Fire Nation drill


 * This article is about the object. For the episode, see The Drill.

"fire"

- This drill is a feat of scientific ingenuity and raw destructive power. Once it tunnels through the wall, our troops will storm their city. The Earth Kingdom will finally fall, and you can claim Ba Sing Se in the name of your father. Nothing can stop us.

The Fire Nation drill was a very large, hydraulic, metal drill which was designed solely to penetrate the "impenetrable" walls of Ba Sing Se, so the Fire Nation could conquer the Earth Kingdom capital and ultimately win the War. The operation was overseen by Princess Azula at the battle of the drill; it resulted in failure, however, as Team Avatar intervened.

History


The drill was originally designed by the Mechanist at the Northern Air Temple, who was forced to invent and construct new weapons for the Fire Nation under the threat of the destruction of the Temple. It took the Fire Nation laborers over two years to construct.

After the drill's completion, War Minister Qin and Princess Azula personally led a major attack on Ba Sing Se from inside the drill, using the large machine in an attempt to breach the city's outer wall. Aang noticed the drill's approach when he had split from his friends and flew ahead to Ba Sing Se in order to find Appa. The Avatar and his friends reunited and offered General Sung their assistance in stopping the threat. The General refused at first, however, as he had sent the Terra Team, an elite Earth Kingdom platoon of skilled Earthbenders, to halt the drill's advance. Although they managed to knock away several tanks that escorted the drill, they were quickly overpowered by Mai and Ty Lee. Before they had time to react, Ty Lee used her chi-blocking to disable the entire team, leaving the wall vulnerable and unprotected. The defeat of his elite team caused Sung to accept the Avatar's help.



Sokka came up with a plan to destroy the drill from the inside after hearing Katara's explanation of how the effects of chi-blocking felt. While Toph attempted to slow the drill down from the outside using an earth column, Aang, Katara, and Sokka infiltrated the machine. Using schematics they stole from an engineer, they discovered that the outer shell was sustained through the use of various support girders connected to the engine, so they proceeded to destroy them. Unfortunately, the drill made contact with the outer wall and actually succeeded in drilling a hole clear through the barrier before the group could sabotage the girders and destroy the drill. The group sped things up by only partially cutting through the girders with Waterbending so that the shell would collapse when Aang delivered the final blow to the top of the machine.

Azula, Mai and Ty Lee eventually caught on and sought to stop the team from further damaging the drill. Azula faced off with Aang at the top of the drill while Ty Lee and Mai pursued Sokka and Katara. The siblings escaped through the drill's slurry, though Mai bailed out as the slime disgusted her. To keep Ty Lee at bay, Katara and Toph bent the slurry, forcing it back into the engine along with Ty Lee, building up pressure inside the shell. The battle atop the drill between Azula and Aang was interrupted when the some of the slurry burst out the front of the drill and knocked the two combatants down. Aang recovered the fastest and utilized Azula's absence to shove an earthen wedge into the outer shell, causing the support beams to dislodge and the shell to collapse. The built up pressure and Aang's final blow caused the drill to explode in an earthen mess when the slurry pipes burst, stopping the mechanism dead in its tracks. The drill was left jammed in the wall, blocking the Fire Nation's only route into Ba Sing Se.



After its destruction, the drill remained lodged in the outer wall, encased by a temporary wall of earth. When Team Avatar tried to convince Earth King Kuei that Long Feng and the Dai Li had hidden the century-long war from him, they led the King to the remains of the drill, proving that there was a conspiracy within the city.

It is unknown if the drill was eventually dismantled, or if it was indeed moved at all after the War.

Design


The drill was massive, larger in size than some villages, being at least a mile or two in length, making it the largest mobile machine known. Due to its incredible size, it actually housed an entire brigade of Fire Nation engineers needed to make repairs and clean out the pipelines. Several metal support beams connected the protective outer shell of the drill to its engine inside. Rolling on massive tank treads, the drill moved each of its sections in a wave-like motion similar to an earthworm, using massive, backwards-facing, hydraulic-powered spikes to provide traction and help drag the gargantuan machine forward. As the drill dug into an earthen structure, the rock was chewed up and turned into slurry, a mixture of rock and water that was dispensed into pipes and dumped out of the rear of the drill. The slurry served three important purposes: clearing away material, lubricating the drill, and reducing heat caused by friction with the rock, which could otherwise cause tool failure or even the metal to melt.

Connection
The drill has a construction and function similar to a tunnel boring machine, the difference being that the tunnel boring machine is made not for war, but for building tunnels for traffic, often for trains. Although it can only drill through hard ground and is very slow and expensive, it is much safer than creating tunnels the traditional way; through the use of laborers.

The machine also bore a resemblance to the Ritter Midgard-Schlange - a 524 meter long Nazi war-machine devised for use in World War II, but was never built - whose main purpose was to breach enemy fortifications.

Trivia

 * It's unlikely that the drill would eject the slurry mix out of the back of the machine. It's much more plausible that the system would be a closed loop, with the rock and earth being separated from the water and lubricants for reuse. The drill would also have to carry an incredible amount of water to be able to expel it as it had.
 * The drill included an elevating pavilion for occupants, such as Azula and War Minister Qin, to oversee the operation. Pipes were used to communicate from the pavilion to the rest of the machine. It is unknown how the pipes were connected seeing that the pavilion was completely isolated from the rest of the drill.