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My name is Abin, a recent MEng Mechanical Engineering Graduate from Heriot-Watt University. I am the Team Manager of Team Aero-Watt; a group of engineering students looking to take part in the IMechE’s Unmanned Aerial Systems (UAS) Challenge. This challenge requires us to design, build and fly a fully autonomous aerial system to take part in a series of challenges at the Buckminster BMFA Airfield. Our UAS will be required to autonomously manoeuvre around a course and release a payload at a specific location which it will have to identify in flight. We will be competing with universities from around the world, with us being lucky enough to take part in a live event even during these pressing times.
Our team of 20 engineers are grouped into three different sub-teams: Airframe & Aerodynamics (AA), Payload & Propulsion (PP) and Software & Systems (SS). Initially working independently, the three sub-teams conceptualized the works of their various systems and how it would meet the requirements of the competition. Our AA Team have been designing the airframe structure considering control surfaces, mass distribution, component storage and overall aerodynamics. The PP Team have been working on the propulsion methods of the UAS alongside the storage and accurate deployment of our payload. The SS Team have been developing our flight control system, including all autonomous functionalities – based off the PX4 autopilot. All three teams have been working incredibly hard independently with collaboration increasing as the project progressed. We are also fortunate to have Dr Wolf-Gerrit Fruh, a professor at Heriot-Watt University, as our Academic Lead and Jean-Luc Belon, a chief engineer at GKN Aerospace, as our Industry Mentor.
Our chosen design is a fixed-wing dual rotator with a boom tail. We chose this initial design to utilise the advantages of speed, efficiency and stability. We chose to have a dual motor/propeller setup to have optimum acceleration and adequate speed. Control surfaces were also introduced on the UAS, including ailerons and the tail, for stability and control during take-off, cruising and landing.
Our airframe was designed to be manufactured using balsa wood, for its low density/high strength properties beneficial for flight. A modular structure was also prioritised to allow for replacement of single parts in the event of crashes, instead of the whole UAS. Storage compartments for the internal components were designed considering the cooling for components, wiring requirements and mass distribution across the UAS. The payload was stored as close as possible to the centre of the mass to minimise its effects on the balance of the UAS once it was released. Our UAS is designed to be fully electric using two motors connected to a LiPo power supply.
Manufacturing initially commenced with the frame of our UAS, which can be seen to be a large model (wingspan 3m!). With our wings, fuselage (the main body of the UAS) and tail being separate, we then worked on assembly and covering regions of the frame with thin balsa sheeting - this adds much needed strength. Our assembly stages involved lots of balsa wood, bolts, screws and plenty of wood glue!
Our next steps were to install and connect the electronic components. This was a particularly challenging task in its own right, we had to ensure wires were not tangled (sometimes referred to as a snake's wedding), they were sized according to the current requirements and ensuring components were accessible after assembly. This required cooperation between our three sub-teams to ensure power was appropriately distributed amongst the different components, leading to plenty of calibrating and rewiring (shown below - where our UAS began getting its blue sheet of coating).
Throughout manufacturing, we tested different sections of our UAS. Installing the electronics required us to test on the go. Testing included (but not limited to) ensuring radio/telemetry devices were calibrated and receiving signals, servos on the flaps/ailerons worked as required and propellers provided sufficient thrust.
One of the key challenges for us when permanently mounting the wings (as they are not mounted in the image above) was to identify the centre of mass of our UAS. We found this by carrying out a simple experiment; hang the assembled UAS using two loops of strings at either end of the fuselage and gradually move them towards each other until the UAS was fully balanced. We adjusted the strings as required whenever the UAS was too 'nose heavy' or 'tail heavy' and eventually found our centre of mass (shown below). This standard practice helps to ensure the centre of lift (the location where our wings will provide the most upward lift) and centre of mass are as close together as possible to give our UAS maximum stability.
With our centre of mass found, we can mounted our wings (they are still removable for transport), continue skinning and perform a lot more tests. With the base structure complete, we even managed to get our assembled UAS outside for a quick photoshoot.
To reach the current stage we are at, we have already experienced multiple challenges. Being the first team from Heriot-Watt taking part, we were required to design our UAS from scratch, develop relationships with sponsors to source funding, develop a methodical team structure and effectively coordinate the working of 20 individuals – completely online for the first 7 months! Alongside these challenges, we have all the others of a typical project (tight deadlines, multitasking, organisation), particularly with more to come as we commence testing. The continued learning experience from the UAS Challenge will be invaluable for those staying on and taking part again or leaving to enter the workplace.
For everyone (particularly myself) it has been an amazing experience so far to go through the difficulties of a true engineering project and the value of individual contribution towards it. This project helps students from different degrees engage in a large engineering project where they meet new people, utilise skills outside of engineering design (media/marketing, safety, sponsor engagement, project promotion) useful in all aspects of work. There are numerous soft skills to be gained and developed too, which can be taken directly into the workplace. The context of the UAS Challenge is beneficial for society in general, through the STEM outreach program and support towards search & rescue missions.
With us still having to complete more testing, we have more challenges ahead, all of which will help the team to solidify Aero-Watt’s foundation for next year. The overall challenge has been an amazing learning experience for everyone thus far, with exciting times approaching as we near the competition!