This Day in McDonnell Voodoo History, February 14th:

In 1947, a revised McDonnell XP-88 design was approved for production by Air Materiel Command.  The most conspicuous change was the change from the unusual “Vee” tail of the original design to a more conventional arrangement.  The contract specified an estimated cost of $5,014,191.10 along with a fee of $285,808.90.

This is a photo of the original Model 36C  Voodoo mock-up, inspected in August 1946.  The "Vee" tail design saved precious weight, critical to the range and altitude performance of a long-range fighter.  However, subsequent wind tunnel testing revealed possible interference effects at transonic speed.  A conventional tail was chosen instead and would be built as the definitive XF-88 Voodoo.  

Photo Credit: NARA via Tony Buttler