NORTHEASTERN UNIVERSITY

Transcription

1 NORTHEASTERN UNIVERSITY POST-LAUNCH ASSESSMENT REVIEW NORTHEASTERN UNIVERSITY USLI TEAM APRIL 27TH 2018

2 Table of Contents 1. Summary Team Summary Launch Summary 2 2. Launch Vehicle Assessment Launch Vehicle Summary Vehicle Dimensions Data Analysis and Results of Launch Vehicle 3 3 Payload Assessment Payload Summary Scientific Value Visual Data Observed Data Analysis and Results of Payload 6 4 Conclusions Lessons Learned Summary of Overall Experience Educational Engagement Summary Budget Summary 8 1

3 1. Summary 1.1 Team Summary Team name: NU Frontiers Mailing Address: Northeastern University, 267 Snell Engineering, Boston, MA Mentor: Brian Hastings Certification Level: L3 1.2 Launch Summary On the designated launch date of Sunday April 8th, 2018, the team launched using a Cesaroni L1115 Classic Motor. The original launch date was Saturday April 7th, 2018, wind and rain conditions required the launch be scrubbed and the backup launch date used instead. The new launch day conditions were excellent with temperatures ranging from F, and wind moving at about 4 mph NNW, with non-intrusive cloud-cover. The rocket, named Red Herald, was judged flight ready both by Northeastern internal review and by NASA and NAR during LRR before launch. The simulation done in OpenRocket showed the rocket would have safe estimated descent speed, final kinetic energy, rail exit velocity, and thrust to weight ratio. Motor ignition and ascent were fully nominal. After reaching apogee at a height of 5481 ft above ground level, the first pyrotechnic event occurred and deployed the drogue parachute. At 550 feet above ground level, the second event deployed the upper main parachute nominally. At 500 ft above ground level the third event occurred which fully separated the rocket into two independent section assemblies, each with their own main parachutes. As planned, two designated team members watched each section assembly. The two section assemblies fell with nominal speed and safely landed at a safe distance away from the spectators of the launch for later recovery. The rover payload was unsuccessful due to a major anomaly in the ejection system that was determined to cause the payload to be unsafe to launch. The payload was disarmed during launch and included in the rocket solely to maintain the launch vehicle mass distribution. The rover was tested after the launch and found to be unsuccessful on the field conditions. 2

4 2. Launch Vehicle Assessment 2.1 Launch Vehicle Summary The rocket flown in Huntsville was unchanged from the March 4th full scale launch, with the exception of changing to the L1115 competition motor and swapping out one questionable altimeter for one known to work nominally. 2.2 Vehicle Dimensions The final launch vehicle is 124 inches long, 6.17 inches in diameter, and weighs 49.3 pounds. The rocket has 2.75 calibers of stability. These final values reflect marginal changes in payload mass as payload integrated components and last minute changes were made to the payload ejection system. Figure 2.2.1: OpenRocket model of the final Launch Vehicle. 2.3 Data Analysis and Results of Launch Vehicle The flight profile was very close to our theoretical expectations, likely a reflection of the increased care taken to make a very accurate simulation that was not taken at previous launches. The launch vehicle had a nominal ascent and recovery. All six black powder charges detonated as planned and all three parachutes deployed cleanly at the nominal altitude. The rocket hit a higher apogee than the theoretical apogee of 5320, as shown below in Table Table 2.3.1: Apogee data from the six stratologgers. 3

5 Altimeter Location in Launch Vehicle Reported Apogee (ft) Lower e-bay Primary Lower e-bay Primary Lower e-bay Secondary Lower e-bay Secondary Upper e-bay Primary 5488 Upper e-bay Secondary 5487 Having an actual apogee one or two hundred feet higher than the sim is common in OpenRocket, as previously noted in the Northeastern FRR Addendum. Again, this difference is caused because the OpenRocket simulation software assumes imperfections that are not necessarily present (such as loss of altitude due to weathercocking, incorrectly angled launch rail, etc.). Figure 2.3.1: Theoretical expected flight profile. 4

6 Figure 2.3.2: Actual flight profile. 3. Payload Assessment 3.1 Payload Summary The payload consisted of the Northeastern University Frontiers Rover (NUFR) and the Payload Ejection System (PES). The rover was built from 3D printed plastic and stock components for motors and electronics. The goal of the payload was to deploy NUFR, once the launch vehicle landed, the PES would activate and deploy the NUFR. The rover would then attempt to drive five (5) feet from the rocket. 5

7 3.2 Scientific Value RADIO DEVICES After experimenting with the XBEE radio devices, the team gained valuable knowledge as to the respective ranges of various radio devices. Radio ranges were determined by testing packet reception at different distances. When packet loss reached +50%, the team terminated the test, determining the distance as the max range of the XBEE device. Completing these tests enabled the team to upgrade their antennae and XBEE devices to successfully transmit and receive at the required distances for launch. PCB DESIGN The NU-Frontiers Team used a protoboard for the subscale payload, after testing with this payload, the team determined that a PCB would allow for a more compact electronics bay, with less chance of wires becoming disconnected (disconnecting vital sensors and radios). After designing the PCB, the team learned several valuable lessons regarding PCB design. While these lessons were learned too late to apply to this project, they will be integral in future NASA SL launches. When designing a PCB, the first traces that should be routed are the traces with the most common connections, for example ground and power. Additionally 90 degree angles should be avoided at all times. Incorrect traces can be corrected by cutting the respective traces, but this should be avoided if possible. 3.3 Visual Data Observed The payload did not achieve success due to a failure in the PES during testing before the launch. This was a result of a wiring error that was determined to make the rover unsafe for launch. This means that the Payload was not activated during the launch and was only for ballast weight during the launch. The rover was tested post-launch and found that the design was not feasible and the NUFR was unable to drive five (5) feet due to the chassis of the rover not clearing the ground. The rover chassis would get stuck on the dirt and the wheels would spin in place. 3.4 Data Analysis and Results of Payload Due to subsequent wiring failure during testing phase prior to launch, the rover was not armed in the rocket, and no data was received. 6

8 Despite the payload not being activated during the launch the testing post launch provided valuable data about the capabilities of the rover. It was found that the rover was unable to traverse the terrain on location due to a design flaw in the chassis. The wheels did not have enough traction to move the rover when the chassis would get stuck in the dirt. This was made worse due to the chassis getting stuck on the clumps of dirt. The main lesson learned from the failure of the payload was that testing under different conditions is extremely important. The rover was successful in our initial testing, but under launch conditions, unforeseen circumstances led to the failure of the payload. 4. Conclusions 4.1 Lessons Learned The club as a whole learned that we need to implement annual budgets. The way that our budgeting had previously been done was on a semester by semester basis. This meant that we could not purchase some of our parts until well into the spring semester, and these parts were not accounted for in the original budget of the project. With an annual budget, the project would have a pre allotted amount of money to spend and would be able to order parts earlier and give us a longer amount of time to finish building the launch vehicle and payload. This has already been implemented into our club and will be used in the future. We also learned that it is important to have a payload checklist in addition to the launch vehicle checklist. Having an additional checklist for the payload would improve the chance for success of the payload based on the success of the launch vehicle checklist. The additional checks may have found the issue that prevented the activation of the payload during launch. 4.2 Summary of Overall Experience Overall, the NASA Student Launch Competition was an amazing educational journey. Over the eight months the team taught underclassmen about rockets, while working towards the ultimate goal of the competition. While we could not bring the whole team to Huntsville, the members that were able to go had a fabulous time touring the facilities and meeting people from other schools. The team found it to be a valuable experience to interact with other teams and we made many friends from all over the country. The day of the launch was full of nerves during final integration of the rocket, broken up by the awe of watching other teams launch. When we finally got to take our rocket to the launch pad and watch it go up, we were all proud of the work we had done throughout the year. The feeling of success after our successful launch was thrilling and we all learned so much from this 7

9 experience. Whether it was learning out to design an electronics bay in the lab, to assembling the fiberglass launch vehicle, we all put in so much time and effort into this project. 4.3 Educational Engagement Summary Throughout the course of the project NU Frontiers was very active in engaging young kids from kindergarten up through high school in STEM related activities. Northeastern University hosts kids from the greater Boston area on campus on Fridays to teach them about STEM. NU Frontiers took part in these events by teaching the students about various rocket components, such as lift, drag, weight and trust. After learning these concepts the students designed and built their own paper airplanes or paper rockets. They adjusted various components, such as fins and weight to try and optimize their rocket or plane. In the end they got to launch their paper rockets or compete in distance with their paper airplanes. The experience of teaching the students and inspiring them to continue into STEM fields was valuable and let us make an impact on their lives. 4.4 Budget Summary Even after a significant setback, namely not being awarded funds from Student Government at Northeastern University, the team was able to secure funding from a grant awarded to student groups engaging in STEM activities, the Scranton Fund. This fund accounted for all materials and equipment the club purchased. $3,200 was awarded, and $3,124 was spent. However, the delay in funding of about a month proved to be a significant setback for our team, and our payload subteam in particular found that, having no funds to manufacture parts, the normal process of designing, constructing, testing and interating was drastically delaye. As for travel to launches and Huntsville over the course of the semester, a different pool of funds was required, as the Scranton Fund is not to be used for travel. The funding was used to pay for gas, food, and lodging for the Huntsville trip (our team drove from Boston and camped in Virginia and South Carolina), as well as gas and food for 3 launches during the semester (an L2 certification launch and two full-scale test launches). For this funding, we utilized a grant from Orbital ATK for $300, an award for competition travel from the New England section of AIAA of $600, an allocation of travel funding from our aerospace engineering parent organization, AIAA at Northeastern university for $1160, $525 in funds raised by members volunteering for the College of Engineering, and $540 accumulated from payments who attended the Huntsville trip. This added to a total of $3,124 for materials and equipment, and $3,125 in travel funding. 8

10 Credit: Randall Monroe; 9