"Tapered" vs "Semi-Elliptical" vs "Fully-Elliptical" vs "Cross-braced"

[Elisha 1]

So what is the difference is the difference in generalities along with some canopy examples. I think I can figure most out, but it would be nice to have something from you more experienced types. Thanks.

make it a sticky?

[crazydiver 0]

No canopy is truly "fully elliptical." Canopies are tapered and can be called elliptical. There is no set standard on what defines these different terms. They are all just marketing words from manufacturers. They also CAN help a person guage how aggressive a canopy is though. While they aren't completely accurate, nor standardized, generally a canopy that is called "tapered" is less aggressive than one labeled "semi-elliptical" and the same for "fully-elliptical." crossbraced is not the planform, its the cell construction. Cross braced does, however, signify that it is more agressive than any ordinary nine cell canopy.

Cheers,
Travis

[marks 0]

an elliptical wing is a tapered wing.

some wings are tapered more than others.

there is no such thing as semi elliptical, just some are more tapered and some less.

crossbraced wing means that there is brace between cells that is added, and it goes across from one side of the rib bottom, to the other rib top. crossbracing holds the wing a little more rigid, and reduces that "bubble look" between each cell, the wing is held a little more flat.

[Elisha 1]

Thanks so far...some examples?

I think someone here has mentioned that the Sabre 1 is completely "square", while the Sabre 2 is "tapered" or "semi-elliptical".

[nathaniel 0]

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an elliptical wing is a tapered wing.

And it's a pity that people use that word, elliptical. That happens to be a math word with precise meaning. Contemporary canopies are no more elliptical than they are circular.

My advice is to do what your parents did; get a job, sir. The bums will always lose. Do you hear me, Lebowski?

[mattjw916 2]

A few examples:

"Square": Sabre, PD Reserve, Triathalon (IIRC)

"Tapered/Semi-Elliptical": Sabre2, Safire 1&2, Lotus, Pilot, Fusion, Spectre, Navigator, Silhouette, etc...

"Elliptical/Fully-Elliptical/High-Performance": Samurai, Stiletto, Nitro(n), Katana, Crossfire 1 & 2, Jedei, Cobalt, Blade, etc...

"Cross-braced": Extreme FX, VX, JVX, Xaos-21, 27, Velocity, etc...

"Defies description": Diablo

NSCR-2376, SCR-15080

[Vectracide 0]

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crossbraced wing means that there is brace between cells that is added, and it goes across from one side of the rib bottom, to the other rib top. crossbracing holds the wing a little more rigid, and reduces that "bubble look" between each cell, the wing is held a little more flat.

I would like to expound on this issue if I can for a minute.... Lets look at the Katana vs. the Velo.

A couple thoughts first:

The dive characteristics are very similar, being the Katana does not dive as much as the Velo.

So, in swooping the idea is to aquire as much speed as possible to go further with more control.

Efficency is the key here, which by my guess, is why the Velo dives and has such a longer swoop than the Katana. The wing is flatter and more effiecent.

SO.....Devils advocate here to create some thought provoking posts.....why the big stigma of "oooohh its a cross-braced", "you shouldn't be jumping that". "Fly the Katana instead, its better suited for you". I see that posted here alot, and for most, its a good argument.

What I am trying to grasp here is why the overruling thought of flying a less effiecient, poorer opening characteristics, less rigid wing with less shut down power if you are going to be flying it the same as if you had a crossbraced at the same wingload?

Your thoughts on the inherent differences between these 2 canopies for inquiring minds.

------------------------------

Controlled and Deliberate.....

[Elisha 1]

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A few examples:

"Square": Sabre, PD Reserve, Triathalon (IIRC)

"Tapered/Semi-Elliptical": Sabre2, Safire 1&2, Lotus, Pilot, Fusion, Spectre, Navigator, Silhouette, etc...

Ahh, thank you. I'm guessing this could be why the Pilot of the same size I jumped seemed to have a little sharper turns than my old Sabre (although I prefered my Sabre's steeper glide).

[Falko 0]

You might want to check out this document from Aerodyne about the "Planform factor".
It describes ellipticity in numbers rather than terms like "semi-elliptical" etc.

Ich betrachte die Religion als Krankheit, als Quelle unnennbaren Elends für die menschliche Rasse.
(Bertrand Russell, engl. Philosoph, 1872-1970)

[tso-d_chris 0]

From Dictionary.com:

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ellipse

n : a closed plane curve resulting from the intersection of a circular cone and a plane cutting completely through it; "the sums of the distances from the foci to any point on an ellipse is constant"

Elliptical is a mathematical term often misused in skydiving. If a wing is truly and fully elliptical, it is shaped as an ellipse, with the ends truncated (cut off). This means that the front taper and the back taper are the same, and (math stuff follows) the combined distance between any place on the leading or trailing edge and each of the two focal points will be constant.

Literally, semi-elliptical means half or partially elliptical. This could mean that only the leading edge or trailing edge of the canopy or the traliling edge of the canopy is based on an ellipse. It could also mean that the profile of the ellipse has been truncated from some number of center cells.

Tapered just means that the chord length of each cell is different, with the outer cells being the shortest, and the center cell the longest.

Cross bracing isn't a characteristic of the airfoil planform; it is a type of cell construction that reduces distortion of the wing, and makes the wing more rigid than traditional canopy designs.

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[EAerodyne 0]

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You might want to check out this document from Aerodyne about the "Planform factor".
It describes ellipticity in numbers rather than terms like "semi-elliptical" etc.

I'd be very interested from people who have read this document as to if they think it is something that we (the industry) could use as a method for measuring a canopy as to it's ellipticity.

The initial reason for this document was to aid some jumpers in countries where it is not permitted to jump an elliptical canopy till they have a "D" or equivalant license. The ideaology was that if we gave a method of measurement, it would allow those countries to make some determination as to if a semi tapered canopy was too aggressively tapered or elliptical for novice/intermediate use.

Blue Skies

Bushman

[tso-d_chris 0]

It is inconsistent with mathematical definitions, which are what should be used, IMO. The methods and formulas offered don't offer me useful info about the planform shape.

[EAerodyne 0]

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It is inconsistent with mathematical definitions, which are what should be used, IMO. The methods and formulas offered don't offer me useful info about the planform shape.

Do you have a suggestion on a format to give you something that is easy for the layman to understand and measure?

Regards

Bushman

[tso-d_chris 0]

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It is inconsistent with mathematical definitions, which are what should be used, IMO. The methods and formulas offered don't offer me useful info about the planform shape.

Do you have a suggestion on a format to give you something that is easy for the layman to understand and measure?

Regards

Bushman

A picture is worth a thousand words. A projection of an inflated canopy would offer an easy way to differentiate the planform of different models. If manufacturers and PIA could settle on an industry standard for getting the projection, it could also be used to compare canopy shapes from one manufacturer to another.

I can take your formula and get the same result for various similar but distinctly different shapes and get the same result. These different shapes would likely have significantly different flight characteristics. So it really doesn't tell me much.

I would rather see detailed (cell by cell) specs on the canopy, including other factors such as trim angle, frontal surface area, etc. And then offer downloadable articles on your website explaining the effects of differences for all the different factors. You will be surprised what new and old skydivers will read to learn more about their equipment.

For Great Deals on Gear

[EAerodyne 0]

I would rather see detailed (cell by cell) specs on the canopy, including other factors such as trim angle, frontal surface area, etc. And then offer downloadable articles on your website explaining the effects of differences for all the different factors. You will be surprised what new and old skydivers will read to learn more about their equipment.

[tso-d_chris 0]

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A daunting project.... and I can only say from my experience of when I still worked at PD, that your request would be a daunting project even with a large company's such as theirs. Basically the resources to actually get all of that from engineering and put into to an educational document would be a hugely time consuming and resource draining excercise.

True. It would not be easy. And probably not fast. But it would be appreciated, and helpful when trying to get out good information. I had to ask.

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That when one gives that much information away regarding your prized product where you spent all your resources for the past couple years developing... there would probably be more than a little concern at that information being available to your competitors.

You don't believe the other manufacturers have not already purchased your gear to test, measure and otherwise scrutinize, do you? They already know your secrets.

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[teason 0]

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No canopy is truly "fully elliptical."

The Firebolt is a true eliptical. I believe it's based on a truncated 3:1 elipse.

I would rather be a superb meteor, every atom of me in magnificent glow, than a sleepy and permanent planet.

[Elisha 1]

I have a math degree, so I was rather sure that at least a or most "Fully-Elliptical" canopies really were not.

So, do I assume correctly that at least industry speak, "tapered" = "semi-elliptical" (e.g. Sabre2, Pilot, Safire2) and "fully elliptical" would be a Stiletto/Katana/Mamba/Crossfire 2?

[rmsmith 1]

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I have a math degree...

Then you know the difference between surface area v. the area of projection, right?

[Elisha 1]

...but I'm not a Topologist.

[rmsmith 1]

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...but I'm not a Topologist.

Use some judgement in your canopy choice, and take the time to see what the old-timers fly. They are still active in the sport many years later because they made wise gear decisions.

/* BTW, do you SAS at your job? */

[tso-d_chris 0]

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I have a math degree, so I was rather sure that at least a or most "Fully-Elliptical" canopies really were not.

So, do I assume correctly that at least industry speak, "tapered" = "semi-elliptical" (e.g. Sabre2, Pilot, Safire2) and "fully elliptical" would be a Stiletto/Katana/Mamba/Crossfire 2?

Yes, I think the general perception is that the semi-elliptical canopies are the "well behaved" tapered canopies while the fully elliptical canopies are the nylon version of a fighter jet.

IIRC, at least the Safire2 is marketed as fully elliptical. I can't be sure at the moment about the Sabre2 or the Pilot.

Take the terminology with a grain of salt.

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[Elisha 1]

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I have a math degree, so I was rather sure that at least a or most "Fully-Elliptical" canopies really were not.

So, do I assume correctly that at least industry speak, "tapered" = "semi-elliptical" (e.g. Sabre2, Pilot, Safire2) and "fully elliptical" would be a Stiletto/Katana/Mamba/Crossfire 2?

Yes, I think the general perception is that the semi-elliptical canopies are the "well behaved" tapered canopies while the fully elliptical canopies are the nylon version of a fighter jet.

IIRC, at least the Safire2 is marketed as fully elliptical. I can't be sure at the moment about the Sabre2 or the Pilot.

Take the terminology with a grain of salt.

I'm just trying to figure out what the terminology is supposed to mean. Are you sure you don't mean the Crossfire2? I wouldn't think the Safire2 would be considered in the same class as the Pilot or Sabre2 if it is indeed considered fully elliptical.

[phoenixlpr 0]

IMHO:
Term like "Elliptical","Semi-Elliptical" vs "Fully-Elliptical"
are Marketing Mambo-Jambo.

Does "multimedia" or "hybrid composite (material)" make any sense?

[jakee 1,489]

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I'm just trying to figure out what the terminology is supposed to mean. Are you sure you don't mean the Crossfire2? I wouldn't think the Safire2 would be considered in the same class as the Pilot or Sabre2 if it is indeed considered fully elliptical.

It's just another example of marketing speak, I'm pretty sure that Icarus uses the phrase 'truely elliptical' to describe not only the Safire2 but also their Spectre equivalent 7-cell canopy.

Truely elliptical and lightly elliptical at the same time.

Do you want to have an ideagasm?