elliptical...semi elliptical...?

[frenchcloud 0]

could someone explain what the difference is between those...?is there a question of experience to fly one or another.?
thanks for helping

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The tongue is NOT only a tool for speech!

[Dazzle 0]

From http://www.performancedesigns.com/faq.htm#5
What is the difference between a tapered, elliptical, or semi elliptical canopy?

These terms refer to the shape of the wing when viewed from above. Any canopy that is not rectangular can be called either semi-elliptical or tapered. The amount of taper affects the canopy handling and performance, though in combination with several other parameters.

While the term elliptical is often used to describe some canopies, no skydiving canopies are truly elliptical. The curve in a canopy is approximated by a series of straight-line segments, and they do not form a true ellipse. What we are really dealing with here is the relative degree of taper from one canopy to another. This involves not only how much taper there is, but where it is located. Some canopies are more tapered than others, regardless of whether they are called "elliptical" or "semi-elliptical.”

PD prefers to use the word "tapered” for several reasons. As soon as skydivers began using the word “elliptical,” many people created the idea that every "elliptical" canopy will have certain specific characteristics, some good and some bad. In reality, a non-rectangular canopy may not have any of those characteristics. We like the term “tapered” because it simply means “not rectangular,” while the term “elliptical” implies certain things about a canopy that may or may not be true.

Rather than the actual shape of a wing, most jumpers are really interested in performance characteristics: how does the canopy open, fly and land? These characteristics are influenced by taper, but not totally dictated by it. The degree of taper is part of a whole package. Airfoil, aspect ratio and trim angle are also very important. Wing loading, or body weight compared to canopy size, is actually the main factor that determines canopy speed. The degree of taper generally influences the responsiveness of a canopy, though other variables come into play. This is why it is not necessary for a jumper to know exactly how tapered or “elliptical” a particular canopy is. The proof is in the performance, and in the handling.

Therefore, it is best to read descriptions of the various canopies, and try demos of those that might suit your needs. Dealing with all the different terminology used can be confusing. Just remember that this terminology is often just one company's choice of packaging, rather than actually describing something different or new. Every company wants their products to be viewed as different from another. These types of word plays are one way to achieve that. In the end, the canopy’s performance in the air is what really matters

[Chrisky 2]

A semi-elliptical is usually not tapered over the whole (or more than 3 outer cells) of the leading and trailing edges, while with an elliptical, the three center cells can be tapered as well, if i got it right.
Anybody with better knowledge please correct/support this.

As for the experience question, i think a semielliptical in general may not be as twitchy as an elliptical, but i haven't flown an elliptical yet. I'm flying a Paratec Faqtor, which is a semielliptical, and after like 80ish jumps on it, it definitely still has a lot more in the envelope than i am willing to push right now.

Transferring from a square to a semi or elliptical also carries differences in handling. Where i could do a quick left/right input on my square, it rocked a little, but that was it. A semi or elliptical may start spinning up, as they tend to respond quicker (although that attribute also largely depends on the canopies' size b/c of line length and resulting leverage).
HTH

The mind is like a parachute - it only works once it's open.
From the edge you just see more.
... Not every Swooper hooks & not every Hooker swoops ...

[johnny1488 1]

Its tough to say. The stiletto, one of the origonal "ellipticals" only has a taper on the 2 end cells.

A safire is tapered on the 4 outer cells.

Usually the term tapered or lightly elliptical means midrange canopy (safire2 sabre2 lotus ect.)

The term elliptical or highly elliptical usually means higher performance (crossfire2 stilleto katana samurai ect.)

Up until the safire1 I dont think many "elliptal" canopies in any sense were meant for anything other than experts. Now it seems manufacturers are moving towards more efficient designs for every type of jumper.

Elliptical itself does not inherantly cover any kind of flight characteristics, only the shape of the canopy. Make sure you know what you are jumping before you jump it!

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Chrisky 2]

Just curious; If not for shape and profile (and trim), how else can you determine (in terms of designing) a canopies' performance range?
I imagine there are different width and depth sizes among same sqft canopies, and i can imagine that to be quite a difference in their performance (ie. creation of lift, toggle input, stall properties).
Do manufacturers change the profile of a canopy along the width of the wing?

Any other factors i am not aware of? Materials for drag?
Of course handling of different canopies is hard to compare due to different frames of reference as well.

The mind is like a parachute - it only works once it's open.
From the edge you just see more.
... Not every Swooper hooks & not every Hooker swoops ...

[damion75 0]

Quote

Just curious; If not for shape and profile (and trim), how else can you determine (in terms of designing) a canopies' performance range?
I imagine there are different width and depth sizes among same sqft canopies, and i can imagine that to be quite a difference in their performance (ie. creation of lift, toggle input, stall properties).
Do manufacturers change the profile of a canopy along the width of the wing?

Any other factors i am not aware of? Materials for drag?
Of course handling of different canopies is hard to compare due to different frames of reference as well.

The ratio of the length to width is the aspect ratio - which is normally listed along with the other technical whatnot.

It varies hugely: My spectre is at 2.14 while the Sabre2 150 is 2.58 and the Stilleto 150 is 2.68...

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Not one shred of evidence supports the theory that life is serious - look at the platypus.

[johnny1488 1]

Generally lower aspect ratio canopies (7 cells) have a thicker profile (brainfarting on correct term), making them fly a bit slower but have a slower stall speed and better stall recovery traits. Likewise, higher a/r canopies (9+ cells) have a thinner profile and need more speed to fly. They also tend to stall at a higher speed and dont recover from stalls as well as 7 cells.

The trim, nose design and brake configuration/settings all help the manufacturer control the traits of their wings.

Johnny
--"This ain't no book club, we're all gonna die!"
Mike Rome

[Chrisky 2]

I KNEW there was a term for it...
Now i wanna find out mine! (Nope, it's not on the manufacturers' page... Looking for my manual&airwortyness certificate...)

The mind is like a parachute - it only works once it's open.
From the edge you just see more.
... Not every Swooper hooks & not every Hooker swoops ...