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in2jumping

Re: [The111] Fatality - Tampa Bay, FL - 20 Jan 2010

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Right. But through the airmass, the canopy will fly exactly the same.

No matter how the airmass is moving (as long as the movement is steady).
"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

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I don't know why people keep comparing apples to oranges.

When you ride around in an airplane, it is a big fixed object.



Here is something for you to consider that might help you understand.

Imagine a GIANT airplane flying through the sky. I mean huge. Like 100 miles tall and 100 miles wide. Heck, it's just a giant flying cube made of a thick metal shell. And inside the cube, it's empty. Well, not quite empty. It's full of air. Now, the cube is moving above the ground at 50mph from east to west. All the air inside of the cube is perfectly still, just like the air inside an airplane, right? Since that's all the cube is, is a big airplane. Now, all of a sudden, magically, the cube disappears, only everything that was inside it is still there, and is still moving at 50mph from east to west, like the cube was. What would you call that giant block of air moving through the sky with no metal shell around it? You'd call it WIND.

Now, if there was a canopy flying around inside the giant metal cube (since there is a lot of space inside there, it's so big)... when the cube disappeared, would the canopy pilot even know? The walls of the cube were mile and miles away before they disappeared! Now, when the walls still existed, he was flying in non-moving air, right? But all of a sudden the walls disappeared, and now he is flying in moving air? Wrong. Everything is always in motion, and he was always flying in moving air. Whether there are metal walls around you in close proximity (airplane body) or far away (magic metal cube), the air is still moving.

When you are flying your canopy on a "no wind" day, you're flying in moving air. Because the whole damn earth is moving. It's rotating about its own axis and orbiting the sun.

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When you fly around under a canopy, you can move independently. If a canopy stops quickly, the person can move forward of it, or to the side.

A canopy can turn much faster than the body underneath
it. Easily illustrated with line twists. The canopy reacts faster than the body underneath it.



Everything you have said above is true. But it is equally true on a no wind day as it is on a 50mph wind day. It's true if you're flying your canopy inside of a giant metal cube which is moving over the ground, both before and after that cube magically disappears.

The reference frame you keep repeating is that of someone tied to the ground while kiting a canopy.
www.WingsuitPhotos.com

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>They are not one solid unit with one flow through the air like an airplane.

Right. Perhaps they are more like a helicopter, with the (rotary) wing affixed much more loosely to the fuselage, with many more degrees of freedom. Or perhaps they are more like an airship, with a rigid gondola attached to the envelope via lines and fittings. Or perhaps more like a hangglider, with a pilot/harness suspended beneath a semi-rigid wing.

In all four cases, the theory is exactly the same. All four care about their motion relative to the air around them. They do not care about what the ground is doing relative to them (until, of course, they arrive back at the ground.)

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Because the whole damn earth is moving. It's rotating about its own axis and orbiting the sun.



Easy there, it's not the whole "damn" earth. This is just a discussion.

The rotation of the Earth affects LARGE masses like
the air stream.

Snopes - Coriolis Effect

A lot of science sleuth/barhounds believe that it
affects small things like the way your water spins in the sink drains (or canopies). Not true.
It only affects big things like, say, cyclones.

I hope that helps you understand.

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Can you tell which way the wind is blowing, or how strong the wind is blowing, under canopy with your eyes closed?

If so, please explain how.




Everyone knows that grazing cows always face into the wind.


So if you throw a cow out on jump-run you can easily tell...if you plan on jumping with your eyes closed, it's best to ride the cow down. :)



Ask a technical question...get a technical answer~;)










~ If you choke a Smurf, what color does it turn? ~

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Right. But through the airmass, the canopy will fly exactly the same.

No matter how the airmass is moving (as long as the movement is steady).



Absolutely correct.

However, when making our toggle inputs on turning from downwind to base to final, we generally are making our flightpath decisions based on the ground that we can see, not on the airmass that we can't see.
...

The only sure way to survive a canopy collision is not to have one.

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Can you tell which way the wind is blowing, or how strong the wind is blowing, under canopy with your eyes closed?

If so, please explain how.




Everyone knows that grazing cows always face into the wind.


So if you throw a cow out on jump-run you can easily tell...if you plan on jumping with your eyes closed, it's best to ride the cow down. :)



Ask a technical question...get a technical answer~;)



The cows also helped with the problem of chapped lips.

Before boarding the a/c, lift up the cows tail and give
it a big kiss on the ass.


It doesn't heal chapped lips, but it will certainly keep
you from licking them.
:)

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Can you tell which way the wind is blowing, or how strong the wind is blowing, under canopy with your eyes closed?

If so, please explain how.



Magical canopy faeries tell me which way the wind blows.



I have noticed that in a strong, constant wind - my speed relative to the ground varies.
If my ground speed varies while the wind speed is
constant, then I must be changing speed inside the
airmass also.

Example - on a long spot, with the wind to my back -
I spread out my arms and get big so that I catch as
much air as I can. I make my suit act like a sail.

The air has a higher ground speed than I do,
so it moves around me. If I block it, it gives me an
extra push.

I think everybody will admit to having done this because they understand how it works.

Also, the air seems to have different drag on my body and my canopy. Shape, weight, material, profile.

Obviously, this works in a vertical column of air, so it
also works as we move through a horizontal one.
Simple concept.

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I don't know why people keep comparing apples to oranges.

When you ride around in an airplane, it is a big fixed object.



Here is something for you to consider that might help you understand.



:D:D:D
You think he doesn't understand that.
:D:D:D

Again...you're arguing a different point than what was presented to you. Hence, the apples/oranges.
My reality and yours are quite different.
I think we're all Bozos on this bus.
Falcon5232, SCS8170, SCSA353, POPS9398, DS239

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>my speed relative to the ground varies.

Correct. It also varies relative to other canopies, the center of the earth, the speed of the water in the river you are over etc.

>If my ground speed varies while the wind speed is
>constant, then I must be changing speed inside the
>airmass also.

Incorrect. You AND the airmass may be slowing down (for example, the winds are decreasing as you descend.)

>Example - on a long spot, with the wind to my back -
>I spread out my arms and get big so that I catch as
>much air as I can. I make my suit act like a sail.

You can indeed. And that increases your drag, which changes your glide angle. Result - you may not make it back.

A jumper who wished to make it back might wisely loosen his chest strap, and ball up a bit. This will (slightly) decrease his drag. He might also go to half brakes. This will increase the lift he generates. Both of these, done together, will flatten your glide and allow you to make it back.

Half brakes will have another effect. Since going to half brakes decreases your descent rate, you will be in the air for a longer time, and thus will cover more ground (since the wind is helping you cover more ground the longer you are in the air.)

>The air has a higher ground speed than I do,
>so it moves around me.

If you really believe that the relative wind comes from behind you when you are flying with the wind - I recommend you take a wind indicator on your next jump and prove to yourself that that is incorrect. A pullup cord will suffice.

>If I block it, it gives me an extra push.

It does indeed, and it pushes you in the same direction drag always pushes you - backwards (i.e. in a direction opposite your motion.)

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I don't know why people keep comparing apples to oranges.

When you ride around in an airplane, it is a big fixed object.



Here is something for you to consider that might help you understand.



:D:D:D
You think he doesn't understand that.
:D:D:D



I know he doesn't understand it. He called an airplane in flight a "fixed object." Do you think that is true? If that were true, all skydivers would be BASE jumpers. He also perceives a canopy in flight as a fixed object, fueling his belief he can somehow get "pushed" from behind when flying downwind.

We spend a lot of time on these forums encouraging new jumpers to listen to the more experienced regarding things like downsizing, swooping, etc, and we get frustrated when they don't, citing their own fallacious reasoning for why the rules don't apply to them.

Those of us who have spent most of our lives studying physics and aerodynamics get similarly frustrated when someone cites anecdotal perceptions/observations as proof that the most basic rules of relative motion are invalid.

I applaud Bill for being more patient than me in his responses/explanations. I should probably duck out before I lose any more sanity.
www.WingsuitPhotos.com

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Example - on a long spot, with the wind to my back -
I spread out my arms and get big so that I catch as
much air as I can. I make my suit act like a sail.

The air has a higher ground speed than I do,
so it moves around me. If I block it, it gives me an
extra push.




This is as wrong as wrong gets. Combined with the other comments you have made in this post, I'm hoping that you have been pulling everyone's chain, and you know that what you are saying is incorrect.

If you honestly believe the things you are posting, I would urge you to take some sort of basic aerodynamics class, or a canopy control class. Your ideas about how things work up there are incorrect, and it would benefit you greatly to be operating with a correct set of ideas. No joke.

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Example - on a long spot, with the wind to my back -
I spread out my arms and get big so that I catch as
much air as I can. I make my suit act like a sail.

The air has a higher ground speed than I do,
so it moves around me. If I block it, it gives me an
extra push.



Absolutely wrong. Incredibly, unbelievably wrong.

When running with the wind you have a higher groundspeed than the airmass, because your groundspeed is your horizontal airspeed plus the windspeed.

Think about it this way - the air inlets of your canopy are at the front. If you're catching air with your back, how the hell is your canopy staying inflated?

Try it - blow some air at the back of your canopy and see what happens:S
Do you want to have an ideagasm?

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Can you tell which way the wind is blowing, or how strong the wind is blowing, under canopy with your eyes closed?

If so, please explain how.



Magical canopy faeries tell me which way the wind blows.



You've been doing hop & pops with Dead Bryan again.
Every fight is a food fight if you're a cannibal

Goodness is something to be chosen. When a man cannot choose, he ceases to be a man. - Anthony Burgess

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:D:D:D
You think he doesn't understand that.



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I know he doesn't understand it...

We spend a lot of time on these forums encouraging new jumpers to listen to the more experienced regarding things like downsizing, swooping, etc, and we get frustrated when they don't, citing their own fallacious reasoning for why the rules don't apply to them.

Those of us who have spent most of our lives studying physics and aerodynamics get similarly frustrated when someone cites anecdotal perceptions/observations as proof that the most basic rules of relative motion are invalid.

I applaud Bill for being more patient than me in his responses/explanations. I should probably duck out before I lose any more sanity.



I think you're all just being had and HappyThumpkin is laughing everytime you get trolled.

His next post? "If you get a big enough canopy, you'll actually gain altitude."
Every fight is a food fight if you're a cannibal

Goodness is something to be chosen. When a man cannot choose, he ceases to be a man. - Anthony Burgess

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Can you tell which way the wind is blowing, or how strong the wind is blowing, under canopy with your eyes closed?

If so, please explain how.



Magical canopy faeries tell me which way the wind blows.



I have noticed that in a strong, constant wind - my speed relative to the ground varies. If my ground speed varies while the wind speed is
constant, then I must be changing speed inside the
airmass also.

Example - on a long spot, with the wind to my back -
I spread out my arms and get big so that I catch as
much air as I can. I make my suit act like a sail.

The air has a higher ground speed than I do,
so it moves around me. If I block it, it gives me an
extra push.

I think everybody will admit to having done this because they understand how it works.

Simple concept.



Y'know, I've really been mulling this over and I've had a change of heart - I think HappyCamper's actually on the right track here... this could work!

Consider this: You're in the cabin of an aircraft flying 500kts and, depending on which way you walk fore & aft in the aisle, your ground speed varies. The acft has a higher groundspeed than I do, so obviously it's acting on me. (I hope all you 'calcumlater & nummers' guys are following this)... If I spread out my arms, legs, etc. so I get more contact with the acft, I'm clearly going to get more push. Now, admittedly, I generally doze off, BUT as evidenced emperilikly, I always seem to get to my destination faster, thereby proving my theory!

I think everybody will admit to having done this.
All you fizziks-geeks can go stuff it.;)
Every fight is a food fight if you're a cannibal

Goodness is something to be chosen. When a man cannot choose, he ceases to be a man. - Anthony Burgess

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>You're in the cabin of an aircraft flying 500kts . . .

> If I spread out my arms, legs, etc. so I get more contact with the
>acft, I'm clearly going to get more push.

That's an excellent point, but I have an even better idea.

Airliners often fly in the jet stream, where they get 100mph+ tailwinds that help to increase their groundspeed. Right now, pilots foolishly retract flaps, landing gear and speed brakes (i.e. "clean the plane up") hoping to minimize drag and maximize speed and fuel economy.

We should suggest that they drop the flaps, deploy the speedbrakes and extend the landing gear! The additional drag will give them an extra "push" from the jet stream. This simple approach could save hundreds of thousands of gallons of jet fuel a year.

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Can you tell which way the wind is blowing, or how strong the wind is blowing, under canopy with your eyes closed?

If so, please explain how.



Magical canopy faeries tell me which way the wind blows.



I have noticed that in a strong, constant wind - my speed relative to the ground varies. If my ground speed varies while the wind speed is
constant, then I must be changing speed inside the
airmass also.

Example - on a long spot, with the wind to my back -
I spread out my arms and get big so that I catch as
much air as I can. I make my suit act like a sail.

The air has a higher ground speed than I do,
so it moves around me. If I block it, it gives me an
extra push.

I think everybody will admit to having done this because they understand how it works.

Simple concept.



Y'know, I've really been mulling this over and I've had a change of heart - I think HappyCamper's actually on the right track here... this could work!

Consider this: You're in the cabin of an aircraft flying 500kts and, depending on which way you walk fore & aft in the aisle, your ground speed varies. The acft has a higher groundspeed than I do, so obviously it's acting on me. (I hope all you 'calcumlater & nummers' guys are following this)... If I spread out my arms, legs, etc. so I get more contact with the acft, I'm clearly going to get more push. Now, admittedly, I generally doze off, BUT as evidenced emperilikly, I always seem to get to my destination faster, thereby proving my theory!

I think everybody will admit to having done this.
All you fizziks-geeks can go stuff it.;)



Fizzik geek here.

Nice work. The energy balance is interesting too.

Say the person's mass is 80kg (176pounds) and they can walk at 2m/sec down the cabin of an A/C doing 250m/sec (approx 500mph).

Then their kinetic energy (0.5*m*v^2) has increased from 2.5 Million Joules when standing still to 2,540,160 Joules when walking at 2m/sec, an increase of 40,160 Joules.

To go from zero to 2m/sec on the ground increases the person's KE by 160 Joules.

Which goes to show that walking down the aisle of the plane takes 251 times more work than walking on the ground.

Flight attendants are underpaid! The FAA is doing you a favor by making you stay in your seat for the last 30 minutes of your flight.



(What it actually illustrates is that energy arguments about downwind turns are forgetting something important)
...

The only sure way to survive a canopy collision is not to have one.

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>You're in the cabin of an aircraft flying 500kts . . .

> If I spread out my arms, legs, etc. so I get more contact with the
>acft, I'm clearly going to get more push.

That's an excellent point, but I have an even better idea.

Airliners often fly in the jet stream, where they get 100mph+ tailwinds that help to increase their groundspeed. Right now, pilots foolishly retract flaps, landing gear and speed brakes (i.e. "clean the plane up") hoping to minimize drag and maximize speed and fuel economy.

We should suggest that they drop the flaps, deploy the speedbrakes and extend the landing gear! The additional drag will give them an extra "push" from the jet stream. This simple approach could save hundreds of thousands of gallons of jet fuel a year.



You could even get a deployable sail that pops up from the top of the cabin. Then you would REALLY be hauling ass.

/if he's trolling, it's one for the record books
//if not, i'm terrified that someone with 2000 jumps actually thinks like this
///golfclap

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>You're in the cabin of an aircraft flying 500kts . . .

> If I spread out my arms, legs, etc. so I get more contact with the
>acft, I'm clearly going to get more push.

That's an excellent point, but I have an even better idea.

Airliners often fly in the jet stream, where they get 100mph+ tailwinds that help to increase their groundspeed. Right now, pilots foolishly retract flaps, landing gear and speed brakes (i.e. "clean the plane up") hoping to minimize drag and maximize speed and fuel economy.

We should suggest that they drop the flaps, deploy the speedbrakes and extend the landing gear! The additional drag will give them an extra "push" from the jet stream. This simple approach could save hundreds of thousands of gallons of jet fuel a year.


>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>.

Might have a problem landing with no gear and flaps.
:D

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I am really surprised that people don't understand this concept. Flying in the wind is different than flying without wind due to inertia and airflow issues. Take the ground out of the discussion and this fact doesn't change. Lets look at this example:
Flying a remote control aircraft, even with a means of propulsion that a parachute does not have, one must fly very different in wind. If you make a dramatically sharp turn without wind the same turn with wind will cause the aircraft to stall as the inertia of the craft keeps it from moving with the wind during the turn. I have seen numerous crashes due to people making this very mistake! When turning down wind you must turn slower when making down wind turns and turn harding into the wind in really strong winds. When you factor in inertia and airflow over a wing and other surfaces wind plays a big factor!

Lets put it this way: What would happen if an aircraft turned down wind on takeoff?
Why does an aircraft climb quicker into the wind than when downwind?
The same factors effecting the aircraft effect the us in parachutes.

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