It's good that I'm now able to watch these new episodes online, and since I can set aside more time on Thursdays than on Wednesdays, I'm completely fine with waiting until the day after the premier to watch these new episodes. Anyway, onto this week's episode (which also marked the end of this year's MythBusters holiday mega-marathon).
If a flaming arrow is shot into a car's gas tank, will the car instantly burst into flames?
First, they built a small clear tank to see if a gas tank could even explode when ignited. A full tank did nothing (due to not enough oxygen), but a quarter full tank with a hole in it got ignition, but the flame went out quickly, so they figured that the gas leaking out of the hole would provide the best chance of ignition. Next, they tested to see if a crossbow arrow would even penetrate a car's gas tank, and despite the small ideal target area, it definitely made it through. However, to ensure they could get gas to leak out, they tested different types of arrowheads, and the only one that gave them the desired result was the broadtip. Next, they tried to see what type of fuel to put on the arrow to deliver the flame to the car, but nearly all of them went out due to how fast the arrow was shot, with the only one that worked was the cannon fuse. Finally, on the full-scale test, despite shooting a lot of flaming arrows, they just couldn't get every part of the myth to occur, so they simply shot an arrow to puncture the tank, then remotely ignited the leaking gas. Although they finally got ignition, it was not an explosion, and it took half an hour for the car to become completely ablaze. Busted.
Based on an old South American tribe's initiation that involved shooting an arrow straight up and staying perfectly still until it falls back down, would a falling arrow be lethal?
First, they had to measure how fast an arrow falls, so they went out into the desert, fired arrows straight up (and immediately retreat to the safety of a mobile bunker), then waited for the arrows to fall. The arrows landed across a wide area, so to ensure the falling arrow would fall within view of the high-speed camera, they decide to simply drop the arrow from a drone from the highest point an arrow fell from (which they determined by attaching some tiny device to an arrow before shooting it straight up). Once they finally got the measured speed, they made a simulated human head, tested how far to pull the bowstring to get the arrow to fly at the desired speed, and then placed the head in front of the target and fired an arrow at it. The arrow managed to penetrate the skull, so even though it's very unlikely the arrow will fall straight down onto the shooter, if it does hit it will definitely be lethal. Confirmed.