This medium size helicopter comes in many versions, all of which have in common the two engines placed on top of the fuselage, in front of the main rotor with exhausts at the side. The single or double wheel main landing gear retracts in small stubs or larger sponsons. The nose gear has two wheels as standard. The tail rotor is mounted at the right top of the vertical stabiliser, with a horizontal stabiliser on the opposite side.
The Gazelle was one of this first helicopters with a shrouded tail rotor. Additionally, it has a droplet shaped fuselage, on top of which the engine is slightly separated from the (rear) fuselage. The helicopter has a three blade main rotor, and skids with standard tubes.
Sud-Est/Sud Aviation/Aérospatiale Alouette II & Lama
The Alouette II & Lama are composed of three elements: a framed, dome-shaped cabin with a lot of windows, the middle with fuel tank and an uncovered engine on top, and an open framework tail boom. The helicopter has a three blade main rotor and two blade tail rotor, on the right. Most have skids as landing gear, but some have a four leg wheeled gear.
Sud-Est/Sud Aviation/Aérospatiale Alouette III
The Alouette III retains the exposed engine and basic rotor system of the Alouette II, but for the rest it is different. The wide cabin and fuselage form one entity with a lot of windows at the front. The tail boom is covered though, and the Alouette III has a fixed tricycle gear. The helicopter has a three blade main rotor and three blade tail rotor, on the right.
TAI T625 Gökbey
This helicopter is quite similar to the Leonardo AW139. However, the T625 has a more rounded side of fuselage and tail boom (no 'body line') and has end plates at the tips of the horizontal stabilisers. Other differences are much smaller. (photo: tolgaozbekcom/WikiMedia)
Westland Lynx & Leonardo Wildcat
The best way to distinguish the Lynx or Wildcat is by looking for the long rounded nose and the tail boom that is somewhat pointing down. The Lynx can be fitted with skids or a wheeled gear. In case of wheels, the two main gears are tilted around the vertical axis, so that the heli cannot taxi on its wheels.
This helicopter has a four blade main rotor and a two blade tail rotor. The fuselage and tail boom have external, horizontal stiffners. The turboshaft engine is not covered and the horizontal stabiliser with small oval end plates is put directly underneath the end of the tail boom. The front, in particluar the short nose and window configuration, reminds a bit of a locust/grasshopper. The Scout is very similar in appearance to the Westland Wasp, the wheeled navy version.