The helicopter has reached speeds in excess of 250 kt (460 km/h) in level flight, besting the official record of 217 kts set by a (then Westland) Lynx, and the unofficial record set by its predecessor, the XH-59A demonstrator, of 236 kts.

It also appears that it could achieve a speed of 265 kts with the addition of a “sail fairing” between the two rotors.

It’s unclear to me, however how this is a helicopter speed record, and not a compound helicopter speed record, since the tail thruster makes a significant difference in just how power is applied at higher speeds.

I was under the impression that either a wing or a horizontal thruster made it a compound helo, but it appears that the definition being used here is that it’s specifically the wing that makes it a compound helicopter.