Belly landing Airplane - Propulsion

Propulsion: 

In the initial phase of designing and establishing the propulsion system, our approach began with aircraft sizing. Upon completing the aircraft sizing process, we determined the maximum thrust value, specifically focusing on the climb phase. This maximum thrust value served as the foundation for sizing our motor.

To identify the optimal motor and propeller combination that would align with our performance requirements, we referred to the propulsion charts available on rcdudes.com (https://rcdude.com/resources/prop-charts.html). These charts provided valuable insights, guiding us in selecting the appropriate components for our desired outcomes.

Following the careful selection and procurement of the motor, we proceeded with a thorough testing phase to assess its performance and validate its suitability for our hand-launched belly landing plane project. Propulsion testing added an exhilarating dimension to our project—it was undeniably the most enjoyable test we conducted. Originally planning a makeshift test bed that we would mount upside-down on a weighing scale for thrust measurements, luck smiled upon us when we discovered an actual test stand in the lab.

After some safety modifications, a brief initial test confirmed the motor's functionality. Moving outdoors for safer experimentation, our target was 2000g's of thrust, guided by the insightful experimental datasheet from rcdudes.

The joyous surprise came when we surpassed expectations, hitting an impressive 2458g's of thrust. While the motor didn't make it into the final build as the plane turned out much heavier than anticipated post manufacturing, this test proved crucial. It allowed us to informed decisions on the fly, and switch to be bigger motor, as we were aware of the exact capabilities of this one. 

Following the tests and considerations mentioned earlier, we initially selected the COBRA C-2820/10 BRUSHLESS MOTOR with a KV rating of 1170. However, due to an increase in the weight of the aircraft during the manufacturing phase, we needed to reassess our motor choice. Ultimately, we opted for the COBRA C-3520/10 BRUSHLESS MOTOR with a KV rating of 980, ensuring compatibility with the revised weight of the aircraft and meeting the necessary performance criteria.