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DEAR COPENHAGEN SUBORBITALS GUESTS, We'll get right to it: We need your help to run Copenhagen Suborbitals. This is a 100% non-profit project driven by sheer joy and hard work. We survive on donations averaging about $10, that we use to pay for raw materials, tools, our workshop, electricity and most importantly, rocket fuel. The entire CS team are unpaid volunteers, building rockets in our spare time. If this project brings you joy, please donate to keep it running. Thank you.

After having flown Nexø I & II it is now time to gear up to something bigger.

Much bigger.

It is time to go all in and attack the Spica rocket and all the sub-projects it will carry. It is therefore my pleasure to announce the latest project in CS; a rather ambitious project that will kickstart the Road ahead towards towards the first flight of the Spica rocket. We call the project:

“BPM100 in 100 days”

The goal is quite tangible. It’s simply to design and build the first prototype of a 100 kN engine in 100 days!

And no, none of us have taken a brick to the head, we take this quite seriously. But is it at all possible to design and build the first version of the world’s most powerful amateur liquid bi-prop in 100 days? Well, I frankly don’t know but if we don’t try, then we certainly will not succeed… so now we try and then we’ll see.

If all goes well, we’ll have a test ready engine in 100 days. But then it will be missing a test stand. By our scale, a rather massive test stand that is. A test stand of that caliber is a project on its own, so it is definitely not included in the 100 days project, although it is obviously necessary to use the first engine for what it is meant for.

But how do you get started on such a massive project and in such a short time frame at all? Well, unfortunately, you have to start by taking one step backwards and look at the design of the entire rocket system. We have so far talked about a 100 kN engine, but it is based on an aging preliminary design of the Spica rocket. We need to have a solid and detailed overview of the entire system in order to determine the total mass. Remember, space flight is to a great extend an advanced battle against gravity, and in this regard, mass it is crucial. In fact, mass is everything.

Thus, we currently have three major work packages in CS. First and foremost, we look at the entire Spica rocket and the complete launch system that it is part of. We are therefore attempting to define all systems and the essential requirements for them through a Work Breakdown Structure. Then we can look at what components these systems should consist of and from there we can estimate their weight and finally the total weight of the system.

Only then can we actually dimension the final engine and determine if at all it is a 100 kN engine. Maybe it is only 90 kN, maybe it is 120 kN! However, at the moment we can look at overall design of the engine. With overall design, I mean we can look at something as important as manufacturing technologies. Producing a double-walled combustion chamber in that dimension is not trivial at all.

But much more about it over the next 100 days, this morning, I just wanted to share the great news with you. I hope that many of you will join us on an exciting journey for the next few months to the engine that will send the CS astronaut to Space.

T minus 100.

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Published by Thomas Pedersen on


Jørn · 15th October 2018 at 12:45 pm

lykke til

Terry · 15th October 2018 at 1:56 pm

Awesome, onwards and upwards.

Jens Krabbe · 15th October 2018 at 11:04 pm

That’s what we’ve been looking forward to for the past ten years:-)
I can’t wait to see what you come up with – and to experience the test runs 🚀

Rodrigo · 19th October 2018 at 10:22 am

Did you abandon the idea of a turbopump? I could help with that.
All the best!

    Jacob Larsen · 21st October 2018 at 5:17 pm

    Hi Rodrigo,

    A turbopump has never been a part of the ciritcal path of the Spica rocket, mainly due to its complexity and requirement of a very high level of engineering. We have decided to go with the DPR (Dynamic Pressure Regulation) system for the time being.

    We won’t rule out the turbopumps completely, though. They are pretty much the holy grail of rocket propulsion, and if we manage to design one some day, we might even consider flying with it.

    The performance leap one could get from such marvels of engineering…. 🙂

Mikael Nielsen · 1st December 2018 at 5:55 am

We are now around T – 50 days. What is status?

    Thomas Pedersen · 3rd December 2018 at 11:23 pm

    Status is that things are progressing a bit slower than planned. We are discussing a few schemes of attaching the inner and outer parts of the combustions chamber and would like to make a few tests before settling on a choice. I hope to write an update blog one of the coming days.

Niels · 14th January 2019 at 11:51 am

What is status on the goal here 101 days after T-100 days?

    Thomas Pedersen · 21st January 2019 at 9:40 am

    Status is that we certainly did not make our own 100 day goal. We have also chosen to do a few more tests that originally planned so things are all in all going to take more time that anticipated. We will soon be doing tests on swirl injectors which will be the final piece of the puzzle before cutting metal for BPM100.

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