WOW! Those are the only words that come to our minds when we reflect back on our testing days. It was such an amazing experience! We first arrived to Los Angeles on Wednesday evening after a half day of school. As a team we split up: half of us went to go rent the Penske truck from Home Depot, and the other half went to the hotel to wait for the crate shipment. As soon as our crate arrived, we immediately started to unpack, and assemble our pod; our pod is completely modular, so we took apart almost the whole entire design to ship. After three hours, our pod was completely rebuilt and we loaded it into the Penske truck eager for the day to come.
Day 1: When we first drove up Rocket Road, we were amazed; construction of the mile track was in progress and the SpaceX complex was amazing. The actual place for our testing was in a parking lot right next to SpaceX. We were assigned badges and met everyone at the entrance. We had from 9am-6pm to complete as much testing as possible. The first step before anything was our safety briefing. The number one priority for both our team and SpaceX was safety. This briefing lasted around an hour and went over everything from how many people should be carrying our pod to the lithium batteries and the air tanks. In transit, our pod shifted a little and one of our suspension parts broke, but we fixed it after a stop at Home Depot; one of multiple learning lessons due to something going wrong. We tried to plan out our day to be efficient as possible as we only had a combined 18 hours to test, and so the first thing we wanted to cover was to put our batteries in the vacuum to make sure that the batteries would not explode. It took approximately 30 minutes for the testing vacuum to pump down, and we eagerly waited. Our batteries worked amazingly! Nothing happened which was exactly what we wanted. After this, it was all hands on deck to try and finish our electronic system and get a test with our whole pod inside the vacuum chamber. We wanted to make sure that the electronics system would work in the vacuum and that our secondary braking system—linear actutaors with friction brakes—would work As seen above, we had to connect and zip-tie down our whole system. This process took around 3 hours because we constantly had to make sure everything was connected properly and receiving the right voltage. Simultaneously, we were also checking everything on our suspension system and tested for leaks. After finishing the board around 3:00pm, we decided to do a full-scale test of our linear actuators before testing the exact system in the vacuum. When we set up everything, nothing happened! We quickly focused all of our energy in checking every aspect of the code and the electronics system. We spent the next 2 hours trying to figure out how to fix one of the most important parts of our pod as we were not testing our magnetic braking, our primary system. Sadly, we could not figure out the exact problem before 6pm. We packed up and headed back to our hotel in the Penske Truck.
We were determined to figure out the problem, so after an hour break we unloaded from the truck at our hotel and spent the next 4 hours testing and making sure that everything was correct. We finally figured out that the kill switch wasn't rated for the amperage that we needed. After testing everything else in our pod, including fixing the leaks in our air system, we went to bed excited for the next day.
DAY 2: After a team breakfast, we drove to SpaceX determined to get in the vacuum right away and test our linear actuators. After unloading and talking to our SpaceX advisors we proved, to them that our linear actuators actuated outside the vacuum. Because of this, we were allowed to test in the vacuum!!! We placed our pod in the vacuum, took a couple of pictures (the one above) and anxiously waited for the vacuum to pump down. One other thing that we had to test was that our raspberry pi interfaced with the NAP correctly to send the signal to actuate; it worked outside, but we weren't sure if it would work. After a 20 minute pump down, Andrew ran the program and it started actuating!! We were ecstatic that it worked ! To ensure that our actuators would work for a period of time, we kept the system running for 10 minutes.
Now that that we had passed the vacuum test, we wanted to get on the sub track. Out of the 10 teams that went to the original testing week, only 2 teams—MIT and Delft— had run on the external sub track and we wanted to be the third. The first thing that we had to figure out was how to prevent our actuators from twisting and how we were going to interface with the pod pusher. One of the most important things to us and SpaceX was that we did not start breaking while the pod pusher was still attached and accelerating our pod. We decided that limit switches were the best option, so we went to Radio Shack and bought them. Our pod is made with 80% of hardware store parts mostly from Home Depot, Lowes and Radio Shack. Now, we had to come up with a solution to stop the twisting. As a temporary soltuion, we decided that wrapping bungee cords around the metal attached to our actuators would be the best idea. SpaceX laughed at this, but decided that for this low speed test it would be ok. The next system we had to figure out was the code and the electronics for the limit switches and the linear actuators. Originally, nothing was working as expected. Throughout this whole process of testing the code and moving our pod physically, one of our brake pads fell off. However, like every other time something went wrong, we had to move on and learn from our mistakes. We decided to stop messing with everything and focus on the factors that were most important. Once we showed SpaceX, that all of the systems were working, the "pod-pusher guys", the people that built the pod pusher, came out. Once we saw them and talked to them, we slowly started to realize that we were going to be allowed to test on this subtrack. It was aorund 5pm at this time and none of the other two teams there with us were ready, so we had the pod pusher all to ourselves. After a little trial and error with connecting to the NAP, Andrew just decided to stick his computer on the pod and hope that nothing would happen. We anxiously checked over the pod one more time before giving the go. After stepping past the clear zone, the pod pusher started to accelerate, which accelerated our pod. Although it only went up to around 5mph, it felt like it was going so fast and we anxiously waited to see if it would break and it did!!! We were the third team on the subtrack and the only team to use an active braking system on this track to break; the other two teams used drag from their magnets. The feeling that went through all of us when we saw it work was something that I cannot explain. Everything we had worked on for the past 15 months at that point was so worth it and everyone at SpaceX congratulated us and was amazed. We had a little crowd of SpaceX employees who stayed after hours well past 7pm to see our pod work. After this, we decided to slowly start to increase the speed. Every time, we had to adjust the amount to seconds between the break from the pod pusher to when we started to actuate the brakes. This was a very meticulous process because if we waited too long, the pod would run out of track to break on. We tested around 3 more times each slowly increasing the speed the pod accelerated to. On our last test, at around 15mph, we crashed into the atuator. However, our pod survived completely. We were beyond happy with the results from testing week. We learned so much through things braking and not going as expected, and we were ready to go back to Houston and prepare everything for Competition Weekend.