Vertibird

Vertibirds are Enclave helicopter vehicles used as scouts and troop transports. In 2241 one of them crashed near the trapper town of Klamath, and was the first sign of the Enclave encountered by the Chosen One. The Chosen One later stole the Vertibird Plans from the Navarro base, but it is not certain whether he gave them to the Brotherhood of Steel, the Shi, or simply kept them.

Design background
The Vertibird is a lateral twin-rotor (non-synchronized) helicopter design. An actual experimental prototype for this type of aircraft was the Platt-LePage XR-1/XR-1A tested by the US Army in the 1940's. Others included the German Fa 223 and the McDonnell XHJD-1 "Whirlaway". The XR-1 was the first American military helicopter to takeoff and hover with good control, but the lateral design was generally plagued by significant vibration and control problems when in motion. Synchronized lateral rotor aircraft like the Kellett XR-10 worked better, but the concept was eventually abandoned in favor of the tandem (fore-aft) twin-rotor configuration that is in use today (e.g. the Chinook). Note that while the Vertibird bears an interesting resemblance to the V-22 OSPREY, it is not a tilt-rotor design like the Osprey. For example, the long thin rotor blades are not "proprotors" that can be used as propellers.

The name "Vertibird" is the trademark for a toy helicopter playset popular in the 70's (i.e. when the Fallout team members were children). Some design aspects of the unusual aircraft appear to be inspired by that hovering insect, the dragonfly. For example, the six legged landing gear and twin bulges in the forward fuselage.

Appearances in games
Vertibirds appear only in Fallout 2.