As you can see we had some issues with this method, the bottle made the drone very hard to fly, and the bottle soon started oscillating.

This doesn't seem to be a method that would work in practice as it would be very hard to pilot the drone, especially in the dark.

Our previous work showed that the drone kicks of a serious amount of ultrasound, enough to make recording from a ultrasound recorder on the drone useless. Our plan was to see if we could suspend a detector under the drone, far enough away to avoid interference. We used a water bottle, weighing the same as the detector in place of an expensive ultrasound detector, to avoid unnecessary accidents! 

Our first test of the autopilot was done on a windy day (15-17mph). The drone was programmed to fly in a square before returning to where it was launched. everything seemed to go to plan, however the wind proved problematic. The autopilot seemed to over correct to gusts of wind causing erratic flight.

We would not normally fly the drone in these conditions, especially since bats tend not to fly in high winds. Note to self, 'wind is bad'