What is the difference between the V-shape tail and the straight tail on the Beechcraft Bonanza? In one of the answers to the question which aircraft is the oldest in production, the 
Beechcraft Bonanza is mentioned. While reading the Wikipedia entry on this interesting plane, I noticed that there are some models with a V-shape tail and some with a more conventional tail.

What is the difference between the two designs?

 Source: Wikipedia 

and 

 Source: Wikipedia
V-tails have been fashionable in the Fourties and Fifties, and the claim was that they would cause less drag than an equally effective conventional tail. This has two reasons:


Average chord length is longer, so the Reynolds number of the airflow is higher, causing relatively less friction drag.
Instead of three surface-fuselage-joints, the V-tail has only two, so less interference drag is created.


Flight testing of V-tails showed only marginal advantages, and in damping they are less effective than a conventional tail which is dimensioned for the same control effectiveness. The control effectiveness of a control surface is proportional to the cosine of the V-angle, but the damping characteristics go down with the square of the cosine.

@nimbusgb mentions the tendency of the V-tailed Bonanza to fishtail: That is a consequence of too little lateral damping.

Also, when a combined elevator-rudder input is commanded, the V-tail will produce a very high deflection on one side, while the two commands will cancel out on the other side. This will reduce overall control power in cases where a combined elevator-rudder input is commanded over what is possible with a conventional tail.

Even the glider designers, who had enthusiastically tried out V-tails, have now returned to conventional tails (more precisely, T-tails) because the expected benefits did not materialize. And glider designers will try anything to improve the aerodynamic quality of their designs.