NERF data!
A good part of the allure of the Nerf hobby is a new and interesting source of different data sets to explore. In this case the data that I found intriguing was the population statistics around projectile velocity at varying distances using different blaster modifications while attempting to track accuracy. To that end I targeted the Nerf Retaliator platform as the basis for this data collection effort. This is a widely available and popular blaster that has a variety of off the shelf modification kits available, and there are some interesting do it yourself modifications that are a bit more involved, but that could yield additional interesting data points.
Special thanks to Monkee Mods who donated a spring for this study, and to Tacticool Foam who donated an Artifact plunger head. I purchased the balance of the kits used in this study unless I mention differently in the write up.
Methodology
This study involved:
- Muzzle velocity studies at <1ft from the chronograph for a variety of dart types and spring / breech kits.
- Projectile velocity at varying distances using 100 shots while determining accuracy as a function of what percentage of those shots were able to be read by the chronograph.
The chronograph
A complication for me was the calibration of the chronograph. I’m using a Caldwell Ballistic Precision Chronograph with the optional light kit for indoor use.
I picked this up on sale for about $60, and it had the benefit of working out of the box with an iPhone to easily export data sets. I added the lighting kit after having difficultly recording measurements indoors. The light kit works great for me, and I can now record measurements while firing from varying distances from the chronograph. My concerns though surround how to compare my results against those of others. Caldwell states this chronograph is factory calibrated:
Higher accuracy was achieved by using a high speed 48 MHz processor and by designing a circuit with an advanced data interface that allows each unit to be computer calibrated at the factory after assembly. The end result is the ability to provide much better accuracy than other chronographs on the market (+/- .25%).
I really don’t have a mechanism to sufficiently baseline my chronograph against other folks. The best I can do is baseline a stock blaster, note how my chronograph profiles it, and use that as a relative baseline for how different blaster modifications impact chronograph results.
I’ll keep researching other solutions, but for now, I’ll leverage profiling stock blasters as my primary method for comparing my results to external results.
Why all the concern? Well, my initial readings for a stock Retaliator came in at around 50 fps for the off the shelf blaster. This is markedly lower than what many other folks report. Typically I see stock Retaliators reported at 65 to 70 fps. Is my Chronograph that far off? Are my methods suppressing velocities?
Testing procedure
My currently methodology has the muzzle of the blaster within 1 foot of the chronograph. For official data points used in a study I record at least 100 readings and calculate the population statistics. I’ll then create summary comparison plots that illustrate the differences between configurations. Items to note:
- I record data indoors
- There’s no wind or significant air currents impacting the projectiles
- I record the type of dart in use and vary the darts to measure any impact on velocity
- I use a tape measure to record distances from the chronograph within my house
- I currently manually fire the blaster – I don’t have a portable vice or way to secure the blaster. This could be improved later if I want a more complex way to fix the blaster while range testing.
OK, enough of this, on to the pretty plots!
The tacticool blasters
These are the two heavily modified Retaliators I was using for this study. The first one has a Worker Stefan Kit upgraded breech and different springs in use:
It’s also using an Artifact aluminum sled, and an Artifact aluminum plunger head. These don’t help with performance, but rather durability. A second blaster was used for profiling the performance of the Artifact Punisher Stefan Kit. Similarly it’s using an Artifact aluminum sled, and various springs:
Both blasters are using a worker pump grip & shell kit. The muzzles are on for show. They were removed for testing.
Velocity studies
Muzzle velocity
This study looks at the progression of a series of velocity tests where different springs were used in the blaster. Retaliators function by compressing a spring which when released compresses air within a plunger tub by forcing a plunger forward within the tube pushing air through the breech and forcing the dart through the muzzle. I’m measuring the velocity of this projectile as it exits the muzzle and crosses the sensors of the chronograph.
My first test looked at:
- a stock retaliator with a 2.5kg spring
- a Retaliator with a worker stefan kit / breech replacement and a 7kg spring
- the same Retaliator with a 9kg spring from Titan
- the same Retaliator with a 10kg spring from Aus NertTurf (thank you Monkee Mods for giving this to me!)
Note I am using an Artifact aluminum plunger head in the Worker tests as well. The stock plunger is simply shredded by these upgraded springs even with a padded plunger tube, so consider that when planning on modifying your blasters.
Here’s the summary of the data I collected:
