Two Helicopters X, World's Fastest

Their names are both using the letter X. Which one is Sikorksky X2, others named Eurocopter X3.

Both helicopters are capable of flying faster than ordinary helicopters.



Using the body Eurocopter Dauphin, X3 has several modifications from its predecessor's.

As quoted from the site Physorg, X3 adds an extra engine that is used to drive two extra propellers located on the short wing on either side of its body.
Although only a single additional machine, but the plane is now still at the experimental stage that can run faster than ordinary helicopters.