12 January 2010

Chrono Fun - Nerf edition

The SCSon cashed in a couple Christmas gift cards tonight and came home with a "Nerf N-Strike Recon CS-6". This is a caliber .50, magazine fed, removable stock, changeable barrel with rails top and bottom, lights and sights. It even has a "shoulder thing that goes up". [insert your own grunt sound effect here]

He opened it up and started having fun swapping parts around... like any of us and our AR pattern rifles. In typical free association mode he asked "Hey dad... how long would it take to set up that speed sensor thing".

Hmmmm I smell a teaching opportunity in the best Mythbusters/James May kindof way. The chronograph only took a few minutes to set up, but it took far longer to take the data not only from the new acquisition but from the rest of the Nerf collection. That includes the CS-6 at top, a double barrel shot gun lower left and a six shooter on the right. We took 10 velocities from each gun. times 2 for the CS-6, once as a rifle and once as a pistol to see what difference the barrel extension made.

The data shows a couple surprises. Firstly the average velocity for all three guns was just over 50fps (three over, one under). This is likely because they all are powered by the same basic mechanism - a spring powered air pump. This is similar to AirSoft pistols.

Next surprise is that the difference between the CS-6 as a rifle and as a pistol. Velocities were 17% higher for the pistol than the rifle which might mean the extra barrel length actually slows the dart. However the rifle was more consistent with it's velocities showing a standard diviation was about 32% lower with the rifle barrel installed.

Finally the shotgun had the highest speeds both average and single shot - nearly 78 fps. But it also was the least consistent with a range on nearly 44fps. It's probably a combination of leakage between the air pump and dart, and how many times the dart bangs its way down the inside of the barrel.

Here is the raw data for the sake of completeness:

What's it all mean? Abso-fraking-lutely nothing! THESE ARE TOYS! But it was an excuse to pull out the tools and run the data. And sometimes "Because we can" is reason enough.

"Nerf" is a registered trademark of the Hasbro company.

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