Rockets. If there’s one thing a MYTHBUSTERS fan loves it’s … well, it’s explosions, but what’s a rocket but explosions with wings? And in this week’s episode of MYTHBUSTERS, “Rocketman,” fans got their final fill of explosions with wings.
Over fourteen years, MYTHBUSTERS has seen its fair share of rocket launches, including four attempts to launch a car with rockets and five to run a car by rocket sled into a concrete wall — all among my personal favorite episodes. This week, Adam Savage and Jamie Hyneman tested the idea that you can use almost anything within reason as a fuel source, say a hydrocarbon like sugar in the form of gummy bears.
To test the idea, Adam and Jamie used a hybrid rocket consisting of two main parts. One part was a “fuel grain” containing some form of the fuel. The second part was the accelerant, in this case liquid oxygen. The two were ignited by an explosive.
Their fuel grain was a tube inside of a tube, between which was fed the gummy bears. Inside the middle tube sat the explosive.
Unsure which form of gummy bears would serve best as a fuel grain, Adam created three. In form one, Adam and Jamie tightly packed raw, in-natural-form gummy bears — the tighter together the better to reduce air pockets between them. In form two, Adam melted gummy bears into one uniform gummy bear. And in form three, Adam heated gummy bears into a hard crystal, boiling out all the water.
Adam filled the channel between the two tubes in the fuel grains with the different forms of gummy bears, and the crew left for the Mojave Desert testing grounds for lift off. There, Adam and Jamie assembled the fuel grain, liquid oxygen canister, and nose cone with drogue chute and altimeter for each rocket and let the rocket engineers fill the canisters with liquid oxygen. The rocket engineers are like the explosives experts in other episodes, who are the only ones allowed to work with dangerous explosives on set.
Adam called out the usual countdown, flipped the switch, and tapped the launch button for the first fuel grain, containing the gummy bears in their natural state. There was an ignition flame and sizzle, but no launch. “That’s the sound of an engine not working,” Jamie said glibly. “That’s the sound of failure,” said Adam, grimly. Looking at the rocket nozzle afterwards, they found a gummy ooze.
In launch two, Adam and Jamie switched out fuel grains for the uniform gummy bear and prepared the rocket for launch. Once again, Adam counted down to zero and tapped the launch button. There was a flame and a hum, but again no movement.
In launch three, they went through the same procedure with a fuel grain made of crystallized gummy bears. The result was the same: no launch.
Never a crew to accept three fails-to-launch as a sign of total failure, Jamie sprayed the inside tube with some adhesive and poured in gunpowder for some added “encouragement” and tried the crystallized gummy bears rocket one more time.
Again, they were rewarded with a flame but they failed to launch, and Adam and Jamie wondered, was the myth busted or was their methodology at fault? For a glimpse into the possibilities, they replaced the gummy bears with paraffin, a standard-type fuel, and the rocket took off as it should, although it only flew between 600 and 700 feet, far short of the height it should have reached.
- Conclusion: None
The MYTHBUSTERS crew decided they had bit off more than they could chew with the hybrid rocket and moved on to a single stage or solid rocket motor, which is a mixture of solid fuel (gummy bears), oxidizer (oxygen), and binder, with an igniter at the bottom. Such rockets require a license to create the actual solid fuel cylinder, so Adam created a powdered form of gummy bears to ship off to rocket makers.
For his part, Jamie had another idea, one that he thought might have more useful applications: using poop as a fuel. Poop is more readily available on, say, a space station, where it would be waste product not good for anything else. If they could prove it would launch, then their experiment might actually be useful. So Jamie brought in bags of puppy poo, dried it, powdered it, and sent it to the rocket maker to also create a solid fuel cylinder.
Once they received the solid fuel cylinders from the rocket makers, Adam and Jamie returned to the Mojave Desert and once again set up the rocket launcher.
Before using their gummy bear and poo solid rockets, they tested a standard paraffin-fuel solid rocket as a control. It launched beautifully, attaining a height of 1,130 feet. That seemed shallow, but then they realized there was quite a lot of wind at launch, so they waited for the wind to subside and retested, reaching a height of 4,491 feet.
Next, it was time to test the powdered gummy bears solid rocket. It, too, launched wonderfully, reaching a height of 3,691 feet, 82 percent of the standard fuel. Adam and Jamie decided that while that was amazing, the goal of any fuel is to maximize thrust to attain the greatest height, and the gummy bears fell short of the control standard.
Finally, they tested the powdered dog-poo solid rocket. Jamie was rewarded with another amazing lift off, this one reaching a height of 2,900 feet. Interestingly, even though it didn’t reach the height of the gummy bears rocket, Jamie concluded this rocket had merit.
His reasoning was that while gummy bears with its high sugar content might launch kids like a rocket, it isn’t as readily available as a potential fuel source as poo is. And while poo isn’t as powerful as standard rocket fuel, in a pinch and with refinement, it might actually be useful.
- Conclusion: both plausible
Miss the show? Catch the relaunch on the Science Channel Wednesday at 9:00 p.m. ET (6:00 p.m. PT) and midnight ET (9:00 p.m. PT). Oh! Did you catch the shout-out to MYTHBUSTERS this past week on CBS’s LIMITLESS? A side character mentioned watching MYTHBUSTERS and noted how sad that this was its final season.