7-cell vs 9-cell

[JohnDeere 0]

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This has nothing to do with the subject but many, many moons ago (before I joined the Army) I worked on a dairy farm in Wisconsin. I remember driving a John Deere 4020 tractor...

Shit i like this topic better than the one that this post turned into!

Nothing opens like a Deere!

You ignorant fool! Checks are for workers!

[kallend 1,672]

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So if you can't spot the answer is to get a different canopy?

Did I say anything about lack of spotting ability or getting a different canopy? I really tried to make it clear that I was talking about you and your twin brother, who were late divers on a bigway and the organizer, billvon, led you out on a bad spot.

Dave

The very fact that you had to specify particular models indicates that just knowing the number of cells is insufficient information. And since we're late divers the chances are that we are running with the wind, and the one with the lower wing loading will go farther regardless of number of cells.

Fact is, skybill's statement "You will walk further with the 7" is only correct under a very limited set of circumstances, and most of the time your walking distance has nothing to do with the number of cells in the canopy.

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

[mx19 0]

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So if you can't spot the answer is to get a different canopy?

Did I say anything about lack of spotting ability or getting a different canopy? I really tried to make it clear that I was talking about you and your twin brother, who were late divers on a bigway and the organizer, billvon, led you out on a bad spot.

Dave

The very fact that you had to specify particular models indicates that just knowing the number of cells is insufficient information. And since we're late divers the chances are that we are running with the wind, and the one with the lower wing loading will go farther regardless of number of cells.

Fact is, skybill's statement "You will walk further with the 7" is only correct under a very limited set of circumstances, and most of the time your walking distance has nothing to do with the number of cells in the canopy.

But they are saying that the wing loadings are equal! so everything is equal apart from the number of cells!

[Baksteen 84]

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So if you can't spot the answer is to get a different canopy?

Did I say anything about lack of spotting ability or getting a different canopy? I really tried to make it clear that I was talking about you and your twin brother, who were late divers on a bigway and the organizer, billvon, led you out on a bad spot.

Dave

The very fact that you had to specify particular models indicates that just knowing the number of cells is insufficient information. And since we're late divers the chances are that we are running with the wind, and the one with the lower wing loading will go farther regardless of number of cells.

Fact is, skybill's statement "You will walk further with the 7" is only correct under a very limited set of circumstances, and most of the time your walking distance has nothing to do with the number of cells in the canopy.

But they are saying that the wing loadings are equal! so everything is equal apart from the number of cells!

and apart from the taper, trim and (possibly) size of the canopy. Just to name a few off'f the top of my head.

"That formation-stuff in freefall is just fun and games but with an open parachute it's starting to sound like, you know, an extreme sport."
~mom

[mx19 0]

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So if you can't spot the answer is to get a different canopy?

Did I say anything about lack of spotting ability or getting a different canopy? I really tried to make it clear that I was talking about you and your twin brother, who were late divers on a bigway and the organizer, billvon, led you out on a bad spot.

Dave

The very fact that you had to specify particular models indicates that just knowing the number of cells is insufficient information. And since we're late divers the chances are that we are running with the wind, and the one with the lower wing loading will go farther regardless of number of cells.

Fact is, skybill's statement "You will walk further with the 7" is only correct under a very limited set of circumstances, and most of the time your walking distance has nothing to do with the number of cells in the canopy.

But they are saying that the wing loadings are equal! so everything is equal apart from the number of cells!

and apart from the taper, trim and (possibly) size of the canopy. Just to name a few off'f the top of my head.

Haha ok fair one.

[kallend 1,672]

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So if you can't spot the answer is to get a different canopy?

Did I say anything about lack of spotting ability or getting a different canopy? I really tried to make it clear that I was talking about you and your twin brother, who were late divers on a bigway and the organizer, billvon, led you out on a bad spot.

Dave

The very fact that you had to specify particular models indicates that just knowing the number of cells is insufficient information. And since we're late divers the chances are that we are running with the wind, and the one with the lower wing loading will go farther regardless of number of cells.

Fact is, skybill's statement "You will walk further with the 7" is only correct under a very limited set of circumstances, and most of the time your walking distance has nothing to do with the number of cells in the canopy.

But they are saying that the wing loadings are equal! so everything is equal apart from the number of cells!

No, the designs are different. We have already established that a 7-cell velocity has a flatter glide than a 9-cell katana.

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

[mx19 0]

Ok let me ask you... if the same person was jumping equally sized canopies one a spectre and one a sabre2 in the exact same conditions, which one would travel further?

[kallend 1,672]

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Ok let me ask you... if the same person was jumping equally sized canopies one a spectre and one a sabre2 in the exact same conditions, which one would travel further?

Depends on what they do with the risers and brakes.

Fact is, in your lame attempts to justify the statement that you have to walk farther if you jump a 7 cell*, you have to come up with all kinds of absurdly contrived examples. The primary determinant of how far you walk is the canopy pilot, not the canopy.

* the statement objected to was the one referring to walking distance, not glide ratio.

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

[mx19 0]

Omg! did i really need to say flown in exactly the same way aswell!....

[kallend 1,672]

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Omg! did i really need to say flown in exactly the same way aswell!....

As I wrote, you have to come up with all kinds of contrived examples.

And remember, the topic in dispute is walking distance, not glide ratio. I never disputed that, in general (and with exceptions) 9 cells have a better glide ratio.

I claimed and continue to claim that the primary determinant of how far you walk is the canopy pilot, not the canopy.

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

[kallend 1,672]

Now let me ask you. If the same person was jumping equally sized canopies, one a Velocity and one a Katana in the exact same conditions, in the exact same way, which one would travel further?

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

[mx19 0]

ok so in the majority of situations the 9 cell will get you back from a longer spot better then the 7 cell will, thus meaning you will probably have to walk farther under the 7 cell, if you are coming back from a long spot.

[kallend 1,672]

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ok so in the majority of situations the 9 cell will get you back from a longer spot better then the 7 cell will, thus meaning you will probably have to walk farther under the 7 cell, if you are coming back from a long spot.

Without knowing the statistics of ownership of various designs of canopy and their wing loadings and the skill level of the jumpers, I don't think that can be verified.

Additionally, I dispute that the "majority of situations" are "long spots".

If YOU are having trouble with YOUR spotting, you might like to take a look at my presentation on exit safety:
www.iit.edu/~ugcol/separation.zip


It has some hints to help you.

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

[mx19 0]

I don't know about katanas or velocity's but i doubt the op is looking for one of these seeing that he only has 20odd jumps and is also looking for a 170.

I think in the op's situation my comment stands.

I didnt say that the majority of situations were long spots but meant in the majority of situation's that involve a long spot the 9 cell will get you back better.

Just for the record i am having no trouble with my spotting.

[kallend 1,672]

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I don't know about katanas or velocity's but i doubt the op is looking for one of these seeing that he only has 20odd jumps and is also looking for a 170.

I think in the op's situation my comment stands.

I didnt say that the majority of situations were long spots but meant in the majority of situation's that involve a long spot the 9 cell will get you back better.

Yes, in a LIMITED set of circumstances SOME 7-cells will get you back better than SOME 9-cells, assuming you fly them correctly. In the great majority of circumstances how far you walk depends on the jumper and not the canopy.

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

[wmw999 2,166]

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In the great majority of circumstances how far you walk depends on the jumper and not the canopy

I'd change the bolding on that:
In the great majority of circumstances how far you walk depends on the jumper and not the canopy.

Planform is a factor, but there are several other more important factors. It's like saying that a Ferrari will get you to the grocery store faster than a Honda.

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[kallend 1,672]

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In the great majority of circumstances how far you walk depends on the jumper and not the canopy

I'd change the bolding on that:
In the great majority of circumstances how far you walk depends on the jumper and not the canopy.

Planform is a factor, but there are several other more important factors. It's like saying that a Ferrari will get you to the grocery store faster than a Honda.

Wendy P.

I bolded "how far you walk" because this post is what started the discussion.

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

[wmw999 2,166]

I'm just trying to be obnoxious.

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[skybill 19]

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I'm just trying to be obnoxious.

Wendy P.

Hi Wendy,
Good Fun, I like it!

Funny how confounding experiments to skew the results in one's favor can be so much fun!!! Kal baby's hangup on 7 cells is so 15minutes ago!! The real issue at hand is not the number of cells,(7 vs. 9) but,"Varying the aspect ratio per unit of area holding all other variables constant." Now, back to the drawing board!!

SCR-2034, SCS-680

III%,
Deli-out

[JohnDeere 0]

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I'm just trying to be obnoxious.

Wendy P.

But you will never compare to the great "obnoxious" one

Nothing opens like a Deere!

You ignorant fool! Checks are for workers!

[champu 1]

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Omg! did i really need to say flown in exactly the same way aswell!....

Just as there aren't canopies that are "exactly the same except for the number of cells" you can't really specify that two different canopies be "flown in exactly the same way." either. I know you meant to say, "flown in their respective best way possible considering the spot," in which case, yes, higher-aspect ratio canopies and those with less drag will generally "win."

What Kallend is trying to say is that if you (taking your example) fly both a sabre2 and a spectre back from a bad spot "in their respective best way possible considering the spot," and the sabre2 makes it back but the spectre doesn't, then you should sort out your spotting rather than (or at least in addition to) buying a new canopy. Barely making it back from spots all the time is a good way to have yourself an accident.

Even if you choose to go with a 9-cell, which one do you pick? A pulse or a stiletto are going to make it much easier (their full flight mode is trimmed flatter) to get back than a sabre2 or a silhouette, but each come with more characteristics than just full flight glide. You're right back where you started in that it's in your best interest to try a wide variety of canopies, and once you're doing that it doesn't make sense to exclude 7-cell canopies.

[kallend 1,672]

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I'm just trying to be obnoxious.

Wendy P.

I can give lessons.

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

[wmw999 2,166]

I'm not quite sure I'm ready to be your naughty student

Wendy P.

There is nothing more dangerous than breaking a basic safety rule and getting away with it. It removes fear of the consequences and builds false confidence. (tbrown)

[Skydivesg 6]

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Now let me ask you. If the same person was jumping equally sized canopies, one a Velocity and one a Katana in the exact same conditions, in the exact same way, which one would travel further?

John what is your answer to this question?

Be the canopy pilot you want that other guy to be.

[riggerpaul 1]

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Now let me ask you. If the same person was jumping equally sized canopies, one a Velocity and one a Katana in the exact same conditions, in the exact same way, which one would travel further?

John what is your answer to this question?

Look, John already mentioned somewhere up thread that the canopy with the better L/D has the expectation of going the farthest.

That's not in dispute.

At question is the cute bit of wisdom that 7 cells means you walk more.

It has been years and years since I landed off the dz with my Spectre. Lots of people on their Sabre2s have landed off and I go to pick them up. Many of them even had a lower wing loading than I do. So the cute bit of wisdom doesn't always hold true. It depends on the pilot. That's what John has said over and over again.

If the 7 cell pilot lands next to the road instead of in the middle of the field next to the 9 cell pilot, who walks less? Probably the 7 cell pilot who doesn't have to walk so far to the ride that picks them both up.

7 cells or 9, poorer pilots walk more than good pilots.

Skilled pilots land where they want to.
Less skilled pilots land where the parachute takes them.