Modding the Nerf Rapidstrike - A Budget, 16DPS Build

The Nerf Rapidstrike is one of Nerf's fully automatic flywheel magfed blasters. Released in 2013, it was the first fully automatic flywheel blaster in Nerf's stable, and it remains one of the premier modding platforms for fire rate. While there have been other full auto blasters released later on like the Hyperfire, the Rapidstrike is more preferred for modding because of the pusher system, which can be pushed to very high fire rates without skipping darts, which the conveyor belt systems in later blasters are wont to do. 

Target and Parts

I am targeting a very budget build, utilizing relatively affordable components compared to what's out there. Battery will be 3S to maintain commonality with my Stryfe, as I plan on using that as my only battery. FPS will be in the 150-ish range, if not slightly lower to stay within the FPS limits of our local group. Fire rate will be as high as possible, and the highest I have seen so far is around 16DPS. Now that's not practical at all compared to a more sane fire rate like 10DPS, but the point of this blaster is to be a dart hose. I've got a Stryfe if I wanted to conserve ammo.

I've had good luck with my budget setup on my Stryfe, and I have essentially duplicated the parts here. The flywheel cage will be upgraded to the Worker Polycarbonate 42.5mm Straight Cage, which I have had good luck with. The downside is it doesn't have a dart guide, but that can be added to the shell after the fact. The flywheels are the Worker "Smoothie" Black Flywheels, which pair well with the cage. Flywheel motors are the ever affordable OOD Valkyrie 3S motors, while the pusher motor is a MTB Honey Badger 2S motor overvolted to reach the fire rate goal. The only bottleneck I might encounter is with the flywheel motors bogging down from the fire rate, but that will require testing. Wiring is with some 16AWG Silicone Wire from my previous project. All in all, the parts added up to around $25. 

Wire Diagram

For mine, I decided to go with a dead center 3 switch design. It's safer compared to the stock live center design as it will cut power to the pusher in the event of a pusher crash or mechanical switch failure. It also parks the pusher far more reliably than a simple 2 switch design, leading to fewer jams when changing magazines. The only downside is less trigger control, as it's possible to short stroke the pusher with too short a trigger press. However, at such high fire rate for my build, it shouldn't matter too much as any trigger pull would most likely fire off more than one shot.

Wiring diagram courtesy of Captain Xavier, with change made for dead center

For clarity (or maybe not), here are the wires superimposed on the actual blaster with the switches and motors in position. 

Wire schematic. The pusher motor is not shown, but the terminals for it are notated by the scribbled dots

Disassembly and Soldering

Stock Rapidstrike taken apart

Ultimately, there's not too much to show in terms of intermediate steps. The first step is to unscrew all the screws holding the clamshell together. Take note of which screw goes where, as the screw lengths are slightly different depending on the hole. The battery terminal wire is attached to both sides, so make sure to pull that out to fully split apart the halves. Then I ripped out all the electrical components. I am using a 3D printed switch plate I found on Thingiverse, so I took out the trigger assembly as well. Be sure to keep the pusher assembly though, as that will be reused. 

3D printed switch plate

A few things I do want to touch upon are some shell changes to get everything to fit. The original pusher motor has its terminals on the side, while the new ones have it in the rear. This means I had to dremel out some space for the wires and contacts to stick out of. On the switch plate, I did not have any suitable screws, so I used an 1/8" steel rod cut into small pieces to attach them on. It's not great, but it holds reasonably well. They still need to be glued in to actually hold against the plate. I used hot glue for the task, as it's strong enough to hold the parts in place, yet still can be removable in the future.

Space dremeled out to allow for the motor contacts

Completed rewire

Be sure to test often, as the last thing you want is a short caused by bad soldering. I had an issue with the trigger getting caught on the switch, so I had to remove some material from the top of the switch for it to slide smoothly. The roller switch on the pusher also got caught occasionally behind the pusher, so I had to bend it slightly to improve reliability. I tested using a 9V battery, as any issues would be caught at a slower speed, which means less damage. Plus, an alkaline battery is considerably safer than a LiPo if there is a short or other issue. 

After it was tested, the other shell half was screwed back on. Be sure to not crossthread any of the screws. I opted to keep the jam door off, partially because there was no way to keep it in place since I had removed the holder. There's probably a way to preserve the functionality of the jam door, but since there's a handguard already I decided it would be ok to do without it, just like on my Longshot.

Conclusion

I think these two videos speak for themselves:

Before:

After:

Fire rate and power are considerably improved compared to stock, with a full 18 round magazine emptied in just over a second flat. The Valkyrie motors don't bog down nearly as much as anticipated, and are able to maintain a satisfactory FPS for me. As expected, it's quite loud, although I was surprised at the amount of clacking the pusher made. The battery tray is more than large enough to accommodate any battery that also fits the Stryfe, and fit the 1000mAh Turnigy 3S battery no problem. 

Overall, it was a worthwhile build, and a fun blaster to play around with. It's not the most practical, and eats through ammo like no tomorrow, but that's precisely why it's so fun.