The very title of the states that take-off and landing gears up for take-off and landing of helicopters. In addition, the chassis of helicopters used for parking and movement of the helicopter on the ground (on the water) during taxiing or towing.
According to the chassis construction of helicopters can be very different, but they all boil down to three types: a wheeled, skid and float. From time to time helicopter Combined gear set, for example, axle with pneumatic (as needed) cylinders. In order to withstand the loads acting on the helicopter during landing and movement on the ground (for example, the impact energy when it lands), not counting the wheel chassis is equipped with shock absorbers. Springs absorb the kinetic energy of roving helicopter, turning it into a work force reduction strut. Pneumatic wheels with their crimped as well (although nekordinalno) absorb impact energy.
The basic scheme chassis on modern helicopter is a wheeled chassis with front nose strut. This scheme provides a good helicopter Putney stability in the run and run, as more ordinary and unthreatening landing in bad visibility criteria and on unprepared sites. When all this is usually set as a support for the tail rotor control protection from hitting the ground in the event of incorrect or rough landing. From time to time a helicopter has not one, but two bow racks, for example, the Mi-4 and Mi-10. The main advantage of the wheel chassis front skid is to enable movement of the helicopter on the ground with a pretty bolshennymi speeds (up to 80 km / h), which allows you as needed to make taking off and landing on an aircraft.
Skid chassis simpler and has the smallest mass than wheeled. Depreciation in it at the expense of the design meander chassis that acts as a spring. To move the helicopter on the ground on the guides are installed small wheels. With the crank can be lowered below the level of the runner, which allows you to move helicopter on the ground.
Float chassis provides helicopter landing on water (and land) and hold it afloat. Skid and float in the main landing gear used on some light helicopters. In flight, the fixed gear rack and wheels (floats) chassis experiencing significant air resistance, especially when flying at great speeds. Resistance fixed landing gear can be up to 30 — 40% of drag forces non-structural parts of the helicopter. It is clear that the power expended in overcoming the forces of air resistance increases in proportion to the speed helicopter flight to the third power. Because the acceleration of the flight all the more urgent task is cleaning chassis in flight.
Retractable landing gear is heavier than non-retractable. Because gear retraction in flight is suitable in this case, if the power expended in overcoming the forces of drag fixed landing gear, more power, the need to carry extra weight of the landing gear. Such conditions are usually flying at speeds of over 250 km / h
Because in the modern high-speed helicopter used retractable landing gear in flight. Usually the wheels and landing gear retracted into the fuselage special niche. This provides a significant reduction in drag of the helicopter, which simplifies data retrieval largest flight speeds. Cleaning and release chassis in the permitted range of flight speeds do not actually have an impact on the behavior and balancing the helicopter.