I agree with all the feedback here so far (yes, even you, Kraken
) in that it isn't really that important how a tumbling plane falls when it's missing a wing, but considering all the complex properties of a wing (lift, collision shape, etc) it surprises me that mass isn't one of them. Anyway, I guess it's no good complaining - as others have mentioned it's probably OK to dismiss the strange angle as a result of uneven ground or hidden objects in the grass.