DIY Guided Missile (…err Model Rocket)

Hackers [Navic] and [K.o.D] have fitted an Arduino Pro Mini and an array of components into an off the shelf rocketry kit to create a guided model rocket, taking the whole idea of Arduino-based space technology to another level

The Arduino reads signals from internally mounted accelerometers, and adjusts balsa fins (via 4 micro servos) to correct the rocket’s flight path. Due to the nature of model rocketry, the active guidance is limited to the 3 seconds that the rocket is traveling upwards. A valiant effort nevertheless. Videos of the rocket’s maiden voyage, and a system check after the break.



116 thoughts on “DIY Guided Missile (…err Model Rocket)

    1. You can stack motors ontop of each other to create multiple stages. I think this is more of a proof of concept. Having a rocket with a failing guidance system and several stages is a bad combo

  1. ummm.. an IMU for a missile should have 6 degrees of freedom. I’m only seeing 3 (tri-axis accelerometer). You also only need 2 servos to control it, one for up/down and one for left/right.

    It this roll stabilized? If not, there’s a really slick way that they stabilize some missiles called a rolleron.

    Pretty cool though.

    1. I’m on the rocket team at my school and last year we designed rollerons into our fins to try and quantify their benefits. Unfortunately, you have to be going pretty darn fast before you see any sort of added stability — speeds that most Estes engines can’t propel a model to. If you scale up your rocket and get to a few hundred miles per hour, the rollerons can come in handy.

    2. Rollerons are generally used for air-launched missiles. In this case, being in the moving airstream pre-spins the rollerons and you get stabilization right from launch. I suspect it would not work well with your ground-launched rocket because it will take extra time for the rollerons to spinup.

      1. Look up mim 72A and mim72c
        They go like Hell after launch and are stabilized by rollerons and are ground launched. This is an old Army Air Defense
        Missile that is a modified Sidewinder Air to Air Missile.

  2. Cool! I wonder if there is an engine that lasts longer. Flight time will definitely be restricted with the normal class A/B/C engines unfortunately. I see the potential though and this is a great proof of concept :D

  3. Don’t bother watching the second video, its merely some misaligned fins wiggling about for 1:17! :(
    waste of time, all it served to show was how low the build quality was. I’m amazed it didn’t just veer off wildly.
    Don’t get me wrong, I like the concept but I think a test with all fins set to straight would’ve been interesting just to prove that they were straight before attempting any active control.
    Also are 4 servos really necessary? Surely two would do if you didn’t mind a little roll?
    I wonder if they bothered to program the servo response differently considering 2 of them pivot in a drastically different way to the other pair of control surfaces, it will have a big effect.
    Micro hobby servo response times might also be an issue at this sort of speed

  4. rolleron’s look like a such a neat solution, can’t believe I’ve never heard of them before, thanks ke7eha.
    Glad you come to similar conclusions about the number of servos

  5. “taking the whole idea of Arduino-based space technology to another level”

    Er… no. Programmable chips in amateur rockets have existed since we have, well… programmable chips and amateur rockets. The “outer space” is commonly said to begin at a 100km height. These rockets don’t even go at 1 km.

    I am no arduino hater, but this is just similar to literally thousands of projects who just use similar or more poxerful programmable chips in rockets.

  6. Two of the fins are hinged so far aft that I’d be concerned that the airloads would overpower the servo and twist them around, or at least make them difficult to control. Repositioning two servos and using pushrods might be an option.

  7. Step 1: Put your rocket on a balloon.

    Step 2: Put your balloon up to the edge of space.

    Step 3: Launch multistage rocket with camera and GPS.
    Step 4: Launch Multistate rocket with video and transmitter toward moon trajectory for weeks of video phun.

    Ahhh…soo close….and yet so far…

    1. I don’t think the Delta-V cuts it. You need to accelerate to about 9km/s to escape earth; dosen’t matter how far you are because gravity has infinite range. Newton, homie

      1. Even if you launched from 200km (balloons can’t dream of getting that high), you need to be traveling at 7.4 km/sec to be in orbit. This thing might get 200 m/sec, plus the earth’s rotation means about 500 m/sec. Only 6.9 km/sec to go! My point is you need a wayyyyyy bigger rocket to even dream of getting to orbit.

      2. Since gravitational force is inversely proportional to the square of the separation distance between the two interacting objects, more separation distance will result in weaker gravitational forces.

  8. Yeah buy your arduino now before Homeland Security finds this project.Guided missiles (no matter how inaccurate or short flight) will not be allowed by the powers that be. I know many here fancy themselves rebels or out of reach/under the radar/invisible to the men in black suburbans but you WILL change your tune when the roll up at your house…

  9. @Patrick: Stuff it. Take your political raving elsewhere, we have all the crazy we need here already. This is hack-a-day, not the comment section on a Brietbart story. Assuming that it even is an FAA violation, it would have been FAA regs written by the previous administration (or, as I suggested, before).

  10. I agree with the previous comments regarding legality of this hack. I’ve certainly looked into making guided model rockets (I’m a UAV engineer), but without a special license, it’s illegal pretty much everywhere. Curiously, though, if you use a propeller instead of a rocket motor, it becomes a model aircraft and is governed by much more forgiving rules. Remember kids: save the rocket motor for the terminal kill-vehicle! :P

  11. Back on topic: I wanted to congratulate the guys working on this. It looks like an awesome project. I agree with the above poster that suggested this might make a cool Rockoon (balloon launched rocket). Though, if you’re going to do that then you might want to think about ways to vector the thrust instead of turning fins. At the altitudes those weather balloons go to I doubt there would be enough atmosphere for the fins to work.

  12. Congratulations!

    You either have a federal contract, a federal permit, or a federal warrant.

    Any rocket no matter what the size that has a guidance system is classified as a missile and thus a destructive device. Its a law that has been on the books since the sixties.

  13. a guidance system is not against FAA rules, and as long as the rocket doesn’t go higher than a certain altitude, it doesn’t need to have a flight plan filed.

    the NAR doesn’t seem to have any rules against guidance systems either.

    as long as you’re not guiding it toward a target, (thus making it a destructive device, and under the BATF) you should be fine,

  14. I agree with the sentiments regarding the missile vs rocket thing. Adding guidance to a model rocket without authorization is fiercely illegal. You should not post this.

  15. This isn’t a guidance system. It performs no navigation. Rather, it appears to perform closed-loop maneuvers using feedback from a 2-axis accelerometer. I can a few raised eyebrows given their choice of maneuver (transition from vertical to horizontal flight) but, it still wouldn’t call it a guidance system.

  16. I am no fan of Bush either.

    But, I’ve seen anti-Bush comments remain on this web site, despite the fact that they were “Off topic”.

    However, anti-Obama comments are imeadiatley removed.

    Why is there selective inforcement?

    Clearly the moderator is “in love” with Obama.

    1. Yeah, that’s completely untrue. I should know, because I moderate the comments. I just checked the trash, and I can’t find anything related to what you’re asserting. Present some evidence or shut up.

      BTW, several people reported comments from your IP. Notice how they’re still up.

  17. I think an interesting application of guidance would be in the *return* of model rockets. I remember launching a few 3-stage Estes rockets when I was a kid, and in every instance, we never got the top stage back. It went so high that the winds caught it and carried it off.

    A GPS guided and servo-steered parachute or parasail, however, could assure that that the payload stage comes back and lands near where it was launched.

    The question is whether or not this would qualify as “targeting” and whether or not, according to the accounts of some here, this would render the system a weapon.

  18. Cool project, but how is this ‘guided’?

    They have used some code and an accelerometer to get some basic attitude control.

    If it could follow a predefined path, then I’d call it guided.

  19. Really awesome project. It only looks like the steering is not very accurate or fast. The flight looks just like a regular model rocket flight. I see no influence of the steering, at least no good one…

  20. Oh yeah, I see whats the problem. The accelerometer doesn’t work without a proper gyro, therefore it only reacts correctly to slow changes. The quick changes just produce overreactions.

  21. Great start, I love this kind of stuff… Here’s my efforts..

    you need to GEAR DOWN hobby servos. 4:1 or more you only need 3-6 degrees of turning and if you cand gear them down so you get 50% servo turn = the full 3 degrees then you are golden.

  22. How bout we change the hate to something else, like the ARDUINO! That shit is still on the board!
    You don’t have to be a ROCKET scientist to take it off.
    BTW, went to Makerfaire saw a bunch of Arduinos and wanted to die. Some Makers didn’t even know the name of the chip! I almost shit.

  23. I like the rhythm the fins give off in the second video. kinda catchy.
    Cool concept tho, I’v always wanted to build a miniature space shuttle modle, but never had the funding.

  24. “I’m amazed it didn’t just veer off wildly.”

    This contradicts your prior sentence- it was not a complete waste of time. It did something interesting, and maybe of dubious legality (but gee whiz, give it a rest. Unless you are a federal agent charged with enforcing the rules, MYOFB.) There was some loose shit involved, but they didn’t make any bones about that, either.

    It was cool, and did something unexpected; as far as I am concerned, this makes it a win, despite being a bit lopsided, with an somewhat inadequate control system. You need 6 DOF, but you can do some stuff with 3 DOF.

    The whole point of projects like arduino, or wiring, is to be like a nail- a tool to hold stuff together. It is a tribute to the Arduino effort that they DON’T have to know what the micro is, Anon. It is a tool to do stuff, not a nerd badge of courage and righteousness. You don’t like them? Don’t use them.

  25. Why does the article say it is only “guided” during the powered phase? Most of your course correction will come during the coast phase, up until you deploy the recovery systems (and even then, some recovery systems will benefit from guidance as well).

  26. @Dave Eaton: I agree with you about the Arduino, but I don’t think I’ve seen anything here to suggest that anyone is mentioning the possible illegality of a guided model rocket as a way to brow-beat the project makers. Personally, I brought it up because I’m not 100% sure about the status myself and felt that it’s, directly, related to the project. Besides myself, either this project’s creators and/or others looking to replicate a similar project might want to know that they are, or aren’t, breaking federal law. I, personally, don’t have a problem with what they’re doing, but the simple fact is that if it violates FAA/Homeland Security rules it can get you into a lot of trouble (even if it’s just a light model rocket). I just figured it made sense that we should be aware of the issue so that we know, ahead of time, that we may, or may not, be risking an things like hefty fines.

  27. @Colecago — In that case, I take it back. It succeeded nicely. Although, I suppose the NAR might have something to say about that. Nevertheless, I look forward to more from these builders.

  28. Fun project, works nice.
    Would me even more fun, if the missile would be able to track and hit a model airplane, by using a camera, and some pattern recognition algorithms on a fast microcontroller to detect the plane

  29. I agree we should try to comply with the law. I am in the dreaming and calculating phase of a high altitude balloon project (no, not arduino, but not because I don’t just love my dweenos- I just need more horsepower.) I don’t want to piss off the FAA or cause a plane to crash, so I want to do it right. I didn’t mean to suggest being a scofflaw is a good idea. The project was getting a bit more beating than I thought it deserved, so I was just fussing.

    We should be critical, in the sense that we offer suggestions, question the designers (their design choices, not their politics or fashion sense) and argue amongst ourselves about the best way to do it.

    Epic fail? No. It took off, and some shit happened, and dudes learned something, and we’ve spent a good time bitching back and forth about it. Did it do what was intended? Heck, I’m not sure I know what was intended. If it failed to launch, or caught fire, then that would be epic. This is a run-of-the mill failure. It didn’t work all that well, and it parameterized what you can get away with in doing such a project. I learned a bit, even from you lot, so the fail isn’t epic in my mind. Comic, a little. Typical, mostly. Instructive Fail is usually not a category we use, but why not.

  30. wow pat.. way to turn this in to something its not. No one here is going to get “rolled up on” because of some guys fairly inaccurate execution of a guidance system (yet commendable idea, I have planned an R/C version of this since I was little and it was going to have similar build quality probably). Just some people having fun…if you are in to extremest websites and plan to be an idiot and launch in a sensitive area then yes, I agree, you will and probably should be “rolled up on”. I don’t like that I can be wiretapped at any time but come on this isn’t politics, its some guys fulfilling a childhood fantasy.

  31. First of all, I’d like to thank Hack A Day for posting this. K.o.D and myself read the articles on here all the time.

    The term ‘guided’ was commented on, and perhaps isn’t the best word. I picked it as relative to the rocket itself, the electronics guided the rocket’s flight. Controlled would be a better term. As mentioned earlier, there is no navigation and if the definitions are not correct oh well, but I call a rocket something w/o navigation and a missile as something with navigation…. If that’s wrong, my bad.

    Arduino haters: It’s modular! Once this project was done I literally took the parts out and used them on other stuff with ease, that’s all. I could have soldered up a 328 barebones, but that pretty much solidifies those components to that application…. I like being able to do multiple things quickly with fewer parts, hence Arduino is the choice.

    This project was for fun and to learn, as Dave Eaton said. Getting controlled motion to work for a short period of time was the goal, and it worked. Efficiency was not a focus for this project, but will be for future projects of this type.

    About the legality of this project – I have no idea. As human beings, we both made sure there were no aircraft in the area, we had water in case of fire and launched it far enough away from houses it wouldn’t create a problem. If it’s illegal and a law enforcement official comes to hunt me down, oh well. If ‘sorry’ isn’t good enough then oh well for me, lol. Doesn’t take away the fun and success of this project.

    Thanks for all the comments!! Keep ’em coming!

  32. Hmm Im not up to terms here but In order to be considered a missile doesn’t it need to carry an “explosive payload”. There are tons of things that have a guidance system and I do believe a model rocket with a micro controller and some servos is the least of anyones worries.

  33. Good point RBRat3!

    I forgot to mention the cool technical stuff… Rollerons are awesome, btw. We wanted to put a video camera onboard so we could see the amount of roll relative to the ground, but didn’t have one at the time. It doesn’t take too much fin deflection to counteract the rolling for stable flight.

    Rockoons are my current favorite topic, and plans are in the making for a flight to high altitude (FAA approval WILL be granted for this, so don’t worry everyone). A friend of mine that is a NAR high power rocket club member is helping me out with this. Any ‘control’ that a rocket will use at high altitude will need a gimbaled motor as mentioned before.

    As for this project, there were a lot of different things that could have been used, as mentioned but we took the idea and made it work with what we had, it’s not like it was a huge undertaking. We had a 2-axis accelerometer in our parts bin, so we used it. 3-axis gyros or even a full blown IMU would be a better option, but that stuff wasn’t in our parts bin. If we were paid to create something like this, or were getting some kind of credit for a degree then yeah it’d go from a weekend project to a couple months with fancy graphs, schematics and waiting for parts to come in. Same with the servos, yeah 2 work fine with all the hardware to connect them to the fins and all, but we had 4 so why not simplify?

  34. @Hirudinea: I think you are underestimating those rich islamic fundamentalists. They got the money and the brains to pull this off (hey, they go to the best schools in the US and Europe!). Let’s just hope the Dept. of Homeland Security is doing its job.

    On another note, I don’t see why the Arduino haters aren’t happy. Crash it and you get to kill an Arduino!!

  35. @Hirudinea: I think you are underestimating those rich islamic fundamentalists. They got the money and the brains to pull this off (hey, they go to the best schools in the US and Europe!). Let’s just hope the Dept. of Homeland Security is doing its job.

    On another note, I don’t see why the Arduino haters aren’t happy. Crash it and you get to kill an Arduino!!

  36. 2 things, first – seriously how bad is the programmer if he/she didn’t add some sort of averaging to the system so that he/she allows the fins to wriggle all over the place even in a steady smooth movement, I mpknow this thing will be moving fast but it looks like this guy is just reading x and y of his spark fun accel breakout and sending it straight to the cheap noisy servos. I mean, really, it’s not hard to do a moving average, and at 16MHz you can do that many times per second, even allowing for I2C bus speeds (typically around 200Khz I beleive) and the time to send it to the servos.

    Ok, 2nd, how long before an arduino does make it to the moon? You’d think that it isn’t so much of a leap from a weather balloon to the moon, is it perhaps the dedication needed to monitor the rockets progress and send it trajectory updates 24/7 ? (I guess GPS doesn’t get you to the moon:P) but timezones are surely on your side in this situation…

    Hmm.. Long distance arduino communication tests would be interesting,, anyone out there got some ideas on this?

    3rd (I lied about 2) shouldn’t the rocket be black with a silly shark face?! :P

  37. This hack is legal by US law. By federal law, 26 U.S.C 5845, a missile is only classed as a destructive device if it has an explosive or incendiary payload of more than 1/4 ounce. A rocket is classed as a destructive device if it has more than 4oz propellant. Other than that, they need to be licensed and/or registered.

    The law can be found here:

    You guys probably want to look up legal terms before you [over]react.

    By the way, this is only US federal law. Laws vary by state, so look it up to make sure you are legal.

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