In the animé Attack on Titan, armed forces use a special device called 3D maneuver gear (also called vertical movement gear) to move through the air. The system is based on a pair of grappling hooks shot from the waist, and compressed gas. The gas is used both to shoot and reel back the wires, and to propel the user in multiple axes through a pair of exhausts on the back. The exhausts are mounted on gimbals to allow for rotation. The system is operated through a pair of wired controllers, one for each side of the user.

Here are some schematics:

Schematics part 1

Schematics part 2

And here is the thing in action:

Run, Eren, run!

I believe that such a system, in real life, would be useless for its intended purpose (military action, specially against giants). The main reason for its creation is a mix of plot necessity allied with the Rule of Cool. I think it is also anachronistic for its setting, and slightly Steampunk-esque.

However! Suppose that some billionaire from our real world wanted to build a functional 3D maneuver gear. Would it be possible?


To build a wearable device that would allow the user to swing among buildings, trees or other high/tall elements of their environments, by combining grappling hooks, steel wires and compressed air or some other gas.

The objective is to have one or more prototypes - mass production is beyond scope.

Edit: Achieving the velocities seen in the show is not necessary. Alternatives can allow for a leisure ascencion or descent, for example.


The project will start with a technology level that we are expected to have on the next five years. It is ok (even expected) if new technologies are developed for and because of the project.

The real life 3D maneuver gear may be larger than the fictional one - a very large backpack would be accepted, but should not be heavier than 60 kg.

Money is not a constraint.


This tool may be used by firefighters, search & rescue personnel, mountain climbers and window cleaners. Also the Rule of Cool.

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    $\begingroup$ Just as with Spiderman slinging around, and (he and Superman) snatching people falling at terminal velocity, I predict lots of shattered vertebrae. And energy densities are always astronomically higher in fiction than in real life. So... no. $\endgroup$
    – RonJohn
    Oct 11, 2018 at 16:42
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    $\begingroup$ How maneuverable does this maneuver gear need to be? Having a gas-powered grappling hook allow someone to climb up a wall or swing across a gap seems pretty straightforward, but to get the motion in that gif either the grappled ledge, the rope, the person's bones, or physics would probably need to break. $\endgroup$
    – Giter
    Oct 11, 2018 at 16:42
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    $\begingroup$ Forget the gear, I want the knees of these guys who can land at those speeds on their feet and keep running without any injury. $\endgroup$
    – SJuan76
    Oct 11, 2018 at 17:31
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    $\begingroup$ There's also the fact that at the velocities shown in the series, human response time is insufficient. It's like the speeder bike chase on Endor - at those velocities, people can't dodge unexpected obstacles. IRL, they'd just die. $\endgroup$
    – jdunlop
    Oct 11, 2018 at 17:36
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    $\begingroup$ And heavier. Cables are pretty darned heavy. $\endgroup$
    – RonJohn
    Oct 11, 2018 at 18:23

8 Answers 8


Part one responds not to the technical difficulties of such a device, but a more fundamental conceptual issue.

Competitive Fencers are some of the fastest humans on Earth (both by self-selection into the sport and the Darwinian aspect that if you are able to win enough bouts to want to keep doing it...) and for us, the difference between you scoring a touch first or me scoring a touch first is set to 1/32 of a second, which is half of the lower end human response time of 1/16 of a second.

And I gotta tell you as a fencer, martial artist and a high performance motorcyclist - that's pretty amazingly quick response time.

So @jdunlop is onto a really solid point here: at the velocities indicated in the OP and the video, it's very unlikely a human swinger-operator could respond quickly enough to not end up pancaked against some built environment element or other.

It's also worth noting that humans "run out" of fast-twitch decisions pretty quickly, reaching "decision fatigue" when they are likely to make wild misjudgements or fail to decide - or more typically just... freeze.

In this scenario, either result is likely to be terminal!

Part two looks briefly at the physics (without maths)

Strength of materials is an immense issue with this concept, both for the device and its components and for the built & natural environment elements being used as hoist points for this idea.

The device:

Steel cabling would not be even close to strong enough or have enough longevity under the continually varying stressors applied, and would very rapidly reach metal fatigue and shear. Bear in mind we're not talking about the load of just the mass of the swinger-operator and the mass of their compressed gas canister and gas inside, we are also talking about the inherent load of the length of cabling itself, and more crucially, the force (simplistically Mass x Acceleration [more accurately see the vector equation below])being exerted along that cable (tension) by the moving mass of the swinger-operator and their equipment - and then subsequently massively changed in both amplitude and vector with each new connect-pull-swing-jet-disconnect event. Every hard stop event is a massive deceleration - placing immense strain on those cables - ask a crane operator about working load factors and braking stress - they ease those heavy loads down due to the huge impact sudden changes can have on hoist cables - and in fact the other massive failure mode for hoist cabling is sudden detensioning after overload - leads to a kind of unraveling / unweaving called "birdcaging" which then gets run through the various pulleys and blocks in the crane and the cable gets chewed to heck.

So the only material we know of at the moment which comes close to this level of tensile strength, strength-to-weight and resilience is natural spider silk.

enter image description here

where vector p is the momentum of the system, and vector F is the net (vector sum) force. If a body is in equilibrium, there is zero net force by definition (balanced forces may be present nevertheless). In contrast, the second law states that if there is an unbalanced force acting on an object it will result in the object's momentum changing over time.

Compressed gas has mass - and the more compressed it is, the denser, the higher the mass; in addition, pressure vessels are incredibly dense and have to be manufactured to pretty exacting specs - and they are heavy (ask a scuba diver) in the extreme. This adds immensely to the load on the putative steel cabling - and the more compressed your gas, the denser the pressure vessel has to be to constrain that gas. Moreover, to have enough gas to lift the swinger-operator through space and reverse vectors when necessary means your reservoir is staggeringly large. And of course, you have an ever-escalacting version of the rocketry lemma: more reactant = more mass to move = more reactant needed - but in this case with the additional constraint operating inside a 1G gravity reference frame.

Harness webbing / straps - the harness being worn to throw that human body around would need to be not only strong and tight fitting (with these forces, even the slightest slack will lead to immense impact damage from the straps slapping home on the swinger-operator's body with each event); the straps would need to be hecka wide in any place bearing significant load, and yet somehow conformable enough to body shape to not be incredibly uncomfortable or joint-de-articulating.

Swinger-operator - pretty much either isn't an unaugmented human to begin with or dies very quickly - even assuming we somehow handwavingly beat the reaction time point I raised above, the huge acceleration loads (3-5 gravities) in quick succession in varying directions would induce blackouts, redouts, broken limbs, de-articulated joints, broken spine, broken neck, decapitations...

Built or natural environment elements - each of the things being used as a point of purchase by the "grappling hooks" would be subject to both compressive and tensile loads in very quick succession in very small point-load sized areas, and in most cases we can assume things like concrete, stone, glass and other similar facade system materials - once in a while wood, and even less frequently steel or other metallic surfaces. With these kinds of impacts and loads, the grappling hooks will simply break through materials as load increases; as each grappling hook pops free (punching out concrete fragments from around its attachment point such that they become shrapnel moving towards our swinger-operator) suddenly plunging our swinger-operator out or down into space and shifting not just the remaining but now increased load onto other grappling hook connections - these too will catastrophically fail... I think you get the furry, flat and squidgy meaty pancake on the groundplane idea here.

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    $\begingroup$ Whether or not the gear is terminally unwise to use doesn’t change whether it can be built, surely? We come from a race that thought ‘Spandex with squirrel wings? I can jump off a cliff in that!’ $\endgroup$
    – Joe Bloggs
    Oct 11, 2018 at 19:18
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    $\begingroup$ One point to note for contexts' sake is that some of the best fighters in Attack on Titan are actually superhuman (eg. the Ackermans), which explains how they can efficiently use such a device. Perhaps some modern day artificial intelligence/machine learning/control systems could alleviate the need for some of the response times required to do such sharp turns. $\endgroup$
    – Enthu5ed
    May 7, 2020 at 21:00

This is anime, so you already know the answer. Any one element of the task has a snowball's chance in hell of working. However, all of them working together... well. Let's just say good luck.

First, ditch the "pressurized gas container" that has far too low of energy density. Its a non-starter. At least start with a real power source, like burning hydrocarbons. A liter of gasoline goes a long way.

Second, it looks like he's throwing the grappling hooks. There's no way a human is going to be able to pull that off. The grappling hook falls with gravity at exactly the same rate as the climber. So if you want it to go much higher than you, you're going to have to fling it up really hard. Physically speaking, people dont have the muscle strength to do that. You're going to want to fire these grappling hooks from guns powered by that gasoline engine.

Third, darts glance off things. It's really hard to design a dart which embeds itself 100% of the time. A reasonable safety margin would involve making sure that the existing darts you have in place can keep you from becoming a splotchet on the ground before trying to fire another. Your aerial parkour practitioner is probably going to want 6-10 cables, and something really creative to keep them from entangling themselves.

Fourth, darts that are hard to embed are hard to take out. There's a very good chance that you're going to want to retract a cable in a direction it doesn't want to go. You cant just have the gas engine jerk on it, because that'll change your trajectory a bunch. You're going to need active darts which can get thinner on command to disengage. Generally speaking, that's opposed to the properties you'll need for a dart to penetrate in the first place.

Fifth, these wires would create some very brutal shocks. You need a static line to avoid stretching during use and maximize endurance, but you need some dynamic stretch as you start to lay into the line. This is actually the easiest to solve part of the puzzle. Each of the wire spools needs to be on its own little elastic mount. Still going to hurt, but better than what we see in the anime.

Then there's the human side, which many have mentioned. Training these perfect reactions so that you never once make a mistake, with your life on the line, is not going to be easy.

Speaking of which, do you know how many time the guy correctly threw the grappling hooks in the little clip you linked? Zero. Not a single one of them was correct. He actually became a bloody little splotchet multiple times over. You need to have a cable that's above you to oppose gravity. If all you do is launch them forward, you never gain altitude. He did manage to do a web-slinger like move once where he shot one to the side, but it was improperly balanced, so that just made him a bloody splotchet on the wall.

Oh, and the one throw that was useful also was the kind which would glance off the stone, so it probably was another red puddle on the ground as well. Tough angles.

Very hard to learn indeed.

  • $\begingroup$ "Second, it looks like he's throwing the grappling hooks." In the animé, the hooks are shot from a muzzle on each side of the belt, powered by the gas. Anyway, great answer. $\endgroup$ Oct 11, 2018 at 20:03
  • $\begingroup$ @Renan Ahh. It's hard to tell. The lines were laughably loose when they were launched, so it looked more like a throw. The lines really should be taut while being launched. $\endgroup$
    – Cort Ammon
    Oct 11, 2018 at 21:47

Watched that anime, was quite interested and fascinated with ODM gear. Reasons why nothing like that can't and won't ever exist in real life:

  1. Grappling hooks. There is no way to penetrate anything concrete-like with a shot projectile and have a reliable grip to sustain a human weight. It is possible with the wood, but even then you won't be able to pull it out easily enough.
  2. Gas operating system. Its efficiency is ridiculously exaggerated in that anime. You can sometimes see people fly vertically with it, while in real life you would use up all your reserve and barely got few meters high. To fly on a compressed air you would need hundreds of times more compressed air.
  3. In general, soon we are gonna be able to fly with electric motors and lithium batteries. A bunch of things like that exist already, and they're only gonna get better. Obviously it is a working concept and allows you real 3D maneuvering anywhere, although applications for that are meager and is mostly for fun.

It can be made.

Graple guns.- We have them right now but instead of using gas, controlled explotions with gunpowder could send them flying. The graple head can be design to penetrate and deform while traverse a material, to lash and stay anchor at it (not all materials of course).

The cable would detach from the grapel head when called and the system should set a new one for his reuse.

Motor.- We could adapt the motor of a motorcycle to reel the cables when need it. With enough tinkering it would work for 15 minutes or more with just a few liters of gasoline.

Cable.- Whe have strong enough cables rigth now to support an adult human without trouble (at set speeds).

Augmented Reality Googles.- As stated in other answers, 3D movility is hard and complicated, thats why our tester would need the support of a navigation system that calculates distances, speed of the reeling, collition and targeting of the grapel guns while the driver only sets his destination.

They idea would be at some extent like the autonomous car tech that we have today adapted to this niche.

You wouldn't be able to do some of the movements that can be seen in the anime, but with enough training really cool acrobatics could be achieved.


I wont say outright that its impossible, but lets create a checklist of what can be currently built and what needs to be figured out.

1) Strong enough Cables: Carbon nanotubes wound into a rope. Stupidly expensive, but will do the job, easy.

2) Hook that penetrates walls, grips the wall, and releases on command: All three can be accomplished by controlled explosions, as long as control wires are built in the rope. At time of contact with wall, explosive thrust from the base of arrow hook can be used to penetrate the wall, and a timed explosion from within the hook, opening the flap outwards, can help it create a grip. With a control wire, you can retract the flap and release the grip, making it easy to roll back in. The advantage of this approach is the reduced requirements on the device that will launch the cable, since it need not bother with penetration, just reach the wall. The problem to be solved is how to reliably reload the explosive charges. But I am sure that's not a big issue.

3)The engine to launch and retract the cable(without much tension in it): Launching and retracting the cable are two very different business, and require different characteristics from the engine. Launching requires a high instantaneous force, whereas retracting requires slower but steady, gradually changing force, otherwise the cable hook will whiplash into your face, just imagine suddenly pulling a thread tied to a stone. Electric motors can be used reasonably well with a few modification, for launching. I would recommend a powerful spring to be stretched by the motor, launching the cable would require releasing the spring. While retracting, the motor can again stretch the spring via gears. You no longer need a gas cylinder, just some battery packs.

3 b*) Pulling yourself when retracting the rope: Now is the first and main hurdle. Pulling that much weight (about 100 kg overall), at the speed shown in the anime, is ridiculous. Using a motor and gear assembly, you can achieve both torque(for weight) and rpm(for speed) but not simultaneously. A probable (but limited) solution would be to use a bungee rope like cable. But it won't let you move like Levi in midair. In conclusion, you can swing like Tarzan, but Mikasa won't be impressed.

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    $\begingroup$ carbon nanotubes will also break the riders neck, climbers use rope with give for a reason. the explosive charge has a problem with making the "hook" very heavy and also making it breaks down quickly, sensitive mechanisms and explosives are not a stable mix. A spring is not going to generate sufficient force to move the hook and cable a useful distance, not without weighing many hundreds of pounds. $\endgroup$
    – John
    Dec 12, 2019 at 16:56

As usual, a frame change is needed in order to accomplish what is being depicted without making the user into a splotch on the pavement. The previous posts have summed up the issues very well, so I won't repeat them here.

I would suggest the time and energy and resources would be much better spent on some sort of jetpack or personal flying device. Rocket and jet powered jetpacks have been around since the 1960's, with Bell pioneering a rocket pack which used the decomposition of highly concentrated H2O2 to create a steam rocket. Early rocket packs simply could not hold enough fuel for more than a few seconds of thrust, which made them spectacular for stunt work, but otherwise impractical.

However, modern technology has offered several more practical alternatives (for certain versions of "practical"). Personal flying devices using large enclosed rotors have been demonstrated, as well as a "flyboard" using small turbine engines.

enter image description here

Martin Jetpack

enter image description here

Zapata flyboard

So from a technological viewpoint, getting a person in the air and flying around between buildings and treetops is actually possible. The Martin Jetpack is likely more economical from an efficiency viewpoint (accelerating large masses of air slowly is more efficient than accelerating small amounts of air rapidly), while the flyboard is far more compact and mobile.

The real issue which has been alluded to is the speed of human reflexes, and the G loading of the body when making rapid changes in direction. To rapidly fly in an erratic path through a constrained space (like an urban setting or forest) is going to be beyond the ability of a human pilot. It is likely the machine will have to be on autopilot, with the human pilot essentially saying something like "get me to point D via way points B and C, and never rise above rooftop level" and leaving the machine to do the rest.

This would also need a change in how the human is carried in the machine, since being unrestrained (like on the flyboard) is going to result in either being flung off during flight, or suffering severe injuries as you are flung about in flight. The Martin Jetpack is somewhat better in that regard, although the person is likely going to have to be far more rigidly constrained, and probably wearing a "G" suit to supply counterpressure and prevent blood and fluids pooling excessively as the vehicle flings itself around the buildings.

As a sort of extreme checksum, you could go far faster (say in a laser propelled "lightcraft" extracting laser energy from an orbiting satellite) if you were packed in a tight tube full of oxygenated fluid which both surrounded you and also infused all the spaces inside your body as well. Jumping out to confront giants after that might be somewhat problematic, however...

enter image description here

Conceptual model of a single person lightcraft

So while there is no practical way to jump around urban or other settings using cable apparatus as depicted in the show, if you actually want to be able to do 3 dimensional manouevre at high speeds, it is somewhat plausible for a very advanced flying machine to do the job, so long as the passenger is properly protected and restrained. Fighting giants in this way is another matter altogether.


not like in attack on titan, probably, but i think alternatives would be feasible. for example: cryspr on spiders:

give them loyalty toward humans (like dogs)

proper lungs,(bugs and spiders and stuff don't have breathing muscles, but instead have a bunch of tubes around their bodies, and rely on passive oxygen intake)

a much larger size (again, dogs as an example: from wolf size to tiny pugs).

you could then wear the spider on your back and have it shoot webs.

you could also do something mechanical, but that's too expensive and boring

  • $\begingroup$ You really think developing these real life pokémon would be cheaper than inve ting machines? $\endgroup$ Oct 26, 2020 at 3:08
  1. Battery

  2. Strong motor for pulling human, and setting the ''gun'' to lock

  3. Gun like part for shooting the hook

  4. Switch with 4 different actions. One switch would pull the wire of pressed all the way,The Second would move you(human) the same action but less strength for the hook to not be removed, Third switch would shoot the hook.

The wire should be strong enough to support a human. The environment is a big deal for the hook to Grab And Stay there unless you trigger it

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    $\begingroup$ What do those numbers refer to? $\endgroup$
    – L.Dutch
    Jun 21, 2019 at 13:49
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    $\begingroup$ Welcome to the site, geo k. Please note that the Worldbuilding SE is dedicated to providing detailed answers to specific questions a user has while building his/her fictional world. Answers should provide details and supporting information (and be well-formatted, though we can help with that) that makes the answer useful and clear. You may want to revisit this to expand on the idea presented here; otherwise, it may be deleted for being low quality. Feel free to take the tour and check out our site culture. $\endgroup$
    – Frostfyre
    Jun 21, 2019 at 14:31
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    $\begingroup$ This doesn't really seem to answer the question... $\endgroup$ Jun 21, 2019 at 16:19

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