Gas-Cylinder Rocket

Dear Lord, protect this rocket house and all those who dwell within the rocket house.

"Can you recharge these for me if I need more air?"
"No." He shook his head, beaming. "Used to have charging room, but also assistant who broke valve one day. Tank went through wall here and flew three streets away, finish through side of bus!" Peals of laughter. "Nobody hurt, but take permission from me."

— The Mandarin Cypher by Adam Hall

Whether accidentally or as an Improvised Weapon, the nozzle of a pressurized gas cylinder is easily broken off in fiction. When this happens, the canister will go shooting away like a rocket, blasting itself into the air and smashing through any thing (or anyone) unfortunate enough to be in its way. Sometimes this serves as an attack or a battering ram; occasionally, a reckless character will actually ride the thing.

Less credible, but still common, is a gas cylinder being ruptured by a gunshot and possibly shooting off like a missile. Whether this results in a Gas Cylinder Rocket or merely Stuff Blowing Up generally depends on whether the target it's being used against is right next to it or somewhere up ahead.

Both variations are partially Truth in Television. The valve is the most fragile component of a pressurized gas cylinder, and the gas inside does store more than enough energy to hurl the cylinder around the room. For just this reason, gas cylinders are supposed to have a protective cap screwed over the valve at all times when not actually in use. However, breaking the valve isn't exactly easy, and punching a hole in the cylinder itself is much, much harder. A gunshot may not even make a dent (depending, of course, on the tank, the gun, and the round).

Sister Trope to Aerosol Flamethrower. Sub-Trope of Improvised Weapon and Explosive Propulsion. Compare Recoil Boost, which uses More Dakka for propulsion instead of compressed gas. See also Exploding Barrels, for when the "rocket" part is absent.

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Examples:

Audio Plays

• In Chapter 40-2 of We're Alive, Victor shoots a scuba tank that a Little One had become entangled with, sending the tank and Little One skidding across the street at high velocity.

Comic Books

• The title character of Gaston Lagaffe once converts his Alleged Car to run on gas, with gas cylinders strapped to the roof as fuel. As per usual, Gaston has made a slight error in his design. When trying to start the car, the cylinders blast off... into a passing police van.

Film — Animation

• In Bolt, a gas canister at the animal shelter is damaged and goes shooting into the parking lot, where it knocks down an illuminated sign that topples onto a car, resulting in a huge explosion.
  Esther: Sweet Sister Frances! What did you do to my new truck?!
  Martin: [runs right in] HOLD ON RIGHT THERE!
  [startled, Esther pepper sprays Martin, who falls to the floor in pain]
  Martin: AAH! GOLLY, ESTHER! [moans in pain]
  Esther: Both you boys need serious help!
  Martin: SPICY EYES!
• Not actually a gas cylinder, but a similar effect occurs in The Croods when Gran, attempting to beat the fire that's burning the end of her staff to death against the ground, sets some giant corncob-like plants alight. The flames heat up their oversized kernels until they pop, sending the cobs streaking in all directions; the "rocket" analogy is taken even further when the ones that fly upwards explode into colorful sparks, like fireworks.
• In Incredibles 2, Helen shoots the oxygen tanks Evelyn has on her back with a Flare Gun, causing them to blast off like a jet pack.
• In a variant, Wyldstyle in The LEGO Movie 2: The Second Part jetted between two space vehicles by popping the cork on a bottle of champagne.
• In Over the Hedge, a broken propane tank sends a grill skyward, even flying over an airplane.
• In Rio, Blu attaches Nigel's leg to a fire extinguisher, then sets it off. The evil cockatoo is dragged from the plane by the rocketing canister.
• In Robots, Rodney is magnetically attached to a gas cylinder as several other metal objects (including a dumpster) also chase after him. When the valve breaks, he flies into the air, with an inanimate metallic mob flying after him.
• In Titan A.E., Korso uses a fire extinguisher to propel himself and Cale to the Valkyrie after their stolen ship's cabin windows crack.

Films — Live-Action

• In 3 Ninjas: High Noon at Mega Mountain, the boys try to dispose of a time bomb by strapping it to three oxygen tanks and then breaking the nozzles off with a hammer. However, they turn out to not be strong enough to break them. Fortunately, Dave Dragon shows up and is strong enough to break them. For bonus points, the bomb gets propelled to the escaping bad guys' boat just as the timer hits zero.
• In the similarly-stupid Atomic Shark, the two heroes use SCUBA gas cylinders to propel their boat safely out of range of the mini-nuclear blast that's set off when the title creature finally dies.
• A variation in Backdraft when Exploding Barrels are shown shooting into the air as their contents ignite during a fire in a warehouse full of volatile materials.
• In Chain Reaction, Eddie chops the valve off a tank of hydrogen gas to shove open a safety door so he and Dr. Sinclair can escape.
• In the Syfy Channel Original Movie Dam Sharks, the heroes launch a couple of gas cylinders into the shark-built corpse dam by chopping off their nozzles with axes. The cylinders blast off and streak through the air to lodge themselves in the dam, yet somehow still have enough pressure left to explode and destroy it.
• The Flash (2023): Flash has to do a mid-air save of some babies falling out of a collapsing hospital wing, including one who's about to fall into the flame spurting from a damaged oxygen bottle. As part of a Rube-Goldberg sequence of acts to fix the problem, Flash shoves the baby into a (disconnected) microwave to shield it from the flame, then turns up the valve to shoot the cylinder off in the opposite direction so it will strike something else he needs moved.
• In Die Hard 4.0 (Live Free or Die Hard in the US), John throws a fire extinguisher down a hallway towards a baddie and then shoots it, blowing said baddie out a window.
• An unlucky victim in Final Destination 4 is struck by one of these and slammed into a chain-link fence with enough force to turn his back into chunks.
• In Freddy vs. Jason, Freddy launches a series of scuba tanks at Jason when they're battling at the abandoned Camp Crystal Lake.
• Likewise in Gravity. A fire breaks out on the International Space Station, and when Ryan Stone tries to extinguish it the thrust of the extinguisher slams her against the bulkhead, knocking her unconscious for a moment. This becomes a Chekhov's Gun when she later uses the extinguisher to maneuver herself to another space station.
• Averted in Jaws, when the diving gas cylinder merely explodes rather than takes off (but see Mythbusters example below).
• In Jumanji, Peter creates a rocket sled in a sporting goods store by strapping two scuba tanks to a canoe, and then breaking the ends off by dropping a barbell on them.
• Machete Kills: When Machete and Mendez are at the chop shop, the wheelchair bound mechanic pulls a pistol on Machete. Machete snatches it off him and shoots the oxygen tank on the back of the wheelchair, which propels the chair (and its occupant) out into the courtyard, and into a fusillade of gunfire from the cartel assassins.
• Played for Laughs in the 2000 New Zealand comedy film Savage Honeymoon. The main characters get drunk on whisky, and one of them throws an LPG (propane) cylinder on a bonfire, causing it to shoot in the air like a firework. This scene was notable for causing trouble with the New Zealand film censors, where a compromise was eventually reached by certifying the film with an R15 sticker.
• In Scooby-Doo: Monsters Unleashed, Scooby uses a fire extinguisher to freeze a monster and then ride it around on the frozen monster like a snowboard. He then kicks off the end of the extinguisher and rides it briefly like a rocket.
• There is a literal variation in SpaceCamp that is definitely not Played for Laughs. After Andie is successful in supplying the space shuttle Atlantis with an extra supply of oxygen, she forgets to turn off the oxygen tank when she takes the hose off, which results in the oxygen tank rocketing backwards with her holding on to it, until she gets knocked unconscious from running into the side of the ship.
• Bronson in Street Trash is killed when a gas cylinder is send flying his way, and it removes his head.
• In Transporter 2, Frank pushes a hospital cart with a gas cylinder on it into Lola's path, then throws a chemical carboy into the light fixture above it. The collapse of the fixture knocks the nozzle off the cylinder and sets its gas on fire, causing it to shoot down the hallway and blow up right next to Lola.
• Used by Domino from Deadpool 2, to knock Cable out the back of the DMC transport vehicle with a gunshot-ruptured gas canister.
• In the workplace safety film Will You Be Here Tomorrow, an office worker is struck in the head by a runaway gas cylinder, which also sets fire to the office, killing him.

Literature

• In Meddling Kids (2017), Kerri uses a large oxygen tank to propel a mine cart, allowing the gang of young investigators to escape the collapsing tunnels.

Live-Action TV

• On CSI, a canister of nitrous is ruptured by a stray bullet during a shooting at a rave. The canister lifts off, trailing sparks, and flies erratically back and forth before slamming down among the party-goers, injuring several who were too high to get out of the way.
• Due South: In 'Mountie on the Bounty', Fraser and Ray K use ruptured air tanks as rocket packs to escape the sinking ship.
• Turned up a few times in London's Burning, usually played somewhat more realistically in that the source of the explosion was the building or vehicle the cylinders were stored in being on fire, which is easily the most reliable way of getting this effect in real life. Episodes 11 and 12 of series 7 are a particularly memorable example when a fire breaks out in a builder's yard behind a row of terraced houses, with a large amount of them shooting off like bottle rockets and crashing down all around whilst Blue Watch try frantically to evacuate the local residents and get the fire under control. Being 1994, there's no CGI. It's all practical and a real feat of filmmaking to have stunt cylinders on fire crashing down around the actors. Jaffa is badly burned when a cylinder hits the fire engine he was in. We later find out that the fire took three days and fifteen crews to bring under control.
• MacGyver (1985):
  • In "To Be a Man", Mac uses a butane tank as torpedo to knock down a bad guy.
  • In "The Odd Triple", Mac is locked up in the cellar of a winery. Needing to escape, he attaches several oxygen tanks to a large wheeled wine cask. Knocking the heads off the cylinders, he turns them into juryrigged rockets that propel the cask through the wall like a Battering Ram.
• MythBusters:
  • The group tested this one, and confirmed that a large gas cylinder under sufficient pressure could smash its way through a concrete wall (!), although it slid across the floor rather than taking off and flying.
  Jamie: It was the lard that did it.
  • They also got this effect accidentally when they simulated the ending to Jaws. Rupturing the gas cylinder didn't cause it to explode, but it did blow backwards with sufficient force to tear their foam-latex shark head to pieces and deform the shipping container they were using as a bunker.
  • Subverted when they tested an Urban Legend about a propane tank that blasted off like a rocket, as every attempt to rupture or ignite one either failed or blew it to pieces.
  • They did, however, succeed it turning a water heater into rocket that literally blasted off and smashed through a roof that was built to Californian construction codes.
• On Scorpion, a slow-leaking gas canister (along with a rip in its butt) propels the Super Fun Guy parade balloon that carries a nuclear hazard out over the ocean and safely away from Los Angeles.
• An episode of Sliders ("The Exodus", part 2) had Quinn and company locked in a room as the evil Rickman was sliding without them. They used an oxygen tank attached to a rolling metal hospital tray as a rocket to bust the door open.
• In an episode of Stargate Atlantis Ronon tried to use an oxygen tank rocket to break down a sealed door, having gotten the idea from watching Jaws. It didn't work.
• On Z Nation, Doc mercies two zombie asylum inmates by knocking the hose off a wheelchair-bound zombie's oxygen tank, then sticking the hose's end into a broken light fixture. The electrical shock from the light travels to the canister, setting the zombie on fire. The fire then ruptures a second tank containing fuel for the wheelchair, causing a jet of flaming fuel that propels the wheelchair, its occupant, and another zombie standing behind it several yards down the hallway before both tanks explode.

Music

• In the music video of the song Let's Go by Stuck in the Sound, the astronaut does it on the moon with a beer keg instead of a gas cylinder.
• In the Star Trek filk song "The Ballad of Transport 18", the crew of a broken-down cargo spacecraft use beer as a means of foam-powered propulsion toward the nearest space station. Their joy at the prospect of rescue is muted by realizing that they won't be able to guzzle all the cargo.

Video Games

• Black Mesa: Blue Shift changes the original Blue Shift's setpiece of using gas cylinders on a door to instead involve a TOW launcher, but also introduces similar cylinders as a recurring environmental hazard in other parts of the game.
• In Broforce, this is the only reliable way to deal damage to the Megacockter, by shooting the gas cylinders scattered around the rooftops causing them to fly up and explode on it.
• In The Finals, explosive carriables take the form of red gas cylinders. Upon being thrown or damaged, they'll be propelled forward and explode shortly after.
• In the Vivendi expansions of First Encounter Assault Recon, there are green gas cylinders that will fly about uncontrollably in unpredictable physics-oriented patterns when shot at or hit by an explosion... except they're completely harmless. All they really do is distract you with their antics (aside from the crazy flying, they make one hell of a lot of noise both before and during their explosion) and you alone, since the AI doesn't bat an eye at them.
• At one point in Half-Life: Blue Shift, Calhoun must shoot the ends of some compressed-oxygen cylinders, propelling them into a locked freight-yard door until they break a hole through it.
• Valve Software's Source engine, used in every Valve game released in the 2000s starting with Half-Life 2, includes code to create a Gas Cylinder Rocket. The relevant reference material.
• In Halo, you can place these in Forge mode in games from Halo 3 onward (like Halo: Reach).
• One Henry Stickmin game, Infiltrating the Airship, has Henry try and ride on a propane tank to escape from the titular airship. It... doesn't quite work out for him. Cue fail.
  Hank Hill Quote^note ...Tell ya h-what.
• You can do this in Just Cause 2; it's even possible to ride the canister.
• In Max Payne, gas cylinders typically behave like that when someone shoots them. It's entirely possible to ride on them for the fun factor by standing on them before shooting at them, although there are only a few short, room-size "routes" possible.
• In a variation, the Trandoshan enemies in Star Wars: Republic Commando have jetpacks which send them shooting off into space when hit.
  Scorch: I didn't know Trandoshans could fly!
• In the casual hidden object game Surface Mystery Of Another World, you can use a Gas Cylinder Rocket to propel a large statue out of your path.

Western Animation

• In the CGI animated series Mighty Mike, Mike the Pug uses a pink gas canister of helium to launch himself into the air, to rescue a kitten which a pesky raccoon had inflated with the helium and sent skyward as a distraction.
• Instead of a gas canister, a malfunctioning surgical laser goes ballistic in the Roger Rabbit Short "Tummy Trouble".
• In the The Simpsons episode Mountain of Madness, a propane tank attached to a cabin gets its end knocked off and propels the structure downhill:
  Homer: [praying] Dear Lord, protect this rocket house and all those who dwell within the rocket house.
• Done with a fire extinguisher in the Gigi Hadid episode of Scooby-Doo and Guess Who?. The extinguisher's stream of foam sends it careening around a fashion-show gallery, along with the Monster of the Week gargoyle Velma launched it at.

Real Life

• A very bad day on a Russian highway...
• This video shows an almost perfect example; a burning propane canister gets hit by a bullet and goes flying into the air. Had a tree not been in the way to stop it from continuing to climb, it's quite possible it would have kept flying until it ran out of gas to propel it!
• Liquid nitrogen tanks have pressure relief valves for a reason, folks.
  ... the force of the explosion was directed upward and propelled the cylinder, sans bottom, through the concrete ceiling of the lab into the mechanical room above. It struck two 3 inch water mains and drove them and the electrical wiring above them into the concrete roof of the building, cracking it.
  • There is a (possibly apocryphal) story floating around Caltech observatory staff that sometime in the late '80s a liquid nitrogen canister used for cooling the cameras at Palomar Observatory ruptured and flew across the observing floor, missing the telescope's mirror assembly by inches before punching out a door on the equipment bays. The practice of storing all compressed-gas canisters in the basement and only bringing small amounts of LN2 onto the observing floor at any one time in Caltech observatories is attributed to this incident.
• There's a welding safety poster floating around out there showing a mostly demolished building, with Those Two Guys standing around outside remarking, "Looks like Bob forgot to secure his oxygen canister again."
• One recurring image◊ often shown in safety briefs depicts the aftermath of a gas storage cylinder that blew out its base—namely, a neat hole punched in the ceiling, straight through a subsequent concrete floor, and into the room above it. Not visible: the utter state of disaster of the lab where the accident took place, because the cylinder blew out all the walls when it ruptured.
• Older pressure cookers were likely to carry out a variant of this trope should their steam vents have become blocked. After building up enough pressure, the resultant explosion would be enough to send the lid and much of the casing as shrapnel flying through the air with enough force to splinter countertops and leave dents in the ceiling.
• Note that in real life rocketry there is a type of rocket (pressurized gas rocket) that sounds like this trope but shouldn't be confused with it. Here, either the propellants or, more commonly, a neutral gas in a third thank are pressurized so that release of this pressure forces the propellants out the nozzle before its ignited. This is done to increase reliability and reduce mechanical complexity by eliminating pumps.
  • However maneuvering thrusters powered by pressurized air sometimes used on small suborbital rockets, incidentally the same sort that tends to use the above. It's cheaper than using the alternatives like, engine trust vectoring, fly wheels, or monopropellant powered thrusters.

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