Episode 78: Ninja Myths - Walking on Water, Catching a Sword, Catching an Arrow
- Running on water (using special shoes): busted
- Catching a sword: busted
- Catching an arrow: busted
Ninja fans will be disappointed as the MythBusters busted several ninja-related myths. They investigated several skills that ninjas mythically possessed but were unable to replicate any of them. While it is debatable whether or not ninjas actually existed, one historical theory about ninjas is that they were peasants who developed unusual fighting techniques to defend against the samurai class. Their skills were reputed to be 'supernatural.' The MythBusters don't have supernatural abilities, so they relied on their usual means for testing.
Dale Seago of the San Francisco Bujikan dojo served as their ninja expert during the testing of these tests.
Running on Water
Myth: Ninjas could walk on water using the aid of mizugumo
Mizugumo (Japanese for 'water spider'): flat wooden disks meant to be strapped to the feet
Adam and Jamie wanted to test if mizugumo would have allowed ninjas to walk across water. Adam manufactured a pair using pine board cut into four quarter-circle pieces and a rectangular center piece. The entire contraption was laced together with twine.
Here's a photo of mizugumo in a Japanese museum:
photo by markcbarrett
Adam sunk like a rock as soon as he stuck his first foot in. He decided to do go crazy fast for the second run, "like cartoon," for the second run -- same result.
Adam: "I don't know about you, but these seem a little cumbersome to me... the important thing is I look damn good"
As it turns out, mizugumo were actually meant for rice paddies and mud flats, like snowshoes.
Adam's ninja feet
Adam designed his own set of buoyant ninja feet using snowboard boots, several layers of packing foam, aluminum sheeting on the sole, and a lightweight rail for rigidity. He calculated that the foam displacement would give him 265lbs of buoyancy.
Adam's first test run ended quickly: he tipped head-first into the water as he got into the water too quick.
Adam: "If I had any dignity, that would have been humiliating"
On his next run, he got into the water more gingerly. He was able to stand up but he ended up falling into the water as he strained to get them moving.
Adam: "I give up on my ninja shoes. They're not stealthy, they're not easy, and they don't move"
Walking on corn starch water (non-newtonian liquid)
Jamie showed that it is possible to walk across fluid -- non-newtonian liquid. The viscosity of non-newtonian fluids increases as you apply force to it, making it possible to walk across as long as you move fast enough. As it turns out, cornstarch and water is a easy way of making non-newtonian fluid.
Adam was able to walk across their own mixture of cornstarch+water. Here's a youtube clip of people walking across a whole pool of it:
busted. The myth of ninjas walking on water may have been a result of the desire of ninjas to be mythical -- ninjas could have put wooden posts in water to make it look like there were walking on water.
Catching an Arrow
Myth: Ninjas could catch an arrow with their bear hands
Their first test was simple: Jamie shot arrows with tennis-ball tips towards Adam (in protective garb), while Adam did his best to snatch the arrow as it whizzed past. Jamie's bow was with different 'marks' to indicate how far he was pulling back the bow.
- Mark 1 (slowest): Adam was able to catch an arrow in two tries
- Mark 3 (58mph, 3x slower than real arrow): Adam was able to catch an arrow after several tries
The tennis ball made the arrow three times as heavy and the speed was three times as slow. They decided to switch to mechanical rigs so that they could test at even faster speeds.
They timed their expert Dale Seago closing his hands in front of a high-speed camera. It took him 35ms to close his hands. Jamie built an evil-looking mechanical hand to Dale's speed measurements. 5 pieces of heavy chain to formed the individual fingers and lace 'tendons' were weaved through the chain and attached to pneumatic actuators. A leather work glove was added for grip.
Adam built an arrow shooting rig that consisted of a bow mounted to a steel frame. Timers were set to both Jamie's hand and the bow so that they could be triggered together.
- Test 1 (170mph): the hand rig was 2ms slower than Dale and missed the arrow
- Test 2: based on the first test, they were able to calibrate the timer exactly. The glove closed at the correct time but the arrow was able to slip through -- Dale's hand speed was too slow.
- Test 3 (super-fast hand): they spring-loaded the hand rig to close five times faster than a human hand. At this speed they were able to seize the arrow out of mid-air.
busted: it took a mechanical hand operating on a timer at 5x human speed to catch an arrow
Stopping a Sword
Myth: Ninja could stop a sword with their Hands
See also: Cutting a Sword
- Sword-swinging rig: They were able to resurrect the sword-swinging rig from Cutting a Sword myth. This time they set it up to swing downwards instead of sideways.
- Fake hands: they were able to catch some ballistics gel hands from dental alginate molds of Tory's hands
- Sword-catching rig: They built a new rig to swing the fake hands together.
- Trigger switch: As the sword-swinging rig swung downwards, it clipped a trigger switch that released the sword-catching rig. The location of the trigger was adjustable to change the timing.
They needed to measure hand strength for the sword-catching rig. The build team took turns slamming their hands together on a measurement pad. Grant had the strongest strike with 1000N of force, so they used his data to to calibrate.
They also had to measure sword-strike speed. Tory, Adam, and Grant all took their swings at the ballistics gel head in front of a high-speed camera and measurement grid. Grant again did the best with a ~47mph strike.
The sword catching rig performed to the correct speed but the hands bounced when they came together, creating a small gap through which the sword could slip. Tory strengthened up the rig and was able to eliminate the bounce.
Test 1: The rig caught the sword... on the rebound. After the sword bounced upwards from the fake head, the sword-catching rig came together and seized the blade.
Test 2: Grant moved the trigger to release the hands even sooner. It wasn't soon enough as the sword penetrated the head to the eyebrow.
Test 3: They moved the trigger again and caught the sword. However, the sword-catching rig triggered about 5ms too early and the sword was stopped mostly because the sword sliced through one of the ballistics gel hands in its way.
Test 4: Grant added a timer to give them even more precise control over the timing. The hands came together right as the blade passed between, but the sword still passed right through, slicing a bit of the hands.
They visited the expert Dale Seago for his opinion on the myth. While he said that they prefer to evade, he did show how a sword could be stopped with the hands. He put shuko, ninja climbing claws, and Kari swung a dulled sword right at him. Instead of clamping both hands together on the blade, he instead raised one of his shuko claws up and stopped the blade with one hand. With an assistant, he also showed how he could absorb the force of the swing and then redirect the strike towards the attacker.
Season 5, ninja myths, water myths,