Pitching moment

About: Pitching moment is a research topic. Over the lifetime, 3213 publications have been published within this topic receiving 38721 citations.

Aerodynamic Characteristics of a Small-Scale Shrouded Propeller at Angles of Attack From 0 to 90 Degrees

Abstract: : An investigation has been made to determine the effects of airspeed and angle of attack on the lift, drag, and pitching moment of a shrouded-propeller model, having a shroud length of about two-thirds the propeller diameter, over an angle-of-attack range from 0 deg to 90 deg. Tests were made of the complete model with the propeller operating and also of the shroud and motor combination with the propeller removed. The effect of inlet-lip cross-sectional radius on the static-thrust characteristics was also studied. These tests were made in connection with the design of a vertical-take-off free-flight model and the results are presented herein without analysis as it is felt that they may be useful in the design or analysis of other aircraft.

Stall Hysteresis of an Airfoil with Slotted Flap

Abstract: Stall hysteresis discovered in wind tunnel performance of GA(W)-2 airfoil with 25%chord slotted flap is examined further by using the data obtained for lift, pitching moment, surface pressure distribution and hot film velocity vector. Test cases include 30 and 40 deg flap deflections each having an optimum and narrow gap at chord Reynolds number of 2.2 million and Mach number of 0.13. The flap optimized to produce the highest Clmax for each flap angle apparently did not have a proper contour and nose location for the slot flow to function effectively at off-design conditions. It is shown that suction pressures over flap, suppressed by thickening wing wake at stall, are not reversible to their pre-stall values within the decreasing α side of loop. It is suggested that the flap design include the use of a new flap parameter called slot flow angle to describe the slot flow orientation and a pressure recovery factor to select a proper contour for flap upper surface.

Flow Patterns and Aerodynamic Characteristics of a Wing-Strake Configuration

Abstract: Surface oil flow visualizations, force tests, and pressure measurements were conducted at low, transonic, and supersonic speeds. Four flow patterns on a wing with strake at low speed have been found. The flow on the wing upper surface is affected and controlled by the formation, development, and breakdown of the strake vortices. The differences in flow patterns are reflected in the force and moment results. The lift increment results from the effect of the strake vortex not only on the inner panel but also on the outer panel. The nonlinear variations of the pitching moment are discussed. The lift increment is decreased with an increase in Mach number at transonic speeds, primarily because the flow over the wing without strake changes from leading edge separation to leading edge attached flow with shock-induced separation. An increase in the lift-drag ratio is due to the lift increase at low speeds and the drag decrease at supersonic speeds.

Numerical simulation of laser energy discharge for flight control

Abstract: The numerical investigation of the interaction of an off-axis laser discharge in front of an ogive cylinder at Mach 3.4 is presented. Details of the physics of the interaction of the blast wave and heated region with the ogive cylinder shock structure and the effect of this interaction on the drag, side force and pitching moment are included. The location of laser discharge and the amount of energy added to the gas by the laser are two main factors affecting the flow. Increasing the energy absorbed by the gas increases the drag reduction, the desired side force and pitching moment. Increasing the distance of the discharge from the axis reduces both drag reduction and side force achieved by the laser discharge.