Due to lack of directional stability, it had a third fin added.
It is not to be confused with directional stability, as experienced by aircraft in flight.
Such a condition will cause the aeroplane to lose its directional stability and also to fly one wing down.
The qualitative behavior of this equation is considered in the article on directional stability.
The Mk1 had a tendency to roll, affecting its directional stability.
However, it continued to share a number of problems with the earlier He 112, notably a lack of directional stability.
A strong directional stability is the first way to reduce adverse yaw.
A side effect of this was that the boat lacked directional stability and was extremely difficult to hold on a straight course.
The test pilots found the aircraft easy to fly, but the control forces were very high at speed and it lacked enough directional stability.
Small fins for directional stability were mounted at the rear of the skids.