Search results
Results from the WOW.Com Content Network
[1] As the airspeed increases without an increase in height, there comes a point where the pilot's reaction time would be insufficient to initiate a flare, and prevent a high-speed ground impact. Each increase in height increases the pilot reaction time. This is the reason the bottom right part of the H/V curve has a shallow gradient. If above ...
The signs of VRS are a vibration in the main rotor system [8] followed by an increasing sink rate and possibly a decrease of cyclic authority. [9]In single rotor helicopters, the vortex ring state is traditionally corrected by slightly lowering the collective to regain cyclic authority and using the cyclic control to apply lateral motion, often pitching the nose down to establish forward flight.
Its comprises helicopter aerodynamics, stability, control, structural dynamics, vibration, and aeroelastic and aeromechanical stability. [1] By studying the forces in helicopter flight, improved helicopter designs can be made, though due to the scale and speed of the dynamics, physical testing is non-trivial and expensive.
The charts show the added lift benefit produced by ground effect. [ 3 ] For fan and jet-powered vertical take-off and landing (VTOL) aircraft, ground effect when hovering can cause suckdown and fountain lift on the airframe and loss in hovering thrust if the engine sucks in its own exhaust gas, which is known as hot gas ingestion (HGI).
It is a common emergency procedure taught to helicopter pilots as part of their training. In normal powered helicopter flight, air is drawn into the main rotor system from above and forced downward, but during autorotation, air moves into the rotor system from below as the helicopter descends.
As with fixed-wing aircraft, a helicopter may be properly loaded for takeoff, but near the end of a long flight when the fuel tanks are almost empty, the CG may have shifted enough for the helicopter to be out of balance laterally or longitudinally. [1] For helicopters with a single main rotor, the CG is usually close to the main rotor mast.
Many of his designs, such as a four-person screw-type helicopter, have severe flaws. He did at least understand that "An object offers as much resistance to the air as the air does to the object." [10] (Newton would not publish the Third law of motion until 1687.) His analysis led to the realisation that manpower alone was not sufficient for ...
Military helicopters are a significant part of the helicopter market In 2017, 926 civil helicopters were shipped for $3.68 billion, led by Airbus Helicopters with $1.87 billion for 369 rotorcraft, Leonardo Helicopters with $806 million for 102 (first three-quarters only), Bell Helicopter with $696 million for 132, then Robinson Helicopter with ...