Unmanned Aircraft Systems (UAS) Drone Challenges

Institution of Mechanical Engineers (IMechE) holds many events which focus on enhancing the Mechanical Engineering students' skills and experience. One of such events is the Unmanned Aircraft Systems (UAS) challenge in which students are required to create an Unmanned Air Vehicle (UAV), capable of automatic take-offs and landings. Moreover, the UAV is tasked to follow a set of route points and also perform a certain maneuver in air like dropping a payload (imitating a medicine drop or a disaster relief package drop). 

UAS 2022

In March 2022, our team, called Team Raptors, took up the task to create a UAV for IMechE UAS 2022 which was to be held around November of the same year. In 2022, the task of the UAV, besides automatic take-off and landing was to spray a colorful liquid (imitating agricultural pesticide). Total area that was sprayed due to the liquid was noted and graded as points. 

According to our Preliminary Design Report (PDR), our drone looked something like this:

This design was used only for our Preliminary Design which was later changed, because it had certain flaws. First of all, the vertical stabilizer was absent. Moreover, the design was created very quick and was very crude. 

According to our Critical Design Review (CDR), our drone looked something like this:

This design included some major changes, for example, a vertical stabilizer was added. Moreover, the position of the motor was also changed (from wings to center). Moreover, the wing was changed from separate to joined at center, which allowed easier assembly. 

Unfortunately, for the year 2022, our team could not make the drone due to financial issues. However, we did pass the PDR and CDR stages to the finals. Here is the certificate that I received:

Even though we couldn't make the drone, we did, however manage to make it to the finals after clearing the PDR and CDR stages. This was a great achievement for us.

UAS 2023

By the end of 2022, we managed to create our drone that we could not make last year. We did that so that we could participate in future drone events like UAS 2023, Teknofest 2023, and Design Build and Fly (DBFC). We made another team by the name of Team Irtifaah which would target these events. By this time, we expanded our team and managed to recruit some highly skilled Electrical and Mechanical engineers. 

We made a drone, which we call "Green Drone" whose body was made of Balsa wood which is not only lightweight, but also extensively used in making drones. The final result of "Green Drone":

Check out the following video of the "Green Drone" that we made:

Our team managed to secure 4th position in DBFC challenge by using this drone. 

For UAS 2023, we decided to create another drone. This was made by insulation foam board. For cutting the foam board, we made special cutters with the help of nichrome wire and PVC pipes.

The drone nose was a challenging part. We decided to the nose with the help of small foam cut-outs and joining them by glue.

The final "Pink Drone":

The pink drone was promising and had a very good stall margin, however, due to its foam material and even though the landing gear was made of carbon fiver, the upper body could not bear many landings and we could not use this drone for UAS.

We created some more drones; some were fixed wing, while some were quadcopters, but we did not use them in UAS challenge. For example, this drone during its construction:

At the end, we decided to use the "Green Drone" for UAS 2023. Even though the event is designed for both fixed wings and quad/hexacopters, the take-off/landing area was not well designed for fixed wings to take off. Due to this, even though our team was ready for take-off could not take-off during the competition.

Why decide on a fixed Wing?

We decided to create all these fixed wings drones because, honestly, creating most of a quad/hexacopter mostly requires only a couple of internet searches. You cannot learn as much as you can during you can when creating a fixed wing drone. Deciding on a proper airfoil, designing for a balance between weight and flight time, choosing the proper Lift to Drag ratio, choosing the proper material for the drone body, flight time, and battery pack selection are just few to name. As discussed above, we did make a quadcopter, however, we did not take them to the competitions. 

Analysis performed

During the events, Besides CAD modeling, I was also responsible for performing CFD and Static Structural analyses. Following was an analysis that I performed present in form of UAS 2023 design reports.

In this specific analysis (of "pink drone"), the total deformation of the main wing is very large (~255mm). This is because the wing's semi-span is also very large (1.3m/1300mm). This analysis was done for worst case scenario. Moreover, our drone was not this much heavy either to support such a large load. Horizontal stabilizers pose no issue, however, and their deflection is under control (0.4mm). 

The stresses were not high enough to cause a yield, as we observed in our flight tests as well.

Another tool that we used was MS Excel for the general sizing calculations of the drone. See the image below which shows the calculations and the measurements that we used for our drones. 

A sample image of the MS Excel spreadsheet. (Not made by me)

Concluding

Overall, the learning in these drones was worth it. Moreover, choosing fixed wing instead of quad/hexacopter helped much more. I have learnt drone designing as well as manufacturing skills and learnt from faults and blunders along the way.