Size vs. Shape For Increased Performance

[bmcd308 0]

I am probably 220 out the door.

I'm considering replacing my trusty Hornet 190 with a sportier model. I want advice from people about the relative merits of a big elliptical canopy (Maybe Stiletto 170) versus a smaller canopy with a less aggressive cut (maybe a Nitron 150).

I jumped, in perfect conditions, a Nitron 135 a couple of months ago, and I had a good time on it, although I know that I do not want a Nitron at that wing loading as the canopy I have to land every time.

I also jumped a Stiletto 170 this weekend, and I had a great time on it.

In an attempt to try to keep this on topic, I am just looking for general opinions on the whole shape vs. size thing. An example of a question I would like answered is whether you guys would rather have a bigger elliptical than a smaller square when you are landing off in a difficult area.

All responses appreciated.

Brent

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www.jumpelvis.com

[PhreeZone 15]

Who says a Nitron is not as "shaped" as a Stiletto? They are both fully ellipitical canopies that are designed for advanced pilots.

Personally, a better canopy would be a semielliptical canopy. Sabre2, Lotus, Safre2 are all options.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[bmcd308 0]

>>Who says a Nitron is not as "shaped" as a Stiletto? They are both fully ellipitical canopies that are designed for advanced pilots.<<

Interesting point. I am certainly not in a position to argue that the Nitron is any less aggressively cut than the Stiletto. I will say that my perception of the Stiletto 170 at 1.3 was that it had response to the toggles that was similar to the Nitron at 1.6.

Interestingly, I thought that the Stiletto may have required MORE front riser pressure to start a diving turn than my Hornet does. The Nitron felt like it was looking for a place to break my pelvis as soon as I pulled down on a front riser.

Brent

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www.jumpelvis.com

[diablopilot 2]

Quote

(Maybe Stiletto 170) versus a smaller canopy with a less aggressive cut (maybe a Nitron 150).

There is nothing less agresive about the Nitron (or Nitro) vs. the Stiletto.

It is rarely advisable to downsize AND change to an eliptical in the same step.

If and ONLY if you are comfortable under the 170 size, you might consider the 170 Nitron, or Stiletto to be a next choice. The 150 is NOT a sensable choice,at this time if your profile is up to date as your loading would be nearly 1.5 lbs per sq ft. You want to be comfortable with the planform you are flying prior to making the jump to that loading.

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You're not as good as you think you are. Seriously.

[jmfreefly 0]

Also realize that 'size' is not always equal between mfgs (or even within a mfg.. case in point, Safire and Safire2 have size calculated differently)

I agree with you that the Nitron turns slower (to my feel). But it can dive like a banshee (looking for that pelvis breaking spot).
Also a factor in perceived quickness of turns is the line length. Different sized canopies are not usually exact copies that are exactly proportional. I think some of the very small canopies actually make the line lengths longer (so the canopy retains a proper shape).

j

[Ron 7]

Quote

I'm considering replacing my trusty Hornet 190 with a sportier model. I want advice from people about the relative merits of a big elliptical canopy (Maybe Stiletto 170) versus a smaller canopy with a less aggressive cut (maybe a Nitron 150).

Size equals speed in most cases. (A more agressive line trim will also effect speed)

Shape will effect toggle presure, and response to inputs...Harness, toggles, risers...ect.

You need to decide what level of feel (Shape) you want, then pick a speed (Size) that you like and can handle.

I tell folks to change shape before picking a size.

"No free man shall ever be debarred the use of arms." -- Thomas Jefferson, Thomas Jefferson Papers, 334

[psw097 0]

I think yellow canopies are the most aggressive. Otherwise, all canopies at the same wingloading will fly about the same speed. Some will turn fast with toggles, some faster on front or rear risers, blah, blah, blah. Personal preference.

The whole elliptical = agressive thing is nothing but marketing. We have to have something to differentiate products.

[NeedToJump 0]

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The whole elliptical = agressive

Right, so you're saying it's just marketing telling me that a Stiletto 120 turns faster and is more responsive than a Sabre 120?

Wind Tunnel and Skydiving Coach http://www.ariperelman.com

[psw097 0]

Nope - its marketing that tells you that because it's "eliptical" it turns faster and is more responsive.

Your Stiletto is much more tapered than my FX - do you think it turns faster and is more responsive? What is the definition of responsive, aggressive, faster. The same stiletto to sabre comparison - which one is "faster?" The Sabre is trimmed steeper and will feel fast - does that make it more aggressive?

It is marketing that tries to envoke an emotional response based on one or two parameters. Its engineering that defines the entire package.

[prost 0]

A same size and same loaded Stiletto will turn faster than an FX. The FX will dive a lot more causing it to build up more speed for landing but it will not turn as fast.

[Tonto 1]

Smaller the landing area, the bigger the canopy.

"If you have holes in your jumpsuit - your canopy's too small."

t

It's the year of the Pig.

[diablopilot 2]

Quote

Nope - its marketing that tells you that because it's "eliptical" it turns faster and is more responsive.

If you believe that tripe, I've venture the hypothesis that you haven't done a whole lot of real world testing, and you are not able to separate the different factors that contribute to "performance".

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You're not as good as you think you are. Seriously.

[DancingFlame 0]

From PD's document (wingload.pdf)

General Concepts that are frequently misunderstood

A. Different canopy models of the same size may perform differently, but they will
fly approximately the same speed.
Wing loading is the biggest determinant of speed. A Stiletto 190 is not really faster
than a Sabre 190, or even a PD 190! Other aspects of performance will be different,
however. (Turn rate, glide angle, etc.) These differences may influence a person’s
impression of speed.

B. A person evaluates a canopy’s speed according to their individual frame of
reference, which has been created through their own, unique experiences.
Example: Jumper A and jumper B weigh the same, jump the same canopy, and have
the same number of jumps. They may have completely opposite opinions of the
speed and handling of their canopies. Why? Different frames of reference! The
canopy may be the smallest one jumper A has flown. He may have chosen it to get
more speed, quicker turns and hotter landings, and might feel that it’s a handful! Yet
jumper B may have moved up one or two sizes to this canopy, to create more
forgiving handling and easier landings than he had previously.

C. When discussing the speed and forgiveness of a particular canopy, remember
the different frames of reference of the individuals involved.
Be careful to avoid projecting your frame of reference onto a person to whom you’re
describing a canopy. Example: If a person is asking advice about trying a new
canopy that is much larger than what you are currently jumping, you’ll likely consider
it rather slow and docile. But telling them so could be a big mistake if they’ve spent
their whole skydiving career on a much larger canopy. Regardless of how you feel
about the canopy, it will be the fastest, most responsive canopy they’ve ever jumped.
This is true regardless of any wing loading calculations you might make.

D. It is not necessary to heavily load a high performance canopy to make it fly and
land correctly.
This is a common misconception even with many experts. If a person’s canopy is
going the speed they are comfortable with, then that should be fine. If they’re not
getting good landings on a properly designed canopy flown at a lower wing loading,
they’re probably not flaring it correctly.
E. Choose your canopy size by reflecting on your impression of the canopy sizes
and models you have recently flown, combined with your desire to go faster or
slower.
Choosing a canopy this way is much safer than using only a chart published by a
manufacturer. Such a chart may be a rough guide, but cannot be used effectively
without applying your own experience. If you don’t want to go faster, don’t go smaller
than what you are using!

[diablopilot 2]

Quote

A. Different canopy models of the same size may perform differently, but they will
fly approximately the same speed.
Wing loading is the biggest determinant of speed. A Stiletto 190 is not really faster
than a Sabre 190, or even a PD 190! Other aspects of performance will be different,
however. (Turn rate, glide angle, etc.) These differences may influence a person’s
impression of speed.

I've seen this, John LeBlanc does a pretty good seminar on it.

The danger in puting someone who is inexperienced on an "eliptical" planform does not come from "speed". As can be see from the above, a 190 Stiletto for example is really no different in SPEED than a 190 Sabre. The difference, and the danger (aside from opening problems) lies in the fact the the Stiletto will a) react (turn) more radicaly (read: unexpected) to a smaller control input, and b) react faster to a control input.

Example: A novice flying a Sabre loadeds at 1:1 comes in crosswind and flares weakly and unevenly due to percived motion across the ground. Result: the crash in, but because the reactions from the cotrol inputs is reativly docile, the dust themselves off and walk in so their buddies can joke about it with them.

Same situation, but the novice is flying a Stiletto of the same size, the reactions from the SAME control imputs cause the canopy to dive radicaly to the down wind side, producing a broken ankle, leg, hip, or worse. It the novice is lucky they can joke about it from their hospital bed.

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You're not as good as you think you are. Seriously.