True SQ footage of a canopy?

[crotalus01 0]

I recently switched from a Sabre 1 190 to a Safire 1 189 after my Sabre tried to kill me and was shredded in the process. I know the Safires have odd square footage numbers, and was wondering what the actual sq footage of the 189 is - I have heard it is closer to 180 sq feet but wanted to see if anyone here knows. Thanks.

As for me and my house, we will serve the LORD...

[Deyan 36]

Quote

I recently switched from a Sabre 1 190 to a Safire 1 189 after my Sabre tried to kill me and was shredded in the process. I know the Safires have odd square footage numbers, and was wondering what the actual sq footage of the 189 is - I have heard it is closer to 180 sq feet but wanted to see if anyone here knows. Thanks.

Will be around 170-175.They are 8-10 % smaller.

All best

"My belief is that once the doctor whacks you on the butt, all guarantees are off" Jerry Baumchen

[shropshire 0]

I think that it depends how they measure it ...

Something about 'Projeced Areas' .vs. 'Flat Surface Area' (or some such) comes to mind but I don't recall too much about it ...... I'll do a search.......

(.)Y(.)
Chivalry is not dead; it only sleeps for want of work to do. - Jerome K Jerome

[TheCaptain 2]

This is from a post I did years ago about the Safire1

I e-mailed Icarus and explained that this had been talked about here and if they could give me a reply that I could post so here is Icarus's reply

The Safire-1 and the Omega are measured differently to PD canopies. As a rough guide a Safire-1 or Omega is about the same size as the next size down - eg A Safire 149 is about a 135. A Safire 119 is about a 109. Use an equation of 8%.
The Safire-2 and Omni (Omni supercedes Omega) are measured the same as
PD.

All other Icarus Canopies are measured the same as PD.

The reason for the difference is due to Precision measuring their canopies differently. Icarus have always measured the same as PD however when we originally commenced in the USA, Precision were building parachutes for us under license and were doing it using their size equations and not Icarus/PD's.

We have therefore had to wait to supercede these models to change the size equation.

Only the Safire and Omega were affected.

Blue skies
Simon

Icarus Canopies
USA: 1S671 Bender Lane, West Chicago, IL 60185, USA
Ph. (630) 562-2735, Fax (630) 231-4430
Europe: P.I. El Ramassar, c/ Vallés, s/n O8520,
Les Franqueses, Barcelona, SPAIN.
Ph. (34) 938 496 432, Fax (34) 938 497 971
www.icaruscanopies.com

Kirk
He's dead Jim

[crotalus01 0]

Okay, so the bottom line is that I am now jumping a 170 even though Icarus measures it as 189 square feet?

As for me and my house, we will serve the LORD...

[phoenixlpr 0]

Do you have the concept of projected area?

[Skydivesg 7]

Isn't that when you start out making the canopy, you project the size to be 189 sq feet but because you were running low on material, it actually ended up being 170 sq feet?

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

[riggerrob 643]

There are two popular methods for measuring ram-air canopies: PIA and PD.

The PIA method measures chord straight from the top leading edge to the tail seam and measures span across the top skin, 6 inches back from the top leading edge. The PIA measurign method was developed by Para-Flite, who taught PISA, etc.

Since the PIA method works best for canopies in the 200 square foot range, and is awkward with tapered (aka. elliptical) canopies, Performance Designs invented a simpler measuring method that measures span across the bottom skin, so that PD canopies fly "bigger" than their advertised size. Most manufacturers now use the PD measuring method.

Just to mess with you (Tee! Hee!) in 2001, Icarus changed their measuring method from PIA to PD.

[riggerpaul 1]

Quote

I recently switched from a Sabre 1 190 to a Safire 1 189 after my Sabre tried to kill me and was shredded in the process. I know the Safires have odd square footage numbers, and was wondering what the actual sq footage of the 189 is - I have heard it is closer to 180 sq feet but wanted to see if anyone here knows. Thanks.

It is not trivial to determine what is the "right" way to measure a canopy.

As has been pointed out, there are methods in use that result in different numbers for different designs. None of these methods is "the right" one. All are approximation.

Further complicating the matter is the question of *when* to measure. Do you measure on the cutting table or in flight? Canopies are not rigid - they change their shape and size when you inflate them.

Rigid wings on aircraft are generally measured using the "planform area" technique. This is approximately using the shadow of the wing on a flat surface below it. Another way to think of it is to imagine a the cross section of a vertical column containing the wing. If the wing is sharply tilted nose-up or nose-down in that column, the area can change signigicantly.

The planform area technique works well on rigid wings, but is not so easy to do on an inflated wing like a ram air parachute.

Then there's the question of how to factor in other aspects of the design, like the effect of the stabilizer design. Part of the effect of the stabilizers is to alter the "leaking" of high pressure below the canopy around to the top of the canopy. This is similar to winglets that are now often found at the wingtips on airplanes. Limiting the flow of high pressure from below the canopy means that you get better efficiency from the available lifting area, effectively increasing the span of the wing. If you don't factor this in, the performance of one canopy in relation to another may not be accurately represented. Two canopies, one with stabilizers that are more effective at this than the other, could result in the same number for measured area. But that number would not necessarily give you an accurate representation of the performance you should expect to experience from either canopy.

The stabilizer question is just one factor, I am sure there are lots of other things that come into play as well.

Simply measuring the canopy, by whatever method you prefer, is not necessarily going to give you the information you really want to know. - that being, how this canopy will perform when it is being flown.

That's why the best advice is to fly all the canopies you are considering and seeing which one your prefer. The number just won't tell you what you really want to know.

[billvon 3,120]

>If you don't factor this in, the performance of one canopy in relation to
>another may not be accurately represented. Two canopies, one with
>stabilizers that are more effective at this than the other, could result in
>the same number for measured area. But that number would not
>necessarily give you an accurate representation of the performance you
>should expect to experience from either canopy.

Definitely true - but also true for far more than canopy size. A Katana is not going to fly like a Triathalon no matter what measurement system you use.

Canopy size, at best, is just one step in figuring out how a canopy will fly and whether or not it's appropriate for a jumper. Having a common way to compare canopy sizes is pretty useful for that. It doesn't have to be accurate, it just has to be consistent from canopy to canopy and manufacturer to manufacturer.

[crotalus01 0]

Thanks for the info. I was just trying to recalculate my WL.

As for me and my house, we will serve the LORD...