A study on the kinematic relationship of the variables of helicopter motion in steady, coordinated turns involving inherent sideslip is described. A set of exact kinematic equations which govern a steady coordinated helical turn about an Earth referenced vertical axis is developed. A precise definition for the load factor parameter that best characterizes a coordinated turn is proposed. Formulas are developed which relate the aircraft angular rates and pitch and roll attitudes to the turn parameters, angle of attack, and inherent sideslip. A steep, coordinated helical turn at extreme angles of attack with inherent sideslip is of primary interest. The bank angle of the aircraft can differ markedly from the tilt angle of the normal load factor. The normal load factor can also differ substantially from the accelerometer reading along the vertical body axis of the aircraft. Sideslip has a strong influence on the pitch attitude and roll rate of the helicopter. Pitch rate is independent of angle of attack in a coordinated turn and in the absence of sideslip, angular rates about the stability axes are independent of the aerodynamic characteristics of the aircraft.

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Kinematic properties of the helicopter in coordinated turns

A review of mathematical modelling techniques for advanced rotorcraft configurations

Army Helicopter Performance Trends

: The high-g maneuver capabilities of the AH-1G have been investigated in this effort Flight test data for 132 high-g maneuvers have been studied and statistically analyzed to determine the relationships among the variables A series of fixed-collective symmetric pullups was simulated, using the Rotorcraft Flight Simulation Program C81, to determine the mechanisms limiting high-g maneuvers of the AH-1G Statistical analysis of the C81 data was used to supplement the analysis of the test data Three additional maneuvers, similar to the most severe test maneuvers, were simulated

An Investigation of High-G Maneuvers of the AH-1G Helicopter

: The AH-1G helicopter manufactured by Bell Helicopter Company (BHC) was designed specifically to meet the US Army requirements for an armed helicopter. Tandem seating is provided for a two-man crew. The main rotor system is a two-bladed, semi-rigid, 'door hinge' type with the stabilizer bar removed. The engine is derated to 1100 shp due to the maximum torque limit of the main transmission. Distinctive features of the AH-1G are: the narrow fuselage (36 inches), the stub midwing with four external store stations, the integral chin turret. The flight control system is of the mechanical, hydraulically boosted, irreversible type with conventional helicopter controls in the aft cockpit (pilot station). The controls in the forward cockpit (copilot/gunner station) consist of conventional antitorque pedals and sidearm collective and cyclic controls. An electrically operated force trim system is connected to the cyclic and directional controls to induce artificial feel and to provide positive control centering.

Engineering Flight Test AH-1G Helicopter (Hueycobra). Phase D. Part 1. Handling Qualities

: The AH-1G helicopter maneuvering limitations flight test program was conducted The purpose of the test program was to study in detail the characteristics of maneuvering flight and to identify any limitations required to improve flight safety The program included investigation of steady-state turns, three types of return-to-target maneuvers, and simulated operational maneuvers Repeated instances of untorquing of the tail rotor retention nut were encountered during flight and constituted a safety-of-flight deficiency Four shortcomings were noted

Marvin W Buss

Papers

Engineering Flight Test AH-1G Helicopter (Hueycobra). Phase D. Part 1. Handling Qualities

Engineering Flight Test AH-1G Helicopter (HUEYCOBRA). Maneuvering Limitations