Author: Lewis Rawlinson, leader of our Bath University Man Powered AirCraft (BUMPAC) team.
In February 2015 seven Aerospace Engineering students were tasked to design a Human Powered Aircraft from scratch. The BUMPAC team designed an innovative aircraft with rigid lift struts and modern composite structure. A year later four of the original members based their final-year engineering projects around HPAs. We came together to revive BUMPAC and continue the work started by HPA teams before us.
Inheriting a skeleton set of wings, a fuselage and a few other components, we set about redesigning and building our aircraft, which would later be christened Angel. I designed and built the drivetrain, as well as taking responsibility for all organisational, admin and logistical tasks for the team. This included dividing jobs, setting deadlines and advising the rest of the team on technical and interface aspects.
Angel’s first flight
In July we took Angel to the airfield for the BHPFC Sywell competition. After fixing damage sustained in transit and waiting for a weather window we attempted our first flight. Unfortunately there were issues with the drivetrain that prevented the propeller from getting to full speed. We anticipated this might be an issue and had already manufactured tensioning devices, but had left these off the aircraft in an attempt to save weight. We fitted our tensioning devices and made a number of adjustments to the aircraft, particularly increasing dihedral and modifying the control system interface.
On the morning of July 20th weather conditions looked perfect. With a slight headwind the team rolled the aircraft out onto the concrete apron, pointed into the wind and started pedalling and pushing hard. Angel leapt six feet into the air taking the whole team by surprise. Unfortunately she then lost a lot of airspeed causing her to stall and come crashing back down a few seconds later. Nevertheless, with this taste of success we set about fixing the damage again and making more adjustments. This time looking for more stability and easier control!
24 hours later Angel flies again
Just 24 hours later the team were back out and ready for more, but with no wind this would be a much harder effort. Lining up again on the concrete apron, pointing out towards plenty of space the props started spinning and the aircraft accelerated, very quickly running out of tarmac and bumping along the grass to a gentle stop. The team rolled her back as far as possible, lined up and went again. This time Angel accelerated more quickly, tapped onto the grass and with a pull of the stick lifted gently into the air. Alarmingly in taking off, she had rolled slightly and started turning right towards the hangars. The pilot (me) pulled off the power, touched down and rolled to a stop. Crisis averted with no damage! We put Angel away for the first time without damage. A very welcome respite.
34 seconds of flight
Throughout the next day we tinkered and rested, eagerly awaiting the evening’s flying. This time the team made their way all the way up to the end of the main runway. When the all clear was given, the props slowly started spinning up, the ground handlers started running, the front wheel lifted off the ground and a few seconds later the rear followed suit. Flying just above the ground Angel swept down the runway gracefully, eventually touching down 34 seconds later. She pulled off the runway and came to a gentle stop, caught by the ground handlers who had been following behind on bicycles. I collapsed to the floor, overwhelmed by the effort and joy of what had been achieved. Angel once again went away unharmed.
Angel's final flight
Dawn broke on the last Saturday of the competition. The controls and cg had been slightly adjusted in the hope of reducing the power requirement and making it easier to take-off. The latter was achieved arguably too successfully. With a slight headwind, Angel set off down the runway under full pilot power, climbed and rolled aggressively, and came back down with an almighty crack. The left wing tip caught the ground and tore the wing from the fuselage, shattering a handful of ribs, destroying the centre section of the wing and tearing the fuselage apart at the base of the chain tube. With that, the competition was all but over for us.
I’m proud of the incredible success that was achieved by just four passionate guys with buckets of enthusiasm. The remains of Angel were packed away and sent back to the University of Bath, in the hope that the next generation will carry her on and make her great once again.