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What's the real difference?

 

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andrewstewart

Sep 26, 2002, 9:14 PM
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What's the real difference? Can't Post

Hi,

I am told by an experienced individual that "any canopy that does not have exactly the same rib section in every cell is elliptical".

Given that, what is the real difference between say a Sabre2 and a Crossfire2 other than the degree of taper?

What factors contribute to the differences in the ways the canopies behave - given their separate design goals?

Many thanks in advance!

Regards,

- Andrew


rgoper  (C 32349)

Sep 26, 2002, 9:20 PM
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

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neither of these canopys are elipitical. i've heard of the Sabre2 being referred to as "semi-elipitical" BUT, i'm not sure about the Crossfire2, it may be fully elipitical, i'll have to check their website, when i do, i'll post some links that will help with your research.

Quote:
The Ultimate High-Performance 9-Cell!

When we released the Icarus Crossfire, we revolutionized what was possible with a 9 cell non-cross braced canopy.

The Crossfire is categorically a step up in performance from any other 9 cell in the world. Its swoop capability almost rivals cross-braced canopies such as the EXTreme FX while maintaining many other more desirable flight characteristics including a long recovery arc, an incredible swoop distance and with openings that are unparalleled.

The Crossfire 2 has the same impressive capabilities and now incorporates some of the most responsive toggle and riser control inputs of any canopy in the market. It has a light front riser pressure and an even longer recovery arc.

The Crossfire 2 is a highly elliptical, constant cell aspect ratio, closed nose, fully surface shaped inflatable wing capable of unrivaled performance.

It will out perform any non cross-braced 9 cell available.

Design:
The Icarus Crossfire is a High Performance Elliptical ZP 9-cell canopy designed specifically for experienced ram air pilots. The Crossfire is Highly and Truly elliptical in its planform shaping on both the leading and trailing edges. The cells vary in width across the canopy maintaining a constant cell aspect ratio to control distortion, and drooped wing tips are incorporated to minimize wingtip drag.

Unlike any other 9-cell, the nose is partially formed to give the canopy a more efficient leading edge (much like an aircraft wing). Our nose design not only improves the aerodynamics it also assists in controlling the openings. The structure of the nose also diagonally supports the non-loaded ribs during flight creating further rigidity at the leading edge & reducing distortion during the flare.

One big problem with HP elliptical canopies to date has been diving off heading openings. Through our development work with the Crossfire we reduced this dramatically. The Crossfire openings are among the most consistent and comfortable "stress free" openings available. The turns are very snappy and the canopy has a large recovery arc enabling it to dive for a long time and making it very easy to pick up speed. The flare is powerful and only exceeded by Cross Braced Tri-Cell Canopies like the EXTreme FX & VX. (Note: The Crossfire is NOT cross-braced and does NOT incorporate any valve systems.)

THE RESULT - An AERODYNAMIC WING with LESS DRAG, INCREASED RIGIDITY & MORE LIFT offering a greater performance than other 9 cells at both low and high speeds. The Crossfire is specifically designed for experienced skydivers wanting Maximum Performance from a Modern HP Elliptical who don't want to go as far as a Cross Braced Tri-Cell, or for those who have been wanting to fly high performance 9-cells but have been previously cautious about opening issues.

THE ICARUS CROSSFIRE: An impressively balanced, No hassle High Performance Wing. Truly Elliptical - High Performance ZP 9-Cell - No Cross-Bracing or Valve Systems - Fully Formed Nose - Superb Openings - Impressive Landings. As with all our canopies the Crossfire is available in any size you choose.

We recommend wing loadings from 1.4psf to 2.1psf.

The Crossfire2 Is fully elipitical, 9 cell zp canopy, this is off of Icarus's website.

now this from Sabre's website, i shall retrieve more information to answer your original question.

Quote:
A new breed.
Not just a modified Sabre, the Sabre2 is the latest, totally new design to emerge from 15 years of ongoing research and development.

This canopy is destined to become one of the most popular designs we have ever conceived.

From the moment you release the pilot chute, the Sabre2s consistent, soft, on-heading openings will please you. Pilots of the original Sabre will immediately notice the Sabre2s more crisp and positive response to toggle input, along with its lighter toggle and riser pressure. When it comes to landings, everyone will be amazed with the incredible amount of lift available on landing. This lift gives the Sabre2 pilot a tremendous ability to slow down when you wish to.

The Sabre2 will feel aggressive at higher wing loadings while maintaining its incredible ease of landing and forgiveness at lower wing loadings. The Sabre2s performance envelope is huge.

If you are looking for a canopy that represents the evolution of modern, carefree performance, the Sabre2 is it.

no mention of being elipitical at all.


(This post was edited by rgoper on Sep 26, 2002, 9:35 PM)


Premier PhreeZone  (D License)
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Sep 26, 2002, 9:21 PM
Post #3 of 63 (2057 views)
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

Trim, Airfoil design, planform, aspect ratio, etc all decide on how a canopy flys.


Kris  (D 26033)

Sep 26, 2002, 9:25 PM
Post #4 of 63 (2053 views)
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

Technically, they are both elliptical.

However, their difference in aggressiveness depends on several factors such as amount of planform taper, trim, angle of attack, etc...

Whereas you could put most newbies on a Sabre2, Spectre, or Safire loaded 1:1 with no problems, that same person on a Crossfire2 or Stiletto is going to be flying a much more maneuverable, unforgiving (in handling & opening stability), and twitchy canopy.

I'm sure one of the propeller-heads (Yo! Bill!) will be in here soon to give exact details.

Kris


AndyMan  (D 25698)

Sep 26, 2002, 9:26 PM
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

A real eliptical is exactly that - an elipse. An elipse is sort of a smushed circle. A true eliptical approximates the mathematical shape of an elipse. A true elipse is symetrical along both its X and Y axis. A stileto comes close, I don't think a Sabre2 does.

That said, to answer your question of what is the difference between a Stiletto and a Sabre2 besides degree of taper? Well, the difference mostly IS the degree of taper. I understand there's also a difference in trim, as well.

_Am


Premier PhreeZone  (D License)
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Sep 26, 2002, 9:26 PM
Post #6 of 63 (2052 views)
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

The Sabre2 is elliptical, and the Crossfire2 is for sure. The only truly non ellipticals being made any more are Sabre's (not Sabre2's), some Base stuff, Lightnings, reserves, Tri's and other older square designs.

A lot of it its semielliptical or elliptical is in the marketing. They market the lesser agressive canopies as semielliptical and the more agressive as fully elliptical. Technically you were right that if any rib is a different length then the rest the planform is considered elliptical.

A Crossfire has more taper angle then a VX, but the VX can swoop further thanks to the other factors.


(This post was edited by PhreeZone on Sep 26, 2002, 9:27 PM)


andrewstewart

Sep 26, 2002, 9:31 PM
Post #7 of 63 (2046 views)
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Quote:
neither of these canopys are elipitical. i've heard of the Sabre2 being referred to as "semi-elipitical" BUT, i'm not sure about the Crossfire2, it may be fully elipitical, i'll have to check their website, when i do, i'll post some links that will help with your research.

With all due respect, as the quote in my original post says - they are both elliptical.

I do appreciate however, that canopy manufacturers (specifically PD in the case of the Sabre2) prefer to use terminology other than 'elliptical' for marketing reasons.

I was trying to get to the reasons other than taper that contribute to the level of "performance".

Cheers,

- Andrew


andrewstewart

Sep 26, 2002, 9:37 PM
Post #8 of 63 (2039 views)
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Re: [PhreeZone] What's the real difference? [In reply to] Can't Post

Is there any documentation online or in a book that I can learn about trim, airfoil design, planform, aspect ration, angle of attack, etc?

Canopy flight school / pilots training / rigging courses are all beyond my financial capabilities at present! So Internet or book based materials would be ideal.

Thanks in advance,

- Andrew


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Sep 26, 2002, 9:43 PM
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

Get the stuff off PD's site on flight differences of the canopies, read BigAir Sportz manual, the stuff on here is great (manufactors post all the time), search the archives of rec.skydiving at groups.google.com. Look for people like George Galloway and John LeBlanc (PA and PD designers). Pick up Pointners Parachute manuals Vol 2 is focused on ram airs, Vol 1 is rounds mainly.

There is also a document out there from the Parachute federation in Aulstrlia that is geared right at what you are looking for.. .formulas complex theroy, the whole deal.

Shoot me a Private Message if you need more help then these.


(This post was edited by PhreeZone on Sep 26, 2002, 9:49 PM)


rgoper  (C 32349)

Sep 26, 2002, 9:45 PM
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Quote:
Is there any documentation online or in a book that I can learn about trim, airfoil design, planform, aspect ration, angle of attack, etc?

Go Here

this site should provide some useful information, and answers to your questions.


andrewstewart

Sep 26, 2002, 9:45 PM
Post #11 of 63 (2016 views)
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Quote:
no mention of being elipitical at all.

Just because PD doesn't mention that it isn't elliptical, doesn't make it not so ;-)

According to the definition that I was given (and quoted in my original post) it *IS* elliptical. Any other description is just marketing speak...

The point of my post was to say: "okay, so if these canopies are all 'elliptical', what other factors contribute to their performance in addition to degree of taper?".

- Andrew


andrewstewart

Sep 26, 2002, 9:48 PM
Post #12 of 63 (2010 views)
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Re: [PhreeZone] What's the real difference? [In reply to] Can't Post

 
Thanks PhreeZone for those links. Much appreciated.

- Andrew


rgoper  (C 32349)

Sep 26, 2002, 9:54 PM
Post #13 of 63 (2004 views)
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

Quote:
Just because PD doesn't mention that it isn't elliptical, doesn't make it not so ;-)

if it was, they'd say so, Icarus didn't mind saying it, it's a "selling point" and i posted you a link to further your own investigation(s) so you wouldn't have to rely solely on us in here. hope this helps.

Sabre2 Specs

follow this link, and you will see the Sabre2 IS NOT elipitical, it's "slightly tapered."


(This post was edited by rgoper on Sep 26, 2002, 10:01 PM)


andrewstewart

Sep 26, 2002, 9:58 PM
Post #14 of 63 (1998 views)
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Quote:
Just because PD doesn't mention that it isn't elliptical, doesn't make it not so ;-)
Quote:
if it was, they'd say so, Icarus didn't mind saying it, it's a "selling point" and i posted you a link to further your own investigation(s) so you wouldn't have to rely solely on us in here. hope this helps.

Er... are you actually even *reading* what I'm saying?

PD don't say "elliptical" when describing the Sabre2 precisely BECAUSE of marketing reasons.

Regardles, the Sabre2 *IS* elliptical by the definition given to me which is quoted in my original post. We're splitting hairs here.

- Andrew


Premier PhreeZone  (D License)
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Sep 26, 2002, 10:02 PM
Post #15 of 63 (1991 views)
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Anything other then a striaght edge canopy is elliptical. Tapered, semi-elliptical... they are just marketing lingo that targets specific audiences. A Safire is sold as "semi-elliptical" but it is really a true elliptical canopy since its leading edge and its trailing edge are not straight edges. A Stiletto is a higher proformace canopy that got the term elliptical a bad rap due to it being such an extreme departure from the norm when it was released a lot of people had never worried about flying the openings and thus it resulted in lots of spinning mals. Elliptical was a bad word in terms of students and low time jumpers so the marketing departments had to come up with something that was'nt so feared by people that had been aroud for a while and heard the stories about how wild an elliptical was. Semi elliptical was what some chose to use for marketing since it was'nt as much of a taper as the original elliptical designs.

My final word on this one for the night... if the canopy is not a truely straight leading and trailing edge the canopy is elliptical no matter what the marketing lingo is they have placed on that canopy.


rgoper  (C 32349)

Sep 26, 2002, 10:03 PM
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

Quote:
Regardles, the Sabre2 *IS* elliptical by the definition given to me which is quoted in my original post. We're splitting hairs here.

please follow the link posted above, in my last post, if further litigation is desired, i'd prefer you take it up with PD themselves, the canopy is, what they say it is in the adobe acrobat file in the link i posted.


Kris  (D 26033)

Sep 26, 2002, 10:04 PM
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Re: [PhreeZone] What's the real difference? [In reply to] Can't Post

Erk, Thanks for posting all of that before I had to.Cool

Quote:
please follow the link posted above, in my last post, if further litigation is desired, i'd prefer you take it up with PD themselves, the canopy is, what they say it is in the adobe acrobat file in the link i posted.

Richard,

What PD is discussing is marketing-speak, we're talking actual geometry and design.


Kris


(This post was edited by Kris on Sep 26, 2002, 10:07 PM)


andrewstewart

Sep 26, 2002, 10:07 PM
Post #18 of 63 (1977 views)
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Quote:
follow this link, and you will see the Sabre2 IS NOT elipitical, it's "slightly tapered."

*sigh* I don't think I need to say anything more. Other people reading the thread can make up their own minds.

By the way, the person who said the quote on my original post was Dan from Atair. Don't you jump a Cobalt Richard?

- Andrew


(This post was edited by andrewstewart on Sep 26, 2002, 10:08 PM)


Premier PhreeZone  (D License)
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Sep 26, 2002, 10:08 PM
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

http://www.performancedesigns.com/docs/Sabre2-Flight.pdf

>no mention of being elipitical at all.
Taken from the flight profile info: The Sabre2 from Performance Designs is a slightly tapered, zero-porosity nine cell canopy.

Other canopies that are marketed under terms like this: Safire, Hornet, Sabre2, Lotus.


rgoper  (C 32349)

Sep 26, 2002, 10:10 PM
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Re: [Kris] What's the real difference? [In reply to] Can't Post

Click Here For ALL PD Canopies

you guys need to do some research, it's all on their site. black and white letters, in english. you'll notice the x-braced, fully elipitical canopies are described as just that, as are the others as to what they are/are not. Wink


andrewstewart

Sep 26, 2002, 10:13 PM
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Quote:
you guys need to do some research, it's all on their site. black and white letters, in english. you'll notice the x-braced, fully elipitical canopies are described as just that, as are the others as to what they are/are not

You seem to exist in a world in which every word that is written on a web site is taken as a literal truth. Listen to what PhreeZone and the others are telling you!

- Andrew


rgoper  (C 32349)

Sep 26, 2002, 10:14 PM
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Quote:
The HORNET Range of main parachutes are a "semi" elliptical 9 cell design incorporating zero porosity fabric and microline. HORNET sizes range from 120 Sq. ft. with a maximum all up flying weight of 144 lbs to 230 Sq. Ft. for a maximum all up flying weight of 276 lbs. HORNET parachutes, just as their close relative the HEATWAVE, are manufactured with unique fabric woven with the finest microfilament yarns available but with more yarns per square inch than any other zero porosity fabric. The unique fabric is marginally stronger and lightly coated with silicon which ensure easy neat pack jobs every time. The top panels, bottom panels, and all ribs of the HORNET Range are accurately, and individually cut to an exact shape and contour to fit into the neighboring panels + ribs of the planform of the entire airfoil. The result of such an advanced contoured design is a canopy with reduced drag and enhance lift (or performance).
The semi elliptical design offers quick turn speeds but a canopy known for on-heading openings while at the same time maximizing interior pressurization for maximum stable penetration and light toggle pressure.
Quote:

ahem......................straight off of Pisa's website.


rgoper  (C 32349)

Sep 26, 2002, 10:18 PM
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You seem to exist in a world in which every word that is written on a web site is taken as a literal truth. Listen to what PhreeZone and the others are telling you!

no, actually i live in a world of "reality" and i do my own research from the manufacturer's websites. i've provided you with the same advantage, don't listen to what any of us are saying, go look! Cool


andrewstewart

Sep 26, 2002, 10:19 PM
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Re: [rgoper] What's the real difference? [In reply to] Can't Post

Quote:
The HORNET Range of main parachutes are a "semi" elliptical 9 cell design

ahem......................straight off of Pisa's website.

So in fact we agree! Any canopy that is not "square" is elliptical. Terms such as "semi-elliptical" and "tapered" are simply marketing speak.

- Andrew


rgoper  (C 32349)

Sep 26, 2002, 10:21 PM
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Re: [andrewstewart] What's the real difference? [In reply to] Can't Post

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Don't you jump a Cobalt Richard?

yep, but i've jumped each and every one of the canopies in disscussion here at one time or another.


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