PD brake line trim question

[SethInMI 174]

I just got a Sabre 2 canopy with about 140 jumps on it. My rigger and I hooked it up using the brake settings (existing loops) of the previous owner. I jumped it, it flew like the brake lines were too short (bucked alot on front riser turns). I measured the brake lines according to PD instructions and they were about 3.75" too short, chart says 18" for a 170.

The line trim chart has an note "Due to development methodology, the finished BK-TOG dimensions may not scale" What does this mean?

Can I just move the break line settings to the suggested 18" length, or should I step it out more slowly?

Thanks,

Seth

It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

[councilman24 37]

Not everybody wants to be able to pull a front riser with the toggle in their hand.

There are several ways to set the toggles. One, to get full and quick response out of steering line inputs you can set the toggles so there is no slack in the brake lines when the toggles are all the way up. The tail shouldn't be pulled down but should immediately begin deflicting when you start pulling the toggle. This will make the canopy react immediately, but the stall will be the highest. In other words you need to find the stall point high in the air and be careful when you flare to not stall the canopy before your on the ground.

Or you can set the toggles so you can pull down a front riser with the toggles still in your hand and not deflect the tail enough to cause bucking or other undesirable effects. At this setting you may NOT be able to stall the canopy. All of this depends on riser length and arm length. So you may not get the most flare out of the canopy. Often student canopies are set up with extra long brake lines so that students can't stall the canopy.

Neither is right or wrong. It is personal preference. I actually don't understand the may not scale comment unless they mean there are different lengths for different people.

So, you can go to the factory length and see if you like it. But, determine your stall point high and be aware turns may not be as immediate and flare may not be as strong.


I don't swoop so I set mine with no slack.

I'm old for my age.
Terry Urban
D-8631
FAA DPRE

[ZigZagMarquis 9]

[Disclaimer:] I am not looking at the canopy you have!

I'd reset (re-tie) the brake likes to the factory recommended 18" setting and go from there.

When you get open and the canopy is in full flight (brakes unstowed, hands all the way up) there should be a slight bow in the steering lines.

Do a few practice flares, turns (toggle and front riser) up high. You can always take a wrap if the steering lines are now too long... but some folks don't like that... over to you to decide.


Aside... If we're talking Spectra here... Personally, when a PD canopy is BRAND NEW, I've always found PDs initial setting for where to tie the toggles to be way long, but somewhere in the first "X" number of jumps, the lines shrink up as the canpy "breaks in." I tie them at the factory setting and take a wrap until you knock the new out of the canopy... again, some folks don't like taking a wrap and would rather retie their steering lines a lot. Over to y'all.


[/Disclaimer]

[riggerpaul 1]

There's more information I'd want to have to make a firmer statement - I'd really liked to have seen the canopy in flight, but it is probably safe to move the toggles the entire distance to the factory setting.

You might, in fact, see little difference in the overall handling of the canopy.

At the factory brake setting, there is usually around 4 to 6 inches of slack in the brake line. When you pull the down the toggle, the first 4 to 6 inches results in very little deflection at the tail. Once those 4 to 6 inches has been exceeded, the action at the tail is pretty much direct from the toggle - an inch of depression at the toggle results in an inch of deflection at the tail.

The 3.75" is just a bit less than this normal slack, so the canopy is still flying nearly at full glide. That is, the brake lines are nearly full length and there will be little deflection at the tail. Any shorter might result in the canopy not achieving its full glide speed. This might be most apparent in landing, where your flare power might be decreased. But I wouldn't expect your 3.75 inches short to have a huge effect on the canopy.

One possible advantage of having your toggles a bit on the short or tight side is that the stall point at the bottom of the toggle stroke comes up a bit. If you have short arms, you might get a bit more flare power, but you can also be getting closer to really stalling the canopy.

When you use the front riser while holding the steering toggle even the factory brake setting might not be long enough to stop all the bucking. Some jumpers lengthen their brake line past the factory setting to allow more front riser input without dragging on the steering.

One possible disadvantage of setting the brake lines long is that you might lose some of your flare at the bottom of the toggle stroke since you won't be able to pull down the line as far as when the brake line is shorter. Some people take a wrap of steering line around their hands to take the extra length out of the brake line. But this is not without its down side as well. There have been cases where "taking a wrap" caused problems for the jumper when he got stuck in the line or dropped one side while flaring, for example.

(The other responses weren't posted yet while I worked on mine. I agree with all that has been said. Nice to see us all saying pretty much the same thing!)

[SethInMI 174]

Thanks for the responses.

I will just move them back to factory and try it. I have relatively long arms, 73" wingspan, so I think I could still get a good flare out of it, but I see the benefit of having them shorter.

Seth

It's flare not flair, brakes not breaks, bridle not bridal, "could NOT care less" not "could care less".

[chutingstar 1]

You only mentioned measuring the BRK-TOG measurement of this canopy. Before just adjusting that section, I would recommend doing a full line measurement check on the LSTs, USTs as well as the A, B, C & D lines. You'll more than likely find that you are out of trim on everything...but just adding to the lowers of your brake lines won't automatically fix your problem. You may also need to retrim or replace the LSTs and/or retrim other parts of the canopy...or it is possible (but not likely at 140 jumps) that the whole lineset may need a replacement.

Anyway, just wanted to make sure you do a full line trim check...

And the scaling part of your initial question has to do with the lengths given for each size don't always scale up...just to make sure you don't assume a misprint in the numbers on the chart.

Mike

ChutingStar.com