Steps to build a DIY low-cost fixed-wing drone for biodiversity conservation

-2.523079˚, long: -44.202738˚). The flights were carried out at 120m AGL, maximum altitude permitted by the local civil aviation legislation, and at 15 m/s (Table 1). The camera was also triggered automatically using the “Survey Mode” and with 70% overlap and side lap among each image. These flights were planned to support the “Secretaria de Meio Ambiente do Mar- anhão–SEMA” in identifying degraded areas, opening of trails and unauthorized access within part of the “Area de Protec¸ão Ambiental do Itapiraco´”. In addition to identifying trails in these flights, we tested the drone ability to generate useful data for creating orthoimages, georefer- enced maps and other products. For these flights, two observers with direct communication with the pilot were positioned at opposite extreme points within the flight plan grid for con- stant observation of the drone (EVLOS flights). Ethical statements The flight tests followed Brazilian Civil Aviation Special Regulations (RBAC-E No. 94). The local civil aviation legislation does not allow BVLOS flights (Beyond Visual Line of Sight) with- out prior special registration and authorization of the drone, the flight and the pilot. Therefore, all flight tests were performed in VLOS or EVLOS mode as reported above. The individual shown in Fig 4 has given written informed consent (as outlined in PLOS consent form) to publish his picture in this study. Results We completed the development of the DIY model named “Asa-Branca-I” (Fig 4) in five months, with 30 hours of weekly dedication for development, plus another month for all per-

formance tests and final adjustments. The purchase process and delivery time of the compo- nents corresponded to 20% of the development time, considering that the majority of the components were shipped from China and delivered to Spain. The model developed in this project had a material cost of $995 (details in Table 2). The average price of small fixed-wing commercial drones used in conservation studies that could Table 1. Main pre-programmed flights features. Pre-programmed Flights Mode Flight Pattern Flight Type Altitude (m) Wind speed (m/s) Range (km) Flight time (min) GSD (cm/px) 1 Corridor Scan EVLOS 100 10 15 65 2,8 2 Corridor Scan EVLOS 100 9 17 50 2,8 3 Circular Grid VLOS 25 11 0,1 13 0,7 4 Circular Grid VLOS 25 8 0,1 13 0,7 5 Circular Grid VLOS 50 10 0,1 8 1,4 6 Circular Grid VLOS 50 9 0,1 7 1,4 7 Circular Grid VLOS 75 12 0,1 6 2,1 8 Circular Grid VLOS 75 10 0,1 6 2,1 9 Circular Grid VLOS 100 9 0,1 5 2,8 10 Circular Grid VLOS 100 9 0,1 4 2,8 11 Specific Grid EVLOS 120 8 2 25 3,3 12 Specific Grid EVLOS 120 9 2 27 3,3 All flights were performed with a 70% overlap (front and side) and 15m/s drone speed. Wind speed was obtained using the UAV Forecast app. https://doi.org/10.1371/journal.pone.0255559.t001 PLOS ONE Building a DIY low-cost fixed-wing drone for biodiversity conservation PLOS ONE | https://doi.org/10.1371/journal.pone.0255559 August 13, 2021 9 / 17