7-cell vs 9-cell

[billvon 3,075]

>How far you walk depends on how accurately you land, not on how many
>cells your canopy has.

Of course. But in general a 9 cell will make it back from a bad spot more often than a 7 cell. If that's important to you it might be a consideration in canopy selection.

[kallend 2,106]

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Hi np,
Don't know if ya' did much research last night but there's no really short answer. Without a lot of whiz/bang ya gonna get more horizontal distance coverage per unit of sink with the 9 cell. You will walk further with the 7.

How far you walk depends on how accurately you land, not on how many cells your canopy has.

Hi kal baby,
Howard cosel once said,"'Ya can't argue with ignorance!" (or something very close to that!!) Now, here's the deal. L/D has nothing to do with accuracy!! The bottom line is this," For a given number of square feet, a canopy with a higher aspect ratio [mean wing span/average chord] {holding all else constant; fabric type, airfoil shape, type of lines, suspended weight} will provide more horizontal distance covered per unit of sink. Got that???" Now, if you took a 7 cell, like an old Mike Furry Django "Pegasus" and expanded it to the same wingspan/chord as the "Dragonfly," without adding the additional ribs to make it a 9 cell the airfoil would baloon out and reduce its efficiency. If you took the 7 cell "Pegasus" and a 9 cell "Dragonfly" and with same suspended weights , opening side by side, the Dragonfly will "outglide" the Pegasus, (You can do this same experiment with countless other canopy designs) "SO," if you used the maximum Pegasus spot for both canopys, both canopys will make it to the target , it's just that the Dragonfly will have some extra altitude to burn off before landing. Sorry about that old man. Conversly if you were in the Pegasus on the max Dragonfly spot, "You'd be walking to the target!!" That's all the whiz/bang I'm gonna' get into for you....."GOT THAT???"

What have you been drinking?

...

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

[timmyfitz 0]

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Hi np,
Don't know if ya' did much research last night but there's no really short answer. Without a lot of whiz/bang ya gonna get more horizontal distance coverage per unit of sink with the 9 cell. You will walk further with the 7.

How far you walk depends on how accurately you land, not on how many cells your canopy has.

Hi kal baby,
Howard cosel once said,"'Ya can't argue with ignorance!" (or something very close to that!!) Now, here's the deal. L/D has nothing to do with accuracy!! The bottom line is this," For a given number of square feet, a canopy with a higher aspect ratio [mean wing span/average chord] {holding all else constant; fabric type, airfoil shape, type of lines, suspended weight} will provide more horizontal distance covered per unit of sink. Got that???" Now, if you took a 7 cell, like an old Mike Furry Django "Pegasus" and expanded it to the same wingspan/chord as the "Dragonfly," without adding the additional ribs to make it a 9 cell the airfoil would baloon out and reduce its efficiency. If you took the 7 cell "Pegasus" and a 9 cell "Dragonfly" and with same suspended weights , opening side by side, the Dragonfly will "outglide" the Pegasus, (You can do this same experiment with countless other canopy designs) "SO," if you used the maximum Pegasus spot for both canopys, both canopys will make it to the target , it's just that the Dragonfly will have some extra altitude to burn off before landing. Sorry about that old man. Conversly if you were in the Pegasus on the max Dragonfly spot, "You'd be walking to the target!!" That's all the whiz/bang I'm gonna' get into for you....."GOT THAT???"

What have you been drinking?

I believe he has been drinking knowledge and correct information. How about you?

[skybill 22]

Hi Tim,
Thanks.

Trouble with guys like kal, they went thru the quickie FJC and never bothered to read up on theory. "No aeronautical knowledge syndrome!" They get told pull the left toggle to go left etc. etc. and never figure out why. Funny how kal's profile says he's some whiz/bang prof of physics or something , he should have it down pat!!

SCR-2034, SCS-680

III%,
Deli-out

[pilotdave 0]

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Trouble with guys like kal, they went thru the quickie FJC and never bothered to read up on theory. "No aeronautical knowledge syndrome!"

Oh that's funny. Hope he's got a witty british-style response!

Dave

[wolfriverjoe 1,523]

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Trouble with guys like kal, they went thru the quickie FJC and never bothered to read up on theory. "No aeronautical knowledge syndrome!"

Oh that's funny. Hope he's got a witty british-style response!

Dave

Ok, who's got the popcorn??

I'll argue with the prof on some things, but not this

"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

[kallend 2,106]

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Hi Tim,
Thanks.

Trouble with guys like kal, they went thru the quickie FJC and never bothered to read up on theory. "No aeronautical knowledge syndrome!" They get told pull the left toggle to go left etc. etc. and never figure out why. Funny how kal's profile says he's some whiz/bang prof of physics or something , he should have it down pat!!

I was jumping a 7-cell Spectre on Sunday. On every jump I had a shorter walk than others on the load who were jumping 9-cell canopies.

The distance I get to walk depends on where I CHOOSE to land, not on the number of cells in my canopy.

Your mileage obviously differs

...

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

[kallend 2,106]

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Hi np,
Don't know if ya' did much research last night but there's no really short answer. Without a lot of whiz/bang ya gonna get more horizontal distance coverage per unit of sink with the 9 cell. You will walk further with the 7.

How far you walk depends on how accurately you land, not on how many cells your canopy has.

Hi kal baby,
Howard cosel once said,"'Ya can't argue with ignorance!" (or something very close to that!!) Now, here's the deal. L/D has nothing to do with accuracy!! The bottom line is this," For a given number of square feet, a canopy with a higher aspect ratio [mean wing span/average chord] {holding all else constant; fabric type, airfoil shape, type of lines, suspended weight} will provide more horizontal distance covered per unit of sink. Got that???" Now, if you took a 7 cell, like an old Mike Furry Django "Pegasus" and expanded it to the same wingspan/chord as the "Dragonfly," without adding the additional ribs to make it a 9 cell the airfoil would baloon out and reduce its efficiency. If you took the 7 cell "Pegasus" and a 9 cell "Dragonfly" and with same suspended weights , opening side by side, the Dragonfly will "outglide" the Pegasus, (You can do this same experiment with countless other canopy designs) "SO," if you used the maximum Pegasus spot for both canopys, both canopys will make it to the target , it's just that the Dragonfly will have some extra altitude to burn off before landing. Sorry about that old man. Conversly if you were in the Pegasus on the max Dragonfly spot, "You'd be walking to the target!!" That's all the whiz/bang I'm gonna' get into for you....."GOT THAT???"

What have you been drinking?

I believe he has been drinking knowledge and correct information. How about you?

If the distance you get to walk depends on the number of cells in the canopy you fly, you need to get some instruction in spotting and accuracy landing.

...

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

[pilotdave 0]

Weak response. Not even funny. Disappointing.

Anyway, obviously they're talking about long spots. You know, when someone other than you does the spotting because you're a late diver. And they spot too far upwind. And now you and your spectre need to go really far to get back to the DZ. And your twin brother is flying next to you under his sabre2 at identical wingloading and size. Given that both of you are experts and will use optimal technique to maximize glide ratio, who will make it closer to the DZ and therefore have a shorter walk back? And don't say you'll land at the bus stop right below.

Got another boring, obvious, deflecting-the-question response?
Dave

[kallend 2,106]

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Weak response. Not even funny. Disappointing.

Anyway, obviously they're talking about long spots. You know, when someone other than you does the spotting because you're a late diver. And they spot too far upwind. And now you and your spectre need to go really far to get back to the DZ. And your twin brother is flying next to you under his sabre2 at identical wingloading and size. Given that both of you are experts and will use optimal technique to maximize glide ratio, who will make it closer to the DZ and therefore have a shorter walk back? And don't say you'll land at the bus stop right below.

Got another boring, obvious, deflecting-the-question response?
Dave

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

I really don't think you want a treatise on induced drag (and don't think for one second that I couldn't give you one).

...

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

[billvon 3,075]

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

Pretty much. Just like if you can't pack, carry a reserve. Do you carry one?

[skybill 22]

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Hi Tim,
Thanks.

Trouble with guys like kal, they went thru the quickie FJC and never bothered to read up on theory. "No aeronautical knowledge syndrome!" They get told pull the left toggle to go left etc. etc. and never figure out why. Funny how kal's profile says he's some whiz/bang prof of physics or something , he should have it down pat!!

I was jumping a 7-cell Spectre on Sunday. On every jump I had a shorter walk than others on the load who were jumping 9-cell canopies.

The distance I get to walk depends on where I CHOOSE to land, not on the number of cells in my canopy.

Your mileage obviously differs

Hi kal baby,
I'm really glad that I don't personally know you and I really hope that we never meet. If per chance we end up on the same dropzone if I end up on the same load as you I will surly scratch off. BTW I do drink beer, I'll never buy you any and you can keep drinking your koolade.

SCR-2034, SCS-680

III%,
Deli-out

[champu 1]

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Anyway, obviously they're talking about long spots. You know, when someone other than you does the spotting because you're a late diver. And they spot too far upwind. And now you and your spectre need to go really far to get back to the DZ. And your twin brother is flying next to you under his sabre2 at identical wingloading and size. Given that both of you are experts and will use optimal technique to maximize glide ratio, who will make it closer to the DZ and therefore have a shorter walk back? And don't say you'll land at the bus stop right below.

I have an easier time making it back from long/short spots with my 7-cell velocity than I did with my 9-cell katana.

[pilotdave 0]

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I have an easier time making it back from long/short spots with my 7-cell velocity than I did with my 9-cell katana.

Ya know I originally wrote 7-cell and 9-cell in my post. I changed them to spectre and sabre2 specifically because I KNEW someone would bring up the 7-cell velocity.

But anyway since kallend refused to answer, I'll give my non-answer. It depends. I haven't liked most of the 7-cell canopies I've jumped, but it's too canopy dependent. I don't think it's even worth making generalizations about 7-cell and 9-cell canopies anymore. Gotta compare specific canopies. I don't think there's any real practical difference between modern 7-cell and 9-cell canopies when it comes to getting back from long spots. Some canopies do better than others, but technique is far more important unless you're trying to win a glide distance competition or something.

Dave

[pilotdave 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

[champu 1]

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But anyway since kallend refused to answer, I'll give my non-answer. It depends. I haven't liked most of the 7-cell canopies I've jumped, but it's too canopy dependent. I don't think it's even worth making generalizations about 7-cell and 9-cell canopies anymore. Gotta compare specific canopies. I don't think there's any real practical difference between modern 7-cell and 9-cell canopies when it comes to getting back from long spots. Some canopies do better than others, but technique is far more important unless you're trying to win a glide distance competition or something.

Agree completely. The truth is that these days there's a canopy design out there for everyone, and 7-cell and 9-cell canopies are going to have overlapping flight characteristics. You can demo any of them* from the manufacturer for a couple weeks or you could find a used one in decent shape for 700 bucks, put a few hundred jumps on it and sell it for 500 bucks.

* note to the OP that if you're just off student status you shouldn't demo either of the canopies in my previous post

[jumpwally 0]

I think his twins question is a reasonable one that could be answered here without pulling out the "expert card" or any other text book shit,,
sure spotting is key, and sure ,canopy skills change the out come, but the question wasn't how to get back to the spot !! the question was , given the scenario whats the likely or common outcome...this used to be a fun forum till everyone wants to argue theory and split pubic hairs...

smile, be nice, enjoy life
FB # - 1083

[Baksteen 84]

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The truth is that these days there's a canopy design out there for everyone, and 7-cell and 9-cell canopies are going to have overlapping flight characteristics.

DING DING DING

Ladies and Gentlemen, we got ourselves a winner.

"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

[kallend 2,106]

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

Pretty much. Just like if you can't pack, carry a reserve.

Or just pay $6 to a packer, it's cheaper than buying a reserve and doesn't encourage device dependence.

OTOH you COULD learn how to spot.

...

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

[billvon 3,075]

>Or just pay $6 to a packer, it's cheaper than buying a reserve . . .

I like it! "Use Packing Cathy and you don't need a reserve!"

>OTOH you COULD learn how to spot.

Definitely! Smart people know how to pack AND carry a reserve; smart people know how to spot AND can get back from bad spots. Since no matter how careful you are, bad spots and malfunctions happen.

[kallend 2,106]

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>Or just pay $6 to a packer, it's cheaper than buying a reserve . . .

I like it! "Use Packing Cathy and you don't need a reserve!"

>OTOH you COULD learn how to spot.

Definitely! Smart people know how to pack AND carry a reserve; smart people know how to spot AND can get back from bad spots. Since no matter how careful you are, bad spots and malfunctions happen.

Knowing HOW to fly your canopy will generally be more helpful. I know you have read lots of misinformation in the canopy forum on how to penetrate a headwind.

And I know how often you have cautioned against device dependence.

...

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

[billvon 3,075]

>Knowing HOW to fly your canopy will generally be more helpful.

Again, agreed. The ideal skydiver can spot, has a canopy that will get him back from bad spots, and can fly his canopy well. (And can probably do many other things that you may subsequently list.) Take away his higher glide ratio canopy and give him a steeper one, and he will land out more often - everything else being equal.

Is that a bad thing? At Perris, not really; it just means Tim comes and gets you. At other DZ's it might be a bigger deal. (Rumor has it there are alligators in the swamp in Spaceland, although I think that's mainly a story to scare wayward first jump students.)

[JohnDeere 0]

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Hi kal baby,
I'm really glad that I don't personally know you and I really hope that we never meet. If per chance we end up on the same dropzone if I end up on the same load as you I will surly scratch off. BTW I do drink beer, I'll never buy you any and you can keep drinking your koolade.

Nothing opens like a Deere!

You ignorant fool! Checks are for workers!

[skybill 22]

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Hi kal baby,
I'm really glad that I don't personally know you and I really hope that we never meet. If per chance we end up on the same dropzone if I end up on the same load as you I will surly scratch off. BTW I do drink beer, I'll never buy you any and you can keep drinking your koolade.

Hi JD,
I can hear yur laughter all the way here from NC By the way,
next Saturday 17OCT09 here in NC, in Sampson Cty, at McDaniels crossroads (just down the road a piece from my house) is going to be the "Old School" Sorghum Festival!!! They open up the old one room school house, community building, old general store/post office, people bring out old crafts, jelly-preserves making, "Sorghum syrup making" , stuff like that "AND" some old farts break out their old "JOHN DERRE" farm tractors (the antiques!!) and the old J D pump machines and RUN THEM!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Last year I heard the sound of an old JD tractor that I havn't heard in 40 years that old POP
Please note, 'just found out my date for the festival was a week off (I corrected above!) Freddie at the crossroads store told me the other day it was this comming sat the 10th, he was off by one week, sorry about that so I stand corrected it is the 17th!! the website for the festival is www.oldschoolsorghum.com check it out!!

SCR-2034, SCS-680

III%,
Deli-out

[fossg 0]

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...