BASE stunts: Begging for trouble? (OT)

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Reilly

Mountain climber

The Other Monrovia- CA

Apr 25, 2016 - 07:21am PT

The primary issue squirrels face is their lack of aspect ratio. The only way to solve that is by
means of a rigid extension of the arm. Employing that will partly solve their second main issue
of their floppy fabric. Yes, the clever inflatable tubes partially address that but if they adopt
rigid extensions they can easily do away with fabric where it matters most. I could see their
GR's easily going up to an honest 5 or 6:1. The carbon fiber wing used by Yves Rossy looks
to have a good 8:1 if not a bit more. With that kind of rig you could jump off the Schilthorn and
almost make it to Interlaken!

Bad, the top sail planes now are 60:1! With a 2000' tow they can glide 20 miles in still air!

climbski2

Mountain climber

Anchorage AK, Reno NV

Apr 25, 2016 - 07:29am PT

Even now one of the biggest challenges to long flights is arm strength/endurance. More glide ratio won't help that.

Reilly

Mountain climber

The Other Monrovia- CA

Apr 25, 2016 - 07:35am PT

It would with a rigid strap across the chest. Maybe that isn't squirrely enough but I would
rather fly further more easily and safely, but that's just me. I find the current Bram Stoker
look pretty cave.

Gunkie

Trad climber

Valles Marineris

Apr 25, 2016 - 08:20am PT

Changing thread direction a little. I built the graph below from data on the BASE fatality list. However, the big missing data here are the total number of BASE jumps in each year from 1981 through 2015. I suspect that this is pretty much impossible to derive, let alone capture in some database.

My expectations are that BASE jumping safety is actually increasing as successful (e.g. non-fatal) jumps rate of increase severely outstrips the fatality rate of increase. Does that make sense?

snakefoot

climber

Nor Cal

Apr 25, 2016 - 08:23am PT

per above, i agree that it is common to hold a 2.5 glide ratio that can be sustained without losing too much speed on most flights. the speed is important if one needs to change to a higher glide for whatever reasons. In most of the proximity vid you see, these guys are diving hard, going really fast and not maxing glide at all. as one famous dude once said when i asked what his favorite line was...he said "straight out!" People don't really want to carry a large wing or solid structure around (reminds me of hang gliders)...and these ideas of larger wings, persons needed strength and wing aspect ratios have been thrown around for a very long time.

edited for gunkie, i do think it is generally safer these days (better gear, instruction and more exits available)... simply more people and some are really pushing the limits , also the interweb where info is immediately available that makes it seem worse. the swiss base assoc has the most accurate data, but again, this is not a regulated sport and many jumps go without much ado or press.

The guy above

climber

Across the pond

Apr 25, 2016 - 10:35am PT

Yeah, I've heard 3:1 as the best the squirrel people can manage at this time.

Sustained 3.5 up to 4 is now possible, and in competition settings the record is now a hairs breath below 5:1 (4.98 or something like that i think it is). That is measured over a vertical km though, so it allows the flyer to dive and build up speed before entering the measured section.

In BASE speed is somewhat more important than GR, as that energy can be converted to achieve very high glide ratios for short periods in case you need to take evasive action, so the average GR is kept intentionally low.

Here's a good video from a few years ago showing all the data from a BASE jump. Notice how towards the end a strong flair achieves a GR of nearly 5:1 for a few seconds with a vertical speed of barely 15mph.

http://vimeo.com/70570559

Edit. Pretty much what Snakefoot said. Should have kept reading before replying :)

Reilly

Mountain climber

The Other Monrovia- CA

Apr 25, 2016 - 10:45am PT

a strong flair achieves a GR of nearly 5:1 for a few seconds

In the real world that isn't how glide ratio is measured. By that metric many sailplanes
would have a 'glide ratio' well over 120:1 and jetliners would be like 50:1! ;-)

snakefoot

climber

Nor Cal

Apr 25, 2016 - 11:06am PT

With all due respect, this is the real world and people are talking about it. i have achieved much higher glide ratios for a short time after a long vertical dive, but this is besides the point.

The guy above

climber

Across the pond

Apr 25, 2016 - 11:24am PT

In the real World glide ratio is measured by dividing horizontal travel by vertical travel within a given timespan. Sailplanes can have moments with GR's much higher than 120:1. It is the timescale within you measure it that defines what's what.

As pointed above, an average glide ratio of 4.98 or thereabouts has been done over a vertical kilometer. That is, the flyer travelled 4.98 kms horizontally and 1 km vertically. I doubt that would get you free beer at your local glider's club, but it is nonetheless accepted in the wingsuiting world.

Edit: I keep getting ninjaed by Snakefoot

snakefoot

climber

Nor Cal

Apr 25, 2016 - 11:39am PT

guy above, your input is appreciated regardless...

raymond phule

climber

Apr 25, 2016 - 11:42am PT

In the real world that isn't how glide ratio is measured. By that metric many sailplanes
would have a 'glide ratio' well over 120:1 and jetliners would be like 50:1! ;-)

I am not sure what you mean because it should be obvious that a sailplane could have a glide ratio of infinity over a short time period. A steep dive to gain speed followed by a climb while loosing that speed.

Even a hangglider can dive and pull up just above the ground to perform a looping without crashing into the ground.

Heisenberg

Trad climber

RV, middle of Nowehere

Apr 25, 2016 - 02:31pm PT

Gunkie: more missing you your graph than those 2 variables.

Snakefoot brings up good points. But the innovation of WS and TS has changed the game. WS proxy fatalities should be an entire sub category. There are no variables on that graph other than a fatality number. Auto fatalities graph would look the same honestly....

The individuals at this level (one is a F-15 fighter pilot (retired) takes in more information on one WS proxy flight than someone doing 300 off the Potato. The data he collects prior to and from other jumps brings an entirely new level of sniper like precision to the sport.

climbski2

Mountain climber

Anchorage AK, Reno NV

Apr 25, 2016 - 03:13pm PT

^ gag

2 ways people approach this proximity bullsh#t

Im a f*#king moron who thinks I have my sh#t down but I dont and I'm playing Russian roulette unknowingly.

Or I'm a person who values the experience more than long life and knowingly is playing Russian roulette.

Actually there is a third way.. but it does not apply to wingsuits..

I'm in the US military and my job is to play Russian roulette. We lose approximately 70 aircraft and 20 to 40 colleagues every year.

Reilly

Mountain climber

The Other Monrovia- CA

Apr 25, 2016 - 03:26pm PT

Raymond, don't get in an aerodynamics gunfight with a dull butter knife.
There is only one glide ratio for a given wing, period. Trading airspeed for
altitude is a fool's errand in the long run, if the long run is your goal.
If you want to avoid the rock in front of you or you want your pursuer to
blow past so you can get on his 6 then it is a good deal, but that doesn't
mean you have a better glide ratio than when you started. Flying is most
simply understood as fluid dynamics, aka energy management. I can provide
you with a lengthy reading list.

BASE104

Social climber

An Oil Field

Apr 25, 2016 - 03:31pm PT

This is the last place to get info on BASE. Basejumper.com has some lively forums, like this one but without the off topic stuff, like this. They don't judge climbers in their forums.

This is all that I know, having never wingsuited. Regular BASE, yes, in my time I was a stud, but this is something truly separate. I don't know why they even call it BASE. It has gone further. I bet that those guys don't spend much time doing bridges.

The wing area of the suits has vastly grown. They have inflatable cells which create an airfoil, too. Similar to parachutes, they have openings on the leading edge, and they inflate pretty quickly.

The new suits are almost pure rectangles. The first ones had wings from the wrists to the waist and the new ones have a much higher glide ratio. I've heard 4:1 tossed around, but I can't be sure. Anyway, it takes more skill to fly the bigger flying carpet type suits.

The big new ones take experience to fly. It is one of the easiest ways to die: move up to a big suit without enough experience. That is how a good friend died last year.

They don't turn on a dime. They kind of slide in the turns. So you have to be really good to get everything out of one of those suits. Almost all incidents are from impact during flight, so if they wanted to just fly out over the valley and enjoy themselves, it would be easy. However even the first wingsuiters found that it was more intense to fly these proxy lines.

On a new line, they first fly over it. Then they refine the line just as a slalom skier might. They get lower and lower until they are going between trees and all that. It requires a lot of experience with the suits. You can skydive with them, and get a feel for them, but people refine those lines until they are double black diamond skull and crossbone lines if anyone tries them cold. If you want to do a repeat of someone else's line, you have to work your way through it, sometimes over many jumps.

In my day, if you had a hundred jumps, you were in the top ten in the world, and we felt like we were jumping hard. These guys spend all summer doing the legal sites in Europe, and they are good at it. Many have thousands of jumps. Still, it is deadly to make a mistake, and we are seeing a rash of deaths. In normal old BASE, most mistakes are beginner bonehead moves, but now almost all of the deaths happen on wingsuits. Too close.

It looks like the most intense thing imaginable. We would have been all over it, but were born 30 years too early. It takes a ton of skill.

The guy above

climber

Across the pond

Apr 26, 2016 - 10:28am PT

Raymond, don't get in an aerodynamics gunfight with a dull butter knife.
There is only one glide ratio for a given wing, period.

Oh dear... Someone needs a new spork...

3-17
Any change in the gliding airspeed will result in a pro-
portionate change in glide ratio. Any speed, other than
the best glide speed, results in more drag. Therefore, as
the glide airspeed is reduced or increased from the
optimum or best glide speed, the glide ratio is also changed.

And that's before even touching trim, flaps, slats, angle of attack or variable camber wings. But i guess you know better than the FAA?

raymond phule

climber

Apr 26, 2016 - 10:51am PT

Raymond, don't get in an aerodynamics gunfight with a dull butter knife.

I don't understand what you mean with your post. Remember that you where the person that said something about 120:1 for sailplanes.

I can of course also give you a reading list about aerodynamics if this is some kind of pissing match about credentials.

The glide ratio at different air speeds is of course usually defined at steady state but you can of course also talk about glide ratios in different context if you want to, you just have to define what you mean, and it can be useful in some contexts.

It can for example be useful to know that the glide ratio from a dive in a wing suite can be 5:1 over a distance of 50 m.

I still have no idea why you wrote something about 120:1 when the obvious number for an sailplane would be infinity (at very many "starting" air speeds at least) if you as in the wingsuite examples are allowed to trail speed for glide over a short time interval.