The QAV250 is a symmetric 250mm size airframe that accommodates 5" props. The 250mm is measured motor shaft to motor shaft diagonally.
The new v1.1 updates the 3mm carbon fiber unibody to give it maximum strength. The arms now have more carbon and smaller holes giving them extra strength. Also the point where the arm meets the body has been significantly beefed up. The new v1.1 design can handle the harsh impacts a high speed 250 racer takes.
The airframe is designed to support a 3s-4s lipo setup with light and powerful Lumenier RX2206 2350kv motors.