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BMAC615

A License on >1:1 WL?

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Skydive Cross Keys A License jumper on FB w/ 45 jumps weighing in at 200 lbs. + gear looking for a rig w/ a “PD 170.” Claims his instructors and coaches and S&TA have already had him on a 190 for the past 20 jumps and are guiding him to purchase a Pulse or Sabre 170. What are the coaches, instructors & S&TAs thoughts on this?

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Edited by BMAC615

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I'm not an S&TA or AFF-I but I wouldn't be advising this for someone with 45 jumps and find it difficult to believe anyone with those ratings would be either:

image.thumb.png.e65715bda4775aa49ec49905c5703ad5.png

I have nearly 1200 jumps but, after a hiatus, I have similar jump numbers to him since returning to the sport. I'm feeling reasonably comfortable again but I've only got myself back to a wing loading lower than that (1.32) so far. I'd be very wary of the wing loading I'm currently on if I didn't have the previous experience to call on.

The one saving grace might be that a 1.35 wing loading on a 170 is a bit different from a 1.35 wing loading on a 107 or 120 but I still don't think it's a very good idea.

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(edited)

Without knowing the skill of the person in question, and altitude/climate of the local dropzone, it seems excessive, but I can see the circumstances under which those would be considered acceptable. A lot of people don't have the money to change gear very often, so the idea was probably to get the guy a container that will be useful for a couple of future downsizes, providing he doesn't get hurt for the first 20-30 jumps while he is getting used to the canopy. If the local dropzone has rather constant winds, low altitude, and a C182 which limits the number of simultaneous people in the air to 4,  it might not be the smartest idea in the world, but it isn't a catastrophic one. I would also recommend a Safire over a Sabre as it has a shorter recovery arch. 

While in the ideal world of the average person advocating safety on this website (conservative people with infinite money, strong safety culture, and highly regulated skydiving) this situation would be frowned upon and this person would be prevented from jumping that gear, we are living in the real world, and things often need to be optimized using more than one parameter (the likelihood of the jumper getting hurt). I have seen it very often that the first canopy a person buys at under 100 jumps is a 170 by default, regardless of a wing loading (and sometimes even a 150 with a very light person). 

Edited by Kenzdik96
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(edited)

Thank you for your response. I think what I’d like to get a better understanding of is the philosophy that downsizing and increasing wing loading beyond 1:1 is necessary or inevitable - especially for someone with less than 100 jumps. I recognize having fun under canopy is part of the skydive, but, why do we have a culture of being able to rapidly downsize in order to land progressively smaller canopies?

Edited by BMAC615

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8 minutes ago, BMAC615 said:

I think what I’d like to get a better understanding of is the philosophy that downsizing and increasing wing loading beyond 1:1 is necessary or inevitable

I'm not convinced this philosophy is actually prevalent. I haven't see people being told they need to downsize. Not here and not at any DZ. There are practical drawbacks to limiting yourself to 1.0 psf, but I haven't seen anyone criticized for accepting those.

 

15 minutes ago, BMAC615 said:

I recognize having fun under canopy is part of the skydive, but, why do we have a culture of being able to rapidly downsize in order to land progressively smaller canopies?

Did you type that wrong or are you now taking the position that we should not be allowed to downsize "rapidly", whatever you mean by that?

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1 minute ago, nwt said:

I'm not convinced this philosophy is actually prevalent. I haven't see people being told they need to downsize. Not here and not at any DZ. There are practical drawbacks to limiting yourself to 1.0 psf, but I haven't seen anyone criticized for accepting those.

 

Did you type that wrong or are you now taking the position that we should not be allowed to downsize "rapidly", whatever you mean by that?

Rapidly as in moving beyond 1:1 WL within the first 20 jumps and beyond 1:2 before 50 jumps.

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Just now, BMAC615 said:

Rapidly as in moving beyond 1:1 WL within the first 20 jumps and beyond 1:2 before 50 jumps.

Could we dispense with the ratio nonsense and express wingloading as pounds per square foot? I don't understand what you mean by 1:2 before 50 jumps.

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(edited)
3 minutes ago, nwt said:

Could we dispense with the ratio nonsense and express wingloading as pounds per square foot? I don't understand what you mean by 1:2 before 50 jumps.

1:1 & 1:2 is how a ratio is expressed in mathematical terms. 1:1 is the way we say 1lb per sq ft. Sorry, I mistyped, and meant 1.2:1

Edited by BMAC615

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1 minute ago, BMAC615 said:

1:1 & 1:2 is how a ratio is expressed in mathematical terms. 1:1 is the way we say 1lb per sq ft. Sorry, I mistyped, and meant 1.2:1

Canopy loading isn't a ratio any more than your car's speed is. Sammy Hagar isn't complaining about driving 55:1, he's complaining about driving 55 miles per hour. Sorry, but this has always irked me. The only effect of using this prevalent but incorrect notation is to cloud the conversation with additional numbers and additional words that sound like numbers that have no meaning and provide no clarity.

"one point two pounds per square foot"

vs.

"one point two to one"

Sorry, was that 1.221?

Anyway... You're arguing something should not be widely accepted that I'm not convinced actually is widely accepted. You opened the thread with a screenshot of someone's planned progression not being accepted, as if it supported your point.

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12 minutes ago, BMAC615 said:

Thank you for your response. I think what I’d like to get a better understanding of is the philosophy that downsizing and increasing wing loading beyond 1:1 is necessary or inevitable. I recognize having fun under canopy is part of the skydive, but, why do we have a culture of being able to rapidly downsize in order to land progressively smaller canopies?

It is neither necessary, nor inevitable, but it will statistically happen to a vast number of people. I have read your post in the Perris fatality thread about pilot progression and encouraging learning other (than high performance landings) aspects of canopy flight (like canopy formations, practical accuracy, and similar), and while I agree with you that those are valuable skills, it is not really necessary to teach those at 7 cells loaded below 1.0. 

Slightly higher wing loadings give you increased ability to penetrate wind and higher stability in turbulence, while 9 cells give you a better glide and better flare over 7 cells. A Safire, Sabre, Volt, Pilot, or a similar semi elliptical canopy loaded at 1.4-ish gives you ample opportunity to learn majority of aspects of canopy flight, will tolerate all but the stupidest of mistakes, and still enable you to get back from that bad downwind spot. Adding on, a 170ish canopy with vectran lines has a sufficiently small pack volume for you to have a normal sized rig that will not kill your back while you are waiting to board the plane, and will help prevent snagging your pins on objects in the airplane (which also requires training and attention on the side of the skydiver, but is also much easier to do with something holding a Safire 169 than a Navigator 240). 

I have not seen people being forced to downsize everywhere, and while I have seen some instructors push people to downsize more and more, those were rather rare instances. The reality is that a lot of (especially younger) people perceive high performance landings as fun. While those carry certain risk, a lot of people are willing to accept them as after all, if our primary concern was safety over fun, we would be playing chess every weekend instead of jumping out of somewhat serviceable airplanes. 

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(edited)

I appreciate your input and thought process.

I would not encourage anyone to dock or down plane with a 9-cell or any canopy w/ vectran lines. I’d rather see people learn proximity and bump end cells with a 7-cell @ </=1:1 vs. a 9-cell semi-elliptical @ >1:1. You’ll bounce off a large 7-cell whereas a 9-cell will be more likely to wrap with aggressive contact.

I’d be interested to see the glide ratio of a Spectre at 1:1 vs a Sabre at 1.4:1 in various wind conditions.

Completely disagree about 1.4 tolerating mistakes and the weight difference of a 170 vs 210 canopy is about 5 lbs. and should not be a problem for a 200 lb man.

I’m not saying anyone is being forced, but, there sure seems to be a lot of encouragement. Nothing wrong with high performance landings, I just think people should learn how to do them on a lower wing loading vs a high wing loading to give themselves the chance when the inevitable miscalculation happens. 

@sfzombie13 wrote in the other thread, “we need to start an awareness program and stop using this wing loading bullshit to get folks to downsize before they're ready.  we need to make it desirable to keep larger canopies until the proper skills are learned to handle the smaller ones.”

I think there’s a whole exciting world of canopy piloting that new jumpers aren’t being exposed to that would give them better canopy piloting skills before moving to small, high performance canopies.

Thank you for your perspective. It is helpful for me as I formulate my own opinions.

Edited by BMAC615

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5 hours ago, nwt said:

Canopy loading isn't a ratio any more than your car's speed is. Sammy Hagar isn't complaining about driving 55:1, he's complaining about driving 55 miles per hour. Sorry, but this has always irked me. The only effect of using this prevalent but incorrect notation is to cloud the conversation with additional numbers and additional words that sound like numbers that have no meaning and provide no clarity.

"one point two pounds per square foot"

vs.

"one point two to one"

Sorry, was that 1.221?

Anyway... You're arguing something should not be widely accepted that I'm not convinced actually is widely accepted. You opened the thread with a screenshot of someone's planned progression not being accepted, as if it supported your point.

While not 'notationally correct' (is that a real term?), canopy wingloading has usually been expressed as a ratio. More correct would be "lbs/sq ft". 
All the jumpers I know understand that "1.3:1" means "one point three pounds of jumper per square foot of canopy".

It's still fairly prevalent and widely accepted. I know newer jumpers who went onto 'medium-ish loaded' ellipticals at fairly low jump numbers. Most of them did mostly ok. Some biffed and got hurt. OTOH, I know newer jumpers who screwed up and biffed while flying lightly loaded canopies.

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1 hour ago, wolfriverjoe said:

While not 'notationally correct' (is that a real term?), canopy wingloading has usually been expressed as a ratio. More correct would be "lbs/sq ft". 
All the jumpers I know understand that "1.3:1" means "one point three pounds of jumper per square foot of canopy".

I understand this. I'm asking can we please stop because it's stupid.

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1 minute ago, base615 said:

Why is it stupid? It's the correct way to express it, no?

 

6 hours ago, nwt said:

Canopy loading isn't a ratio any more than your car's speed is. Sammy Hagar isn't complaining about driving 55:1, he's complaining about driving 55 miles per hour. Sorry, but this has always irked me. The only effect of using this prevalent but incorrect notation is to cloud the conversation with additional numbers and additional words that sound like numbers that have no meaning and provide no clarity.

"one point two pounds per square foot"

vs.

"one point two to one"

Sorry, was that 1.221?

 

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1 minute ago, nwt said:

 

 

I get your point but I disagree with it. Miles per hour works because it's a constant - an hour never changes for anyone so only one part is variable. In the case of a wing loading, both parts are variable since it is expressed as a load for a particular canopy so I feel the ratio better signifies that.

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3 minutes ago, base615 said:

I get your point but I disagree with it. Miles per hour works because it's a constant - an hour never changes for anyone so only one part is variable. In the case of a wing loading, both parts are variable since it is expressed as a load for a particular canopy so I feel the ratio better signifies that.

I've never seen the second part of the ratio change. It's always been ":1"

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I’ll join in on the pedantry:

 

I accept that people say things like “1.5 to 1” or write “1.5:1”.   Yes we understand what they mean (so their language has worked), but it is a messy way to state things and shouldn’t be encouraged in formal use.

 

It is entirely redundant to say something like “a wing loading of 1.5 to 1” when one could just say “a wing loading of 1.5”. Either way, units are missing and we assume that one is using US standards.

 

It isn’t a true ratio of the same units on both sides of the equation -- you aren’t comparing square feet of one thing to square feet of another thing.  The units are different, pounds vs. square feet.

 

Using a ratio in this situation is as dumb as saying that you inflated your car tires to “32:1”.

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Just now, base615 said:

Of course it is, I'm saying that because the canopy component is also variable, the ratio makes that more apparent.

A square foot is no more variable than an hour. Just as your canopy may have multiple square feet, your drive may take multiple hours. There is neither technical nor practical difference here. ":1" conveys no meaning and and has no intuitive benefit--it isn't making anything "more apparent". If you don't believe me, just start leaving it off and see if anyone's confused--nobody will be and it's commonly left off anyway. 

I'm not suggesting you actually say the units every time. Leave it off just like when you're telling someone how fast you were going. But if you feel the need to add units, then actually add the units and convey something useful. 

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(edited)
9 minutes ago, pchapman said:

Yes we understand what they mean (so their language has worked)

Mostly. It's often impossible to tell whether someone means "1.22" vs "1.2 to" until you hear whether or not there's a "1" coming. It doesn't sound like much, but it can really fuck with you if you're trying to organize a load of hop n pops next to running turbine engines that want to leave.

Edited by nwt
added 'next to engines'

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(edited)
1 hour ago, nwt said:

Mostly. It's often impossible to tell whether someone means "1.22" vs "1.2 to" until you hear whether or not there's a "1" coming. It doesn't sound like much, but it can really fuck with you if you're trying to organize a load of hop n pops next to running turbine engines that want to leave.

Okay. I’d like to redirect the conversation back to getting input from coaches, instructors and S&TAs and their perspectives regarding recommending a WL > 1 for A and B license jumpers, if they do it and why.

Edited by BMAC615
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13 hours ago, BMAC615 said:

I would not encourage anyone to dock or down plane with a 9-cell or any canopy w/ vectran lines. I’d rather see people learn proximity and bump end cells with a 7-cell @ </=1:1 vs. a 9-cell semi-elliptical @ >1:1. You’ll bounce off a large 7-cell whereas a 9-cell will be more likely to wrap with aggressive contact.

And we agree here, as I would not encourage anyone to do downplanes or make stacks with anything but a dedicated CReW canopy. (which doesn't have to be a 7 cell, nor does it have to be lightly loaded, have you seen the PD Tango?) But downplanes and canopy docks are exercises which are applicable only to people doing CReW, and I don't want to force anyone to get into full contact canopy relative any more than you want to force people to go into swooping. Contactless canopy proximity flying on the other hand is an exercise that makes you a much better canopy pilot, regardless of the discipline you choose to pursue afterwards. When you have another canopy in the air next to you, you can see exactly what happens when you initiate any sort of toggle, riser, or harness input, because you will have a frame of reference (which you normally only have during landing, when the ground is getting closer), and you will learn how to control your canopy horizontal and vertical speed, as you will need to match them to another person (and this can't be done properly on very lightly loaded wings, as both the front and the rear risers are way to heavy to be useful, and harness is almost unresponsive). 

13 hours ago, BMAC615 said:

I’d be interested to see the glide ratio of a Spectre at 1:1 vs a Sabre at 1.4:1 in various wind conditions.

Glide ratio is a constructive characteristic of the airfoil, and is independent of wing loading. A 9 cell will typically have a better glide ratio than a 7 cell, purely because the aspect ratio of the wing is greater, and aspect ratio positively affects wing efficiency (that is why gliders have very big wing spans in relation to their chord, and consequently very high aspect ratios). When we say glide ratio, we are referring solely on airspeed. When it comes to penetrating wind, it is not only the glide ratio you need, but horizontal speed, as ground speed (difference between you airspeed and the speed of the wind) is what you need to get over that powerline/highway/barn. When wind gets sufficiently strong, you will be standing still with anything loaded at 1.0, but something at 1.4 might get you moving forward. And before someone responds with "you shouldn't be jumping if winds are too strong", wind can change during jump, and people are eager to jump so in the real world wind limits will routinely be pushed. 

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