Month: May 2014

Summer Time!

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Summer is coming and most of the Team members are leaving Sweden: do you maybe think that the SCRAP team will have a rest? Of course not! There are problems to be solved, components to be manufactured and new ideas to be discovered! Holidays, internships, projects won’t stop us (hopefully).

Have you all a good time and enjoy your summer!

The SCRAP Team




REXUS Rocket: how it’s made

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After some umbilical problems happened during yesterday morning,   REXUS 16 launch has just been launched few minutes ago! Congratulations for the teams who took part to the launch and for the entire experiment!

After watching this video, as an aerospace engineering student like most of us, a big question flashed in me: how REXUS rocket engine is made?

REXUS rocket is equipped with an Improved Orion motor, and it supports a payload of 120 kg, and is capable of achieving 110 kilometres of altitude, depending on payload size.

The rocket is designed to be rail launched, and can be supported at most fixed and mobile launch sites.   The system typically uses spin motors and has a total weight of approximately 420 kg, excluding payload.

The Improved Orion motor uses a “bi-phase propellant” system which provides it with around 8600 kg of thrust during the first four seconds of motor burn. The thrust then tails off to approximately 1400 kg of thrust until burnout occurs at around 25 seconds. The fins are normally configured so that the rocket will have a stabilizing spin rate of approximately four cycles per second.

Lots of technical details, pictures are always more clear than words!


Last thing but not the least, also KTH’s ISAAC team is going to launch their FFU, stay tuned and watch its launch tomorrow!

This thriller is killing me

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This thriller is killing me

As you all know, REXUS 15/16 Launch Campaign is going on right n… What?! You did not know about the launch campaign?!
Ok, Ok, all cool, but you can get updated, just like this page on Facebook! Right now!

So, as we were talking, the launch campaign is going on. In Esrange, Sweden, students and experts from all over Europe join forces to assemble in two rockets the endeavors they have been working in the past one and a half year.

Then, when everything is ready, the suspense begins: The rocket is carried to the launch pad and only when the engineers are completely sure that every single thing is working nominally, the countdown starts.

SCRAP Experiment understand the significance of this moment to all teams involved and wish the best of lucky to all of them. Particularly to ISAAC, since their experiment will provide very useful information to ours. Simply, we will share the same rocket module and same ejection system. So, I think you can imagine how much excited we are!

The launch was schedule for today at 08:00 o’clock and this are the messages that popped up in REXUS page:


New attempt tomorrow. We will cross our fingers!

CDR and Space day coming up!

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The SCRAP team has been working hard the last couple of days to bring the SED up to CDR level. After the CDR (Critical Design Review) the experiment design should be finished and ready for manufacturing. So as you can imagine there are allot of things to do at the moment. But there are more exciting things coming up. On Friday is the big space day at KTH and the SCRAP experiment will be presented amongst several other space related projects being conducted at KTH. For more information on the KTH space day check KTH’s web-page.

And for more information on the SCRAP team and its progress towards CDR and beyond remember to follow us on Facebook.

/The SCRAP Team

“Do you get any credits?”

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This is one of the most commonly asked questions. The SCRAP team members works on the experiment on a daily basis and our fellow classmates of course are aware of the heavy work load we have and then adding something of this magnitude on top of it seems a bit strange unless we get credits for it. This is not the case for us, if credits was our prior aim I think we can all agree on that any other university course would be an easier pick! However, from this hands-on project, we have gained invaluable experience of how to carry out an aerospace project, every step of the way from idea, proposal, research, design, testing and soon manufacturing.. and the journey does not end here! So many things ahead, for example THE LAUNCH just to mention one. We have also gained a lot of experience in teamwork, outreach, the aerospace industry and networking as well as dealing with multiple tasks at once, sometimes during very high time pressure. But to answer your question: yes many of us have chosen to get some credits for it but its not really proportional to the work one puts in. Hannah, Matteo C and Rasmus are getting rewarded with 15 credits this semester for their work in REXUS, same goes for the bachelor students Linnea, Hannes, Mikael and Joel in form of credits for their thesis work (15 credits). And probably other members in the team will do the same in the future, the bachelor students could possibly take out another 15 on REXUS if active in the team during their master studies. The REXUS Programme, which SCRAP is a part of, encourage the students to get credits for the work and the teams usually present their idea with this at the selection.


Example Report: to obtain the credits the SCRAP members each would have to write a report that covers what they have worked with during their time in the team and attach their written contributions to the team. 


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So in order to ignite the gun cotton, which in turn will eject the copper particles from the cartridges, we need reliable ignitors. The SCRAP team has come a long way from using unreliable glow plugs and fragile wire connections.

Ignitor CAD

The design for the new ignitor was developed and improved over a long time through discussions and rigorous testing. The design is based on a resistor wire through which two amperes of current is conducted, heating the wire which in turn ignites the gun cotton. The wire that connects the two plugs of the ignitor is 2 cm long and 0.2 mm in diameter. This wire needs to be tied to each plug and then crimped into place. Once that is done the entire piece must be glued with epoxy glue to seal the chamber. It is indeed like brain surgery… or rather rocket science… no wait… ROCKET SURGERY!


The manufacturing of the final ignitor prototype is all about good old fashioned manual labor. Complicated, meticulous and eye-tiring labor… at two in the morning. As a matter of fact this post is posted right after the ignitor shown was completed… so yes we are a bit tired, but nothing works unless you do!


Good night!
/The SCRAP team

Ignition System

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In the wake of the topic of the last post, we will discuss now the prototype of the complete ignition system. When we talk about complete ignition system we refer to the setup of the electric circuit, the ignitors and the cartridges that will be mounted on each of the two FFUs. The system consists of two electric circuits connected in parallel, each featuring a series of five ignitors and cartridges: in total, ten cartridges per FFU.

To understand the reason why we need a circuit in parallel, it is necessary to know that it is important, to ensure the ignition of all the cartridges, that the current in the circuit is uniform and high enough. So, why don’t we connect everything in series? Well, the circuit is powered by a SAFT battery that provides 4 V: if we connect all the cartridges in series, the resulting resistance is such that the current provided by the battery is too low to ignite the gun cotton.

It is now clear why we connect the cartridges in parallel, five per side. And it is also clear that it is crucial that the assembly of the circuit is perfect and that the resistance in the two branches of the circuit is the same in order to obtain a uniform current flow in both the sides and, finally, a synchronized ignition of the gun cotton.

After different attempts and improvements in the assembly procedure, we succeeded in obtaining a good ignition, enjoy this:


/The SCRAP Team