Electromagnetic Launcher

I've always been fascinated by electromagnetism and its ability to move objects at incredible speeds. In 2021, I set out to build an electromagnetic launcher to test just how fast a small projectile could be accelerated using only magnetic forces. This design follows the Gaussian coil gun principle, using a sequence of electromagnetic coils to propel a metal projectile down a barrel. My goal was to create one of the most efficient and space-optimized electromagnetic launchers designed for consumers, incorporating multiple innovations to improve speed, energy efficiency, and control. 

This final design integrates a hybrid power system consisting of two high-energy-density supercapacitors and a LiPo battery, ensuring maximum power output precisely when needed. IR sensors synchronize coil activation in real-time, allowing for optimized acceleration with minimal energy waste. A Bluetooth module enables remote adjustments and performance tracking, while a collapsible frame and compact power supply design make it one of the most space-efficient electromagnetic launchers ever developed. Every component was carefully selected and optimized to push the limits of consumer-grade electromagnetic propulsion.

The launcher uses three coils to progressively accelerate a metal projectile. Each coil is slightly shorter than the projectile itself, allowing the next coil to engage before the projectile completely exits the previous one. This overlap improves efficiency and increases acceleration while maintaining smooth motion. 

Most electromagnetic launchers rely on either high-output batteries or banks of supercapacitors. However, batteries struggle to provide instant power surges, while capacitors discharge too quickly, wasting energy before the projectile reaches the most efficient part of the coil. My solution was to combine both power sources strategically:

• The first coil is powered by a high-output LiPo battery, providing steady acceleration from rest.

• The second and third coils are powered by individual supercapacitors, allowing them to rapidly dump energy when the projectile reaches peak efficiency inside the coil.

To ensure maximum energy transfer, I optimized the coil windings and wire gauge specifically for the capacitor voltage. This helped minimize resistance and heat buildup, improving efficiency with each shot. 

Initially, I machined the frame and shell from aluminum since it is non-ferrous. However, I discovered that using an aluminum barrel created eddy currents that interfered with the magnetic field. To fix this, I used a carbon fiber barrel, which is completely non-metallic and allowed the electromagnetic field to reach the projectile without interference.

For accurate coil activation, I implemented two IR Time-of-Flight sensors:

• Front Sensor: Ensures the projectile is fully inside the barrel before activating the first coil.

• Exit Sensor: Measures projectile speed by detecting the time between the nose and tail passing the sensor, providing real-time velocity data for calibration.

To simplify adjustments, the launcher would feature a Bluetooth module that allows for remote control and monitoring via a phone app. This enables real-time speed readings, power level adjustments, and fine-tuning without needing external controls. There potentially would be a mini-display on the back to show relevant info.

One of my main goals was to make the launcher as compact as possible without sacrificing performance. To achieve this, I made several design choices to minimize size while maintaining high energy output:

• Capacitors in the Handle – Supercapacitors are some of the largest components in the system, so I housed them inside the grip instead of using external capacitor banks.

• High-Energy-Density Components – I selected the most energy-dense capacitors available and used a LiPo battery, known for its high power-to-size ratio.

• Built-in Voltage Booster – Instead of relying on bulky external power supplies, a compact voltage booster recharges the capacitors after each launch, keeping the power system self-contained.

Since electromagnetic launchers are typically large and awkward, I designed a collapsible hinge mechanism integrated into the trigger guard, allowing the launcher to fold for easy storage. The frame was also designed to minimize excess material while maintaining structural integrity, keeping the overall footprint small. These design choices make the launcher far more portable than most similar devices, without compromising performance.

One of the biggest roadblocks was finding a transistor that could handle the full power of the LiPo battery and supercapacitors while switching fast enough to activate the coils at the right moment. The Arduino output was too weak to directly control large MOSFETs, so I used a smaller MOSFET to act as a gate driver for the larger one. This worked initially but introduced delays, preventing precise timing for the second and third coils.

To achieve full automation, I need to explore faster microcontrollers or dedicated gate driver circuits to improve response time. Additionally, refining the coil activation sequence based on projectile speed data could further optimize performance. Learning more about high-speed switching electronics and advanced programming techniques will be key to getting the system running at peak efficiency.