In the history of aviation, the goal to fly vertically was not far away from application. The world’s first practical vertical flight other than hot air balloons was accomplished by Igor Sikorsky who was the designer and the pilot for VS-300 helicopter. The design was using a single main rotor and single tail rotor.
Igor Sikorsky was dominating the helicopter industry by producing the helicopters for the US army in World War 2. But Igor’s design was rough for the pilots to ride and the helicopter. On the other hand, the US Navy was searching for another design and heard of Mr. Piasecki who was influenced by Igor’s helicopter design and developed his own copter for the public called the PV-2.
The US navy then funded the project of PV-2 copter while Mr. Piasecki was working on another big project called the “flying banana” known with model HRP-1. The HRP-1 was a surprise for the US Navy and Igor Sikorsky. As HRP-1 was faster , rides smother ,gets higher and lift more personnel and equipment. Because of the tandem-rotor design which allowed the copter to have greater longitudinal stability and larger range of center gravity.
The physics behind the design of tandem-rotor is to counter act the torque produced by one of the rotors to one another. If we see the single rotor of the helicopter there must be aided by a small tail rotor to counter act the torque produced by the larger rotor. If we need to lift more equipment and people on board with the same design of single rotor design we would need a larger rotor with a heavy engine to have the same capacity of tandem-rotor design which will add more weight to lift.