title_body: Drone simulators for designing and flying aircraft? Is there any free software that can design drones/aircraft and test fly them? Thank you. I’m looking for a software with no controller needed, just to test if the aircraft/drone can hover with stability.
upvoted_answer: I am not quite sure what kind of drone you'd like to build. However, here are the ones I use for a variety of multirotor and fixed-wing drones:
  
  
  I love CoppeliaSim (formerly V-REP) for multitorotors. It makes it very easy to make certain assumptions about forces and torques, and to see the results in real-time.
  X-Plane is great for fixed-wing drones. X-Plane simulates flight dynamics on a fluid-dynamics level so it's actually simulating the plane as it would fly based on its geometry.