BPM5 Story of a rocket engine

On May 10th 2015 Copenhagen Suborbitals tested the first version of the BPM5 engine, a 5 kN liquid bi-propellant rocket engine running on liquid oxygen and ethanol. It turned out to be the most efficient liquid propellant engine we have ever made, this is the short story of how we designed, build and tested it.

Cut through the BPM5 engine.

The main components of the engine are the LOX dome, the injector and the regeneratively cooled combustion chamber. The gas inside the chamber is about 2300 degrees centigrade, so proper cooling is essential!

Different views of the injector. From left to right it is seen from the LOX dome side, from the combustion chamber side and finally a cut through to make the radial fuel channels visible.

The combustion chamber and cooling jacket shell are both made by metal spinning. This is a process where a solid steel cylinder is machined to the desired shape such that it can be used as a mandrel. A steel tube is then pressed onto this and simply shaped by pressing the tube against the mandrel.

Olsen Metaltryk helped us out on the metal spinning process.

After spinning the parts were test assembled. The flange and the LOX dome were fabricated in house but for 5 axis CNC milling of the injector we had to ask for help from Protobuild.

To protect the engine from corrosion most of the parts are nickel plated.

BPM5 nozzle after nickel plating.
Now that is one smooth combustion chamber!

After nickel plating the parts were fitted together...

...and finally welded together.

A series of water flow test were conducted to characterize the flow rates as a function of feed pressure.

The injector was also characterized by water flow tests.

May 10th came finally the day to move the entire test stand and engine to the test site and fire it!

The test crew carefully went through the preparation procedures.

BPM5 mounted and ready to fire.

Mission control kept constant watch over all readings from the test stand during preparations.


Running at a predicted peak thrust of 5 kN the engine performed beautifully!

Post inspection revealed the engine to be in perfect shape.

Post burn look through the nozzle.

Read more about our non-profit manned space flight program at www.copsub.com.

And support us in building the worlds first crowd funded manned space flight system!

Created By
Copenhagen Suborbitals

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