Steering line length (slack vs. taut vs. pulled down)

[peek 20]

Sometimes people surprise me with "new interpretations" of what would seem to be well known gear configurations.

Please see the attached drawing of steering line lengths. It is from a particular reserve canopy, thus the indication that only one of the configurations is correct. (Do not read too much into this for purposes of this discussion.)

We know that "taut" is the preferred length for many canopies, and that slack is appropriate for canopies where aggressive front riser will be pulled, so that the canopy does not "buck".

1. Does anyone know of any situations where "pulled down" might be beneficial?

2. What are you seeing in the field for the other configurations (and more importantly, what explanations have you been given?)

(Edit to correct spelling. It's "taut" not taught, ha, ha! Taught is what you do with students. How about "teached"?)

[parachutist 1]

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1. Does anyone know of any situations where "pulled down" might be beneficial?

"Pulled down" can be useful with some very large canopies, ones where you'd need 10 foot long arms to stall it using toggles. With some of these monster canopies the jumper gets very little result when flaring, unless the lines are already pulling down on the tail a little.

Chris

[Hooknswoop 19]

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"Pulled down" can be useful with some very large canopies, ones where you'd need 10 foot long arms to stall it using toggles. With some of these monster canopies the jumper gets very little result when flaring, unless the lines are already pulling down on the tail a little.

If the canopy is flying in brakes, then it doesn't have the airpseed to trade for lift to flare with. Longer risers would be a fix. If the jumper's arms are to short to reach the toggles with the longer risers then that canopy probably isn't the right choice.

I don't think any canopy should have taut brake lines. during a turn, the wind drag on the lines increases, pulling the opposite side of the tail down. Canopies should always have some slack in the steering lines. If you can pull a toggle down an inch and the canopy turns, the steering lines are set too short.

Derek

[AggieDave 6]

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We know that "taut" is the preferred length for many canopies

Would you please reference a manufacture that recommends that for a modern canopy?

I can't think of a single manufacture that recommends that, in fact the ones I can think of off the top of my head recommend some slack in the lines.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[darkwing 4]

Not an asnwer to your question, but there is room for confusion in the case where the lines are not the same length (not uncommon), so it needs to be clear that one line can be taught and others can be slack (or vice versa).

I do no know of a reason to have all of them slack or pulled down, except in the latter case if you were trying to have a cambered bottom skin on your airfoil.

If I were designing it, I'd rather err on the side of slack.

-- Jeff
My Skydiving History

[matthewcline 0]

Gary,

Just to make sure, we are talking Mains only?

I will answer along that line for now.

For a HP parachute Slack as the type canopy recommends.

For some student canopies slack to avoid a stall in a early and high flare.

For Demonstrator type canopies (Flight Concepts Sharp Chuter, etc) taught to a slight pull down (1 to 2 inches max). This is only do to the way they are flown by the Demonstrators, in deep brakes most of the time to begin with.

But a deep pull down, no not some thing I have seen.

I have heard it was tried to avoid students from going to far back when off the radio, but it did not work out well and was dropped.

Matt

An Instructors first concern is student safety.
So, start being safe, first!!!

[JohnRich 4]

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"Pulled down" can be useful with some very large canopies, ones where you'd need 10 foot long arms to stall it using toggles. With some of these monster canopies the jumper gets very little result when flaring, unless the lines are already pulling down on the tail a little.

If the canopy is flying in brakes, then it doesn't have the airpseed to trade for lift to flare with.

For classic accuracy, with straight down approaches over the target, the canopies are sometimes configured with the tail pulled down a bit even when the brake toggles are full-up in the keepers.

Such accuracy is done only in ideal wind conditions, so the loss of forward speed is not important. And accuracy landings are made at near or in a stall, so the loss of flare is also not important. It also gives you your median control range for the approach with your hands comfortably at about chest level, while you make fine adjustments to your glide. And finally, it allows you to set a comfortable stall point to sink onto the target, without having to push way down to full extension with long gorilla arms.

That's a specialty application, for sure, and not for normal skydiving operations.

[pchapman 262]

Statement #1

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"Pulled down" can be useful with some very large canopies, ones where you'd need 10 foot long arms to stall it using toggles.

Statement #2

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If the canopy is flying in brakes, then it doesn't have the airpseed to trade for lift to flare with. [...]
I don't think any canopy should have taut brake lines.

In most of skydiving, statement #2 is the correct idea. But I'll have to agree with statement #1 instead, for very particular applications.

I have adjusted the brakes on a Parafoil so that it flies in a bit of brakes, under the supervision of very experienced accuracy jumpers. Forward speed (useful for big slow canopies!) was hardly affected, as tested by an anemometer.

I don't care about having airspeed to trade for flare!
I need full and complete control throughout the sink & stall regime to drop it onto the tuffet. I just couldn't get that without moving the toggles up the steering lines a little. And I did this adjustment despite being tall & long armed.

[Edit: Looks like John Rich said much the same thing before I could get this typed up coherently!]

[peek 20]

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Would you please reference a manufacture that recommends ["taut"] for a modern canopy?

I will not, because my question did not limit the canopies to "modern" or any other particular characteristic.

[peek 20]

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Not an answer to your question, but there is room for confusion in the case where the lines are not the same length (not uncommon), so it needs to be clear that one line can be taught and others can be slack (or vice versa).

Good point, I guess I should limit it to canopies with a single lower control line and upper control lines of "similar" length.

I guess that could further be defined as "the shortest line in the group of upper control lines".

I.E. the shortest line being "taut" and the others having (maybe an inch?) of "slack".

[peek 20]

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Just to make sure, we are talking Mains only?

Not necessarily. I'm thinking of a wide open discussion. :)

[SansSuit 1]

I have my main set with a fair amount of slack. I tend to be lazy with extending my arms. So, the brakes are set so that in my "lazy" position, the lines are "taut". The canopy has plenty of flare range so I'm not missing anything at the bottom end.

-Jeff.

Peace,
-Dawson.
http://www.SansSuit.com
The Society for the Advancement of Naked Skydiving