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jws3
Jun 16, 2012, 8:49 AM
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Light Wing Loading
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What are the advantages and disadvantages to going light on your wing loading (i.e. 0.65ish)? Obviously, an advantage is that your descent rate is slower and a disadvantage is that you're carrying a little more weight around, but what else?
(This post was edited by jws3 on Jun 16, 2012, 8:56 AM)
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REDAKTOR
Jun 17, 2012, 8:41 AM
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You'll know when you hit that rock or find yourself in an unlandable area
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avenfoto
Jun 17, 2012, 9:55 AM
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shitty inflation and heading performance come to mind.
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kege
Jun 17, 2012, 11:16 AM
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Personally I don't think 0.65 is a light wingloading in base terms. I'd say 0.5 is light, 0.9 is heavy.
I jump a Troll 285 MDV, weigh about 82kg naked have never felt like I need a smaller canopy. On the contrary, a couple of times I've been very happy about that extra fabric.
edit: IMO, I don't think heading performance correlates much to wingloading. Like that famous basejumper always says, its body position. Body position. :)
Kerkko
BASE1184
(This post was edited by kege on Jun 17, 2012, 12:48 PM)
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mfnren
Jun 17, 2012, 12:36 PM
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I've noticed degradation more below .63... Inconsistent slider up openings, unpredictable snivels, and bad heading performance. Also reduction in flare and tendency to stall more abruptly.
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jws3
Jun 17, 2012, 1:49 PM
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Cool. I'm 180 lbs naked and I've been jumping a Troll 265. I want to get a brand new OSP and I'm thinking of going with a 285 instead of 265. From looking around, it sounds like the OSP 285 is a good call. With Atair's different sizing system, it would put me around 0.65.
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avenfoto
Jun 17, 2012, 2:52 PM
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Aren't the atair's generally +20 to whats on the label? So a 265 is roughly equivalent to a 285 (which would be appropriate for your body weight)
I've jumped a handful of canopies from 220-315sq/ft, and weigh 177lbs naked. The 220's opened fast and positively while providing a great flare, but too much speed (for me) for tight lz's. The 315 was the most inconsistent performance-wise, and I felt like it was an unnecessary risk
After almost breaking my back on it I sold it and spent some serious coin on a ppro/s7ven 285 combo. Nicest rig I've ever owned
I haven't jumped an OSP, but I believe it's a primarily slider-down designed canopy with a steep trim designed for tight unforgiving LZ's.
Call the manufacturer and ask them..
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MMK
Jun 17, 2012, 3:01 PM
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From: http://www.adrenalinbase.com
Choice of canopy size (Troll, Trango and OSP)
Picking the right canopy size is very important. The recommended weights apply for normal use
only. If you perform jumps with landing areas at high altitude or jumps with difficult landing
areas, we recommend you stay in the lower range, close to the minimum recommended weight.
Weight = jumper with clothes and shoes
• 185 min 55kg max 65kg
• 205 min 60kg max 70kg
• 225 min 67 kg max 77 kg
• 245 min 73 kg max 83 kg
• 265 min 79 kg max 89 kg
• 285 min 86kg max 96kg
• 305 min 92kg max 102 kg
From: http://www.http://baserigs.com
* 205 ft.2 = PIA spec 219
* 225 ft.2 = PIA spec 240
* 245 ft.2 = PIA spec 260
* 265 ft.2 = PIA spec 282
* 285 ft.2 = PIA spec 301
* 305 ft.2 = PIA spec 322
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base695
Jun 17, 2012, 3:42 PM
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in my experience at lighter wingloadings slider up sub terminal are more prone to off headings
its not digital....the lighter the loading the greater probability of it not being bang on.
at petrnonas one year, Annie H did some surveys of jumper WL just before exit then recorded the heading accuracy...not sure if she published the results or not but would be good to see. I seem to remember it correlated with my experience but thats probably just my cognitive bias kicking in.
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avenfoto
Jun 17, 2012, 4:13 PM
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Re: [base695] Light Wing Loading
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that's been my experience as well.
everything's a trade-off
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Fledgling
Jun 18, 2012, 6:35 AM
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Re: [mfnren] Light Wing Loading
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mfnren wrote: tendency to stall more abruptly.
Wrong.
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Fledgling
Jun 18, 2012, 6:37 AM
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Re: [avenfoto] Light Wing Loading
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avenfoto wrote: The 315 was the most inconsistent performance-wise.
It's been my experience that this is a problem with 300ft + canopies regardless of loading.
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avenfoto
Jun 18, 2012, 8:55 AM
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Re: [Fledgling] Light Wing Loading
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Yeah that's alot of fabric up there. Also worth mentioning, you may wish to use one size larger pc with the 300sq/ft+ canopies. If a 42 is appropriate for your buddy jumping his 265, you might consider a 46 for the same jump, due to the increased weight and size of your mega-tarp.
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seekfun
Jun 18, 2012, 9:49 AM
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Re: [Fledgling] Light Wing Loading
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Fledgling wrote: mfnren wrote: tendency to stall more abruptly. Wrong.
I've been chewing on this a bit, because wing loading certainly has some effect on stall characteristics. So I began thinking along these lines:
When flying a ram-air parachute, it's the suspended load and its acceleration due to gravity that provide the "thrust" in our analysis of flight forces. A heavier suspended load will "increase thrust", so to speak. As such, in full flight with a heavier load, the wing will be flying further above its stall speed than it would with a lighter load.
I understand that speed is not the only factor in a stall, but that angle of attack factors in as well. But if we assume that angle of attack is normalized for both heavy and light wing loadings, can we make the following set of statements about wing loading and stall characteristics???
1. Within certain limits, a heavier loaded canopy will have more available control range than a lightly loaded canopy.
2. A lightly loaded canopy in full flight is closer to its stall speed, and therefore has less available control range separating it from a stall condition.
Or am I missing 11 other factors?
~ Chris
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OuttaBounZ
Jun 18, 2012, 10:03 AM
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Re: [avenfoto] Light Wing Loading
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avenfoto wrote: Yeah that's alot of fabric up there. Also worth mentioning, you may wish to use one size larger pc with the 300sq/ft+ canopies. If a 42 is appropriate for your buddy jumping his 265, you might consider a 46 for the same jump, due to the increased weight and size of your mega-tarp.
You may. But you may not. I just went from a 260 to a 308 and I use all the same PCs. So far I can't tell a difference in opening speed. My same PC's drag my shlarp out at the same speed as before. Its a weight difference of less than 3 lbs and usually a drag force of more than 20 lbs. This was a huge fear of mine that turned out (so far) to be for nothing. My assumption (taboo on this sight) is that even though it weighs slightly more lifting off your back, it is more area to catch the breeze as you fall, which helps tard it to opening once its exposed anyway. Big canopies rule. Not sure why I fought it for so long.
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mfnren
Jun 18, 2012, 10:35 AM
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Re: [seekfun] Light Wing Loading
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Well said. Maybe I didn't word it clearly. But the way you said it is better. The flare/ control range is shorter w/ a lightly loaded canopy. And shorter range means shorter flare= more abrupt stall.
And a less pressurized canopy is more prone to collapse from turbulence etc.
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RayLosli
Jun 18, 2012, 7:27 PM
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Re: [mfnren] Light Wing Loading
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but that is not what gives major problems or generally kills a BASE jumpers .
I find the Opposite . the Large BASE canopy gives great flight control in deep break, with precision Flat-Turn control & is easier to ride the wire in steep approach into tight landing area.
Big BASE Canopies Do Rule . Big is badass & big and Slow is your friend when shit goes Bad .
.
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avenfoto
Jun 19, 2012, 12:56 AM
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Re: [RayLosli] Light Wing Loading
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when is big too big?
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Skyfallingdoc82
Jun 19, 2012, 1:11 AM
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Not trying to be a smart ass, just wanted to bring the info from the article to light.
http://www.basejumper.com/Articles/Gear/BASE_Canopies_681.html
Wing loading (WL) is the ratio of the weight of the jumper plus gear measured in pounds and the square footage of the canopy measured in square feet. Unlike in the skydiving environment, where usually experienced skydivers jump canopies at higher WL than novices, in BASE usually the WL is more consistent across pilots, regardless of the experience level.
BASE canopies can be flown as low as 0.5 to as high as 1.0 WL. Going outside these limits is not recommended. However those are considered extreme limits not to be used on regular jumps. Flying a canopy at very low WL (<0.6) will result in poor inflation, sluggish control responses, and reduced flare power. Flying at high WL (>0.8) is also counterproductive because the canopy might be too twitchy in flight and hard to land due to the added airspeed and higher stall point, among other things.
Also at high WL the canopy might be subjected to additional stress from the openings. It is my opinion that the golden range for the WL of a modern BASE canopy is 0.65–0.75. Deciding which side of the range to choose is a matter of personal preferences. I personally like my BASE canopies at 0.70, other jumpers might prefer a bit lower while other a bit higher. A rule of thumb is to start at 0.70 and see if you need a bit more penetration and responsiveness.
Lately I have seen a trend of going bigger, i.e. lower wing loading. I have taken FJC freshly graduated jumpers on objects and their canopy size was in my opinion borderline unsafe. Bigger is NOT always better. If you do not have the skills to fly and land on a dime a BASE canopy at 0.70 then you should reconsider your participation into the sport altogether. There are many instances where a little performance is desired and too low of a WL will rob this performance away.
I rarely fly in full flight on a BASE jump but it is nice to know I have some extra speed and penetration when needed. If my WL was too low, this speed and penetration would be non-existent and I know for a fact I saved myself from some possible dire consequences a few times because I was able to out-fly obstacles in head winds or to turn quickly and this thanks to my WL.
In the end be very skeptical when someone recommends you anything lower than a 0.65 WL and again if this recommendation is in part due to your canopy skills, reconsider BASE jumping until those skills are adequate.
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plummy
Jun 19, 2012, 2:13 AM
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Re: [Skyfallingdoc82] Light Wing Loading
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Skyfallingdoc82 wrote: In the end be very skeptical when someone recommends you anything lower than a 0.65 WL and again if this recommendation is in part due to your canopy skills, reconsider BASE jumping until those skills are adequate.
I disagree... It depends on what type of jumping you intend on doing. I tend to assume that I could be in a shit situation, under canopy on every jump.
I jump at a WL of 0.58-0.6 on a Fox 265.
In Australia as many would know, our landing areas are typically tight, particularly by international standards. We have many sub-terminal slider up jumps on shitty walls with equally shitty landing areas. I have no problems with supposed unreliable opening characteristics or heading performance, compared with jumpers of differing WL. It's a subterminal opening! Of course it's going to be variable. If it was so variable over our shit landing areas, I would reconsider.
The reason I jump at this wingloading is for the better flare from deep braked approaches and more forgiving characteristics. Bad heading performance, reduced/or comprised pressurisation, easier to stall; these are not true in my opinion. If you are stalling, you should work on your general canopy skills on YOUR own canopy.
The main disadvantage with a light WL is jumping in higher winds. You obviously will have less penetration into a given wind speed. If the winds are at that sort of speed, maybe your risk assessment needs tweaking. If clearing obstacles are a concern, then maybe you need to adjust your opening height. I generally do not jump in strong winds anyway and yes, I have walked away from several jumps where my mates have jumped.
Everything Ray said, I generally agree with.
Have fun...
Plummy
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Skyfallingdoc82
Jun 19, 2012, 2:34 AM
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Re: [plummy] Light Wing Loading
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I am sure that what you jump works for you, you wouldn't jump it if it didn't. I didn't write that though, that is verbatim from the article on canopies from this site.
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plummy
Jun 19, 2012, 2:47 AM
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Re: [Skyfallingdoc82] Light Wing Loading
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Skyfallingdoc82 wrote: I didn't write that though, that is verbatim from the article on canopies from this site.
No problems, I was aware of that. But I don't agree with what is written and the arguments put forward.
Plummy
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gauleyguide
Jun 19, 2012, 8:54 AM
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jws3 wrote: Cool. I'm 180 lbs naked.....
Do you have any pics?
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GreenMachine
Jun 19, 2012, 10:21 AM
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My naked weight runs 183 (+/- 5 depending
on the season, injuries, training level) and
my rig, clothes, Protec, Hanwags, knee pads,
phone, stash bag, and 1 GoPro = 24 pounds
hence my exit weight bounces around 207.
207 / 240 = .862
207 / 260 = .796
207 / 280 = .739
207 / 300 = .690
207 / 315 = .657
I have SKY jumped wings 117 to 420 and the
ridiculously Lightly loaded wings open really
slowly even with you pumping the rear risers.
I have BASE jumped wings 240 to 300 and in
my opinion that whole range opened just fine
but landing at high altitudes or in tight areas
I prefer flying a canopy around 280ish.
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wingozone
Jun 19, 2012, 11:38 AM
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Re: [GreenMachine] My Wing Loading Experience
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hey
When you calculate your wingloading you have to add the weight of your rig also or not?
for example if I m 171 pounds shoes clothes. my rig is 15.4 pounds my wingloading is 186/300=0.62 ??
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