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

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If you are flying with a 30mph wind

Again, you don't fly in wind. Wind only exists on the ground.

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Also, per the discussion of momentum, obviously the oncoming force of the wind (in that airmass)

Wind is not "oncoming" in the airmass. It is only oncoming to people on the ground. When you are in the airmass, you ARE the wind.

On Sunday, the winds at 3,000 ft were 50 mph (relative to the ground). If you did a 180, back into the wind, your forward canopy speed (relative to the ground) would stop. 50+20 (canopy speed through
the airmass) is 70mph ground speed.

As far as being "the wind", your body has momentum
that is moving in the direction of the wind.
You are changing the direction of momentum 180 degrees.

Because of the difference in momentum, the canopy
will not go forward through the airmass as quickly
the canopy will stop (relative to the ground).

The ground speed of the body will still be over 50.

Body will pass canopy. Linear speed is translated
to rotational speed. Body will spin around canopy.

(btw, I did take Physics 101, but 3rd grade tetherball is
a better illustration)

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(btw, I did take Physics 101, but 3rd grade tetherball is a better illustration)

I can't repeat the same point any more, but you need to go BACK to Physics 101 and study relative reference frames. Bill's post above about the earth's rotation is a good one. You're missing a very fundamental concept, and when it clicks for you, you'll see the problem with what you're saying.

The air doesn't know it's moving. For all intents and purposes, it's NOT moving. The only reason we think it's moving is because we live on the ground.
www.WingsuitPhotos.com

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(btw, I did take Physics 101, but 3rd grade tetherball is a better illustration)

I can't repeat the same point any more, but you need to go BACK to Physics 101 and study relative reference frames. Bill's post above about the earth's rotation is a good one. You're missing a very fundamental concept, and when it clicks for you, you'll see the problem with what you're saying.

The air doesn't know it's moving. For all intents and purposes, it's NOT moving. The only reason we think it's moving is because we live on the ground.

I'm just explaining what I have experienced.

I have been going in the direction of a 40mph wind (ground speed blah blah) and cranked a toggle and
been thrown into a "holy crap" spinning dive.

The same toggle input on a windless day did not.

I have also seen people change the internal pressure
(collapse) their canopy by using toggle inputs.

I doubt that you haven't seen that.

Turbulence is just a change in the air pressure.
I am saying that it can be induced by the canopy pilot.

Remember, the canopy is flying through the airmass.
The pilot is just hanging from the lines.

The thing that causes the whipping action and rotation is the difference in speed between canopy and pilot.
That seems like a simple concept.
That's not Physics 101, that's tetherball.

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(btw, I did take Physics 101, but 3rd grade tetherball is a better illustration)

I can't repeat the same point any more, but you need to go BACK to Physics 101 and study relative reference frames. Bill's post above about the earth's rotation is a good one. You're missing a very fundamental concept, and when it clicks for you, you'll see the problem with what you're saying.

The air doesn't know it's moving. For all intents and purposes, it's NOT moving. The only reason we think it's moving is because we live on the ground.

+1

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there might be something else we just don't understand yet.
I never in a million years would have believed that under certain
conditions hot water can freeze before cold water. Just trying to keep
an open mind, harry houdini once said "the hardest person to fool is
a child and the easiest to fool is a scientist" just sayin

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>I have seen a canopy collapse due to a pressurization
>change brought on by toggle input. So, toggle/riser input
>is obviously not a benign factor to how your canopy flies.

Agreed. Toggle input drastically affects how the canopy flies, no matter what your groundspeed.

>If you are flying with a 30mph wind, the effect of any
>linear speed has been translated into greater rotational speed.

Completely incorrect. The earth spins at about 800mph; claiming that flying east (with the motion) is significantly different than flying west (against the motion) would be absurd. Windspeed is less than 10% of that.

>The greater rotational speed will cause your angle of attack to increase
>and the canopy will be more at a dive angle.

Incorrect. It doesn't matter.

>Also, per the discussion of momentum, obviously the
>oncoming force of the wind (in that airmass) is going to affect
>the canopy a whole lot faster than your body when
>the canopy turns into the 30mph wind.

Again, if that were true, that 800mph speed above the earth would affect you a lot more than a tiny 30mph wind.

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>I never in a million years would have believed that under certain
>conditions hot water can freeze before cold water.

It can't, although that has nothing to do with this topic.

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I have been going in the direction of a 40mph wind (ground speed blah blah) and cranked a toggle and
been thrown into a "holy crap" spinning dive.

I'll try another angle in trying to help explain why that momentum thing doesn't work:

(Maybe there's a visual illusion down low that makes it seem that way?)

Say someone were doing a high hop & pop or cross country, and the wind was howling at 50 knots or whatever up high where they were. If the jumper played around up there with their canopy you DON'T hear them say:

"I'd make a 180 dive and it was really fast. Then I tried it again, and I couldn't figure out why the canopy was so sluggish. Then I realized: I was going downwind the first time, and upwind the second. When I spiralled, it was really weird, as the canopy kept on pickup up speed and losing it, every time it went in and out of facing that 60 knot wind, picking up and losing momentum!"

Or what if a jumper made a hop and pop from some long range balloon that was doing 200 knots in the jetstream? Would it be hard to turn the canopy in some directions while it would go crazy in others?

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If you are flying with a 30mph wind, the effect of any
toggle input is going to be greater because your additional linear speed has been translated into greater rotational speed.

No, it hasn't.

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Also, per the discussion of momentum, obviously the
oncoming force of the wind (in that airmass) is going to affect
the canopy a whole lot faster than your body when
the canopy turns into the 30mph wind.

Don't ever try and do physics based on what is "obvious".

Either in a steady wind or in still air the aerodynamic forces on the canopy and your body are created by the movement of the canopy through the airmass.
Do you want to have an ideagasm?

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I have been going in the direction of a 40mph wind (ground speed blah blah) and cranked a toggle and
been thrown into a "holy crap" spinning dive.

The same toggle input on a windless day did not.

This has nothing to do with the canopy reacting to the speed of the wind. It may have something to do with the instability of the wind, as on a day with 40 mph winds, it's a fair bet that the air is a bit 'unstable'.

Without a doubt, unstable air will effect the flight of a canopy, but the spped is not a factor. As another example, the handling of planes doesn't become odd and unpredictable at higher speeds. The control inputs become more effective, but that's it.

One thing to think about is to just eliminate the ground from your mind while picturing these things. If you have ever opened above a solid cloud deck, you would see the error of your ways. You can't make sense of upwind, downwind, or crosswind because the clouds are moving in the airmass right along with you.

I'll support you that you might have notices handling differences with your canopy on days with higher winds, but it's not for the reasons you stated.

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You're arguing using a different point of reference.
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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The earth spins at about 800mph

... at about 39 degrees latitude.

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Actually, in certain conditions with some types of water, hot water will freeze faster than cold water.
This is the paradox of skydiving. We do something very dangerous, expose ourselves to a totally unnecesary risk, and then spend our time trying to make it safer.

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If you are flying with a 30mph wind, the effect of any
toggle input is going to be greater because your additional linear speed has been translated into greater rotational speed.

No, it hasn't.
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I think the proper term would be inertia. Flying with a 30 mph wind, your body and your canopy have the inertia of an object moving at 50+mph. Flying into a 30 mph wind, you have the inertia of moving at -5 mph. Your canopy has much less mass so will react mainly to the relative wind. Your body has much more mass, so will react mainly to it's inertia.

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Also, per the discussion of momentum, obviously the
oncoming force of the wind (in that airmass) is going to affect
the canopy a whole lot faster than your body when
the canopy turns into the 30mph wind.

Don't ever try and do physics based on what is "obvious".

Ditto...

Either in a steady wind or in still air the aerodynamic forces on the canopy and your body are created by the movement of the canopy through the airmass.

But there's a lot more going on here than just aerodynamics. Do we also want to factor in gravity?
This is the paradox of skydiving. We do something very dangerous, expose ourselves to a totally unnecesary risk, and then spend our time trying to make it safer.

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But there's a lot more going on here than just aerodynamics. Do we also want to factor in gravity?

We have. It's the same in every example given, without or without wind.
www.WingsuitPhotos.com

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There should be a penalty for practicing physics without a license.
...

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

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There should be a penalty for practicing physics without a license.

You're killin' me, John.
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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>If you are flying with a 30mph wind, the effect of any
>linear speed has been translated into greater rotational speed.

Completely incorrect. The earth spins at about 800mph; claiming that flying east (with the motion) is significantly different than flying west (against the motion) would be absurd. Windspeed is less than 10% of that.

Huh????
Toggle input...earth's spin?
You're going to have to
1. Document that relationship...or
2. 'Fess up on the BS
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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>If you are flying with a 30mph wind, the effect of any
>linear speed has been translated into greater rotational speed.

Completely incorrect. The earth spins at about 800mph; claiming that flying east (with the motion) is significantly different than flying west (against the motion) would be absurd. Windspeed is less than 10% of that.

Huh????
Toggle input...earth's spin?
You're going to have to
1. Document that relationship...or
2. 'Fess up on the BS

Sometimes on Saturday mornings, I think about the
Earth going around at 800mph.

I go out to my car and stand on the front of the hood
with my arms out and say, "I'm flying..."

I am all about that Earths rotation.

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...
Sometimes on Saturday mornings, I think about the
Earth going around at 800mph.

I can relate to that. Usually a big glass of water and several aspirin slows it down a little.
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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I think I'm going to hurl.
“The only fool bigger than the person who knows it all is the person who argues with him.

Stanislaw Jerzy Lec quotes (Polish writer, poet and satirist 1906-1966)

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>Toggle input...earth's spin?

Stand outside and face east. You're spinning with the earth at about 800mph. Now face west; you're going backwards at 800mph.

If your momentum really cared about any of that, you'd never be able to stop your car in a reasonable time while driving east. After all, you're doing 860mph!

But it feels no different driving east than driving west, because the road you are on is moving at 800mph with you.

Same thing in the air. It doesn't matter that the air mass you are in is moving 30mph because of wind, or 800mph because of the earth's rotation. It doesn't matter if your toggle input turns you into the wind, or into the Earth's spin, or directly North; your canopy will react the same way. All that matters is what you are doing relative to the air you are in - which for most canopies means moving through it at about 20-25mph. (Which is where the term 'relative wind' comes from.)

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...Same thing in the air. It doesn't matter that the air mass you are in is moving 30mph because of wind, or 800mph because of the earth's rotation. It doesn't matter if your toggle input turns you into the wind, or into the Earth's spin, or directly North; your canopy will react the same way. All that matters is what you are doing relative to the air you are in - which for most canopies means moving through it at about 20-25mph. (Which is where the term 'relative wind' comes from.)

Just to add some more fuel to the fire:

Does a paper airplane behave differently on the ground (say in the hangar where there is no wind) compared to inside an airplane that is flying through the sky?

Is it going to behave differently inside the plane if you throw it toward the front or toward the back?

And if you have a big enough airplane, how about to the side?

And if not, how is it different just because the air is contained in the plane vs the whole airmass moving (as it does in a steady wind)?
"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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...Same thing in the air. It doesn't matter that the air mass you are in is moving 30mph because of wind, or 800mph because of the earth's rotation. It doesn't matter if your toggle input turns you into the wind, or into the Earth's spin, or directly North; your canopy will react the same way. All that matters is what you are doing relative to the air you are in - which for most canopies means moving through it at about 20-25mph. (Which is where the term 'relative wind' comes from.)

Just to add some more fuel to the fire:

Does a paper airplane behave differently on the ground (say in the hangar where there is no wind) compared to inside an airplane that is flying through the sky?

Is it going to behave differently inside the plane if you throw it toward the front or toward the back?

And if you have a big enough airplane, how about to the side?

And if not, how is it different just because the air is contained in the plane vs the whole airmass moving (as it does in a steady wind)?

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

No, but the flight attendants will be pissed.

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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.

The canopy and the suspended body are both flying
through the airmass, but with different flight characteristics. They are not one solid unit with
one flow through the air like an airplane.

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.