This is one of the most fascinating groups I've seen in quite a long time. Check out their YouTube channel too where they show details on the turbopump https://www.youtube.com/watch?v=p6BC1QfA0Ug
They built them using very little money, because they didn't have that much forexample to make the g-test for their rocket they borrowed a free fall attraction in a local amusement park.
Copenhagen Suborbitals truly have the hacker spirit.
... until someone pointed out that building a submarine with ballistic missiles and playing with it in Russia's back-yard probably is a very bad idea.