COAST. I ARTILLERY JOURNAL, - Air Defense Artillery

496 THE COAST ARTILLERY JOURNAL
seconds plus time used by range section in tracking to obtain data (should be less
than 30 seconds), a total time of 69 seconds or less to expect one hit on an illuminated
target maintaining rectilinear flight.
7. Constant speed, direction and altitude are not to be expected; neither are
great variation in average speed or general direction nor much change in altitude
to be expected. That loaded bomber has a mission-to get somewhere, to unload,
and to get back. He can vary his speed within certain limits; he can proceed
on a curved course; he can gain altitude but very slowly and while he can lose
altitude quickly, generally he will not want to come closer to lights and guns.
8. To meet the variations in speed, average deflections can be used or barrage
fire can be resorted to. To meet the sinuous course--such an instrument as the
Wilson Computer will permit predictions on a curved course and the present
equipment would place center of impact now over, now short of actual course of
target, which is not so ineffectual. To meet changes in altitude, arbitrary changes
can be set on range instruments and direct fire continued. In any case, whatever
the variation in any of the elements of flight, illumination of the plane will assist
in barrage fire.
9. To meet the problem of fire upon a target flying an irregular course, the
use of large caliber machine guns with tracer ammunition offers great promise.
10. Barrage fire during the World War was usually placed according to expected
line of approach at expected altitude. By using present sound locators
such fire can be placed close to actual line of approach, with angular predictions
for travel, using estimated altitudes to obtain fuze ranges. It is possible that
future development along the lines of the photo-electric cell may give the line
of sight to the target and some means devised of obtaining range (e.g., twostation
observation or estimate based on known speed and angular travel). If the
future should produce some such devices night fire upon unilluminated targets
would approach the efficiency of day fire.
11. The use of star shells has been suggested. After obtaining approximate
location by sound locator several star shells fired in the vicinity of the plane might
disclose the target and facilitate picking up by searchlights. The efficacy of
continuous illumination by star shell is very doubtful. A short burst might blind
the observer and delay opening fire with H. E. shell. It would appear that the
effectiveness of star shell illumination and best methods for its use can De determined
only by experiment.
lII-Coxcu:SIOXS.
12. The Coast Artillery Board is of the opinion that:
a. ~ight fire on a target illuminated by searchlight is equally as efficacious
as day fire, rectilinear flight being necessary for both.
b. As a rule antiaircraft searchlights properly distributed can hold in the
beam a loaded bomber, once illuminated.
c. Equipment and training should provide for direct fire on illuminated target.
d. When fear of such direct fire causes a pilot to avoid rectilinear flight the
same methods must be used as would be used in like circumstances in daylightcontinue
fire with estimated deflections, open barrage fire, or suspend fire.
IV-RECOJD1EXDATIOXS.
13. The Coast Artillery Board recommends that:
«. Equipment and training of antiaircraft organizations be such as to permit
direct fire upon seachlight illuminated target.