Intermeshing rotors
From Wikipedia, the free encyclopedia
Intermeshing rotors on a helicopter are a set of two rotors turning in opposite directions, with each rotor mast mounted on the helicopter with a slight angle to the other so that the blades intermesh without colliding. The arrangement allows the helicopter to function without the need for a tail rotor. This configuration is sometimes referred to as a synchropter.
The arrangement was developed in Germany for a small anti-submarine warfare helicopter, the Flettner Fl 282 Kolibri. During the Cold War the American Kaman company started to produce similar helicopters for USAF firefighting purposes. Kamans have high stability and powerful lifting capability. The latest Kaman K-MAX model is a dedicated sky crane design, used for construction works.
The 'Flettner double rotor' (Sheetintermeshing rotor) is a propulsion system for helicopter, the two rotors used their axes in a low angle tilted against each other. The first helicopter, which this after its developer Anton Flettner notified principle used was in only 6 copies built Flettner Fl 265, the captain of flight Richard Perlia May 1939 tested. Operating reached maturity but only the Flettner Fl 282, with the Ludwig Hofmann probably at 31 First flew in October 1941.
- Building
The rotor configuration, the two main rotors is not like the coaxial rotors on top, but side by side. In contrast to the tandem configuration overlap here but the rotor levels. Thus, the rotor blades do not touch, the rotary axes in V-arranged position and the leaves take on a mechanical gearbox similar to gears intertwined.
The V-arrangement ensures that the "insides" of the rotors always alternately on the adjacent rotor mast out. For the sloping "foreign sides" not too close to the rich soil, the rotor mast-double of Flettner rotors always relatively high, was viewed as a disadvantage.
The system is known as ineinanderkämmende rotors. The control is done by periodic or continuous angle adjustment modification of the rotor blades (now known as cyclic and collective rotor blade adjustment) or in modern helicopter after the Flettner system on small leaves attached to the control valves whose adjustment angle is adjusted.
- Advantages and disadvantages
Advantages of the double-Flettner rotors are:
- No torque generation, so no tail rotor is necessary and there is no drift generated (see tail rotor configuration).
- The power requirement for the tail rotor and is therefore deleted for lifting and jacking available.
- The gears and the shaft for the rear rotor eliminated.
- Compared with the tandem configuration is the advantage of space-saving design with a central drive, compared to the Koaxialrotor in the simpler mechanics.
- The most larger total surface of a rotor Einrotorsystem, the same load with lower performance lifted. For example, the Kaman K-Max, a similar performance as Eurocopter EC 135 and Bell 429, but has a significantly higher maximum takeoff weight (MTOW). Similarly, with similar types of off weight, such as Bell 412 and Kaman SH-2 has a significantly higher performance requirements.
Disadvantages are:
- The main gearbox is more complex than a single rotor.
- The speed is necessary because of the lower performance, but also significantly greater overall rotor area less.
As beneficial Feels effects include areas where high loads to be transported, or hover or no high speeds are needed.
- Types
One modern helicopter, used to transport external load and for forest fire fighting, that employs the Flettner double rotor is the Kaman K-Max, while Kaman K 225 also uses this system.
- Other works Flettners
The Flettner double rotor should not be confused with the Flettner rotors designed by the same inventor as a means for driving a ship by exploiting the Magnus Effect.
