dropped toggle

[guest]

I know this thread has been addressed in the past, but I'm not sure I ever saw an answer to my question/worry.

Situation: Slider Down Line Over, let's say at the Perrine.

Current experienced wisdom seems to be to drop only the appropriate toggle, and land with one toggle and one riser.

My feelings on the matter:

My plan has always been to huck 'em both and land with both rear risers, as I feel it would be quicker to just look up, see a line over, save the split second it takes to decide which side it is (and in some cases I'm sure that split second can make some sort of a difference), toss em both, and have a smoother and more symmetrical flare both having two identical things to flare with.

I know that these canopies are pretty big and much more forgiving of a one riser/one toggle flare than a stilleto 120, but at the same time I don't usually flare my Stilleto on a beach bordered by wet and trees (I'm assuming I HAVE to land on the beach for some reason) and want to make it as easy as possible.

My guess is that the reasoning is that these low aspect ratio canopies deform more with rear riser input, but it still seems like it would be better to deform symmetrically with both rear risers than flare with a mix....

Whadayathink?

[guest]

I think yer being a dumba$$. if you drop both you effectively decrease the surface area of your canopy by ~40%. Most of the time a "split second" shouldn't matter. assuming your not spinnning uncontralably and about to hit the object (you said the perrine), popping the toggles and and pumping them can clear the LO, if you haven't figured oput which line is over your canopy by this time (~1+ sec) you should go back to skydiving.

[guest]

I would definitely NOT recommend flaring on one riser and one toggle. That'll plant you sideways into the ground.

Conventional wisdom is to keep the non-lined over toggle, then flare on both risers (with the unused toggle in your hand).

That way, you canopy doesn't deform as much (see knowitalls educated, but quite rude, commentary on losing 40% of your wing area) .


--Tom Aiello
tbaiello@ucdavis.edu

[guest]

I always knew BASE jumpers attracted a wide cross section of the population, to include, as in your case Knowitall, a$$holes. You are clearly define yourself as a Mountain Dew drinker. You weenie.

I am a low time BASE jumper, but experienced skydiver. I've never had a lineover on anything. So forgive me if I don't know firsthand what one feels, looks like from below, or acts like.
I'm not sure but it would seem to me a line over that is closer to the center cell would be hard to clear by pumping, and momentarily hard to distinguish which control line is involved.
Now that last paragraph begs the question, "Do these types of line overs happen much?" Idaknow. You tell me. That's why I'm asking.

I don't understand how you lose 40% of your surface area. What do you guys mean by that? If you drop both toggles, is the area behind your D lines no longer prodcing any lift?

Knowitall, your post implied that you would do different things in response to a line over at different objects. I assume you are implying that you would chuck em both if you had a kind of radical line over at Tombstone? I can understand that. But as a lowtimer I'm just trying to come up with a plan that covers the most bases while I'm still learning, to be modified as experience grows. So give me a freakin break dude.

Tom, thanks for your toggle input. I didn't know that. I'm glad I asked that because in talking to some other low timer friends, the perception of what has been said is that we should flare with toggle/riser, not toggle-riser/riser. Thanks for clearing that up.

[crwper]

Ah, see, I guess I've never really paid attention to these threads before, because landing with both rear risers and one toggle in hand makes more sense than landing with one riser and one toggle. The one time I dropped a toggle (my own stupid fault), I decided to let go of the remaining toggle and land with both rear risers only. Nice stand-up landing, no problem. But I can see where I would get a little bit more lift if I held onto the remaining toggle. I am, however, skeptical of the 40% figure. Can anyone explain how this is derived?

Just one thing I'd like to make a note of. The side of the canopy with the free toggle will still fly very differently from the side on which you've kept the toggle. Your flare will need to be a little uneven, and if you're one of these types who flares by muscle memory, that might be tricky.

I think it would be a good idea to practice this before an actual situation arises.

Michael

[guest]

Fair enough, please forgive, caught me at a very bad moment, I think I was being a dumb a$$-hole.

[guest]

It's cool, baby cakes. Want some nude pictures of my sister?

[guest]

It's definitely recommended that you practice one and two riser flares before taking your canopy into the BASE environment. For more (very helpful) canopy drills, download CR's canopy drills:

http://www.crmojo.com/frame_main.htm

then select "library", then "document library", then "fjccanopy.pdf" (make sure you have acrobat reader) .

I think the 40% figure (probably inaccurate) came from a typical "I don't know math or engineering, but it's a lot" jumper shortcut. Really, the theoretical maximum loss ought to be something like 20% (if you lose the entire fifth of the wing area aft of the D lines), or something like that. Like I said, I don't do real math or engineering, so I'm shortcutting.


--Tom Aiello
tbaiello@ucdavis.edu

[guest]

Maybe I'm wrong, But I believe the percentages come not from lost wing area, but from lost controllability. Your canopy provides just as much lift in full flight with your toggles trailing uselessly behind it as it does with your toggles in hand.

If you are flying a fully inflated canopy and have both of your toggles, you have 100% control of your flight path. You can use toggles, front risers, or rear risers to initiate a turn, flare, or change your angle of attack. I think everyone would agree that toggles are the most efficient at performing any one of these jobs, though. Assuming the 100% of control is split 50/50 to either side of the center cell, if you drop one toggle you have just lost 80% efficiency of control on that side of the wing, 40% of the overall.

If I'm wrong or this seems like a remedial math lesson, let the flames begin!

Steve

[crwper]

I think you do lose some lift. If you assume the wing is rigid, then you wouldn't lose lift. But it's not rigid. So when you drop your toggles, the pressure difference on the rear 20% of your canopy stops contributing to lift, and instead it just bends the back portion upward a little bit, I would think. I'm not sure the pressure in the canopy is high enough to keep it very rigid with two dropped toggles.

Now, if you kept one toggle in-hand, that might improve the rigidity of the rear portion of the canopy, and you might actually keep more than 50% of the lift that would have been lost if you had dropped both toggles.

I've landed several times on rear risers with skydiving canopies, but the difference there is that the toggles are still fixed to the risers, sot there's a connection between the back of the canopy and the jumper... Therefore the back can still provide lift. So my experience on skydiving canopies might not mean much here.

But to be honest, I think the hardest thing about landing on rear risers isn't that you lose whatever lift. And I don't think it's that you lose much control... In theory. But the fact is that most BASE jumpers have spent in the neighborhood of 1000 skydives and a couple hundred BASE jumps using toggles. They know how toggles work, they know how to flare with toggles. They know what the stall point feels like.

Unless you've spent a lot of time on rear risers, I think you're likely not going to get as much control from them as you should be able to, and you're probably going to stall the canopy the first time you try to land it that way, or maybe you'll under-flare because you're afraid of stalling. Who knows. I haven't spent a lot of time on rear risers with my BASE canopy. I would probably err toward the under-flaring end of things.

That's why I think practice would be a really good idea.

Michael