Flight in Drosophila

1966 ◽  
Vol 44 (3) ◽  
pp. 567-578 ◽  
Author(s):  
STEVEN VOGEL
Keyword(s):  
Wind Tunnel ◽  
Adaptive Significance ◽  
Fruit Flies ◽  
Flight Performance ◽  
Free Flight ◽  
Body Angle ◽  
Control Reaction ◽  
Level Flight ◽  
Lift Control ◽  
Very High

1. Apparatus has been devised to record the principal parameters of the flight performance of tethered fruit-flies in a wind tunnel. 2. Typically these flies achieve level flight (lift = weight) at 200 cm./sec. and a body angle of + 10°. Lift varies directly with body angle except at very high angles; the stroke parameters are invariant with body angle. 3. Evidence is presented suggesting that these measurements are applicable to free flight. 4. The adaptive significance of the absence of a ‘lift-control reaction’ in fruit-flies is discussed.

The Lift-Control Reaction of Flying Locusts

1964 ◽  
Vol 41 (1) ◽  
pp. 183-190 ◽  
Author(s):  
ERIK GETTRUP ◽  
DONOALD MELVIN WILSON
Keyword(s):  
Angle Of Attack ◽  
The Body ◽  
Qualitative Model ◽  
Body Angle ◽  
Control Reaction ◽  
The Mean ◽  
Lift Control

1. Angle of attack of a distal wing segment was estimated for forewings and hindwings of locusts during constant lift at different body angles. At the middle of the downstroke the forewing angle of attack remained nearly constant, but the hindwing angle varied with the body angle. 2. The results are consistent with earlier electro-physiological findings and emphasize that the twist parameter does not contribute by equal amounts to the mean wing twisting of the two pairs of wings. 3. A qualitative model of the constant-lift reaction includes a factor for simultaneous correction of body pitch.

Biology and Physics of locust flight II. Flight performance of the desert locust ( Schistocerca gregaria )

1956 ◽  
Vol 239 (667) ◽  
pp. 459-510 ◽  
Keyword(s):  
Steady State ◽  
Time Course ◽  
Harmonic Oscillation ◽  
The Body ◽  
Horizontal Wind ◽  
Vertical Force ◽  
Flight Performance ◽  
Free Flight ◽  
Stroke Frequency ◽  
Body Angle

The main purpose is to analyze how a number of wing-stroke parameters are related to the lift (average vertical force) and thrust (average horizontal force) produced by the insect under well defined aerodynamic conditions. The locust was suspended from a complicated balance and flew against a uniform horizontal wind from an open-jet wind tunnel. The wind speed was automatically adjusted to the preferred flying speed (air speed), i.e. the speed at which the thrust equals the extra-to-wing drag . The lift was measured as the apparent reduction in weight; it is given as a percentage of the weight which the individual would have if it had flown for about one hour, was full-grown and well fed but, if a female, with undeveloped eggs ( = basic weight). This figure is the relative lift, and it is used because the actual weight changes much with age, feeding, sexual development, etc., while the dimensions of the flight motor remain constant. The angle between the wind and the long body axis is the body angle and was chosen by the observer or by the insect itself. Most experiments took place at 30° C (constant temperature room), but series were run at the upper and lower limits for flight, including experiments with small flocks of locusts suspended from a roundabout. The rate of evaporation of water from the thorax was kept constant. In a large number of individuals sustained steady-state flight was studied; at regular intervals a set of simultaneous readings were taken consisting of the lift, the speed, the body angle, the stroke frequency, the extreme angular positions of the wings, and of the inclination to the vertical of the stroke planes. In addition, the angular movements of the entire wings relative to the body were estimated from slow-motion films. The results are seen in §§4 to 7. The frequency distribution of the relative lift has its maximum about 100 %, showing that, in this respect, the flight comes near to free flight. It varied from 35 to 175 %, i.e. about five times. During continuous horizontal flight the flying speed was 3•5+ 0•1 m/s and may increase to 4•2 m/s in free flight. At larger lifts (climbing) the steady-state speed could reach 4•5 m/s. During the first minutes the speed was often 4•5 to 5•0 m/s, the maximum observed being 5•5 m/s. No locust lifted its own weight at speeds less than 2•5 m/s. The power necessary to overcome the extra-to-wing drag only corresponds to 1 to 3 % of the total metabolic rate. The effect of altering the body angle is fundamentally different from that of altering the pitch of an aircraft; the lift is controlled and kept constant by the locust and proved to be independent of alterations in the body angle amounting to as much as 20°. This is the basis for the technique and for the treatment of the results. In spite of the large variations in lift, the following stroke parameters varied little or not at all: the stroke angles , the stroke-plane angles , the middle position of the wings , and the time course of the angular movement of the entire wing, y = y(t). The latter function deviates considerably from a simple harmonic oscillation. According to figure II, 20, the average points are determined with an accuracy of better than + 1 %, permitting graphical differentiation. The stroke frequency was rather constant but increased with the reflexly controlled lift, contrary to Chadwick’s experiments on Drosophila , and decreased with increasing size, according to Sotavalta’s findings in other insects. The maximal changes were small, however, amounting to 8 % (lift) and 15 % (size) respectively. The flight performance and the stroke parameters were independent of changes in air temperature (no radiant heat) within 25 to 35° G, although the pterothorax is subjected to similar changes. Sustained flight does not take place below 25° C and above 35° G, but short performances were observed between 22 and 24° C as well as above 37° C. The great variation in lift could not be explained by changes in the measured stroke parameters, and by analogy with a variable-pitch propeller, it must be caused by differences in wing twisting 0(r,t). It was also found that lift and thrust varied in a more intricate way than in a simple actuator disk. The regularity of the stroke and its independence of temperature makes it possible to define a standard stroke , making it easy to compare a given performance with the normal.

scholarly journals On the So-called Constant-lift Reaction of Migratory Locusts

1989 ◽  
Vol 147 (1) ◽  
pp. 111-124 ◽  
Author(s):  
WOLFRAM ZARNACK ◽  
MICHAEL WORTMANN
Keyword(s):  
Body Weight ◽  
Wind Speed ◽  
Wind Tunnel ◽  
Force Transducer ◽  
The Body ◽  
Flight Speed ◽  
Body Angle ◽  
Level Flight ◽  
Tethered Flight ◽  
Thrust Measurement

1. Locusts were fastened to a force transducer in front of a wind tunnel to measure their lift and thrust during tethered flight heading into the wind. The thrust measurement was used to adapt the wind speed to the flight speed of the animals. Thus, the locusts could choose their flight speed freely in the range 0.5–7ms−1. 2. At light intensities of about 0.02 lx (twilight), the locusts generally produced a maximum lift greater than 100% of their body weight. 3. A miniature motor mounted on the force transducer could alter the body angle of the locusts without further interference. Lift was found to be influenced by body angle. No ‘constant-lift reaction’ evoked by exteroceptive information of the aerodynamic flow was found. 4. Flight speed was almost independent of the imposed body angle. 5. Generally, a flight speed of about 3 m s−1 was necessary for level flight. There was no further correlation between lift and flight speed.

Comparison of free-flight and wind tunnel data for a generic fighterconfiguration

1982 ◽  
Author(s):  
G. WINCHENBACH ◽  
R. CHELEKIS ◽  
B. USELTON ◽  
W. HATHAWAY
Keyword(s):  
Wind Tunnel ◽  
Free Flight ◽  
Wind Tunnel Data

Wingbeat frequency of barn swallows and house martins: a comparison between free flight and wind tunnel experiments

2002 ◽  
Vol 205 (16) ◽  
pp. 2461-2467 ◽  
Author(s):  
Felix Liechti ◽  
Lukas Bruderer
Keyword(s):  
Wind Tunnel ◽  
Single Pulse ◽  
Free Flight ◽  
Wind Tunnel Experiments ◽  
Wingbeat Frequency ◽  
Flight Costs ◽  
Radar Echo ◽  
The Mean ◽  
Barn Swallows ◽  
Air Speed

SUMMARYThe flight paths and wingbeat patterns of 39 barn swallows (Hirundo rustica) and 26 house martins (Delichon urbica) were recorded by tracking radar during the spring migration. Depending mostly on flight angle,hirundines performed anything from continuous flapping flight during climbing to single pulse-like wing beats during descent. Unlike most other passerines,hirundines rarely showed regular flapping and rest phases, allowing them to be distinguished from other bird migrants by radar echo signatures. Effective wingbeat frequency (Feff) was calculated as the mean number of wing beats per second, including non-flapping phases. Under comparable flight conditions, Feff was higher in house martins than in barn swallows. Within species, Feff values were higher during climbing and slow flying than during descent. Of the variance in Feff, 71 % could be explained by climb rate,air speed and species; similar results were obtained in the wind tunnel. Under comparable flight conditions, barn swallows and house martins in free flight had significantly lower values of Feff than individuals in wind tunnel experiments (by 40 % and 32 %, respectively). This difference may at least partly be due to the shorter wings of the juveniles tested in the wind tunnel during autumn. However, it seems unlikely that this can account for all of the large difference. It is suggested that wind tunnel experiments might overestimate birds' flight costs compared with free flight.

Gliding Flight of the Dog-Faced Bat Rousettus Aegyptiacus Observed in a Wind Tunnel

1971 ◽  
Vol 55 (3) ◽  
pp. 833-845 ◽  
Author(s):  
C. J. PENNYCUICK
Keyword(s):  
Wind Tunnel ◽  
Lift Coefficient ◽  
Trailing Edge ◽  
Number Range ◽  
High Speeds ◽  
Gliding Flight ◽  
Speed Range ◽  
Simple Regression Analysis ◽  
Drag Analysis ◽  
Very High

1. A bat was trained to fly in a tilting wind tunnel. Stereoscopic photographs were taken, both by reflected and by transmitted light, and measurements of best gliding angle were made. 2. Variation of wing span and area at different speeds was much less than in birds. This is attributed to the construction of the wing, which prevents the bat from folding back the manus in flight, because this would lead to collapse of the plagiopatagium. 3. The trailing edge of the wing is normally deflected upwards in flight, at least in the distal parts. This is interpreted as providing longitudinal stability. The plagiopatagialis proprii muscles appear to act as an elevator, by deflecting the trailing edge of the plagiopatagium upwards. 4. The speed range over which the bat could glide was 5·3-11·0 m/s. Its maximum lift coefficient was 1·5, and its best glide ratio 6·8:1. The Reynolds number range, based on mean chord, was 3·26 x 104 to 6·79 x 104. 5. A simple regression analysis of the glide polar indicated a very high span efficiency factor (k) and low wing profile drag coefficient (Cdp). On the other hand, a drag analysis on the assumption that k = 1 leads to an improbably large increase in the estimated Cdp at low speeds. It is suggested that the correct interpretation probably lies between these extremes, with k ≊ 1·5; Cdp would then be about 0·02 at high speeds, rising to somewhat over 0·1 at the minimum speed. 6. It would appear that the bat is not so good as a pigeon at fast gliding, but better at low-speed manoeuvring. On most points of performance, however, the two are remarkably similar.

scholarly journals Hypersonic Free Flight Investigation on Rudder Reflection of Aircraft

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 542
Author(s):  
Fei Xue ◽  
Yuchao Wang ◽  
Zenghui Jiang ◽  
Yinong Yang
Keyword(s):  
Wind Tunnel ◽  
Degrees Of Freedom ◽  
Wind Tunnel Test ◽  
Model Matching ◽  
Free Flight ◽  
Control Effect ◽  
Time Curve ◽  
Hypersonic Wind Tunnel ◽  
Before And After ◽  
Ejection Mechanism

In order to study the control effect of the rudder surface of the hypersonic vehicle and the coupling dynamic characteristics of the rudder surface deflection and the flight attitude, a technical platform for the deflection and motion coupling of the aircraft rudder surface was designed. The platform ejection mechanism can launch the model into the wind tunnel flow field according to the preset attitude, and model can free flight without support interference. The innovative design of the model internal rudder partial system can guarantee the model to deflect the rudder surface in the free flight process, simulate the real steering process of the aircraft. By changing spring with different springs, the speed of the rudder surface can be changed. The dual optical path and image acquisition technology can capture the motion picture before and after the deflection of the rudder surface from two angles. After the image is matched by model matching, the six degrees of freedom parameter of the model can be changed with the time curve before and after the deflection of the rudder surface, and the area of the six freedom degree curve of the different state model is compared. In other words, the specific influence of dynamic rudder rotation on the motion of the model is known. The wind tunnel test of the model in the hypersonic wind tunnel of the 500 mm is carried out using this platform. The test results are highly repeatable, and the test platform technology is mature and reliable.

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