SCALE systems and further tests

So the launch campaign continues here at Erange. It is now Friday night and the testing continues. Today another three bench tests have been performed and they all went well. Our experiment is working fine with the other experiments and the rocket module.

This morning, hopefully, we made the final tests with the wire boom, SCALE, systems and they are mounted and prepared for the hot bench test where all the scale systems will be tested one final time. During the hot bench test the pyrocutter will be activated and that will test the mechanism for the FFU deployment.

The testing of the wire boom mechanism has continued during this week and we’ve had both success and setbacks. We are working hard at testing the different systems and the GPS and wire booms have given us some extra challenges. The four wire booms have to work at the same time deploying the same amount of wire. The systems are supposed to deploy about 90 cm of cable but for some of them it only deploys about 60 cm before the motor stats to stalling. We have been testing and testing and now feel we have reached some results. The friction in the system has always been a point for improvement but we are now confident we have made some progress. The result so far on the wire boom systems are that they work more than half of the time and we will pray and keep our fingers crossed that the systems will work at launch.

It is now after midnight and we are working hard to make sure the experiment will be ready for the payload assembly tomorrow morning. The hot flight simulation earlier this evening went o but we still have some work to get ready for launch.

Cross your fingers for us and read the blog for the coming week.

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The SCALE system is spinning

During the past week we’ve finally done some real progress on the SCALE system . For those of you who are not totally up to date with that the SCALE system is please check out these posts. To make a long story short, the SCALE system is probably the most central part of the whole experiment, it’s a complex mechanical structure which has one task, to deploy and retract the spherical probes which are used to make the measurements of the electromagnetic field. Due to the drastic changes we had to perform on the landing system the SCALE system where somewhat overseen and tasks which should had been performed much earlier during the project still remained when the team gathered after the summer. However due to great efforts performed by mainly Malin and Mario the system is now finally running and we now focus on optimizing the functionality of it. Below are two videos which displays the system and how it works.

 

The Scale System – progress

For the last couple of weeks I have been, amongst other things, working on the scale system. We have received some more parts from the manufacturer, but there is still a lot to be done before we finally can assemble the whole system. The good thing is that we actually start to see what it will look like and get a feel for the different parts. I have added some pictures of the scale system as it looks so far.  We are still waiting for some parts to be manufactured and some of the parts we will manufacture ourselves in our workshop.

So far I have made one of the cylinders in the workshop. Some smaller adjustments had to be made afterwards to be able to assemble the scale system but it was all within reasons. It was quite some time since I worked in a workshop so it always takes a day or two to get adjusted and to learn where all the tools are. I look forward to continuing the work when I get back from my vacation.

Finally! The SCALE System is Ready

Jiangwei writes

After several weeks’ struggle, the scale system is finally hammered out, hahaha :D, at least it shows what the scale system is and how it works.

Here are two pictures showing the inner structure and the profile.

The Scale System Explosion View

This explosion view shows a lot of details inside the a single scale system, hopefully you could figure out how it works 😀

The Scale System Outprofile

Now it looks really cute~ Exactly a cube of 60×60×60

During the design, quite many engineering and modelling challenges bothered me a lot, as well as other mechanical guys, but eventually, after meetings and discussions, things become clear as if we saw the dawn. For instance, how to mount the scale system? Originally it was supposed to be mounted on the side surface of electrical components box, but now there’s no space for that.Hence, our final decision is simply mounting these scale systems onto the buttom disk, pretty good for saving the limited space. In addition, how to discard the protective door? Due to its “one-way trip”, we shouldn’t make it complex, otherwise, we are more like going to discard a bunch of money in the sky. So a “double-locker” solution was unveiled, which only uses two lockers to constrain the door, and releases the door after lockers activated, thus, the door could be manufactured simply as a disk, no hinge any more.

Here is a brief assembling of the Squid main structure, including the E-box (electrical components box), four scale systems, and the lower disk.

The Brief Assembling

This assembling includes the E-box, four scale systems, and the lower disk.(To me, it looks like a space battle carrier, ready to deploy fighters,yahhhh)

Lots of problems were solved and finally the design come into details, now when I am looking back to these old versions once modelled before, I can easily feel promotions in the current version, and satisfied a lot.

The SCALE System

The main objective of the SQUID project is to test a new deployment strategy that will allow to deploy long wire booms at high speed without residual oscillations. The system in charge of performing the deployment of this wire booms is called SCALE and has been developed at KTH.

The SCALE consists of two coaxial cylinders with a small gap between them. On its initial configuration (before deployment), the cable is coiled along this gap between a pulling ring and a feeding system. The feeding system is an aluminium disc with a channel that guides the cable from the gap between the cylinders towards the empty space inside them, where the spherical probes are stored, releasing the wire parallel to the deployment direction (see figures below). When the deployment starts, a motor drives this feeding system, collecting the wire from the gap and redirecting it towards the deployment direction.

Overview of the scale system with the door closed

Detail of the gear system and the coiled wire (outer cylinder not shown)

Detail of the probe inside the SCALE system on the stored position

In order to maintain the stability of the FFU (Free Flying Unit) during its flight it is very important that the deployment of the four wire booms is carried out synchronized otherwise the unit would start tumbling and the controlled deployment would be ruined!

First SQUID post flight data analysis

After the successful launch and recovery of the SQUID experiment there is still a huge amount of things to do. The experiment recorded a lot of data from the different sensors (gyros, accelerometers, magnetometers etc.) and now we have to analyze the data in order to understand how the system behaved. One of the interesting sensors onboard the FFU were the gyros, that give the angular rate on the three axis. During the deployment of the wire booms, due to the increase of the moment of inertia of the FFU, the spin rate (or angular rate along the z axis) would decrease, so by looking at the recorded data from the gyros we could have a good idea of how the wire booms have behaved, which is specially important as the FFU was lost from the field of view of the camera very soon.

From the gyro data (see figure) one can clearly see the slow down of the spin rate just after ejection along the z axis, while the angular rate along the x and y axis is very close to zero, meaning that the ejection was almost perfect. What one can see on the slow down period is that there is a sudden change of the slope of the spin rate curve. By comparing this curve to a dynamical model of the system we could see that the reason for this seems to be that one of the wire booms failed after deploying around 30 cm. This was of course not good, but it didnt have a big impact on the overall performance of the FFU as it keept on spinning stably.

At the end of the slow down sequence one can see that the curve becomes flat, which means that the other three of the spheres stopped deploying (as it was expected) and the FFU kept on spinning with the wire booms deployed. After this, the retraction sequence starts, and again one can see a slight slope change of the curve, which means that a second SCALE system failed during retraction. The objective of retracting the wire booms was only for preventing them to entangle with the parachute, but luckily this did not happen and therefore it was not a major failure on the system.

One can also see another interesting event on the plot. At the end of the retraction phase, the spin rate of the FFU should be very similar to the initial one, but as one can see this did not happen, as it seems that the spin rate is decreasing (as expected due to the decrease of the moment of inertia of the FFU), but then suddenly it starts spinning up again, and becomes unstable (one can see that the data from the gyros on the x and y axis starts becoming messy). It seems that this was because the FFU started “feeling” the atmosphere before expected. One of the curves is the dynamic pressure, which was derived from the data recorded by the Rexus service module, and as one can see, at the moment on which the FFU becomes unstable, the dynamic pressure starts increasing, meaning that aerodynamic effects start being noticeable.

There is still a huge amount of data to analyze carefully, so this task will keep us busy the next months. We will keep you informed about our progress!

First post flight analysis

After the successful launch of Rexus 10 we still have a lot of things to do. There is a lot of data stored on the FFU which will have to be analyzed in order to fully understand how the system has behaved and recover the scientific data gathered by the experiment. This data is stored in the memory inside the e-box and has not yet been extracted as the FFU was wet after landing in the snow, and as water and electronics dont like each other we decided to leave it drying.

But probably you have already seen the video we posted yesterday. The images are impressive, but the main objective of mounting the camera was to film the FFU in order to be able to check how the spheres were deployed. Unfortunately the experiment module was coning (it had a quite high precession angle) and the FFU was lost from the field of view of the camera after a few seconds. However, if one analyzes the movie carefully can extract some useful information. On the pictures you can see some snapshots taken from the camera shortly after ejection, when the FFU was still in the field of view. Of one checks the pictures from 2 to 7 can see the doors of the SCALE systems popping out gradually (all four of them) which means that the SCALE systems were in fact working, as the doors can only be released if the motor of the wire boom systems are working.

The FFU also appears later on in the video. It was however very far from the experiment module and details can hardly be identified. One can see it in the last pictures, on the bottom half of the photos close to the edge of the ejection spring (dont get confused by the brilliant thing appearing on the top of the photos, which is the nose cone of the rocket). We were unlucky enough to have the sun very close to the area on which the FFU was flying, so on the photos it usually appears as a shiny thing close to the spring. There is however a very interesting photo. If one checks the very last picture, one can see the FFU body very close to the edge of the spring and what seems to be two of the spheres close to it.

We do know that at least two of the spheres were deployed, as when we recovered the FFU two of the cables had been damaged during reentry, probably because the motors driving the wire boom systems could not overcome the centrifugal force during retraction and stalled, leaving the spheres on the free airstream, which ripped them off the cable. We will not know surely how they worked until we really process the data, specially from the sensor wheels on the SCALE systems and of the gyros and accelerometers of the FFU, but so far so good.

Mario

Space ..there we go!!!

Written by Monica

Today is the last day of the first week of the Launch Campaing…that means it is also a special Sunday….many events…..they would put the nosecone to the rocket that means SQUID would be covered and we wouldn’t see it again until we recovered after mission 🙂 …. so we wanted to be at that moment but until then we had some free time so what we did was to go to the marvelous ICE HOTEL..we had access to the art rooms and they are amazing… a bit cold 🙂 but different from last year….you could see some photos .. then after been impressed by the hotel we came back to the ESRANGE but what was our surprise than we not only encounter a group of three reindeer but also another group with four of them …it was very nice to see them running along with us….but of course one needs to be careful….it is very dangerous to crash with them ..and actually we found in the side road a dead reindeer 😦 ..

Then after we return to ESRANGE we had a meeting were the team leaders should explain why your experiment was ready to FLIGHT!!…of course before being able to confirm that…we had a discussion previous the meeting.  We found out 3 major problems in SQUID during this week (1.GPS position, 2.Communication between RMU and FFU and 3. SCALE behavior), but thanks to a group work and dedication we solved them without setbacks and we feel quite confident our SQUID will perform successfully 😀 …then finally Gustav sign the papers where he as a representative of SQUID team say SQUID IS READY TO FLIGHT!!! and as Olle Persson said all we are WINNERS because we arrive to this point 🙂

So the activities ended and we deciide to relax a bit and watch some movies….so then we can start the most exciting and slowly week!!

Final assembly madness

Yesterday was the day when we had to finish the experiment in order to be mounted on the rocket. So more than finished, it shall be FINISHED. Quite a challenging task for us with the different problems we usually have whenever we try to do some similar to mounting the whole thing. From the previous post you should be aware that we were having a very long night, which ended up at 6.30 in the morning. Everything was going quite well, mounting was in progress, the problem with the GPS was solved, SCALES were put together and working etc. But when we mounted the FFU on the RMU a new problem popped up: lack of communication. The preload of the ejection spring was making the gap between the FFU and RMU too big for the umbilical pins, which were unable to have a proper connection with the e-box. This was a massive problem, as if we were not able to speak with the FFU when mounted in the rocket, we would be unable to send the mission mode command and we would fly a dead experiment.

We started analyzing different options, and we even started filing down the umbilical plates in order to be able to move the pins further up, allowing a proper communication. Mikko also came with the idea of modifying the pins in order to increase their length. They would not look as pretty but seemed to be a reliable solution. But we were extremely tired at the time after the 22 hour work day, and as we had to work later in the morning, we decided to go to bed and sleep a couple of hours.

What happened afterwards was a bit confusing. It was decided that some people should try to sleep a bit longer in order to go to the workplace later on and be more fresh. I was one of them, and I was supposed to be there at 10. However, my alarm did not went on (or i was so asleep that i didnt even hear it) and I was woken up at 12 by Georg and Gustav, claiming that it was lunchtime and that all the problems were solved. The pins of the FFU were made longer following Mikko’s solution and that the whole assembly was completely finished, so it was a pretty good way to start the day.

The rest of the day was much more relaxed, we mounted the experiment into the rocket, checked communication almost every time we touched the experiment and fix the last details (putting connectors to the service module and pyro cutter, securing cables etc etc.) After that, dinner, sauna and beer and long sleep.

Mario

Launch campaign, Wednesday and Thursday

Yesterday continued with preparation for the hot bench test and launch. The experiment looks good and only the final touches were required. Planned was to replace the wires with brand new ones for the SCALE system and the final assembly of the E-box. The SCALES worked excellently after receiving new wires and the bad RF board that was bothering us was replaced with the functioning test board, or so we thought. The Scales were functioning perfectly for a few test but started stalling again one by one, also the system does still not receive any GPS fix. So no rest for us then before launch.

Thursday continued with working on the SCALES and bench testing the full flight sequence. I and Gustaf were functioning as the launch officers for the behalf of SQUID. A series of six full simulated launch sequences were carried out with all the REXUS 10 rocket system and experiments and I can say that my confidence of the system grew with every test as SQUID functioned flawlessly every time, even with some hiccups with the ground support equipment.

As me and Georg are staying at Kiruna, we must drive every day to and from Esrange, a rather exciting 45 minute trip with slippery roads close encounters with the local fauna. One could say that thousands of ears of evolution have not prepared reindeers hove to cope with the resent invention of modern motor transportation. At any moment, a pack of reindeers can decide to utilize the flat snow free strip of terrain called road by the humans to try escape the roaring Chevrolet beast we are driving.

//Mikko