The chase for the worlds fastest helicopter

Eurocopter, the European helicopter maker that is one of Sikorsky Aircraft's few rivals, this week said it had begun flight tests for a prototype rotorcraft it calls the X3.

Stratford-based Sikorsky has been making waves this year with its X2 prototype helicopter, intended to be the world's fastest helicopter.

Source:
http://articles.courant.com/2010-09-28/business/hc-first-sikorsky-now-eurocopter-20100928_1_fastest-helicopter-counter-rotating-main-rotors-turboshaft-engines