When Iron Man flies he is shown with fire coming out of his feet just like a fuel-propelled rocket.

Iron Man flying Iron Man flying

Where is the combustible material generating the fire coming from? Does he have a fuel tank? What is his operative range?


Since your images are from the film Iron Man, I'll initially address that universe. In the film canon, Tony constructs a miniature Arc Reactor and implants it in his chest. This provides a fantastic power source for the armors he later builds. In the Mark 2 & 3 armors, Tony uses his Arc Reactor to power repulsors (a fictional technology that uses energy to generate thrust), which his suit contains on the palms and feet (per Wikipedia). The repulsors on his feet provide the thrust you see in the images in the question, while he uses his hand repulsors and flaps on his suit to provide steering.

In the comics, it's decidedly more complicated, but modern Iron Man armors utilize repulsors, like the film version. Older iterations of the armor did use chemical propulsion (i.e. rockets). You can read an extremely thorough listing of his past armors on Wikipedia.

  • 1
    This article would be an interesting read. It looks startlingly similar to the repulsors and function as electric propulsion. – Steam Mar 8 '13 at 13:47
  • 1
    @Yawus Ion thrusters are the real-world tech most similar to repulsors as a concept, although in reality they're useless for atmospheric flight - not enough thrust. – Tynam May 1 '13 at 6:09
  • 3
    @Yawus Our best Ion thrusters today provide about as much force as a piece of paper resting on your hand. Their strength lies in their ability to run for long amounts of time and very very gradually (as in over months or years) build up a high velocity. – ApproachingDarknessFish May 19 '13 at 22:52
  • 2
    I don't think this answers the question. It identifies the power source, but not the where the reaction mass comes from. – Julian Dec 26 '13 at 10:33
  • 4
    @Julian There is no reaction mass, per the first paragraph. Repulsive provide thrust via magic. – user1027 Dec 26 '13 at 12:55

The thrust is generated by the electrical device which keeps him alive and powers his suit.

My expectation is that it is something akin to an Ion thruster:

An ion thruster is a form of electric propulsion used for spacecraft propulsion that creates thrust by accelerating ions. Ion thrusters are categorized by how they accelerate the ions, using either electrostatic or electromagnetic force. Electrostatic ion thrusters use the Coulomb force and accelerate the ions in the direction of the electric field. Electromagnetic ion thrusters use the Lorentz force to accelerate the ions. The term "ion thruster" by itself usually denotes the electrostatic or gridded ion thrusters.[citation needed] Ion thrusters create very small levels of thrust compared to conventional chemical rockets but achieve very high specific impulse, or propellant mass efficiencies, by accelerating their exhausts to very high speed. However, ion thrusters carry a fundamental price: the power imparted to the exhaust increases with the square of its velocity while the thrust increases only linearly.

Because Tony Stark is a brilliant inventor he was able to create a non-conventional electrical power device (electro-magnetic arc reactor) which is not constrained by the size and weight limitations of conventional technology.

  • And, he uses highly efficient portable fusion reactor to power up everything.. – Lobo Apr 7 '12 at 16:59
  • 2
    The fun part of Iron Man: we could totally produce that technology if we could generate the power required for it portably... – Gabe Willard Apr 7 '12 at 16:59
  • 1
    Interesting idea. I always thought that the repulsors were a form of reactionless technology. – SteveED Apr 7 '12 at 19:43
  • 5
    @GabeWillard, have you tried building it in a cave? With a box of scraps? – Beta Apr 8 '12 at 1:08
  • 1
    Technically an ion thruster still has reaction mass (typically in the form of Xenon). It just happens to use it more efficiently than a typical rocket engine, but doesn't produce as much thrust. – Scott Whitlock Mar 6 '15 at 17:40

The answer is simple, its called a VASIMR which is much better than the ion thrusters, tony probably used ion thrusters but a technology which we know today is a VASIMR rocket, similar to the ion, uses electricity and a gas, the gas is ionized then turned to plasma which heats up between 1.8-3.7 million degrees depending on how you use it, it can either act like a ion thruster or a rocket propelled thruster. The advantage of the VASIMR is the very low fuel consumption. The gas used is hydrogen, an advanced suit like the iron man can simply extract the hydrogen from the air through electrolysis, the water is condensed as the suit pressurizes ram air to form water, the hydrogen gas is produced and directly sent to the rocket boots AKA VASIMR.

Here's the link which explains the VASIMR

  • 1
    Interesting speculation. Is there any canon support? – user1786 Sep 24 '13 at 3:08
  • But VASIMR is a plasma engine that uses Xenon and radio friquencies that heat the Xenon gas into plasma in a magnetic field... as far as I know VASIMR is used for deep space traveling and it doesn't have enough thrust to fly in the earth atmosphere... so both Ion thrusters and VASIMR thrusters are out of the question... to lift 1kg of the ground the force needen is 10N, so if Iron man suit has 200-350kg (with Tony in it) it would require at least 2000-3500N to lift him up... to achive flight at high speeds would need high trust, at least 5000N... and Ion thrusters and VASIMR produce only 50-21 – user17925 Oct 12 '13 at 16:18

How about Ironman used Quantum Vacuum Plasma Thruster AKA EmDrive, propulsion based on microwaves. The arc reactor generates a lot of energy, maybe if the EmDrive is powerful enough it could generate enough propulsion.

See a link here.

And here.

  • Just yesterday: Nasa validates 'impossible' space drive: wired.co.uk/news/archive/2014-07/31/… – Wayfaring Stranger Aug 2 '14 at 13:21
  • Let me just point out that, from what I've heard, there are some significant flaws in the NASA-affiliated experiment that the popular press completely omitted. So the vast majority of physicists are not yet swayed to believe that the thing works at all. Of course for purposes of this answer we can just say it does work in the Marvel universe. – David Z Sep 4 '14 at 18:54

In the suspension of reality you can generate more than enough thrust if you are willing to release the nuclear bonds of the atom. At issue would be the resultant radio activity. You would mitigate this by controlling the nuclear reaction so that it would not release any unstable isotopes. The resultant heat energy would be then used to propel the resultant new atomic structures. Even a small amount of material would potentially have sufficient thrust if propelled fast enough. Remember it only took a few kilograms of uranium to produce the first atomic bomb. E=Mc^2 y'all


My theory of Ironman's jet boots is that he uses ion thrusters, which acts like suitable replacement for jet thrusters. I think he ,also, used a metal which is a bad conductor of heat.

  • 1
    All metals conduct heat (they are defined as such). Also scroll up t the top answer and read my take on ion thrusters. – ApproachingDarknessFish May 19 '13 at 22:54

My idea is a bit radical I think Tony's suit might have a mini super cooling device which separates hydrogen and oxygen and liquefies it to produce the reaction that causes the thrust.

  • 5
    Sorry, but that's not radical, just wrong. "cooling" does not separate hydrogen and oxygen, electrolysis does. Nor is liquefying them required. And in any case, it uses at least as much energy as you can later get from burning them. – Michael Borgwardt Dec 26 '13 at 11:07
  • @MichaelBorgwardt Energy production isn't the goal here. Propulsion is the goal. You can get propulsion from burning oxygen and hydrogen, but you can't get propulsion from burning water. – Lèse majesté Mar 6 '15 at 9:09
  • @Lèsemajesté: you need energy to get propulsion. – Michael Borgwardt Mar 6 '15 at 9:22
  • @MichaelBorgwardt: That would be the point of the Arc reactor. – Lèse majesté Mar 6 '15 at 12:41
  • You can get propulsion from heating oxygen and/or hydrogen, most easily by burning the two together, but that doesn't address the question of where the suit is storing hundreds of tonnes of this hypothesized reaction mass. – user1786 Apr 27 '15 at 22:36

The arc reactor powers the thruster to make a large amount of thrust. You can use solar panels to power the suit, but it might fail to produce enough power in time. Or you could make a mini sun to power it.

  • 1
    The 'arc reactor' answer adds nothing additional that's not already provided in existing answer. How would solar panels power the suit in the absence of sufficient daylight (at night for example). And what in the world is a 'mini sun' ? – Stan Jan 8 '14 at 23:00

Tony Stark take an electromagnet at his chest and this saves him from the bomb's tiny particles in his heart. This electromagnet generate electromagnetic waves and he gives thrust to his suit by burning hydrogen.

  • Do you have any basis for this speculation (the hydrogen part)? – user1786 Apr 27 '15 at 22:13

protected by Jason Baker Apr 27 '15 at 19:07

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.