Changes In Wing Shape Research Articles

Aerodynamic design methods for transonic wings

SummaryA review is given of current methods in theoretical aerodynamics which are useful in the design of aircraft wings for subsonic and transonic speeds. These are of two basic types: (A) direct methods for calculating the flow over a givenwing shape. In the design process, these can be used to obtain a rapid estimate of the effect of a specified change in wing shape. The most practical methods of this type make use of the viscous/inviscid interaction technique; some recent methods are described and examples are given of their use, both in two and three dimensions, including comparisons with experiment.(B) inverse methods in which the shape is calculated explicitly, as a result of either (a) specifying the surface pressure distribution on the wing, or (b) requiring that some suitable ‘target’ function, usually the drag/lift ratio, shall be a minimum. At present, these methods are restricted to inviscid flow.Several examples of both ‘pressure’ and ‘optimisation’ methods are discussed, and their advantages and limitations considered.

Classical flight dynamics of a variable forward-sweep-wing aircraft

The X-29 advanced technology demonstrator has established the design of forward-sweep wings. A conceivable variation of forward sweep is variable forward sweep. A variable forward-sweep configuration would likely offer higher performance levels than either forward sweep or variable sweep. The classical flight dynamics for such a configuration are determined and discussed. A classical aircraft stability analysis assuming rigid body, linearized dynamics, and no stability augmentation is used. Results indicated variable forward-sweep configurations can have less of a problem with excessive static margins than variable backward-sweep configurations. Wing location and center of gravity location changes due to variable forward sweep affect the stability derivatives consistently more than the wing shape changes due to variable forward sweep. The steady state trim condition and moments of inertia changes due to variable forward sweep and Mach number are small. The phugoid and roll modes experience the largest effects due to variable forward sweep and Mach number. The average handling quality levels experience no drastic changes due to variable forward sweep and Mach number.

Studies on the female sterile mutant rudimentary of Drosophila melanogaster. III. Cell death in rudimentary wing imaginal discs

AbstractPrevious work on the effect of the locus rudimentary on wing morphogenesis showed that a disproportionate reduction in the number of cells in the posterior region of the wing accounted for the changes in wing shape. In the present study, I used both clonal analysis and direct histological observations to demonstrate that the deficiency in cell number in the adult wing resulted from cell death and that cell death can account for the changes in both the size and shape of r wings. Some discussion was devoted to the possible mechanisms by which an alteration in pyrimidine metabolism might lead to cell death.

Changing the relative size of the body parts ofDrosophilaby selection

1. Mass selection for both high- and low-ratio of wing to thorax length has been carried out on a population ofDrosophila melanogaster. The response to selection was immediate and sustained. When the experiment was stopped after ten generations, the wing area in the two selected lines differed by about 30%. The heritability estimate worked out at 0·56 ± 0·08.2. Thorax length remained comparatively unchanged during selection nor was there any change in wing shape. There was some evidence of assymetry of response since there was a relatively greater change in favour of smaller rather than larger size.3. The tibia length of all pairs of legs showed correlated changes so that the lines with larger or smaller wing sizes had also larger and smaller legs.4. The normal allometric relation between wing and thorax length, associated with variation in body-size, apparently also changed, so that for a given change in thorax length there was a greater or smaller proportional change in wing size in the high- or low-ratio lines.5. The changes in relative wing size are due to changes in cell number.6. It is suggested that the genetic changes due to selection act in the early pupal period when the imaginal discs are undergoing differentiation and proliferation to form imaginal hypoderm and appendages.7. Tests of genetic behaviour failed to show any departure from additivity in crosses which involved the unselected population and the high-ratio line. But highly significant departures existed in the cross to the low-ratio line. Relatively smaller wing size behaves as largely recessive. Stability of the normal wing/thorax ratio involves dominance and probably also epistasis. The genetic properties of the relative size of the appendage are apparently similar to those which characterize body-size as a whole.8. It is suggested that selection provides a valuable tool for studying the constancy or lability of the growth patterns which determine morphology.