Adjustment of Existing Whirl Tower Data

The hover performance of a new rotor design may be estimated using test data from a previously tested rotor, even if they are not identical. The effect of differences in solidity, twist, number of blades, and tip Mach number can be estimated from the hover charts and used as correction factors.

Table 1.1 lists a number of whirl tower tests and the characteristics of the rotors tested.

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

З

2

1

0

Example Helicopter a = .085 0! = -10°

ClR = 650 b = 4

Cutout = .15Я NACA 0012 Airfoil

 

0O = 17.5°

 

.00741

.98

.00719 .000111 .000459

.017

7.2

.0846

.61

1.05

.0070 20,400 lbs. 1,990

 

1,000

 

Thrust Cq

D. L. Cj/cr (D. L.)(C7/a) Meas. Pow.

 

Подпись: Cutout = .15Я

.3 .4 .5 .6 .7

Radius Station, r/R

 

.9 1.0

 

1.45 Results of Sample Calculation

 

image116image117image118image119

TABLE 1.1

Tabulation of Published Whirl Tower Tests

Chord

Radius

Ф)

(in)

@ .15 R

No. of Blades

Twist

(deg)

Taper

ct/cr

Solidity @ .75 R

2.5

2

2 to 5

0

1

.042 to.106

20

9.6

3

-8

.5

.038

20

9.6

3

0

.5

.038

18.6

14.4

2

0

1

.041

18.4

13

2

-6.5

1

.037

7.5

14

2

0

1

.097

18.7

1І. З

2

-5.5

. .77

.032

18.8

11.6

2

-5.5

.77

.033

26.8

16.4

2

-8

1

.033

5

9.4

2

-12

.5

.10

18.8

11.6

2

-5.5

•91

.033

4.5

2.7

5

-14

1

.079

18.7

10.6

2

-6

.63

.030

18

10.9

2

-6

.67

.032

2

2

4

-8

1

.11

5

14

4

0

1

.297

Подпись:Airfoil

0015

14

.22

3

.117

1.26

1937

23015

12

.69

6.6

.177

1.27

1952

23015

12

.69

5.7

.164

1.27

1952

8H12

10

.58

5.9

.146

1.28

1954

63 2—015

15

.71

6.1

.192

1.29

1956

0012

20

.45

2.5

.066

1.30

1956

0017 to 0009

14

.72

4.9

.158

1.31

1958

0015

14

.81

4.7

.189

1.32

1958

0012

15

.70

4.4

.191

1.1

1958

0012

18

.98

22

.118

1.33

1960

63215A018

14

.76

7.0

.177

1.34

1960

0012

25

.95

14

.136

1.35

1961

632A015(230)

14

, .67

3.8

.195

1.8

1961

632A012(130)

15

.75

5.1

.179

1.36

1962

0012

10 to 50

.67

13.7

.108

1.37

1970

13006

10

.58

33

.111

1.24

1971

TABLE 1.1 (continued)

Radius

(fi)

Chord

(in)

@ .75 R

No. of Blades

Twist

Taper

ct/cr

Solidity @ .75 R

Airfoil

Cutout

(%R)

Max.

Test

M, ip

Max.

Test

D. L.

Max.

Test

CT/o

Ref

Date

36

26

6

-6

1

.115

0012

24

.63

12.5

.095

1.5

1971

2.2

1.5 & 2

2 to 8

0-8-16 .

1

.034 to.14

0012

15

.63

11.7

.11

1.5

1971

2.2

1.5

2 to 8

0

1 & .5

.034 to.14

0012 & 23112

15

.63

3.0

.112

1.10

1972

17.5

13

2

-4.2

.71

.039

0015

9

.55

1.9

.103

1.4

1972

3

2.3

3

-7 to -9

1

.061

0012,23012,VR7/8

15

.72

9.8

.15

1.38

1973

2.3

1.5

6

0

1

.102

0012

17

.58

8.1

.09

1.39

1974

26 & 29

16.4

3 & 6

-8 & -9

1

.049 & .089

0012

22

.64

12.4

.125

1.40

1976

– 2

5

1

0

1

.066

0012

20

25

2.8

.076

1.41

1976

8

15.4

4

-8

1

.20

0012

18

.60

27.8

.13

1.25

1977