Pilot chute pull forces

The question “Does a static line jump put more or less stress on your canopy (bridle attachment point) than a free fall jump” has been floating around on the forums for years, and from time to time another experiment (like dragging PC’s behind cars), or mathematical model (that is far from whats going on in reality) pops up and someone thinks he has an answer, although most are flawed in some way.

So here we go again, this time its my turn to give another answer to this issue! My test setup is simple, and enables direct comparison of the static line and pilot chute pull forces the bridle attachment point. (You can find all information and data in this PDF.)

Here’s the conclusion:

On static line jumps done with a loop of standard 80lbs break cord the forces applied to the bridle attachment point are bigger than on any type of free fall jump.

Byproduct of the tests I did with the setup: (all values above should be understood as
approximations)

  • Slider down, PC size appropriate for delay, ~35 kg of pull force on bridle and attachment point are unlikely to be exceeded, although on long delays with an over sized PC this can happen.
  • Slider up, PC size appropriate for delay, ~35 kg of pull force on bridle and attachment point are exceeded (jump with a small wingsuit).
  • Never exceeded ~75 kg of pull force on bridle and attachment point. Slider up & down, terminal with wingsuit, tracksuit, slick.

And here is how i did it, I present the poor-mans-bridle-pull-force-measuring-device.

Since I only want to know if it’s more or less than on a static line jump, this is perfectly good! Maybe it creeps a few people out seeing something like this dangling on the attachment point, but it’s all in the name of science. I did around 60 jumps with this setup, slider up, slider down, tracking, wingsuiting, slick, etc.

You can find all details on what i did and data I collected in this PDF.

Comments and mails are welcome, I would like to hear what people think about this.

wtb

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