Generally speaking there are 4 propellers. Two of them are crossed over each other that form the main propellers, and the other two are at the rear.
black hawk
Propellors are on airplanes. Helicopters call them rotors. The small rotor on the back of the helicopter is used to counteract the torque created from the engine driving the main rotors.
Helicopters require at least two propellers to achieve stability through a concept known as "counter-torque". The main rotor produces torque that would rotate the body of the helicopter in the opposite direction. The tail rotor or fenestron is used to counteract this torque, providing stability by keeping the helicopter from spinning uncontrollably.
No, the Boeing 707 did not have propellers, it had 4 turbo fan engines, two on each wing
in a mueseum
Twin engine
The SUPER Cobra (two engines instead of one) is a "post" Vietnam helicopter used by the USMC because it was cheaper to buy than the newe APACHE attack helicopter.
The AH-64 Apache is a 4-blade, twin-engine is an attack military helicopter with a tailwheel-type landing gear arrangement, and a tandem cockpit for a two-man crew.
The Apache helicopter is used in many nations for an attack helicopter. This type of helicopter allows for a two man cockpit and weapons to be placed all around. The AH-64 Apache helicopter is outfitted with night vision systems, a 30-millimeter chain gun, AGM-114 Hellfire missiles, and Hydra 70 rocket pods. This helicopter was approved for full American military production in 1982. The Apache helicopter is still being made today, under new models.
That is a twin rotoe helicopter
Wheels and cockpit are two parts of a plane with propellers.