A Roundabout for Studying Sustained Flight of Locusts

1952 ◽  
Vol 29 (2) ◽  
pp. 211-219 ◽  
Author(s):  
AUGUST KROGH ◽  
TORKEL WEIS-FOGH
Keyword(s):  
Wind Tunnel ◽  
External Factors ◽  
Flight Performance ◽  
Average Speed ◽  
Preliminary Results ◽  
Air Resistance

A roundabout technique is described which makes it possible to study the flight performance of a small ‘swarm’ of locusts (up to thirty-two individuals) for hours at a time. The resistance of the roundabout was compensated by means of a mill so that the locusts only had to overcome their own air resistance. The speed of the revolving periphery therefore equalled the preferred average flying speed of the suspended locusts. The average speed during a period, as well as the variation in speed in the course of an experiment, were found to be the same in the roundabout and in experiments where single locusts flew in front of a wind tunnel. In the latter case the insects flew in completely normal flight posture. It was concluded that the results obtained with the roundabout were as valid as the results obtained with a wind tunnel. Some preliminary results are given on the influence of different external factors on the flying speed and the ability to endure sustained flight.

Morphing wing with skin discontinuity – kinematic concept

2017 ◽  
Vol 89 (4) ◽  
pp. 535-546 ◽  
Author(s):  
Andrzej Tarnowski
Keyword(s):  
Wind Tunnel ◽  
Performance Optimization ◽  
Numerical Optimization ◽  
Design Methodology ◽  
Control Allocation ◽  
Flight Performance ◽  
Content Type ◽  
Original Contribution ◽  
Wing Morphing ◽  
Kinematic Solution

Purpose This paper aims to describe the concept of morphing tailless aircraft with discontinuous skin and its preliminary kinematic solution. Project assumptions, next steps and expected results are briefly presented. Design/methodology/approach Multidisciplinary numerical optimization will be used to determine control allocation for wing segments rotation. Wing demonstrator will be fabricated and tested in wind tunnel. Results will be used in construction of flying model and design of its control system. Flight data of morphing demonstrator and reference aircraft will result in comparative analysis of both technologies. Findings Proposed design combines advantages of wing morphing without complications of wing’s structure elastic deformation. Better performance, stability and maneuverability is expected due to wing’s construction which is entirely composed of unconnected wing segments. Independent control of each segment allows for free modeling of spanwise lift force distribution. Originality/value Nonlinear multipoint distribution of wing twist as the only mechanism for control and flight performance optimization has never been studied or constructed. Planned wind tunnel investigation of such complex aerodynamic structure has not been previously published and will be an original contribution to the development of aviation and in particular to the aerodynamics of wing with discontinuous skin.

Effects of wind assistance and resistance on the forward motion of a runner

1980 ◽  
Vol 48 (4) ◽  
pp. 702-709 ◽  
Author(s):  
C. T. Davies
Keyword(s):  
Wind Tunnel ◽  
Energy Cost ◽  
Healthy Male ◽  
Forward Motion ◽  
Body Lift ◽  
Air Resistance ◽  
Wind Velocities ◽  
Male Subjects

The aerobic energy cost (delta VO2) of running at different speeds (V) with and against a range of wind velocities (WV) has been studied in a wind tunnel on three healthy male subjects and the results compared with downhill and uphill gradient running on a motor-driven treadmill. In terms of equivalent horizontal and vertical forces, comparison showed that the two forms of exercise were physiologically identical for gradients and WV ranging from -10 to +5% and 1.5 to 15 m . s-1, respectively. The apparent mechanical efficiencies of the work performed with a head and following wind were approximately +0.35 and -1.2. At WV greater than 15 m . s-1 it was more efficient to run against the wind and the corresponding gradient on the treadmill. At high WV the subjects altered their posture and "leaned" into the wind, thus possibly converting potential drag into body lift. The energy cost of overcoming air resistance on a calm day outdoor was calculated to be 7.8% for sprinting (10 m . s-1), 4% middle-distance (6 m . s-1), and 2% marathon (5 m . s-1) running.

RA-2/MWR in-flight performance - preliminary results

2003 ◽  
Author(s):  
M. Roca ◽  
S. Laxon ◽  
C. Zelli ◽  
A. Martini ◽  
C. Celani ◽  
...  
Keyword(s):  
Flight Performance ◽  
Preliminary Results

Energy cost of speec skating and efficiency of work against air resistance

1976 ◽  
Vol 40 (4) ◽  
pp. 584-591 ◽  
Author(s):  
P. E. Di Prampero ◽  
G. Cortili ◽  
P. Mognoni ◽  
F. Saibene
Keyword(s):  
Lactic Acid ◽  
Wind Tunnel ◽  
Energy Cost ◽  
Inertial Forces ◽  
Lactic Acid Concentration ◽  
Body Area ◽  
Direct Estimate ◽  
Unit Distance ◽  
Air Resistance ◽  
Speed Range

The energy expenditure during speed ice skating (PB=650 mmHg; T=-5 degrees C) was measured on 13 athletes (speed range: 4–12 m/s) from VO2 and (for speeds greater than 10 m/s) from blood lactic acid concentration. The energy spent (O2 equivalents) per unit body wt and unit distance (Etot/V, ml/kg-min) increases with the speed (v, m/s): Etot/v=0.049 + 0.44 X 10(-3) V2. At 10 m/s, Vtot/v amounts then to 0.093 ml/kg-m: about half the value of running. The constant 0.049 ml/kg-m is interpreted as the energy spent against gravitational and inertial forces. The term 0.44 X 10(-3) v2 indicates the energy spent against the wind, the constant 0.44 X 10(-3) ml-s2-kg-1-m-3 being a measure of k/e, where k is the coefficient relating drag to v2, and e the efficiency of work against the wind. From a direct estimate of k in a wind tunnel, e was calculated as 0.11. In running, skating, and cycling k/e is similar (approximately 0.020 ml-s2-m-3 per m2 body area), hence at a given speed the energy spent against the wind is equal. On the contrary, the energy spent against other forces decreases in the above order: 0.19, 0.05, 0.018 ml-m-1 per kg body wt. This explains the different speeds attained in these exercises with the same power output.

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