Basejumper.com - archive

Why is 'F-111' or low-porosity canopies used for base jumping over zero-porosity canopies?

The only reason I've come up with so far is that F-111 provides a fast but soft opening compared to zero porosity canopies. I've also read that it provides better on-heading openings, why?

Cheers,

Trent

http://www.basejumper.com/...irst_BASE_Rig_9.html

Hi Flipper, So you're saying the only advantage of a F-111 canopy is it is easier to pack correctly (therefore better on-heading performance)?

That's what I have read, yes. Probably why most reserve canopies are made out of F-111 as well.

Here are my reasons why in order of importance:

1. Heading Performance

2. Flight Characteristics

3. Pack Volume

4. Packing

5. Money

My main is a Sabre2-120 loaded 1.8+
with zero patches and second line set.

I BASE wings between 240 up to 300,
none ever get relined and all of them
end up with at least one patch by the
time they have around 200 jumps.

Keep thinking, researching, and asking.

You guys have already got it sooo wrong I don't know where to start.

This is incorrect. You can get hard openings on any canopy regardless of fabric type. (Dacron lines providing softer opening shock is closer to the truth here).

While F1-11 is easier to pack due to it being less slippery this is not the first reason I would think of for using F1-11 over ZP in regards to packing. Entire ZP canopies while being harder to pack also have undesirable opening characteristics that can result from being packed too tightly for too long ie. shit sticks together. This has been researched in skydiving and is one of the reasons why skydiving reserves are still made from F1-11.

This shouldn't even enter the equation and is incorrect any way. There is no reason why you couldn't pack a ZP canopy into the same space as an F1-11 one.

So why ARE BASE canopies made from F1-11? The predominant reason is the stable/docile opening AND flight characteristics it provides.
Large F1-11 7 Cells will provide:
1. More stable openings,
2. Better heading performance,
3. Better slow flight/sinking characteristics,
4. Less violent malfunctions.
F1-11 over ZP has a lot of other smaller benefits too but the ones above are the primaries.

This doesn't need to be the case. Maybe you could benefit from some canopy control lessons ;-)

It's definitely easier for a beginner to control the nose on an all F-111 canopy.

I've seen all ZP BASE canopies, and the advantages over F-111 were pretty limited (and the disadvantages were real).

Most BASE manufacturers offer an option for ZP on the front third of the top skin, which is well received and offers something like 80% of the flight benefits of an all ZP canopy but without most of the associated negatives.

I did a number of jumps on a Fox 245 with a full ZP topskin and didn't really enjoy it, but I was overloading it. Fuck it would swoop though.


For what it's worth I'm pretty sure that it doesn't need to be the entire third either. I'm pretty sure the benefits come from far less than that and the only reason they stick with a third is for ease of production. Note not all manufacturers do this.

I saw some wind tunnel tests a long time ago that suggested something like 65% of the benefit came from the leading 15% of the topskin, and something like 80% came from the leading 33%. I think that there is definitely a point of diminishing returns somewhere in there, but it's going to be a judgement call on where it is.

FWIW, the canopy I saw was an all ZP Mojo, and I couldn't really see much difference in flight between the all ZP canopy and a (full) ZP topskin version of the same wing.

Docile reliability!
Whereas Skydiving airfoils are moving more and more towards maximum flight performance, ( and incidentally away from opening reliability ), the BASE environment (use of only one canopy, obstacle avoidance, ease of landing in no wind, questionable terrain, durability etc,... ), isn't the place for high performance flight, and most of the efforts to upgrade BASE canopies center on opening reliability since Canopy flight improvements detract from obstacle avoidance.
To use Ski boots as an example, it's really not easy to improve on existing technology for the intended purpose, although improvements in materials allow smaller and more light weight equipment.
You are not likely to see BASE jumpers flying 60 to 70 square foot wings any time soon.
Unlike Skydiving, where Canopy piloting has become a discipline unto itself, BASE is about the jump platform and the freefall environment, the Canopy is simply a tool to safely repeat the experience.
Speed flying and Paragliding are the disciplines that canopy enthusiasts take to fixed object flight, Wingsuit and Tracking suit technology is enhancing the fixed object freefall experience.
Just my opinion, Regards, B.
So to make a long story short, the old technology has proven to be the most suitable.

I've always thought it was due to f-111 inflating quicker because air gets through the skin easier.
I jump a PD-9cell for skydiving and it opens in about 500'. It's fast but not hard.

65% or even 100% of nothing is still nothing. Point being the advantages of zp dont really manefest themselves at base wingloadings but the disadvantages do.

30% zp top is just marketing hype just like vents and black lines. Since the price of seven sell canopies is pretty much fixed by pd ect more ingenious ways need to be found to increase profit margins. classic upsell. Containers are even worse. Sorry for the thread drift.

ZP topskin I agree. Black lines are obviously just an aesthetic, noone really argues otherwise (although there's the whole dye thing). Vents are a very important preference (pros and cons to both)...it isn't a hype. It changes the opening dynamics (specifically timing between stages in the deployment).

Better opening characteristics at slow air speeds.

Thanks for all the info guys

It's more difficult to pack neatly, especially when new. The ZP fabric is more prone to catastrophic failure than 0-3 CFM F-111 *like* fabric. Depending on the coating, it can stick together if packed a long time.

As for CUS (composite upper skin), it has the advantage of helping the canopy to maintain it's performance over more of the life time of the canopy. Performance to me, means all flight modes slow and fast. It is not to be mistaken for high performance such as a skydiving canopy.

Some canopy designs utilize the CUS in a manner that's more efficient than other canopies. Considering it's only a portion of the top skin, it will not be prone to stick together, especially after a few jumps onto a dusty trail.