FreeOrion

Note: These damage numbers come from total damage showed in the pedia ship design info window in the ship design screen, and are for a generic species before laser fighters have been researched. These numbers were generated with a grav hull but I see the same thing with other hulls. Win32 build dated Dec 13.

1 Interceptor Hanger + 1 Launch Bay shows damage of 2
1 Interceptor Hanger + 2 Launch Bays shows damage of 2.66667
2 Interceptor Hangers + 2 Launch Bays shows damage of 4
2 Interceptor Hangers + 3 Launch Bays shows damage of 6
2 Interceptor Hangers + 4 Launch Bays shows damage of 8
2 Interceptor Hangers + 5 Launch Bays shows damage of 8.66667
2 Interceptor Hangers + 6 Launch Bays shows damage of 9.33333

1 Bomber Hanger + 1 Launch Bay shows damage of 6.66667
2 Bomber Hangers + 1 Launch Bay shows damage of 10
2 Bomber Hangers + 2 Launch Bays shows damage of 20
2 Bomber Hangers + 3 Launch Bays shows damage of 23.3333
2 Bomber Hangers + 4 Launch Bays shows damage of 26.66667
more launch bays don't have further effect after this.

The last 4 interceptor values look off, assuming display of average damage per round:

1 Interceptor Hanger + 1 Launch Bay shows damage of 2
(# fighters * damage per fighter; sum of all combat rounds / # rounds)
(rnd 2: 2 * 1 = 2; rnd 3: 4 * 1 = 4; total 2 + 4 = 6; 6 / 3 = 2)
1 Interceptor Hanger + 2 Launch Bays shows damage of 2.66667
(rnd 2: 4 * 1 = 4; rnd 3: 4 * 1 = 4; total 4 + 4 = 8; 8 / 3 = 2.666~)
2 Interceptor Hangers + 2 Launch Bays shows damage of 4
(rnd 2: 4 * 1 = 4; rnd 3: 8 * 1 = 8; total 4 + 8 =12; 12 / 3 = 4)

2 Interceptor Hangers + 3 Launch Bays shows damage of 6
(rnd 2: 6 * 1 = 6; rnd 3: 8 * 1 = 8; total 6 + 8 = 14; 14 / 3 = 4.666~)
2 Interceptor Hangers + 4 Launch Bays shows damage of 8
(rnd 2: 8 * 1 = 8; rnd 3: 8 * 1 = 8; total 8 + 8 = 16; 16 / 3 = 5.333~)

2 Interceptor Hangers + 5 Launch Bays shows damage of 8.66667
(rnd 2: 8 * 1 = 8; rnd 3: 8 * 1 = 8; total 8 + 8 = 16; 16 / 3 = 5.333~)
2 Interceptor Hangers + 6 Launch Bays shows damage of 9.33333
(rnd 2: 8 * 1 = 8; rnd 3: 8 * 1 = 8; total 8 + 8 = 16; 16 / 3 = 5.333~)