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khizarnaeem

Why stow toggles on half brakes when packing?

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What do you mean by stowing them on half brakes?
Skydiving canopies typically have only one setting unlike SD base canopies

There are a few reasons for stowing the brakes from my understanding
1) preventing the canopy from surging forward by a large amount on opening
2) less forward speed for those off headings when you are pointing towards other canopies
3) I think it also helps slow inflation *Maybe*

Where are the canopy designers?

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I'll have a go.

I think brake settings were invented before the ram air, but the idea is stop the tail of the canopy running over the nose during deployment. Without brakes, the end cells tend to inflate first and the deployment is very messy. Brake settings can also be used to fine tune the opening speed, and as a secondary, reduce forward speed after openings to reduce the chance of a collision.

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The Parachute Manual, Volume 2, p328:

"Canopy surge on opening, unless reduced/controlled, can be a major cause of malfunctions to gliding canopies. Unless restrained, the deploying canopy runs right over its leading edge. An effective solution is locking down the steering lines to deflect the trailing edge of the canopy...

The deployment brake setting affects lower surface pressurization, center cell inflation, spanwise internal pressurization and opening surge...

Deployment brakes are usually set at about 50% of the total control stroke available for a particular canopy. Generally, the opening forces can be modulated somewhat by the brake setting but there are practical limits which vary from canopy to canopy. If the brakes are set too low, the canopy will stall on opening. If the brakes are not set low enough, they will have little affect [sic] and canopy surge will occur during deployment. The most common setting for sport ram-air canopies is just above the point where the canopy experiences a stall on opening...

Deployment brakes were first installed on the Barish Sail-Wing by Dan Poynter in 1966."

Keep in mind that this was written in 1991, so the 50% setting may no longer be accurate for newer designs.

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I forgot to stow the brakes on my Sabre precisely once. That opening scared the shit out of me. Super hard and messy.

Coincidence? Possibly. My sabre didn't have a habit of opening hard though.

Since then I decided it was important to remember. :P

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skytribe

Not all canopies stow the brakes.

Icarus tandem canopies are not stowed for deployment. You have to be a bit more carefully about the excess brake lines but they seem to work pretty well.



......................................................................

A local dz uses Icarus 330 and 360 tandem mains. They stow the upper 2 feet of steering line in rubber bands. The rubber bands are looped onto C line attachment tapes. This reduces to risk of tail burns to zero. I also like the way the rubber band holds all the tail lines centre rear as I wrap the venter cell around the canopy, roll it and lay it on the floor. It is reassuring to feel that lump of steering line as I stuff it into the d-bag.

Similarly when packing SET canopies, steering lines that are not stowed at the bottom, get the excess steering lines stowed in rubber bands so that they end up the same length as the stowed brake lines. Again, stowing loose steering lines reduces the risk of line-overs, burns, tension knots, etc.

To quote Bill Booth: "When packing a ram-air canopy, you are mainly packing the lines. Once the lines are straight, it is going to open."

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Used to do that on the 360 we use, but eventually moved away from that and no higher incidence of reserve rides or damage. Last year we were having a higher incidence of rogue hard openings and this year the owner has kept a much closer eye on the packers and problem has diminished.

I think with the extra brake line you have to be more careful to avoid burn damage.

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When we got Icarus tandems mains I wondered what to do. So I asked Icarus USA for advice. They told me to just pack as normal and treat the brake lines as I would d lines. So far so good.
Always remember the brave children who died defending your right to bear arms. Freedom is not free.

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This should have been explained to you during your first jump training course. Its part of the initial introduction to how a parachute works, why it is designed the way it is, how it is built, how it flies, etc etc.

If you were not shown all this your instructor failed in his job....
My computer beat me at chess, It was no match for me at kickboxing....

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obelixtim


If you were not shown all this your instructor failed in his job....



For the benefit of the OP, that's a little harsh. Most first jump courses skip the advanced aerodynamics lectures when showing the basic parts of the parachute and how they work. Maybe you've got very different standards where you are, but I'd expect either that nothing is said about brake settings at all (just that you are supposed to grab the toggles and what to do with them), or to briefly mention that the tail is pulled down at the start to "improve the opening".

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Harsh? I think not.

An advanced aerodynamic lecture is not necessary, but a thorough, clear and simple explanation of how a canopy works is essential, and takes no extra time. I would think brake settings and function is a pretty basic piece of information.

If a first jumper has been told what he/she is strapping to their back, before jumping out of a plane for the first time, it engenders a lot more confidence, and eliminates some of the tension they feel before they jump, all of which has a beneficial knock on effect, and not just in the short term.

If AFF instructors don't have the time to spend 20/30 minutes going through these points, its another flaw (IMO) in the AFF programme to fully prepare people to become skydivers.

I suspect some AFF instructors don't fully understand the technical detail of the rigs they are asking their students to trust.

I explain all this stuff, and my students know what is happening when they ask their equipment to save their life.
My computer beat me at chess, It was no match for me at kickboxing....

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We are straying from the original question.
The best instructors teach "must know" information during the first jump ground school, then add additional layers of "should know" information over the next 24 jumps.
"Could know" information is layered on around the Bon fire or while reading USPA accident reports.
Bottom line too much information can easily overwhelm a first jump student so the best instructors limit FJC information to " must knows" and later add layers of "should knows."

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When you design a canopy, one of the things you play with is the brake settings for deployment. There can be a wide range of behaviors with different settings, and the behaviors are not the same from one canopy design to another.

The original thought was to prevent canopy surge, and to make canopies open better. It is OK to still view it that way. Just don't assume you know what will happen with a different brake setting than your canopy came with.

-- Jeff
My Skydiving History

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obelixtim


Its part of the initial introduction to how a parachute works, why it is designed the way it is, how it is built, how it flies, etc etc.



I tell them that parachute works because of magic. Most of my students understood that and they were fine with it.
Bernie Sanders for President 2016

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stayhigh


I tell them that parachute works because of magic. Most of my students understood that and they were fine with it.



As long as one appeases the gods by doing the magic flaking and folding rituals! For example, don't forget about the slider god ... she gets vengeful if it isn't quartered and against the stops!

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