This paper presents a procedure for determining optimum take-off and climb out trajectory and control law for jet transport that minimize the noise produced during overflight of communities. The procedure is able to take account of operational constraints of aircraft, boundary lines of flight restrictions, constraints for air traffic control and the location of noise sensitive areas surrounding an airport. Based on the interpretation of the subject as an optimum control problem with inequality constraints of control and/or state variables, the steepest descent method is utilized to calculate trajectory and control law that minimize the chosen criterion for noisiness. The criterion is a sum tolal of weighted noisiness, implying sensitive area to noise or insensitive, of plural noise sensitive points which are located close to an airport. The method is applied to the calculation of optimum trajectories for a typical, currently in-service jet transport. Aircraft model including lateral maneuvers is approximated by nonlinear point mass dynamics. Comparison with an ordinary cutback flight procedure and the case of the second criterion which includes an excess attenuation of noise are also given. As a result of the calculation, it is concluded that optimum trajectories and control law are so strongly affected by the relative distance from the airport to weighted noise sensitive points that flight procedure for noise abatement should be established individually for each airport.
A force acting on a cylinder with a uniform temperature in a semi-infinite expanse of gas bounded by an infinite plane wall with a different temperature (thus, the temperature of the gas is the same as that of the wall) is investigated for highly rarefied gas on the basis of the linearized BOLTZMANN-KROOK-WELANDER equation. First, the free molecular limit is considered for a cylinder with an arbitrary convex cross section. It is shown that the behavior of the gas is not affected by the wall and that the cylinder is not subject to any force. Next, the effect of molecular collision is taken into account for a circular cylinder. When the temperature of the cylinder is higher than that of the wall, the cylinder is subject to a force of the order of (ln Kn)/Kn toward the wall, where Kn is the KNUDSEN number. In the opposite case the force is reversed.
The spanwise lift distribution and induced drag of a wing in a circular wind tunnel, with either closed or open working section, are studied. The exact expressions of the spanwise optimum lift distribution and the minimum induced drag are obtained from the TREFFTZ plane Bow field in either case. In the closed tunnel case, as the ratio of wing span to tunnel diameter increases, the lift distribution changes gradually from elliptic to uniform one, and the induced drag also gradually decreases until it becomes zero. In the open tunnel case, the distortion of the lift distribution caused by the presence of the tunnel boundary is rather small, even when the ratio of wing span to tunnel diameter reaches unity. It is seen that the simple ROSENHEAD type of correction based on the elliptic lift distribution is satisfactory for all practical cases in which the lack of uniformity of the airstream or the size of the airfoil chord does not become excessive.
The design method for the frame-structure as a tower was mainly subject to the drag-coefficient. However, when REYNOLDS number (Re) for a steel-pipe quickly changes from critical region to super-critical region, a large lift-coefficient occurs. As a steel-pipe-tower, which is the combination of columns, a large lift-coefficient occurs on the tower under the specified conditions. This paper is concerned with the magnitude of lift-coefficient for steel-pipe-towers. We tried several experiments which is used wind tunnel. Each experiment is composed of a set of two columns and four columns. We are interested in the following results: (1) From the fundamental experiment for the circular cylinders with four different diameters of column, the lift-coefficient is confirmed to increase corresponding to the decrease of the drag-coefficient as 3.5×105<Re<1.5×106. (2) In the cases of combinations of two columns and four columns, the lift-coefficients are confirmed to increase about 1/2 to 2/3 of the drag-coefficient in the wind directionθ=10° to 15°. (3) From a view point of steel-pipe-tower, a large lift-coefficients are confirmed to occur in the wind directionθ=10°to 15°.
Recently the control concept of DSFC (Direct Side-Force Control) was suggested, and the flights in which the heading and the course azimuth can be controlled separately have become practicable. We call these flights of this type "DSF modes" in this paper. We propose a control system for the flights of DSF modes. First we classify DSF modes into DSF mode 1, mode 2 and mode 3, and consider the simplest control scheme for each mode from a practical point of view. According to this control scheme we build a control system based on the decoupling theory in automatic control. Computer simulations used this system are then shown.
A similarity analysis is presented mainly of the outside flow region of a turbulent plane wall jet which flows along a flat surface placed in otherwise quiet surroundings. Experiments about wall jets have revealed that the point of zero shear stress lies nearer the wall than the point of maximum velocity. This is one example of flows which have the countergradient shear stress region. Taking into account such an observation, REYNOLDS shear stress is expressed in the form including the second order term, like τ∞-υ(lUy+0.5ll2Uyy).The coeficients of Uy and Uyy are assumed to be proportional to bυ' and b3υy', respectively, where b is the half-value thickness of jets, and υ' the lateral turbulence intensity and its distribution is given by experimentally observed data. Specifying some values at the point of maximum velocity, integration of a fourth-order differential equation is carried out first toward the edge of the jet, next to the inner flow region. Calculated distributions about velocity and shear stress are compared fairly well with some measurements except for the near wall region.