LATERAL DIRECTIONAL FLYING QUALITIES

Requirements on the three lateral-directional modes to assure a desired level of flying quality can be found in Reference 9.1. Although specific to military aircraft, these criteria can obviously prove of use in the evaluation or design of civil aircraft. Tables 10.1, 10.2, and 10.3 present criteria for the three

Table 10.1 Maximum Roll Mode Constant

Right Phase Category

Class"

Level

1

2 3

A

I, IV

1.0

1.4

II, III

1.4

3.0

В

All

1.4

3.0 10

C

I, II-C, IV

1.0

1.4

II-L, III

1.4

3.0

“ C and L refer to carrier and land operations.

Table 10.2 Minimum Dutch Roll Frequency and Damping

Level

Right Phase Category

Class

Min £

Min £w„, rad/sec

Min 0)„, rad/sec

A

I, IV

0.19

0.35

1.0

II, III

0.19

0.35

0.4

1

В

All

0.08

0.15

0.4

C

I, II-C

IV

0.08

0.15

1.0

II-L, III

0.08

0.15

0.4

2

All

All

0.02

0.05

0.4

3

All

All

0.02

0.4

Table 10.3 Spiral Stability—Minimum Time-to-Double Amplitude

Class

Flight Phase Category

Level 1, sec

Level 2,

sec

Level 3, sec

I and IV

A

12

12

4

В and C

20

12

4

II and III

All

20

12

4

modes as a function of the Cooper-Harper level, flight phase category, and class of airplane. Airplane class is defined according to:

Class I —Small, light airplanes.

Class II —Medium weight, low-to-medium maneuverability.

Class III—Large, heavy, low-to-medium maneuverability.

Class IV—High maneuverability.

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