Ed Handford, Team Bath Drones leader
In the second instalment of a new blog series, Bath University’s Ed Handford updates The Student Engineer on the drone team’s progress towards the IMechE Unmanned Aircraft Systems (UAS) Challenge. Readers can catch up with Ed’s first blog here.
A successful second flight was completed, during which the autopilots stability mode was tested and tuned. Furthermore, the “Return to Home” feature proved successful, allowing for more ambitious flights to come now we have this safety net.
The latest landing gear proved to be a significant improvement on the previous version. Our latest gear incorporates damped suspension developed by team member Oliver Toogood. With our initial landing gear failing under load on the nose gear strut, the latest gear is more rugged. However, after an intimate encounter with long grass, the nose gear failed once more. Unfortunately, the fault has migrated from the landing gear strut to the mount on the fuselage and we hope to improve on this in the future.
The aircraft currently has 5.5kg of static thrust (weighing only 5kg as it stands un-laden), and so has a sporty feel to it in the air. Reverse thrust was tested on landing approach, allowing for a rapid descent rate and for the craft to stop within a 3m strip. The reverse thrust tests were performed in “Manual Control” mode and we aim to integrate this into the autopilot.
Ground target recognition has emerged from the lab and will now be implemented, to be tested on the up and coming 3rd flight test. This system is based on a trained Neural Network developed by team member William Thompson.
Our CNC milling machine has been revived and manufacturing of the new wing moulds is underway. Our estimated cutting times for wing moulds exceeds 40 hours, and as a result the Bath team will be taking shifts babysitting the machine. Once produced, the new fibreglass layup can begin and our new aircraft components will start to appear!
Plan for April
In the next few weeks we aim to test and develop more features with a series of wind tunnel tests. Once these devices have proved themselves they may feature on the final version (but it will remain a secret until then!)
With the explosion of development of brushless motors in the last years, hobbyist quadcopter motors have increased massively in power density and so we are investigated replacing our heavy motors for perhaps smaller, lighter versions. This potential change will bring a large decrease in efficiency, however, the competition this summer no longer requires long flight times, and so we now have the option to trade off efficiency for weight saving on our propulsion system.
Interesting facts about our craft…
Flying time of over 5 hours – with 2Kg of Lithium Polymer Batteries
Near 1:1 thrust to weight ratio achievable
Breaks down into 3 parts for easy transportation (or 100+ pieces on impact)