The engine project of our rockets

0 m


Chimaera is the new hybrid engine from Skyward’s propulsion department and that will push Lynx to 3000m of apogee for the 2023 EuRoC competition.

The propellant used is hybrid, so the liquid oxidant in this case is nitrous oxide: N2O, while the combustible grain, in the solid state, is 3D printed ABS (a plastic filament with which Lego is also made).

Chimaeara has three smaller subsystems inside: the actual engine with the grain inside, the tank and the supply lines and finally the ignition system.

The engine provides combustion chamber (a cylinder essentially), a convergent-divergent nozzle and the grain of fuel. This engine is able to develop 1300N of thrust for 8.8s of burning time, for a total value of more than 10000Ns of total pulse and a specific pulse of about 200s.
The grain of fuel, as mentioned before, is in the solid state and is 3D printed. The material of which it is composed is ABS (Acrylonitrile-Styrene-Butadiene), the geometry chosen by us is a grain with a circular port sinolo (or single circular perforation), and during combustion it is able to develop a regression rate (or regression rate) of 0.8mm / s.

The supply subsystem includes: the tank in which the oxidant is stowed, the supply line and the injection block.

Pressure tank and supply line

The first is a 57.7bar pressure tank consisting of a cylindrical body and two welded caps. A safety valve and a venting line are connected on the top cap during the refuelling phase, once the rocket is stationary on the ramp.

The supply line is a pipe long around 10cm and 1/2″ in diameter, on which a custom valve is mounted that allows the connection between the tank and the combustion chamber.
The injection block includes: a flange that serves as a cap for the combustion chamber, a housing for the supply line and the actual injection plate. The latter is equipped with 12 holes.

Ignition subsystem

The ignition subsystem provides for the presence of a pyrotechnic igniter, the latter is a solid propellant disc based on potassium nitrate and sorbitol. The ignition of the propellant takes place thanks to the incandescent of a Nickel-Chromium filament placed inside the propellant disc during the casting phase of the same. The ignition of the solid propellant generates the pyrolysis of the solid grain and the generation of hot gases to start the combustion of the engine.



2,5 m


15 cm


27 kg


5 kg