An evaluation of the effects of flexibility on wing strains in rough air for a large swept-wing airplane by means of experimentally determined frequency-response functions with an assessment of random-process techniques employed Page: 2 of 77

                                
TECH LIBRARY KAPB, NM
0067239

NACA TN 4291

CONTENTS

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1

BUMMARY  . . . . .  . . . . . . .  . . . . . . . .  . . . . . . .a
IN T  UCTION  . . . . . . . . . . ..............
I. DETEIIAL8TION OF FREQUENCY-RESPONSE FUNCTIONS FOR STRAIN
RESPONSE TO VERTICAL GUS        . . . . . . .ose  * *    .  .   .
AIRPLANE, INSTREUMENTATION, AND TESTS . . . . . . . . . ..
MET3D  OF DEERMI ININ  FREQUE NCY-RESPONSE FUNCTIONS . . .

EVALUATION OF DATA AND RESULTS      . . . . . . .
Evaluation of Time Histories        ........
Strains ..................
Quasi-static reference condition      .....
Normalization procedure . . . . . . . . .
Vertical-gust velocity     . . . . .   . . . .
Power Spectra and Cross-Spectra Determinations
Power spectra ...............
Prewhitenin   of vertical-gust velocity     . .
Crosse-spectra ....t...........
Frequency-Response Functions      ...    .... .

EFFECT OF AIRPLANE FLn0   IBILITT  ON WIN   STRUCTURAL S RA INS
Power Spectra of Strains       .   ............ .
Frequency-Response Functions      ..............
II. REEIABILITY OF ESTIMATES OF FREQUENCY-RESPONBE FUNCTIONS
OBAINED BY RANDM-PROCESS TEC      IQUES . . .     ......
COERENCY FUNCTION AND STATISTICAL RETLIABILITY        ......
Coherency Function     .      .      . . . . . . . . .....
Statistical Reliability .....           ......           . . . .

EFFECTS OF NOISES ON FREQUENY-RESPONSE
Elementary Cases of Noise .....
Case (a): Noise in measured input
Case (b): Noise in measured output
Noise in both input and output . .
Effect of Additional Gust Conponents
Two-Dimensional Turbulence . . . . .

FUNCTION ESTIMATES
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