See Through Potato Cannon at 20,000 fps - Smarter Every Day 156

Destin demonstrates a transparent potato cannon that was previously recorded at 3,000 fps during the day, now being filmed at 20,000 fps at night to observe the internal combustion science.

• What happens when ignition starts from the back of the cannon? • What happens when ignition starts from the middle?

Starting ignition from the middle should produce better results due to even expansion of gases throughout the combustion chamber.

Compare the two ignition methods using high-speed video to observe the actual combustion differences.

The potato cannon is fired with a flint-sparker ignition system located at the end of the combustion chamber.

• A flint-sparker creates a spark at the end of the combustion chamber • Electrodes are set up in the center for the second test method

Electrodes positioned in the middle of the potato gun will create a spark in the center, theoretically producing more even combustion.

High-speed footage reveals how the combustion wave travels through the chamber differently depending on ignition location.

When combustion starts from the end, it creates a wave that travels through the oxygen and fuel mixture down the length of the chamber.

When starting from the middle, expansion occurs but oxygen is consumed faster than fuel, creating an unburned fuel pocket that eventually uses rarefaction to pull oxygen back through the barrel.

• Sidewall cooling: the pipe walls cool gases below combustion temperature, preventing burn near the walls • Unburned fuel pockets form when oxygen is depleted before complete fuel combustion • Rarefaction pulls oxygen back in to reignite remaining fuel

The high-speed video shown is authentic unmodified footage directly from the camera without artificial speed adjustments.

When the explosion overexpands, the system pulls air back through the barrel into the combustion chamber to equalize pressure.

Fresh oxygen from the pulled-back air meets remaining fuel, causing a second burning process to occur.

When gas is squeezed into the narrower barrel from the larger combustion chamber, it must increase speed to maintain the same flow rate.

• The process is inefficient for burning fuel-rich mixtures • Original hypothesis about middle ignition being superior appears to be incorrect based on observed results

Combustion chamber performance depends on both the localized chemistry and fuel-air mixture at each point within the chamber.

• Stoichiometry (fuel-air mixture ratios) at specific locations • Venting method and configuration • How venting dynamics create localized pressures and rarefactions

The ability to observe and understand complex dynamic systems through high-speed footage reveals both the physics and aesthetic beauty of combustion phenomena.

Sidewall cooling and combustion inefficiencies are significant factors contributing to pollution products from engine combustion.

Audible.com has supported Smarter Every Day for an extended period, making high-quality video production possible.

The combustion chamber is set up to create the same flame front but with one side vented, demonstrating the acoustic and visual effects of uncontained expansion.

The vented combustion creates an audible explosion event visible in high-speed footage, showcasing dramatic pressure release.

Viewers can support the channel by visiting audible.com/smarter to access free audiobooks and free trial offerings.