Gupta, Bharat P.
Most widely held works by Bharat P Gupta
Helicopter obstacle strike tolerance concepts analysis by Bharat P Gupta ( Book )
4 editions published in 1979 in English and held by 35 WorldCat member libraries worldwide
A large number of obstacle strikes have occurred during Army helicopter combat missions and nap-of-the-earth (NOE) training missions. Obstacle strike tolerance becomes particularly important for NOE flights in areas containing many obstacles, such as western Europe. This report defines the obstacle strike problem, particularly for tree and wire strikes. Only a small percentage of obstacle strikes produce accidents, but these accidents account for a high proportion of helicopter damage costs. Tree strikes are more common than wire strikes, but the wire strikes are more likely to cause accidents. Generally, the main and tail rotors are most commonly struck, but a high proportion of wire strikes also occur on the fuselage. Helicopter obstacle strike tolerance designs for rotors, fuselage, and controls are analyzed and the most promising concepts are selected for both existing and future helicopter systems. In addition, obstacle strike tolerance design criteria are defined
Analytical Investigation of the Aerodynamic Stability of Helical Vortices Shed from a Hovering Rotor ( Book )
1 edition published in 1973 in English and held by 2 WorldCat member libraries worldwide
A small-perturbation stability analysis of a doubly infinite array of interdigitated, right circular helical vortices has been formulated. This array corresponds to the vortices trailed from the tips of the blades of a helicopter rotor or propeller in static thrust or axial flight condition and at great distance from the plane of rotation of the blades. The analysis makes use of the Biot-Savart law of induction and the Vorticity Transport Theorem. The singularities in the Biot-Savart integration for self-induction have been eliminated by substituting approximate functions. Near-singular behavior in other integrals has been minimized by adding and subtracting functions with similar near-singular behavior and which have exact, closed-form integrals. (Modified author abstract)