Geometry

State_of_the_Project

1  PurposeThe purpose of this document is to mark the completion of the Mars Extended Range Scout (MERS) Project by identifying the location of all assets, the disposition of materials, reconciling the budget and identifying key analysis that have to be completed.1.1  Background The quest to observe and document the red planet has been an ongoing mission for the better part of the past five decades. Beginning with the myth of lost civilizations on its surface that fed popular culture and science fiction, Mars has been focus of public interest. This interest has persisted as researchers made discoveries such as indications of water having once existed in a liquid state on the planet at some point in its history. The existence of liquid water on the Martian surface is among one of the many aspects of Mars that makes it a treasure trove of scientific insight. A planet which once was able to sustain liquid water may have also been able to sustain life in some form. Understanding what has led to the change that Mars has undertaken from its days of liquid water to its current state of frigid barrenness has the potential to answer questions about the formative years of our solar system as well as the formative years of life on Earth. While several potentially habitable Earth analogs have been identified and numerous are hypothesized to exist, the fact that Mars is in Earth’s own solar system has made it the most accessible specimen that we believe may have had earth like environment. This makes geological samples and high-quality data recovered from the planet very valuable to for the progress of scientific efforts. Martian exploration is also a necessary steppingstone in human space travel, similarly to the way in which the in which the lunar landing was a milestone for human exploratory capability in the late 1960’s.Mars is a probable destination for a manned mission in the future and fully understanding the planets resources and hazards is critical to the success of such an endeavor. Today’s efforts to explore Mars’ environment, terrain, geology and history are going to shape exploratory missions of the future, presumably to even more distant parts of our galaxy.These are all the reasons for which billions of dollars have been spent in the effort to reach Mars and retrieve meaningful data on its environment and conditions. Devices including satellites, landers and rovers have been deployed in the past to image, collect atmospheric and topographical data, and samples. The Spirit and Curiosity rovers, delivered in 2004, being the most recent of these deployments were sent to collect high resolution images from the surface of the planet and conduct field studies on surface samples utilizing onboard geological laboratories. The next generation of rover is planned to land on Mars in February of 2021. NASA’s Mars 2020 mission rover is the first to be equipped with a drill to probe beneath the surface of Mars in search of signs of life supporting conditions. It is also the first rover to be accompanied by an aerial scout. This scout is a solar powered, coaxial helicopter and is slated to be the first aircraft to fly on another planet. The mobility of land rovers, like the 2020 rover, is fundamental to exploratory efforts. Although they are designed with considerable regard to this need, there are still complications created by the highly varied and ultimately unknown geography of the Martian surface. Land surveyance vehicles are subjected to movement and directional constraints due to topography, thereby necessitating a means to assess viable routes prior to rover dispatch to optimize time spent moving between sites of interest. Unmanned rotocopters such as the aforementioned helicopter, have been devised for scouting operations to allow for aerial assessment of potential routs for the rover. Aerial vehicles provide similar resolution images to those collected by rovers but can more easily access remote areas and can traverse distances much more quickly than a land rover. The intention of including this helicopter to the Mars 2020 mission is to prove that flight in a Martian atmosphere is possible and a viable option for future missions all while the aircraft fills a valuable scouting role in the 2020 mission. The 2020 Scout’s design, while revolutionary for the groundbreaking accomplishment it is poised to achieve, is not without its own limitations. Achieving flight on Mars presents complications due to the planet’s carbon dioxide atmosphere providing reduced atmospheric density and viscosity relative to that on Earth. Reduced atmospheric conditions require significantly greater power to produce sufficient thrust for the generation of lift than comparable terrestrial rotorcrafts. Low density and viscosity, CO2 rich atmosphere contributes to ultra-low Reynolds numbers, compared to Reynolds numbers experienced by conventional aircrafts flying in standard Earth altitudes. Early attempts to combat atmospheric complications resulted in fixed wing drone prototypes but were ultimately discarded in favor of the more maneuverable, transportable co-axial helicopter design NASA’s Jet propulsion Laboratory produced. This increased power requirement results in a diminished battery life of mere minutes per reconnaissance mission. While this is sufficient for the current scope of the aircraft’s mission, in order to be effective, future surveying aircraft will need to be efficient utilizing power to produce lift in order to extend their range. Increasing the range of unmanned aerial vehicles (UAV’s) on Mars while maintaining maneuverability and takeoff/landing/hover capabilities of rotorcraft has the potential to advance extent and capabilities of exploratory missions beyond what is currently possible with landbound rovers, accelerating timelines and saving money simultaneously.2  Project Completion Work2.1  Work Completed Prototype 1 An airfoil prototype was created with the intention of practically testing the theoretical aerodynamic capabilities of the RAF-6. The prototype was designed to be a scaled down version of the airfoil. The size was geometrically scaled such that the low Reynolds number of the Martian atmosphere at our intended cruise speed within a wind tunnel. The prototype was 3D printed and set at the designed angle of attack. To measure the pressure differential about the top and bottom of the airfoil, pressure taps were designed into the print.  Figure 1 : CAD Model of Printed Wind Tunnel Testing AirfoilPrototype 2A prototype was also made to test the thrust achievable from our rotor and motor assembly. This prototype setup included a motor controller and potentiometer that when connected to the motor allowed for variable speed control. The assembly was affixed to a scale reading the thrust as negative weight on the system and an optical tachometer was used in tandem to read rotor RPM values. This setup allows for a relationship between signal sent to the motor, rotations per minute and thrust output to be established.Figure 2 : Rotor Thrust Test Prototype Prototype 3In order to achieve the rotation of thrust necessary to produce the desired flight profile, a mechanism for rotating the motor and rotor assembly had to be devised. The initial attempt at this, was a housing for the motor that would sit within the wing structure on either side of the aircraft, both of which would connect to a single high-torque servo at the center of the fuselage by way of a shaft with mating ends. One of these can be seen in Figure 5. Figure 3 : Motor Housing Original PrototypeEmbedding two servos into the wings themselves rather than the fuselage, each with slightly higher torque requirement than the original design allows, allows the rotor to rotate about the continuous wing construction without causing clearance issues. Doing so also minimally impact the weight of the design because the larger quantity of ABS material and fasteners that are made unnecessary when mounting within the wing surface displace some of the added weight of the additional servo. Using a second servo also allows individual thrust vector rotation which is advantageous for control of z axis rotation when hovering. The next iteration of the mounting assembly which implements the lessons learned from the original design can be seen in Figure 6.Figure 4 : Rotor-Motor in Wing Mounting AssemblyPrototype 4The final prototype produced was a complete wing assembly. This included foam airfoils, rotor connections and the folding wing component. Several airfoils, each one quarter of the total wingspan of the designed product were produced. This was done because in subsequent testing it is expected that some of these will be lost to failure. Then support structures were added to these airfoils and electrical components were embedded into the foam. this prototype can be seen in Figure 7.Figure 5 : Wing Prototype AssemblyFinancial Closure The group received a grant worth $500 from the MEM department through the Boeing Grant. The team has spent $340 through Drexel orders, leaving $160 in unused funds. A team member also requires reimbursement for the purchase of a $40 sheet of plexiglass for the department’s wind tunnel. Asset TransferAssets purchased include prototypes, raw materials that has not been used, including several sheets of foam board insulation, some wood struts and several electrical components. These are all currently being stored at a member’s home and are intended to be delivered to the Spacelab on the 4th floor of the main building before the end of the term.Information ManagementAll assets that have been used over the course of senior design have been compiled in a shared drive, accessible by any individual through the following link: https://drexel0-my.sharepoint.com/:f:/g/personal/pjs322_drexel_edu/En2nGYQZy6BLqVPdms-QWasBiq_8RyYv8S5YA0Cm5JO7JA?e=1tSN4HThe master file contains deliverables required by both Drexel engineering, and those required to meet individual requests of the faculty advisor. Further, excel spreadsheets and word documents that have been used internally during analysis have been annotated to better facilitate information transfer to an audience less familiar to the project. The following table denotes the contents of the shared folder, along with a brief description of intended use. Deliverable (File Name) File Type (Electronic) Description Progress Report Folder Winter Term Deliverables Poster Presentation Folder Winter Term Deliverables Elevator Pitch Video Folder Video Link to Elevator pitch Propeller Stuff Folder Analysis leading to propeller and motor sizing Weekly Reports Folder Links to weekly updates throughout Senior Design MEM_43_State_of_project word document state of project, Spring quarter Fall_Proposal_Presentation PowerPoint Presentation, fall quarter Component Weight Distribution .dwg Schematic of component weight distribution Budget excel Gantt charts and budget information formulas for Airplane design excel workbook denoting physical design limitations of aircraft mem-43 abstract word document abstract requirement for winter quarter Airfoil & Power Requirements excel workbook assessing power requirements as a function of airfoil / flight feasibility Technical Progress Report word document document denoting work done over winter quarter senior Design Gantt Chart excel Gantt Chart on mars .png picture of cad model Top view .png picture of cad model iso view .png picture of cad model MEM-43_Proposal_fallterm PowerPoint fall proposal of project Aircraft parameters word document denotes geometric boundaries of model Boeing Funding Request word document Request for Funding 2.2  Proposed final analysis Before the end of the term, the team intends to produce a finalized computer aided design model which is to be used to run a computational fluid dynamic simulation. This simulation will be used to establish the aerodynamic properties of the assembled model in each stage of flight. The environment of the simulation will emulate the properties of the Martian atmosphere as reported by NASA, most importantly, the air density, air viscosity and subsequently the Reynolds number of the flow must be accurate to understand how the designed geometry functions aerodynamically. The first stage of flight to be tested is an airplane configuration where the rotors are oriented forward, the wings are fully extended, and the simulated airflow flows from the nose tip to the tail. The second configuration that must be tested is vertical takeoff and landing. In this configuration the wings are in their retracted position, the rotors are rotated upward, and the airflow orientation is from the rotor tips downward. The final configuration for testing is a dynamic one which simulates the transition from a vertical takeoff and landing configuration to an airplane configuration. To do this, the rotors with move from a vertical to forward orientation in sync with the expansion of the wings and a coordinated shift in the airflow from top-down to nose-tail. This combination of these events give insight into a crucial portion of the flight. This analysis will complete the project to the satisfaction of the team.

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