Engine Hacks: A Pulse Jet UAV By Any Other Name Would Still Be A Cruise Missile

Imagine our surprise when we learned [Bruce Simpson], who made headlines in 2003 with his $5000 DIY cruise missile, is still alive, not illegally interned in a black ops prison, and still doing what he does best: building really awesome remote-control airplanes.

The first successful mass-produced pulse jet aircraft was the German V-1 flying bomb. The V-1 had a very primitive guidance system, but the unmanned pulse jet aircraft quickly evolved into a few target drones used by the US Air Force. There was never any significant advancement towards improving the fuel consumption, noise level, or heat signature of pulse jets, so they were superseded by the superior turbojet. Despite their failings, pulse jets are remarkably easy to build and amazingly fast.

Instead of being antagonized by the New Zealand and United States governments, [Bruce] spends most of his time now working on pulse jet projects. He’s flown quite a few modified R/C planes and has an electronic Engine Control Unit for his jets. One of his most impressive projects is the 100 pound thrust pulse jet that was later attached to a go-kart. His no weld version of a pulse jet can be built in even the most minimalist work shop and is the epitome of an easy-to-build jet engine.

To get an idea of how fast [Bruce]’s planes can be, check out his Long-EZ R/C pulse jet in action after the break.


33 thoughts on “Engine Hacks: A Pulse Jet UAV By Any Other Name Would Still Be A Cruise Missile

    1. Stinger: Maverick, you just did an incredibly brave thing. What you should have done was land your plane! You don’t own that plane, the tax payers do! Son, your ego is writing checks your body can’t cash. You’ve been busted, you lost your qualifications as section leader three times, put in hack twice by me, with a history of high speed passes over five air control towers, and one admiral’s daughter!
      Goose: Penny Benjamin?
      [Maverick shrugs]
      Stinger: And you asshole, you’re lucky to be here!
      Goose: Thank you, sir.
      Stinger: And let’s not bullshit Maverick. Your family name ain’t the best in the Navy. You need to be doing it better, and cleaner than the other guy. Now what is it with you?
      Maverick: Just want to serve my country, be the best pilot in the Navy, sir.
      Stinger: Don’t screw around with me Maverick. You’re a hell of an instinctive pilot. Maybe too good. I’d like to bust your butt but I can’t. I got another problem here. I gotta send somebody from this squadron to Miramar. I gotta do something here, I still can’t believe it. I gotta give you your dream shot! I’m gonna send you up against the best. You two characters are going to Top Gun.

    1. Check out some of Bruce’s history. He was illegally harassed by the New Zealand govt (at the behest of the USA) for producing “potential terrorist weapons” equal to multi-million dollar missile systems.

      We would call those “phone powered cruise missiles” now. An android phone with GPS, camera, and cell link to a server would have all the power needed for in-flight re-direction and control, and remote data processing. I’m sure a fuel conserving algorithm could give one heck of a flight-time/range.

      1. They’re just mad that he pointed out that millions for a $10K item is a ripoff. You can’t even use the “but the design cost billions” excuse because consumer devices for <$1000 have all the needed hardware and the hardest part of the software. The major advantage of military hardware is that it's designed to prevent countermeasures or sabotage in-air. Stuff like EMP-shielding and sacrificial coatings. The TESTING is not exactly simple, either. Still, it seems like a good ol' boys industry. :P

      2. A big part of why missiles are so expensive is because of the safety and reliability requirements. The designers are tasked with providing detailed proof that the missile will (1) Pretty much always work, no matter what and (2) Will be safe if absolutely anything, no matter how how small, goes wrong with the missile.
        The missile is the easy part, a crafty fellow in his garage can build one for $5K! But can he *guarantee* through copious documentation of all the self-test systems that his GPS won’t fly it off course, that it will start and run at -50degC, or that it won’t arm itself via short circuit or software bug and blow up the plane carrying it?
        *That’s* why the design costs billions. :)
        Pulsejet instead of turbojet would be cheaper, granted… but I think they’re inferior to turbojet in all aspects but simplicity and cost. Less range per unit of fuel, prone to unpredictable failure of flapper valves, harder to start and keep running, etc. And again, if you’re going to use a missile over enemy territory do you want to run the risk of engine failure / guidance system problem over a civilian area?

      3. @Darkmoon – Yes, military missiles can easily cost several million for dependable operation, but when I can produce a cheap copy of a million dollar missile for only $10K, that lets me throw 100 missiles to your one. Yes, your one MAY have me beat in the performance and dependability categories, but if I can get a successful deployment of even just 2 of my piece of crap missiles, I’ve doubled the performance per dollar over yours. Plus, countermeasures that work on one design, probably won’t work on some others.
        Economics are a very important part of war, ask any logistics and supply specialist.

  1. Sheet that looks fast, on video anyway. Looks to be better to fly on a calm day, so the glide landing is more predictable. Somewhere in the mother earth news archives is a project for a fishing hut heater that use the pulse jet operation principle. To crenn’s list of boxes to check off I’d add cool sound, although it could turn into an irritating noise fairly quickly.

  2. That is just pure awesome. The guy seems to be willing to take some risks as well as smart and humble. It is great to see someone reviving older/simpler technology like this and especially making it publicly available. Thanks [Bruce] you rock.

    1. Sorry for the double post, had a typo. I meant he is willing to take risks, but is also smart and humble. Unlike some dangerous hacks we see where someone is just taking risks out of ignorance.

    1. For many designs it’s not the ignition source but the air compression required to get the thing going that is the problem.

      You see that even in this video where he used a compressed air shot to start the thing. Larger pulse jets are often started using leafblowers.

    1. There was an update to his original article where he spoke of actually building a prototype with his own money, however as stated the goverment, etc. interfered.

      This was all only a few years before UAVs becamea more popular common project; and the difference between a UAV and a cruise missile is basically – a warhead.

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