This sleek helicopter started as the two blade Bell 222, evolving via the 230 in the four blade Bell 430 as shown here. All versions can be fitted with a retractable gear or fixed skids. The trailing link main gear is retracted in sponsons attached to the lower rear fuselage.
This early helicopter has had many different gears, both skids and wheels. Here you see the nose gear version. All have in common a long fuselage without a clear tail boom. The main and tail rotor have two blades. Most have an open cockpit as shown here. The engine is behind the cockpit.
The large bubble canopy and the open frame tail boom are very distinctive recognition points of this helicopter. This version has a two blade main and tail rotor. It comes in different versions though, including ones with a covered tail boom and/or a wheeled gear.
This is a Bell 47 variant, but totally different from the more common one with a sphere like glass canopy. The 47B model has a wheeled undercarriage with four legs and a fully enclosed fuselage with big windows and tail boom. You can still recognise the rotor system though.
Bell 47H & Bell 47J
While still versions of the Bell 47, the H and J model look much different. They have an enclosed cabin with doors, and a covered engine and tail boom. The rotor system is largely unchanged.
Bell 525 Relentless
This slender helicopter has a five-blade main rotor and a four blade tail rotor. Moreover, it has a large pylon on top of the engine/gear box housing. Most of the cabin windows are long and narrow. (photo: Zane Adams/WikiMedia)
Bell AH-1 Cobra
The Cobra couples the tail boom, main rotor, tail rotor and skids of the Bell UH-1 with a new, narrower fuselage. It has a tandem cockpit with flat panels. Under the nose is a cannon, and small wings allow storage of weapons.
Boeing Vertol Chinook
This large tandem rotor helicopter has two three blade rotors on top of the front and rear pylon. They are powered by two turboshaft engined, placed at the side of the rear fuselage, at the junction with the rear pylon. The fuselage has pods at the side of the fuselage, along the full length, and a rear loading ramp at the end. The fixed gear consists of two twin wheel legs at the front and two single wheel legs at the rear.
Boeing-Vertol Sea Knight
The 'other' Vertol tandem helicopter is smaller than the Chinook but is otherwise quite the same. It has sponsons though holding the fixed two wheel main gear. The engines are on top of the rear fuselage, at the side of the rear pylon.
This chopper lost to the YUH-60 as replacement of the UH-1 Huey family. The YUH-61 has a fuselage that gradually tapers into the tail boom. The nacelles more attached to the top of the fuselage, than on the fuselage itself. The nose gear has two wheels. (photo: US Army/WikiMedia)