http://www.nytimes.com/2009/02/15/ny...5crash.html?hp reports that flight 3407 crashed on approach, with the headline "In Plane Crash, Loss of Momentum Still a Mystery."
I am an Australian high school physics teacher and my heart goes out to all the families involved. However, my small group of physics students will want to discuss this incident on Monday - their current unit of work is aviation based, and a number of them want to go onto a career in aviation.
Would you please critique my analysis of a possible scenario, based on newspaper reports to date. I want to introduce linear momentum, angular momentum and conservation of momentum.
Information in current news reports (15/2/08):
The aircraft involved in the accident was a Bombardier DH8.
It was on approach in icy weather.
It crashed in a flat attitude, with very low horizontal velocity, facing backwards along its track.
My interpretation based on readings suggested in other pprune posts, the Nasa video on tail icing and other websites on stalls/spins:
The aircraft entered a spin of some description, and as a result its forward, linear momentum, was transferred into angular momentum. The linear momentum didn't magically vanish, but the difference in airflow over each wing caused a turning moment due to friction force acting more on one wing than the other. As a result, the forward motion of the aircraft was translated entirely into rotational motion, and the effective ground speed quickly became zero.
I am not trying to preempt, or second guess the air accident investigation. I'm not going into any detail of what the passengers experienced in the accident, so I'm not looking at the details of how a tail stall can cause a departure from control. I'm just looking at an analogue of the situation where a model aircraft hits a pole with one wing and spins in horizontal plane. In that case, the plane wouldn't orbit the tree, it would retain some linear momentum. Would any real create a force feedback system where the wings work to 'draw in' any linear momentum and turn it ALL into angular momentum?