Page:Informational Intelligence Summary No. 85.pdf/10

 feet indicated from a cruising speed of two hundred forty (240) miles per hour indicated the P-51 accelerated away from Zero, but slightly slower than at five and ten thousand feet.

P-51 could dive away from Zero at any time. P-51's power plant failed to operate properly above fifteen thousand (15,000) feet so test was not continued above this altitude.

12. :

The Zero is superior to the F4F-4 in speed and climb at all altitudes above 1000 feet, and is superior in service ceiling and range. Close to sea level, with the F4F-4 in neutral blower, the two planes are equal in level speed. In dive the two planes are equal with the exception that the Zero's engine cuts out in pushovers. There is no comparison between the turning circles of the two airplanes due to the relative wing loadings and resultant low stalling speed of the Zero. In view of the foregoing, the F4F-4 type in combat with the Zero is basically dependent on mutual support, internal protection, and pull-outs or turns at high speeds where minimum radius is limited by structural or physiological effects of acceleration (assuming that the allowable acceleration on the F4F is greater than that for the Zero). However advantage should be taken where possible, of the superiority of the F4F in pushovers and rolls at high speed, or any combination of the two.

13. :

The Zero is far inferior to the F4U-1 in level and diving speeds at all altitudes. It is inferior in climb at sea level, and inferior above 20000 feet. Between 5000 and 19000 feet the situation varies. With slightly more than normal fighter load, which may be distributed to give equal range and gun power, the Zero is slightly superior in average maximum rate of climb. This superiority becomes negligible at altitudes where carburetor air temperatures in the F4U are down to normal; close to the blower shift points it is more marked. However, the Zero cannot stay with the F4U in high speed climbs. The superiority of the F4U at 30000 feet is very marked and will persist at considerably higher loads. Attention is called to the fact that in the foregoing condition of loading all fuel in the F4U-1 is protected. In combat with the Zero, the F4U should take full advantage of its speed, and its ability to pushover and roll at high speed if surprised. Due to its much higher wing loading, the F4U should avoid any attempt to turn with the Zero unless at high speed, and may expect the latter to outclimb him at moderate