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chronographing for a nerf war

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#1 pit viper

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Posted 28 December 2014 - 12:48 PM

A club at my school has planned a nerf event for a fundraiser. All of the details have been figured out and it has been approved already.
The only thing that hasn't been figured out is how to tell if a blaster should be allowed. We decided to leave it up to a chrono reading.
The question: what should the blaster chrono at for it to be "safe"? All blasters are firing stock darts and all participants have a moderate pain tolerance.

Edited by pit viper, 28 December 2014 - 12:48 PM.

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#2 Thorn



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Posted 28 December 2014 - 12:56 PM

Im not sure about the pain tolerance, but I can tell you for frame of reference that a stock Elite blaster shoots about 65-70fps, a modified stryfe shoots about 100 fps, most homemades shoot around 190-230 fps, and a modified AT3K can shoot up to 350 fps. It just depends on what you want to allow. I would say around 100-150 fps would be good for safety reasons, however as long as you aren't using a plugged big blast I think you are fine especially with elite darts.
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#3 Doom


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Posted 28 December 2014 - 03:12 PM

I have some incomplete notes on dart safety here: http://btrettel.nerf...-incomplete.pdf

Hasbro uses a factor called KED to measure safety. In this article I detail KED limits for a variety of different injuries like bruising and corneal abrasion. You'll need a chronograph and a small scale to calculate KED. If you mandate using a certain type of darts, then you won't need a scale as long as you know the dart mass. Just convert the muzzle velocity to KED and you're good.

My recommendation would be to mandate use of safety eyewear. I won't make a particular KED limit recommendation, however. It's up to you to determine what level of risk is appropriate. You can look at my document to see how likely certain injuries are if direct impact is made.
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#4 Lunas



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Posted 28 December 2014 - 08:04 PM

like he said ^ MANDATE eye ware at my last event i did not bring my eye wear and got hit in my eye with a stock retaliator it hurt like hell even though it was stock.

I would place certified stock or under 110 fps with stock darts only as my rules 80-110 fps will still shoot over 100ft
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#5 Astech



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Posted 30 May 2015 - 04:14 AM

The question: what should the blaster chrono at for it to be "safe"?

I'm actually doing experimental research on this at the moment. Assuming eye protection, there's really do way an elite dart will do damage. The rubber tips are very soft, resulting in lower impulse and the weight is insufficient for blunt trauma. Unless someone shows up looking like an extra from WWZ and claiming velocities over 200 fps, you've got nothing to worry about. In short; 70 fps keeps legislators happy, 100 fps keeps schools/parents happy and 150 fps keeps players happy, so a 100 fps limit keeps all important parties satisfied and welt/corneal abrasion free.
[Edit] Wow, I really need to be more observant. i just noticed the date on this thread. My bad...



Edited by Ice Nine, 30 May 2015 - 12:35 PM.

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