We continue to experiment with different airframes for Conservation Drones. There clearly is no one-size-fits-all solution. And there is a stark tradeoff between portability/size and long-distance capability.
*Important: whatever airframe you choose to fly with, it is critical to tune it properly:
- Tuning in general: http://plane.ardupilot.com/wiki/flying/tuning/
- Roll, Pitch and Yaw: http://plane.ardupilot.com/wiki/roll-pitch-controller-tuning/
- Navigation: http://plane.ardupilot.com/wiki/navigation-tuning/
- Total Energy Control System: http://plane.ardupilot.com/wiki/tecs-total-energy-control-system-for-speed-height-tuning-guide/
Conservation Drones Techpod
The Techpod is a new airframe designed by Wayne Garris for his KickStarter project and is now available at his store. Wayne spent many hours refining the aerodynamics of this airframe. We tested it in Belize over open ocean and wind conditions of 30-40 km per hour. It is a very impressive 2.5 m-wingspan airframe.
Conservation Drones Penguin
The Finwing Penguin airframe is a stable platform for conservation applications. Its main advantage over the previous airframes we had tried is that it has a built-in landing gear. This makes take off and landing in wide open spaces very smooth and safe. The penguin also has a respectable fuselage space.
Conservation Drones Maja
The Bormatec-MAJA airframe is designed by a German company specifically for UAV use.
Although this airframe is more expensive than previous models of Conservation Drones, the Maja has several unique features that are well worth its cost. For one, the top half of the entire length of Maja’s fuselage fully opens like a hatch to expose a huge storage area, allowing easy installation, access and manipulation of onboard equipment in the field, including the autopilot, batteries and camera. The airframe itself weighs about 2.0 kg (including ~900 g of batteries), and can carry a payload of another 1.0 kg. This essentially allows the Maja to carry both video and still-photo cameras. The Maja can be fitted with either 1.8 m or 2.2 m wings, depending on payload and range requirements. Our test model was fitted with the latest autopilot system from 3DRobotics, an external GPS module, all metal-gear servos, telemetry and two 5000 mAh battery. However, what has gotten us most excited about the Maja is that, due to its superb flight characteristics the Maja drone can perform fully autonomous landing within a 100 x 100 m landing area.
Conservation Drone Skywalker
Another promising candidate is the Condor Skywalker 1880. The main motivation to experiment with the Skywalker is to improve flying time and range. The main advantage of the Skywalker over the Raptor and Bixler drones is that the Skywalker has massive fuselage and wing area. Furthermore, a side door can be cut out from the fuselage to facilitate initialization of the autopilot and camera prior to each flight. *Note that there are more recent models of the Skywalker that are just as successful. For example, HornbillSurveys.com builds a modular Skywalker 2013.
An initial test using two 3S 20C 4000 mAh batteries connected in parallel (8000 mAh total), with an additional dummy weight of 200 g (simulating a GoPro camera payload) suggests a total flight time of ~70 min. That test flight was achieved with a Turnigy D3536/8 1000 KV motor spinning a TGS 9x6E propeller, regulated by a 50A speed controller, and had an All-Up-Weight (AUW) of 2.2 kg (~900 g of payload). If programmed to fly at a speed of 12 m/s, the total range of the Skywalker-based Conservation Drone would be close to 50 km!
Conservation Drone Raptor
Conservation Drone Raptor is based on another popular remote control model plane, known as the FPV Raptor, which has a 2 meter wingspan (the Bixler had a 1.4 meter wingspan). We equip this drone with a much bigger 5000 mAh battery pack, which gave it a longer flight time of up to ~50 minutes. When programmed to fly at a speed of ~10 m/s, the drone can cover a total distance of almost 30 km.
Conservation Drone Bixler: The Prototype
We based our prototype drone on a popular model airplane (Hobbyking Bixler). This airplane is relatively inexpensive (<$100), lightweight (650g), and has ample room within its fuselage for installing the autopilot and an on-board camera. During our field tests, the drone was powered by a 2200 mAh (milliampere-hour) battery, which allowed it to fly for ~25 minutes per mission, and over a total distance of ~15 km.