iCFD Institute of Computational Fluid Dynamics

Haramachi, Meguro-ku, Tokyo 152-0011 Japan

I had a good friend and excellent pilot totally destroy a high performance sailplane recently. The wind was blowing stronger than normal for our location (factor #1). Conditions were gusty (factor #2). Challenging, but flyable. Both these factors contributed to the crash, but as the NTSB often determines in full scale - the pilot failed to recognize,or ignored, the conditions and therefore made no adjustments to the aircraft or flight attitude for the conditions. The adjustments this RC pilot could have made to reduce the likelihood of the stall, lose of control close to the ground, and subsequent unavoidable crash were: (1) Add ballast, to increase penetration and wing loading. (2) Reduce angle of attack on launch.

It sickens the heart to see a beautiful 3 meter composite sailplane , technically superior aircraft, reduced to scrap no bigger than a small trash bag package. I'm sure the pilot will consider the conditions more carefully in the future and adjust. And hopefully he will not lose his confidence in his abilities because of this incident, and will learn from the accident. Luckily, in our RC sport, the pain is in the wallet, not at a funeral.

A small percentage of RC pilots actually can visualize what is happening in a stall. Haramachi, Meguro-ku has put together this animation to illustrate how the boundary layer separates and eventually loses all lift. Click on the graphic and watch the airflow on the upper surface. Then you'll better understand.