DARPA’s “Man Cannon”

DARPA plots emergency man-cannon

Via a reader. The Reg sums it up:

You’d think that with global terrorist threats and fighting two wars, the US Defense Department would have little time on its hands to start a circus troupe.

However, the Defense Advanced Research Projects Agency (DARPA) has filed a patent application for a contraption designed to hurl SWAT teams and other emergency workers onto the roofs of inaccessible tall buildings human cannonball style


New Scientist, the source for this DARPA weirdness, writes in Human cannonballs :

A ramp with side rails would be placed on the ground near the target building at an angle of about 80


  1. To me it makes perfect sense, mathematically that is. Only question is, do you wish to rely on the computer… Same question also relates to the idea of unmanned aircraft. Would you fly in a computer controlled aircraft? Personally I would rely on a well programmed system more than I would a human. But then again I am an engineering student – the general public are not.

  2. Not the moment in time you want to be the lowest ranking individual, or the ‘least mission essential person’. I can just see it now, OK snuffy, it’s your turn, get in the seat, and try not to hang on, you’ll just get hung up on the rail. WHOOSH, OHHHHH $$$HHIIIITTT! Well, there goes the element of surprise, but he made the roof! I can just about imagine the acronym for this thing. It’s the Obstacle Height Supplemental Human Ingress Tactical launcher.

  3. Not me. No way. No how…but, there is a certain segment of the population that might jump at the chance to sit on something called a man-cannon. I’m guessing a lot of them live in San Francisco.

  4. I think it would be better to overshoot by a big distance, then do a base-jump type landing. That why the margin for error is much larger.

  5. I retract my prior comment. This is a bad idea. This design is only good for a no-wind day. Biggest problem I see is an aerodynamic one. Buildings have nice aerodynamic effects, especially near the roof edge. They shed vortices either onto the roof or off it. This depends on direction and surrounding buildlings. While launch may be successfull, it could go badly wrong by either not reaching target height, or the person may start to accelerate forwards (x-direction) or suddenly downwards (y-direction) after he clears the building height. But since when did people ever listen to aeronautical engineers? lol

  6. I think it is a great idea, for at least two reasons: 1. I think that if you throw the poor guy with the head in the wall of the building, the enemy will come on the edge of the roof to laugh and make caustic remarks, and then the snipers can take them out easily. 2. This device should definitely work only in conjoction with the Urban Combat Skateboard (UCS), I mean when (and if) the guy is thrown eventually on the roof, he must use the UCS to create or increase the houmoristic effect described at point #1. Could a red nose and a clown outfit be of any help?

  7. Please remember this as well, they soldier getting on this thing is going to be wearing a bunch of gear with zippers, velcro, snaps, loops, and buttons. I can just picture the excess weight of the gear, and all the entanglements throwing this thing way off. How do you hold your weapon while launching? How do you land ready to fight? What happens if the roof is actually 8 feet, or 6 below the coping? What if the roof is weak, and you fall halfway through on landing? What a mess! How about a ladder that is light and portable enough to carry instead? Yeah, it won’t go 5 stories, or be as fast, but I’d guess you’d have a lot less knee, ankle, or back injuries, let alone the number of wrist and neck injuries inherent in landing on a roof 5 stories up with no knowledge of what the surface is like.

  8. First, unless it’s a very windy day, aerodynamic effects will be minimal. Takes a lot of force to move a 200 lb object off a planned trajectory over the time periods involved. A man would only be affected by a vortex from the roof-line for a fraction of a second. Note that the whole trajectory takes less than 2 seconds to complete, and that most of that is in the relatively low-turbulence area adjacent to the building. Only a fraction of the trajectory involves the area right around the edge of the roof where all the interesting aerodynamics happens. A person just wouldn’t spend enough time in that area to be affected enough to matter (unless it was VERY windy). Second, 7 mph is not fast at all. That’s like a fast walk or a slow jog. You could easily stop yourself from 7 mph. Similarly, even 6-8 foot drop below the parapet would be survivable by someone in pretty good shape. And typically a SWAT team would know what the roof layout was like. Such a drop would not be a surprise. Having said all of that, there’s no f#@%ing way you’d get me on that thing.

  9. One other point I’d like to make is that, regardless of how silly this item seems, I think this exactly the stuff DARPA should be pursuing. i.e. Weird ideas that mostly will not prove feasible. Why? Because one-in-ten or one-in-twenty of these inventions is gonna turn out to work great, and it’s hard to tell up front which one that will be true for. For example, maybe you don’t put men on this thing, but maybe it would work great for putting a remotely operated vehicle onto the roof. Suddenly it makes a lot of sense, no?

  10. Aerodynamic effects are not minimal – hence why no-one ever listens to the aeronautical engineers – since it is hard to imagine wind doing much to move someone. Vortices shed by a building can be strong even on a calm day, it simply depends on the surroundings and building design. You have to imagine that the wind has to go somewhere when it encounters the building… Even a small breeze can be magnified when it is forced over a building. Also, vortices formed are hard to predict in both size and magnitude. Yes, chances are that there would be no effect when this is used, but it is an accident waiting to happen. Even a small acceleration or rotation of the person catapulted could put him off balance or make him land without being able to cushion himself. Yeah, don’t believe me, I’m just an aero engineering student about to graduate. What would I know about vortices!

  11. Remember, according to the diagram, he’s got anywhere from 4 to 7 mph of forward velocity. I’d like to see the vortex that can push a 200 lb weight back with enough force to make him miss the roof. If you’re talking about the guy spraining his ankle, then I think you’re right. A vortex could throw him off balance. But, presumably, this would be used in situations where you’re willing to take the risk of that level of injury. But I just don’t see how he’s missing the roof. Do the math, there’s just too much momentum and not enough time.

  12. Did someone forget that we have helicopters at our disposal? Current roof insertion techniques seem quite adequate to me. And getting a helicopter to a site is much easer than delivering and setting up one of these things.

  13. Do the math on the building size of the building. Then the wind speed. Then work out where this energy has to be shed when it enters slower or stagnant air. Recall that E=0.5mv^2 ie. the energy is the square of the velocity. If it is in a built up area, in ideal conditions forces can be huge.(imagine the end of a long road with buildings either side will channel air nicely to the building at the end of the road) The reason you never feel them is because buildings are designed so that the vortices only occur higher up than where people would be standing. But a launched person would have to pass through this. I don’t expect you to believe me, hence my comment about noone believing aero engineers.

  14. I think it’ll only work if it’s used in conjuction with the silicone-impact suit,that was invented by the japanese(?) a few years ago -to absorb the fall from a similar height!

  15. I’d be more worried about my 200 Lbs, plus gear, landing on a roof I know nothing about, or what is on that roof that may be sharp and pointy (tv antennas, etc.) I know a guy that jumped from one roof to another in Iraq. Ended up with his legs hanging from the ceiling in the room, and his body armor hung up on the edge of the hole. Lucky for him, none of the bad guys were in that room. Took ten minutes until the rest of his squad could get to him, and pull him through the rest of the way. You can bet that was an anxious ten minutes.