knowledge that hot air is less dense and more energetic and colder air is more dense and less energetic, you can hypothesize that in the winter you would have a slower, albeit minor, terminal velocity.
Leroy


..I knew I was an unwanted baby when I saw my bath toys were a toaster and a radio...

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dude.
i have explained this before in the sliderup skydiverig helicopter question forum

1-horizontal and verticle velocity decays and increases independantly of eachother.
2-weight is NOT a factor in acceleration from gravity. it IS however a factor in actual terrminal speed. did anybody else pay attention in HS physics?
3-this question has no value other than personal curiosity, because the times it takes different eople to get to terminal has far to many variables to give the true answer. ( falling object shape/shape shifting/falling object density/ air density/humididty variables/ wind/ empty or full lungs/ etc)

but, you did specify the averager time to get to trerminal.

so....
about 8-12 seconds,

remember, skydivers LOVE to attach definates to different questions and values. because, in all reality, they like to believe that skydiving is a science and really totaly safe. BASE jumpers dont think like that. in my theory, the time to reach terminal out of an aircraft traveling at 70tas, is a lot harder to figure even a ballpark acceleration time than off a tower.

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2-weight is NOT a factor in acceleration from gravity. it IS however a factor in actual terrminal speed. did anybody else pay attention in HS physics? .



I would have thought something heavier with a smaller surface area would reach terminal slightly faster then something of the same size and lighter.

why is this not so ?

if I drop a shot-put and a tennis ball from 10ft the shot-put hits the ground first.

even if one only got in front by 1ft at the start it would still be that 1 ft a head.
or would the heavier item have a higher speed of terminal veloicity and take longer to get there as it has to go higher faster then the lighter object of eqaul mass ?

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Where is yuri base when you need him.
I'm sure he will explain it and proof it with help of mathematical explanation of the phisical laws...
For myself it is not that important if it takes a second longer to reach terminal or not. When I jump I loose my feeling for time.
On a terminal jump you jump, then first it seems that you don't fall at all, then it gets faster and louder and after some time the ground gets to grow bigger very fast and then you pull. I have no idea (and I don't care) after how many seconds the stages are.
Michi (#1068)
hsbc/gba/sba
www.swissbaseassociation.ch
www.michibase.ch

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3-this question has no value other than personal curiosity...



I'll take that one step further and point out that, if we were being at all pedantic about it, there's no magic time when an object "reaches" terminal velocity, but just a range of times in which most reasonable people would agree that it's "pretty much there". So the whole thing is pretty wishy-washy from the start.

There are three ways to increase terminal velocity without changing the thing that's doing the falling -- you can increase temperature, increase humidity, or increase altitude. I've attached a graph of velocity vs. time for standard conditions and a few variations ("M lower" is equivalent to increased humidity) for a jumper with a pretty normal terminal velocity.

You can draw your own conclusions. To my eye, everything but the drop from 5000 m pretty much reaches its terminal velocity in 10-12 seconds. Even the high drop seems pretty near terminal at 12-13 seconds.

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My BASE rig is around 18 pounds. My skydiving rig is about 16.


i did think if it were a 2 canopy system you were jumping off them objects:D:P

18 pounds?
your sure??
I mean your arround 15 pounds right?:P:ph34r:

Stay safe
Stefan Faber

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2-weight is NOT a factor in acceleration from gravity. it IS however a factor in actual terrminal speed. did anybody else pay attention in HS physics? .



I would have thought something heavier with a smaller surface area would reach terminal slightly faster then something of the same size and lighter.

why is this not so ?



acceleration due to gravity is a constant, period.

in High School physics, they like the phrase "neglecting the effects of air." thus, a feather and a sandbag will fall at the same speed, in a vacuum. it explains gravity quite well and explains motion in space.

unfortunately, if the air has NO effect, there is NO aerodynamics and aircraft can't fly.

the air creates a force that fights gravity and changes acceleration patterns. roughly, much depends on the ratio of surface area to weight. compare the surface area/weight ratio of a feather to a sandbag...

people have correctly mentioned pressure, temperature, humidity, etc. as things affecting terminal velocity. I personally think the shape YOU present to the wind will can have a greater impact.
DON'T PANIC
The lies in learning how to throw yourself at the ground and miss.
sloppy habits -> sloppy jumps -> injury or worse

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> How long does it take to hit terminal on a B.A.S.E. jump?
——————————————————————————————
Confirming everything that has been already said by the other folks, I can say the following:
You reach terminal velocity in a BASE jump exactly after the same time as in a skydive as well as in a balloon jump, which is:
1) theoritically: NEVER (you approach terminal velocity in an infinite time)
2) actually: estimating a terminal velocity of 54.402 m/s - 178.484 ft/s, you reach terminal velocity after 12" and 448 m - 1469 ft (conventionally, you CLAIM to have reached terminal velocity after a time when your actual speed is about 97÷98% of your ACTUAL terminal velocity (=determined by instruments when skydiving))
But why do you need to determine the time when you reach terminal velocity with ALL this accuracy?!?!?!?!? B|
After 10" you are already going down pretty fast indeed (= 51.578 m/s - 169.219 ft/s after having fallen down 343 m - 1126 ft), as well as after 8" (48.680 m/s - 159.711 ft/s and 242 m - 796 ft).
Stay safe out there
Blue Skies and Soft Walls
BASE #689 - base_689AT_NO_123_SPAMyahoo.com

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acceleration due to gravity is a constant, period.



Very false. Gravity at sea level is different than gravity at the top of Mt. Everest.

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it explains gravity quite well



Not even Witten himself would make such a bold statement and he is probably the one who at this point in time has the greatest understand of gravity.

NOBODY understands fully what gravity really is hence the total lack of its control.

We are able to "produce" all the other three forces but we have no clue, well some, how to produce gravity.

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unfortunately, if the air has NO effect, there is NO aerodynamics and aircraft can't fly



So how in the hell we sent stuff in space and men on the moon? There is a difference between external and internal aerodynamics.

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the air creates a force that fights gravity and changes acceleration patterns. roughly, much depends on the ratio of surface area to weight. compare the surface area/weight ratio of a feather to a sandbag...



Do you mean an object using air as a medium?
Memento Audere Semper

903

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As a professional physicist, I can tell you that every law or theory of physics has a realm of validity. There will always be more sophisticated and more detailed ways of describing physical natural behavior. Edward Witten's work on string theory etc. is truly irrelevant here. What Hookitt says above is all that really matters in the BASE environment that a majority of us play in, so please ignore the arguing of semantics and hidden variables and irrelevant string quantum theories brought up by some. I do not have experimental data on terminal, but my soon-to-be completed device will provide data, allowing me to test it under a variety of different temperature, humidity, body positions, etc. Therefore, true variations in distances and speeds due to different conditions will soon be available for all to enjoy.
Looks like a death sandwich without the bread - Steve Deadman Morrell, BASE 174

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