Youtuber Integza has developed a functional open-source resin 3D printed prototype of a detonation-powered pulsejet engine.
While pulsejets, valveless engines in which fuel is injected into a pipe before being ignited in a series of pulses, have been around for over a century, they tend to emit a low specific impulse. These lightweight propulsion systems can therefore be created with few or no moving parts, making them easy to maintain, but their low efficiency continues to limit their potential in vehicle-thrusting applications.
Aiming to get around this and develop a valveless engine capable of continuous detonations, Integza has turned to 3D printing. Using the technology, the YouTuber has built his own pulsejet featuring a combustion chamber, complete with printed fuel and oxygen intake valves, and based on this prototype, he has since come up with a revised metal version, which can hit up to ten pulses per second.
Integza says the engine “isn’t the fastest he’s ever built,” but with better valves, “it should do better.” Moving forwards, the YouTuber adds that if he can find a way to build an engine that uses detonation with a continuous flow “the thrust would be insane.” With this in mind, Integza has revealed he’s now working on a rotating detonation engine that could yield a much greater level of efficiency and thrust.
How do detonation engines work?
In essence, a pulse detonation engine works by injecting oxygen and propellants into long cylinders that are open on one end and closed at the other. Once these pipes are filled, their contents are ignited, causing the fuel to burn and rapidly transition into a detonation. The pressure of this shockwave, which can travel at speeds of up to Mach-10, pushes the exhaust out of the pipe exit, creating thrust.
One major advantage of pulsejet engines is that they can boost the fuel and oxidizer at a high enough pressure to function without needing a turbopump. By contrast, typical rocket engines rely on complex, expensive-to-develop turbopumps to push fuel and oxidizer into a chamber at a sufficiently high pressure to avoid it being blown back out.
However, as Integza found out, pulsejets can also be very noisy, making them unsuitable for powering manned flights, and are less energy efficient than internal combustion engines. As a result, such propulsion systems are more commonly used for thermal energy conversion or powering light radio-controlled aircraft than they are for providing jet thrust.
Integza’s 3D printed prototype
As explained by Integza in his video, pulsejet engines feature “clever geometries” that “create a cycle of self-aspiration of air” that mixes with fuel and gets ignited again, but this doesn’t enable continuous thrust. To generate greater amounts of power, the YouTuber theorized it’d be best to “use detonations on this type of engine,” and he tested this theory using a Prusa SL1S 3D printer.
Leveraging the system and a Siraya Tech resin, Integza initially 3D printed a combustion chamber hooked up to a long acrylic pipe and air and fuel valves. Once ignited by a high voltage generator operated via an Arduino controller, the YouTuber wasn’t sure if this setup was creating detonations. To provide his engine with more oomph, Integza, therefore, resorted to injecting pure oxygen into it.
This allowed him to achieve an output of 80 meters per second, enough to punch a hole in a piece of paper and pop a balloon. However, not satisfied with this thrust level, the YouTuber then went further by machining another prototype from metal, which he says is capable of creating “clean and consistent detonations” while achieving up to ten pulses per second.
When putting the engine on rails, it also proved capable of propelling a platform forwards, hence he describes his prototype as “a great way to explore detonation.” That said, Integza also believes his design is “flawed because of its pulsed flow,” hence he’s now developing a rotation detonation engine, the likes of which allow one or more detonations to travel around an annular channel continuously.
The larger power output of these engines makes them better suited to vehicle propulsion than conventional pulse-based alternatives, and the YouTuber has now committed to making his own in his next video. In the meantime, Integza has made the 3D model design files for his jet engine prototype available to download for free, enabling those brave enough to try their hand at 3D printing one at home.
Content creators such as Integza provide makers everywhere with an accessible way of learning more about 3D printing and how to deploy the technology in innovative and exciting ways. In August 2021, Integza himself developed a 3D printed engine inspired by a Nazi design, powered by a volatile chemical reaction rather than ordinary fuel.
More recently, YouTuber Akaki Kuumeri has developed a 3D printed PS5 controller adapter that enables users to play games one-handed. The content creator is now working on a library of 3D printed parts for game controllers which cater for non-standard hand positions and make playing video games more accessible.
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Featured image shows Integza’s 3D printed engine prototype during detonation. Photo via Integza.