Thank you for taking the time to write this study.It is very enlightening and just confirms what is basically sound common sense.It would be better for manufacturers to take note of your study and at the very least put some further research and development into construction of suitable protection for Pilots.
Interesting read. One question about the last recommendation you made ("Make sure the protector covers up till the T8 vertebrae (bottom of shoulder blades), as the NASA study found that's where fractures happen.")
You use a graphic from the McKenney Report which investigates ejection seat injuries, the original Label is "Incidence of Vertebral Injury In Aircrew Surviving Ejection", how do you conclude a need for higher reaching foam protectors in paragliding? In my understanding the higher vertebrae can snap due to the hard impact being transferred by the lower vertebrae and the higher ones being the "weak-link". A high reaching protector wouldn't help this, right? I think there can be a point made for higher reaching protectors due to reclined impacts from stalls or similar, but there also are about as many sideways and frontal impacts recorded, so why not add protectors in those directions as well? (Here is the only data I could find on impact types in paragliding crashes: https://www.dhv.de/media/jahre/2024/02_fliegen/Lehrmaterial/Artikel/Geraetetechnik/Gurtzeuge/7_2011_172_wirksamkeit_protektoren.pdf)
Thank you for pointing that one out to me. I've updated that part, but I want to clarify this in a future version. I just need to research that area more.
In my experience, I've seen so many crashes around takeoffs where the pilot hit the ground at an angular direction, say 45 degrees. Stalled top-landings are a common example. Also, we are super reclined in these new harnesses! If someone hits an uneven or rocky ground, they directly hit these spine regions.
If this angular speed happens slightly frontal, of course there are the legs, which now I understand are incomparably better compared even to the best protectors, simply because they are long. The side is more of a problem, I've heard of many accidents involving the hips.
Thank you for this - it was really informative. I would have liked to see you share the math on how you got to the numbers for the proposed protector - because it makes it harder to follow along - or check your math.
On a side note - this is definitely something of interest to me - as I am getting into speedflying - I want to fly with protection - but some of these airbags have a ton of drag - and some pilots just fly with no protection at all (which I do not want to do) - so I have been interested in learning more about this as I wonder if a more aerodynamic piece of protection that still allows for a lightweight - quality protection is possible for those that want to speedfly + hike and fly. Oh, also while allowing for someone that weighs more than 205lbs (93kg) - not including gear
Great ideas, thank you for your valuable and informed contributions particularly as civil delegate.
A question: why apply the jerk limitation to the "offset" (back end of the acceleration curve)? Physically, if the acceleration ceases instantly at the moment that the pilot velocity reaches zero, would that high negative jerk cause an injury, since they have already stopped?
The possibility of not needing to include the jerk limitation at the end would change the minimum protector thickness
Of course It's possible that this back end jerk limitation is needed, perhaps due to some sort of elastic rebound of the spinal column if the compression which had resulted from the peak deceleration was stopped too suddenly.
Maybe worth thinking about before firming up the new protector proposals, and perhaps speaking to experts in the field. Civil treasurer Andy Cowley may have contacts in the ejection seat industry such as at Martin Baker from his previous career at Airborne Systems.
Eró, thank you for this study, we basically "knew" the situation.
Are there investigation on "several layer material" where energy is dissipated by pressing air and material sideways out? A bit compared to a water filled ballon with sideways "valves" having a determined opening pressure.
Really interesting thanks for your work! Out of interest have you done any simulations on inflatable protection and what jerk they provide? thanks!
He has the Range X-Alps 3 in the article. It has good values.
The range xalps 3 jerk is listed above as 1186 G/sec
Thank you for taking the time to write this study.It is very enlightening and just confirms what is basically sound common sense.It would be better for manufacturers to take note of your study and at the very least put some further research and development into construction of suitable protection for Pilots.
Really interesting. Thanks for writing this. I learnt a ton in just 10 minutes.
Great Work, Zolt! To me it was totally clear that we need some more cm of foam to break down the speed at a level that the a persons spine can stand.
Interesting read. One question about the last recommendation you made ("Make sure the protector covers up till the T8 vertebrae (bottom of shoulder blades), as the NASA study found that's where fractures happen.")
You use a graphic from the McKenney Report which investigates ejection seat injuries, the original Label is "Incidence of Vertebral Injury In Aircrew Surviving Ejection", how do you conclude a need for higher reaching foam protectors in paragliding? In my understanding the higher vertebrae can snap due to the hard impact being transferred by the lower vertebrae and the higher ones being the "weak-link". A high reaching protector wouldn't help this, right? I think there can be a point made for higher reaching protectors due to reclined impacts from stalls or similar, but there also are about as many sideways and frontal impacts recorded, so why not add protectors in those directions as well? (Here is the only data I could find on impact types in paragliding crashes: https://www.dhv.de/media/jahre/2024/02_fliegen/Lehrmaterial/Artikel/Geraetetechnik/Gurtzeuge/7_2011_172_wirksamkeit_protektoren.pdf)
Thank you for pointing that one out to me. I've updated that part, but I want to clarify this in a future version. I just need to research that area more.
In my experience, I've seen so many crashes around takeoffs where the pilot hit the ground at an angular direction, say 45 degrees. Stalled top-landings are a common example. Also, we are super reclined in these new harnesses! If someone hits an uneven or rocky ground, they directly hit these spine regions.
If this angular speed happens slightly frontal, of course there are the legs, which now I understand are incomparably better compared even to the best protectors, simply because they are long. The side is more of a problem, I've heard of many accidents involving the hips.
Hi Zsolt
Thank you for your insightful post! Inspired by your work, I’ve written an doc exploring the potential of the jerk
criterion as a safety measure for paraglider back protectors. In it, I delve into its feasibility, the challenges posed
by noise in signal processing, and propose alternative approaches such as low-pass filtering and range-based
measurements to improve repeatability and reliability.
There’s still a significant amount of work to be done—both in validating the real-world utility of jerk as a measure and
addressing the technical aspects of its implementation. I see this as a continuation of the discussion you’ve started,
and I hope it can contribute to further exploration and innovation in this field.
Fly safe
Fred
https://fredvol.bitbucket.io/Misc/jerk_analysis/p1/report_jerk.html
Also could you please share which standards you currently were comparing to?
Are they EN1651:2018+A1:2020 and EN12491:2015+A1:2021 ??
Thank you for this - it was really informative. I would have liked to see you share the math on how you got to the numbers for the proposed protector - because it makes it harder to follow along - or check your math.
On a side note - this is definitely something of interest to me - as I am getting into speedflying - I want to fly with protection - but some of these airbags have a ton of drag - and some pilots just fly with no protection at all (which I do not want to do) - so I have been interested in learning more about this as I wonder if a more aerodynamic piece of protection that still allows for a lightweight - quality protection is possible for those that want to speedfly + hike and fly. Oh, also while allowing for someone that weighs more than 205lbs (93kg) - not including gear
Great ideas, thank you for your valuable and informed contributions particularly as civil delegate.
A question: why apply the jerk limitation to the "offset" (back end of the acceleration curve)? Physically, if the acceleration ceases instantly at the moment that the pilot velocity reaches zero, would that high negative jerk cause an injury, since they have already stopped?
The possibility of not needing to include the jerk limitation at the end would change the minimum protector thickness
Of course It's possible that this back end jerk limitation is needed, perhaps due to some sort of elastic rebound of the spinal column if the compression which had resulted from the peak deceleration was stopped too suddenly.
Maybe worth thinking about before firming up the new protector proposals, and perhaps speaking to experts in the field. Civil treasurer Andy Cowley may have contacts in the ejection seat industry such as at Martin Baker from his previous career at Airborne Systems.
Much appreciated effort, we're glad🙏🏼
Eró, thank you for this study, we basically "knew" the situation.
Are there investigation on "several layer material" where energy is dissipated by pressing air and material sideways out? A bit compared to a water filled ballon with sideways "valves" having a determined opening pressure.
Regards Holger
Brilliant summary, thanks Zsolt.
Excellent Summary. Thank you.