ORIGINAL: chipwill
IMAC rules state that the nose must drop before rotation starts. Some planes will do this on their own while others like straight wing Edges hang on forever.
This is not correct. The IMAC rules actually say that the wing must fall in the direction of the intended rotation AS THE NOSE falls. So to say that the nose must fall first is not correct. Ideally it is simultaneous. In fact, if the nose falls prior to the rotation starting that is a downgrade for a forced entry (1 point per 10 degrees).
Please see page F&JG-42 for the discussion of this in the rules.