THE APPLICATION OF THE COLORED BACKGROUND ORIENTED SCHLIEREN TECHNIQUE (CBOS) TO WIND TUNNEL, FREE-FLIGHT AND IN-FLIGHT MEASUREMENTS

2009 ◽  
Vol 16 (4) ◽  
pp. 279-293 ◽  
Author(s):  
F. Leopold
Keyword(s):  
Wind Tunnel ◽  
Free Flight ◽  
Schlieren Technique ◽  
Colored Background ◽  
Background Oriented Schlieren ◽  
Flight Measurements

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.

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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