A positive rear thrust angle is a feature used in the design of some aircraft to help improve their performance. This angle ensures that when an aircraft is taking off or landing, the tail section of the plane creates a downwards force which acts against gravity and helps to lift the nose up during takeoff or keep it down during landing. This improves control and reduces drag while also helping maintain speed and reduce fuel consumption. It also enhances stability by reducing pitch-up forces generated by wind gusts during takeoff or landing. The angle can be adjusted depending on different factors such as weight, engine power, wing configuration, and other characteristics of each specific aircraft model; however typically this angle falls between -2 degrees to 6 degrees for most small general aviation planes.