Re: [ArmitageShanks] wing loading
In reply to:
...at what point does a wingloading become dangerously low, if at all? Would a .65 be problematic? .6? Is there a point you shouldn't go beyond?
I have jumped canopies as highly loaded as .92 and as lightly loaded as .58. Note that the .75 wingloading is a general guideline, which can be innaccurate at the high and low ends of the scale (because canopies do not scale precisely, hence neither does wingloading).
The answer to this question will vary, depending on several things, such as:
1) What kind of object you are jumping
On a solid object, it is more important to have (a) a docile canopy on opening (hence, a bigger canopy) and (b) a quicker, cleaner opening (hence a smaller canopy). When I have taken my wingloading below about .65 (no vents) or .6 (vents) I've found the openings become unacceptably unpredictable. In my experience, this is not a gradual progression. It's more of a bright line. At some point, as you drop your wingloading lower and lower, you hit a size where the canopy just doesn't open right. Adding some weights (or downsizing) pretty much fixes the problem immediately. I suspect that this point occurs at different places on different canopies, generally following the rule that canopies with cleaner openings experience it at lighter wingloadings (so, if you are jumping an unvented Troll or FOX, you will hit it sooner than on an Ace or Mojo, with the vented canopies--Blackjack, FOX and Flik Vtec, Troll MDV--allowing the lightest wingloadings of all).
2) What the landing area is like
If your landing area is wide open, you don't need a giant canopy (especially on a wind-through object, where you won't need docility at opening either) and can get away with a smaller, lighter, cheaper canopy that performs just fine for wide open landing areas and non-solid object openings. (This may help explain why historically, Aussies have jumped the largest canopies and Floridians have jumped the smallest.)
3) How high the wind is
With lots of wind, you'll need a higher wingloading to achieve penetration (cue Beavis). If you habitually jump in high winds, you'll want a smaller canopy (and you're probably jumping mostly towers or bridges). If you jump in light or zero winds, you can get away with a larger canopy (lighter wingloading), and hence you can take worse landing areas, and higher strike potential objects.
4) How high the object is
On a very high object, you will have very little strike potential, so a relatively undocile canopy (i.e. higher wingloading) will be acceptable. If your object is lower, you will need a more docile (i.e. lighter wingloading) canopy on opening. If you are free falling ultra low objects (i.e. sub 200') you may consider downsizing again, as the difference in opening time between sizes becomes noticeable at these altitudes.
5) What your experience level is
Obviously, your ability to control the canopy is the most important factor. If you can stand up a .9 wingloading on jagged talus, then you may be able to load higher. If you can maximize all your control inputs to fight a 20 knot wind at .6 wingloading, you may be able to load lighter.
Your experience and skill are going to be the most important factors--far more important than your choice of canopy size or wingloading.
Hope this helps.
