Episode 40: Confederate Rocket
- The Confederate Army built and launched the first long-range missile (2-stage) from Richmond to DC: mythbusted
This episode was a lot like the JATO and Jet Pack episode: Jamie and Adam against one myth. These episodes are a lot of fun because they really get into the details of the myth and the engineering. In this particular case, the episode had tons of rockets and a brief interlude of accidentally setting MythBusters HQ on fire.
Myth: In 1865, the Confederate Army built and launched the first long-range missile (2-stage) from Richmond to DC.
Short-range rocket experiments
Jamie and Adam built two known designs from the Civil War era: the Hale rocket and the Boxer rocket. The Hale rocket was chosen because it was considered to be the state-of-the-art rocket used at the time. It featured tail fins that sacrificed range for accuracy to give it a range of 2000 yards. They probably chose the Boxer rocket because they thought it was a two-stage rocket. The Boxer rocket was a rescue rocket that was used boat-to-boat or shore-to-boat to transport a rescue line. It's range was only about 300 ft. It turns out that the Boxer was not a two-stage rocket (a rocket that separates mid-flight) but a compound rocket (burns through multiple layers of fuel).
Hale rocket (source and more info: Smithsonian):
Boxer rocket (compound) (source and more info: cyber-heritage):
Jamie welded his rocket shut: "Somehow when we screw up everyone's all over it"
Tori built a simple launcher (channel with adjustable angle) and for safety reasons they had their expert use modern motors with equivalent thrust to the black powder that would have been used in Civil War times.
Adam's percentage predictions for the launch: * 70% spins out 200 ft away * 29% it flies successfully to 3000ft * 1% that it hits the ground and bounces over to us
Launch results: * Hale rocket: It corkscrewed away but managed about 600-700 yards, lodging itself five feet into the ground. * Boxer rocket: The boxer rocket also corkscrewed but managed to fly twice as far as the Hale rocket, about 1300 yards.
Confederate rocket characteristics
They brought in a rocket scientist consultant: Steve Harrington, CEO Flometrics and San Diego State professor.
Harrington: "Unfortunately in the rocket science world there aren't that many women and they are hunted to extinction."
After mulling it over, they came up with a rocket design that could have been capable of accomplishing the myth, though they would have to validate various aspects to see whether or not they were even possible: * Launcher: tube made from naval cannons and embedded in a river bank * Ignition: Gun cotton * Rocket fuel: Powered by ethanol and liquid oxygen, the latter made by Lord Kelvin * Stabilization: Small turbine and a gyroscopic stabilizer contributed by Ernst Mach
The Nazi's used ethanol fuel to make the V-2 rocket. Due to oil-shortages they wanted an alcohol-based design.
Lord Kelvin's Liquid Oxygen
A sub-myth of this myth is that William Thompson (aka Lord Kelvin) in 1865 succeeded in creating liquid oxygen. This is highly doubtful as Thompson never claimed to have accomplished this feat and history first records the creation of liquid oxygen in 1877. In 1877 Cailletet and Pictet independently created tiny amounts of liquid oxygen using different techniques. Cailletet used adiabatic expansion and Pictet used the Joule-Thompson effect. Both relied on Thompson's 1852 observation that gas expanding in a vacuum decreases in temperature.
It was Grant's job to verify whether or not it was possible to create the liquid oxygen. First he had to produce oxygen gas by focusing the sun on mercuric oxide. He eventually gave up on converting the oxygen into liquid form as he couldn't get the gas cold enough. Oxygen doesn't become a liquid until it reaches -118.6 degrees Celsius, and neither the MythBusters HQ nor people during Civil War times possessed the technology to make anything that cold.
They decided to change the design to a hybrid rocket: the fuel is wax, the oxidizer is nitrous oxide. The technology for both ingredients was available during the Civil War. It takes 50 atmospheres to create liquid nitrous oxide versus the 400 atmospheres it takes for oxygen.
This time Grant was successful, but they censored the process that Grant used to make the nitrous oxide. Adam's sniff evaluation: "That burns"
Rocket Tank Design
They scratched the two-stage design. Instead they decide to put a tank of liquid nitrous oxide at the top with a release valve to a tank full of paraffin wax. Carbon would be added to the paraffin wax for an even burn and a graphite nozzle to direct the blast.
Jamie: "It doesn't make any sense it should be this easy. This is some laughing gas and some plumbing fixtures and if it actually goes someplace, that's kinda scary"
Test firing at MythBuster's HQ
They create a mini-bunker in the shop inside which they mount the rocket for a burn test.
They set the inside of their shop spectacularly on fire. The fireball melted their cameras and Adam's hovercraft. It also melted the ballistic glass.
Adam: "Hey! That worked!"
Ernst Mach's Gyroscopic Stabilizer
They scrapped the idea of using Mach's mythical stabilizer and instead decided to use Hale's tail fin design to stabilize the rocket. The fins cause the rocket to rotate so that it flies more stable.
Jamie and Adam give a not-so-thrilled Kari the job of making gun cotton, which will be used to give the rocket it's initial thrust. Once again they censored the recipe for making gun cotton, but it was probably some mixture of nitric acid, sulfuric acid, and cotton. Some test firings of the gun cotton in a miniature cannon announce it's success.
It took 2 days to assemble the final rocket. The final rocket design consisted of components that were available in 1865. However, in Jamie's opinion, it would have been improbable for them to put it all together at that time, though not impossible.
Adam's percentage predictions: * 60% get a lot of flame and fuss and bother and the rocket doesn't leave the tube * 5% the rocket blows up in the tube * 20% success * 15% something unpredictable
After a couple seconds for the nitrous oxide mixing with fuel before it took off, but once it did it flew beautifully up. A successs but ,as the narrator stated, 119 miles short of the myth