exit order question

[rehmwa 2]

Play around with kallend's simulation. Also, there is a preso on exit order where he gives general recommenations. It's also excellent.

Lastly,

1 - anyone (let's except Tandems and people intending to open extremely high, like for CrW-only, for this statement) that consitently counts on vertical separation (ie. opening altitudes) for exit order, is in a fairy realm of make believe. It's not a smart to do so. I'd just as soon they take a separate pass. Counting on vert sep of a 1000 feet difference or not is really wrong, it's a matter of a few seconds freefall only and typically attributed to newbies who have a harder time opening when they think they will.

2 - Most of the time, it's ego, or just a 'always done it that way' for DZs that do it wrong.

3 - here's another crappy reasoning "well, freefallers swoop more" - nuts, freefall discipline today has nothing to do with who owns hotter canopies or swoops more. Lots of newbies go right to freefly directly off student status. Again, swoopers are smart and normally take their own pass. If they take any form of freefall, then getting a swoop at the end is a bonus, not a right. They are in the same traffic as anyone else.

4 - Freefall discipline also has little to do with how long they spend in the door (I've seen extremely long and short setups from both disciplines).

If you hear any of these things, be EXTREMELY skeptical of the exit order from that particular DZ and make sure you take a safe separation if put into a bad exit order. Nothing is worse than letting a faster falling group ahead of you for ANY reason, then finding out in freefall that the upper vs lowers delta was bigger than you thought and you are in freefall looking straight down at open canopies.

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[Ron 7]

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Well, it's a combination of both. (To be exact, it's ballistic coefficient.)

I know, but since most jumpers are within 50 pounds of each other the weight portion of the BC equation is the least important.

BC is the ratio of weight to drag. In the exit question it is about how much drag is evident that makes the difference.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[kallend 1,619]

Ron, it's quite clear that you, Bill and Sundevil understand what is going on.

The issue is how to explain to someone that hasn't yet "got it", and has forgotten (or never had) high school physics, why some skydivers get more forward throw than others. The dart vs birdie analogy explains that perfectly because just about everybody in the western world can relate to it from personal experience. It didn't need a nitpicking debate on mass, drag and BC for anyone's light to be turned on.

...

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

[billvon 2,379]

>I know, but since most jumpers are within 50 pounds of each other
>the weight portion of the BC equation is the least important.

True. About the only time I've seen it make a clear difference is when Luigi (a very light guy) puts on his 50 lb vest for swooping. Most of the issue is drag, which ends up being _primarily_ presentation.

[rehmwa 2]

Love the shuttlecock icon. (Can you get a picture of a real one? not that plastic thing? I'll look for one.)

Another issue in the nitpicking was the whole idea of an 'average' fall rate behavior being used in the calculations and accounting for the (natural)statistical variation just being part of the assumptions (mostly in the initial acceleration on exit stuff). That got a few people hung up on the typical "but what about this single scenario". That's always fun when talking overall effects - somebody always throws in an outlier example and thinks it changes the theory (rather than assists it).

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[Ron 7]

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It didn't need a nitpicking debate on mass, drag and BC for anyone's light to be turned on.

It didn't need it..But most debates on here are things that didn't need to happen and how one or more folks just didn't get the overall concept or wanted to try and debunk a theory using special cases.

If we took that away there would only be Talkback and who is doin the sheep.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[speedy 0]

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The birdie and dart analogy is lousy because both the weight and Cd are very different - very different

The analogy was good since 99% of the people would have been satisfied given it.

I found the anaolgy bad because I thought about the difference in weight as well.

While you may make assumptions about the knowledge and intelligence of students in your physics class, you cannot do the same with the people in this forum. A number of them think that a birdie is one under par for a hole in golf.

Another person who thinks all skydivers weigh the same.

Do you really think I believe that? You have really missed the point You used a bad analogy for the average skydiver and that's why people are still using the 45° rule. It easier to follow than birdies, darts and BC .

Dave

Fallschirmsport Marl

[rehmwa 2]

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that's why people are still using the 45° rule. It easier to follow than birdies, darts and BC .

I gladly know very few (maybe no one anymore) people that use the so-called "45° rule". That's just a result of poor thinking and laziness (it's really just a lazy man's way to look out the door and pull his wait time out of his ass based on 'no data or judgement whatsoever'). Always a good combination for hurting oneself and others.

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[tso-d_chris 0]

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You used a bad analogy for the average skydiver

I think the average skydiver understood the analogy quite well, as it was a very good analogy for our purposes here. It is a vocal minority that are trying to make the professor appear wrong.

For Great Deals on Gear

[rehmwa 2]

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I think the average skydiver understood the analogy quite well, as it was a very good analogy for our purposes here. It is a vocal minority that are trying to make the professor appear wrong.

analogies are always wrong. they are supposed to be 'close' or 'symbolic', not exactly the same - those are called examples - or what would be the point. The prof made an excellent analogy. very descriptive and to the point he was making. he went to analogies, because people didn't get the examples of a skydiver on his head vs a skydiver on his belly.

If you want to get the prof going, just tell him he's wrong on a subjective issue in politics, but there's a forum for that.

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[speedy 0]

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he went to analogies, because people didn't get the examples of a skydiver on his head vs a skydiver on his belly.

That's were the analogy didn't work to well for me personally. I can't see the similarity between a birdie and a belly flier.

I did not say the professor was wrong ! I said that I did not think the analogy was a good one. For expressing that opinion I am accused of being a "nitpicking vocal minority".

BTW, I can see the analogy between a dart and a freeflier, they are both big pricks.

I'm done here.

Dave

Fallschirmsport Marl

[mnealtx 0]

It took me a bit to understand how there could be a difference in forward throw, but I was misunderstanding how FFers tend to present to the relative wind at exit.

Mike
I love you, Shannon and Jim.
POPS 9708 , SCR 14706

[JeffD 0]

How about this analogy.

Jump off of a diving board into a swimming pool. Think of the pool as the Relative wind.

Now dive into the pool and you'll go pretty deep. (Free flier jumping head first into the RW)

Now belly flop, and you'll barely break the surface. (Belly flier presenting whole body to Relative Wind)

Make sure the same person does both so weight is negated.

[tso-d_chris 0]

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How about this analogy.

Jump off of a diving board into a swimming pool. Think of the pool as the Relative wind.

Now dive into the pool and you'll go pretty deep. (Free flier jumping head first into the RW)

Now belly flop, and you'll barely break the surface. (Belly flier presenting whole body to Relative Wind)

Make sure the same person does both so weight is negated.

That explains it well, also.

For Great Deals on Gear

[apoil 0]

[sundevil777 93]

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>I know, but since most jumpers are within 50 pounds of each other
>the weight portion of the BC equation is the least important.

True. About the only time I've seen it make a clear difference is when Luigi (a very light guy) puts on his 50 lb vest for swooping. Most of the issue is drag, which ends up being _primarily_ presentation.

Thank you for agreeing with me.

It doesn't mean that we consider all jumpers to weigh the same, just that for purposes of anologies, only having the drag vary is most useful for the 'physics challenged'. To introduce the effect of weight is best left to a separate analogy, instead of mixing both variables at the same time, in my opinion.

Kallend, to throw out the term ballistic coefficient, without even defining it (I did that), doesn't enhance understanding of the exit trajectory question.

Your birdie & dart analogy is FAR from perfect, it sucks, because both of the important variables changed. It is like implying that freeflyers present less drag on exit, and also weigh more. Not everyone will see that implication, but it is there, and your advocacy of this analogy (against my "nitpicking") does the 'physics challenged' no favor.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[pilotdave 0]

I agree that the analogy is flawed for the reason you mention. But seriously, if anyone came to the conclusion that freeflyers will penetrate farther on exit than a belly flyer because freeflyers weigh more, well, they'd be pretty "special." Hmmm wait, maybe they'd be right... freeflyers fall faster too... must be heavier!

Do we need an analogy here? Wouldn't a simple explanation do? This isn't complicated stuff.

Dave

[rehmwa 2]

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It is like implying that freeflyers present less drag on exit, and also weigh more.

As a free flyer approaches the speed of light, he could have less mass, so he'd weigh less, not more. He'd also act like pure energy, thus light would shine out of his ass, like many like to think....

So now, due to this, I agree, the analogy is crappy.

Anyone have any chocolate?

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[billvon 2,379]

>Your birdie & dart analogy is FAR from perfect . . .

It's pretty good, actually. It demonstrates that two objects of differing mass and drag can go different distances. In skydiving terms, two skydivers of differing mass and drag will have different amounts of throw. Of course, if physics rather than skydiving is your thing, you could find nits wrong with it.

[sundevil777 93]

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I agree that the analogy is flawed for the reason you mention. But seriously, if anyone came to the conclusion that freeflyers will penetrate farther on exit than a belly flyer because freeflyers weigh more, well, they'd be pretty "special." Hmmm wait, maybe they'd be right... freeflyers fall faster too... must be heavier!

Do we need an analogy here? Wouldn't a simple explanation do? This isn't complicated stuff.

Dave

I agree, there is no analogy needed, especially one that varies both drag and mass.

And I also agree that I don't expect anyone to think freeflyers weigh more, but Kallend kept asserting that I and others must think that all skydivers weigh the same, so I offered a bad conclusion from his analogy.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[sundevil777 93]

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>Your birdie & dart analogy is FAR from perfect . . .

It's pretty good, actually. It demonstrates that two objects of differing mass and drag can go different distances. In skydiving terms, two skydivers of differing mass and drag will have different amounts of throw. Of course, if physics rather than skydiving is your thing, you could find nits wrong with it.

Your standard for a good analogy are pretty low. Kallend's analogy, actually it is not an analogy, just a question:

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Try throwing a dart and a badminton birdie horizontally with the same initial speed. Which goes farther?

He doesn't even explain why they go farther. He does throw in the term ballistic coefficient without defining it. Even went so far as to say:

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regardless of mass a dart has a higher BC than a badminton birdie.

That is false. He later quoted the official weight of a dart and birdie, but then why say, "regardless of mass"?

If you think I'm nitpicking, so be it, you've said it. You don't have to keep replying.

He also said that regardless of mass all that matters is the BC. Of course this is true, but is a whole lot less useful than explaning that mass and drag are the only variables that define BC.

FAR from perfect.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[pilotdave 0]

Do you want a reader of this thread to understand a little bit about exit separation, or do you want kallend to admit he was wrong?

Get over it...

Dave

[sundevil777 93]

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Do you want a reader of this thread to understand a little bit about exit separation, or do you want kallend to admit he was wrong?

Both, but as you suspect, mostly the latter.

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Get over it...

As much as I don't like taking orders from you , I will now let it go. I won't care anymore about how much anyone loves Kallend's terribly flawed analogy.

That will be all from me on this - probably will make a lot of people happy.

People are sick and tired of being told that ordinary and decent people are fed up in this country with being sick and tired. I’m certainly not, and I’m sick and tired of being told that I am

[LouDiamond 1]

OK, UNCLE, I give, I'll tell you where hoffa is buried. For the love of God people. This thread has gotten so fucked up with nitpicking and thats what it is. It boils down to some people not likeing the others analogy. The result is that a thread where there was the potential for those out there who could of learned something about this subject was completly and utterly fucking lost. It's no fucking wonder people are still confused about this subject. How about putting this thread back on topic and letting go of the analogy war?

"It's just skydiving..additional drama is not required"
Some people dream about flying, I live my dream
SKYMONKEY PUBLISHING

[Andy9o8 0]

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How about putting this thread back on topic and letting go of the analogy war?

I agree. Analogy wars are like arguing with your mother in law while trapped in a moving car in a snowstorm while hungover. Or maybe a better comparison might be....