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BASE Canopy Brake Stows

In 2016, we did a little work on on brake stow construction. What follows is a summary of what is currently the standard, how our products are built, and what we think can be improved.

Brake Stowes
Standard Brake Stows

Most BASE canopies (including all Squirrel canopies) use 900lb Dacron from CSR Braids (USA) for the main brake line. The actual brake stow material used for the cat-eye varies, but the end result is similar across leading manufacturers: A brake line stowed in the slider down/off LRM configuration has a breaking strength from 400-600lbs (1.7N-2.7N). Using traditional construction techniques, the strongest stow that we tested failed at 2.8N or 630lbs force. The mode of failure was consistent across all lines tested: as the brake line is loaded, the toggle intersects the line of bartacks in a shearing manner.

Is Standard good enough?

Failing brake stows aren’t a major topic of conversation in the BASE world. This is partly because the failures typically occur in situations such as long slider down delays, or on worn gear. Intuitively, most BASE jumpers know that if we are taking long delays slider down with a fully vented canopy, the opening is going to be pretty hard and hard openings can stress our equipment. Also, most BASE jumpers understand that the difference in opening force between 4 and 5 seconds is much greater than that of between 2 and 3 seconds. As we push the envelope, the risk does not increase linearly.

The current trend of more jumpers pushing the limits further is likely to continue. So what should be normal? In situations where the delay is longer than average, the exit weight is high, or the equipment is well used, it is not rare for brake lines to fail at the stow. Enhanced-strength brake stows have been experimented with over the past ~15 years, but the current setting used by all manufacturers has become standard because it is the simplest to install.

Stronger Brake Stows

The first generation of Outlaw brake stows are as strong or stronger than other standard stows. However, we think it may make more sense for the strength of the stow to be closer to the strength of the line, and also to the strength of the stow-loop on the riser. For that reason, we have redesigned the brake stow to increase strength while maintaining the same function and ease of use. The Squirrel BASE canopy brake stow involves a tacked loop of 725lb Spectra secured inside the traditional 900lb Dacron main line (construction detail in the diagram at left). It prevents the shearing action as the toggle interacts with the loaded line. Instead of the toggle edge meeting bartack stitches at 90 degrees, it encounters a loop of 725lb Spectra inside the main line. There is no functional difference from the user’s perspective, yet it is proven to be significantly stronger (see chart) than current standard brake stows. Construction is slightly more complex, and replicating this technique in a custom brake stow requires a slightly higher level of sewing expertise. Squirrel BASE canopies are delivered with factory deep and shallow settings that are optimized for the typical exit weight of each size, with the intention of minimum forward speed in DBS.

Please note that the Spectra cat-eye material may cause wear to the stow loop on your risers, depending on what material it is made from. Carefully inspect this junction each time you pack. Squirrel harness/container systems (from 2016 on) use Spectra for the stow loop, which wears well against the Spectra cat-eye. Other line material on other harness/container systems may not.

We keep the new reinforced brake assembly (a full set including main and upper control lines) in stock and available for free to any pre-2016 Outlaw owner that wishes to install it.

Cheers, from all the Team at Squirrel.

TEST RESULTS
Brake Stow Type lbs kN
Other 401.19 1.784582
Other 438.38 1.950011
Other 470.99 2.095068
Other 339.99 1.512351
Other 480.73 2.138394
Other 461.14 2.051253
Outlaw, New 594.33 2.643711544
Outlaw, New 585.19 2.603054798
Outlaw, >100 SD jumps 449.98 2.001610756
Outlaw, >100 SD jumps 576.1 2.562620464
Outlaw, >100 SD jumps 466.46 2.074917448
Next-Gen Stow 808.23 3.595186144
Next-Gen Stow 991.89 4.412146523
1200lb Spectra Main 1014.16 4.511208418

The password is: PULLIT

Brake Stowes

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