NAVAL AERIAL PHOTOGRAPHY
The problems of naval aerial photography are quite different from those
of military aerial work, and on the whole they are more simple. At the
same time, photography has played a considerably less important part in
naval aerial warfare than in land operations. Photography as a necessary
preparation for attack has not figured in naval practice nearly so much
as have the record and instruction aspects. To some extent this is due
to the nature of the naval operations in the Great War, to some extent
to the limitations of ceiling and cruising radius of the naval aircraft.
A photographic reconnaissance, preceding and following a bombardment of
shore batteries; a photographic record of the ships at anchor, as at
Santiago; a photograph of the forts defending a channel, as at Manila;
photographs, quickly developed and printed, of an approaching fleet—all
these are possibilities of great usefulness in naval warfare between
contestants both of whom “come out” and carry the struggle to the
enemy's gates. But in the recent war the use of the submarine,
operations under cover of fog, the striving for “low visibility,” and
the considerable distances to be traversed to reach the enemy lairs,
have conspired to limit the development of photography as a major aid to
naval combat. Probably when the whole history of the conflict is told we
shall learn that the Zeppelins which cruised over the North Sea, keeping
the Allied fleet under observation, had a regular routine of
photographic work. In the Italian zone, where much of the enemy
territory and several important naval centers lay at only short
distances over the Adriatic, the naval photographic service more nearly
rivalled that of the army than in the English, French and American zone
of activity in the Channel and North Sea.
[Illustration:
FIG. 175.—A lighthouse, as the naval flier sees it.]
[Illustration:
FIG. 176.—A threatened submarine attack. Throwing out a smoke screen
to protect a convoy. British official photograph.]
The majority of the photographs made in the British service were
obliques, taken by short focus (6 to 10 inch) hand-held cameras. This
type was employed partly because of difficulties to be noted presently,
in using other forms of cameras, but more especially because such
pictures sufficed for the kind of information desired. A hand-held
camera formed part of the outfit of each flying boat and dirigible, but,
unlike land reconnaissance, planes ascending primarily for picture
taking were unknown in their naval service. Usually no photographic
objective was predetermined—photographs were made only if objects of
interest were come upon. Mapping also formed no part of the seaplane's
work. Four plates would be carried, instead of as many dozens in the
land machine, and often these would come back unexposed. There were of
course some photographic flights planned out beforehand, for the purpose
of photographing lighthouses and other landmarks whose appearance from
the air should be known to the naval aviator (Fig. 175). Among the
accidental and record types of photograph come convoys (Fig. 176), whose
composition and arrangement were made a matter of record, particularly
if any ship was out of its assigned position. Photographs of oil spots
on the sea surface, or other results of bomb dropping, were necessary
evidence to establish the sinking of a submarine (Fig. 179). Pictures of
all types of ships friendly, neutral, and where possible, enemy—were a
much needed part of naval equipment, in particular pictures of friendly
destroyers and submarines, which should not be bombed by mistake. For
safe navigation it was essential to have photographs of uncharted wrecks
(Fig. 181), of buoys out of place and of ships failing to return signals
or otherwise to comply with rules. The great majority of the pictures
were taken from altitudes of not more than 300 meters.
[Illustration:
FIG. 177.—Submarine coming to the surface.
U. S. Naval Air Service photograph.]
[Illustration:
FIG. 178.—Dropping depth bombs.]
[Illustration:
FIG. 179.—The submarine destroyed. Destroyer on tell-tale oil patch.
British official photographs.]
[Illustration:
FIG. 180.—A convoy at anchor in port.]
Hand-held cameras for naval work have practically the same design as
those for land work. In view of the smaller number of pictures taken on
naval trips, and the consequent absence of any need for great speed in
changing plates, the ordinary two-plate dark slide has been found
satisfactory in the English service. But these are much less convenient
than the bag magazines used in the U. S. Naval hand camera (Fig. 31).
The sights on the naval hand camera are preferably of the rectangular,
field indicating type, especially useful in photographing extended
objects such as convoys. As the flying boat travels comparatively slow,
it is easy for the observer to stand up to take pictures, and the sight
is conveniently placed on top. But if held out over the side for
verticals the sight must be on the bottom. Rectangular sights in both
positions are provided in the English camera (Fig. 186). Naval cameras
should be immune from moisture, which means doing away with all wooden
slides or grooves. A praiseworthy practice is to carry the camera in a
waterproof bag.
[Illustration:
FIG. 181.—Airplane photography as an aid to salvaging. Position of
wrecked merchantman twelve fathoms down revealed by photograph from
the air.
Photograph by British Air Service.]
[Illustration:
FIG. 182.—A sea plane.]
[Illustration:
FIG. 183.—A flying boat.]
[Illustration:
FIG. 184.—A dirigible or “blimp”—possibly the photographic aircraft of
the future.]
[Illustration:
FIG. 185.—English “Type 18” hand camera on bracket for exposing
through side window of flying boat.
British official photograph.]
[Illustration:
FIG. 186.—Camera mounted in bracket from forward cockpit of flying
boat.
British official photograph.]
Cameras other than of the hand-held form have been little used in sea
planes, owing to the difficulties of installation. The hydro-airplane,
consisting of an ordinary airplane fuselage mounted on two pontoons
(Fig. 182), can carry the same kind of photographic equipment as the
land machine. But if it has a single central pontoon this is not
feasible. The hydro-airplane is, however, largely superseded by the
flying boat (Fig. 183), whose fuselage, of boat form, rests directly on
the water. In this type of sea plane, views taken vertically downward
are not easy to make. In the larger flying boats the hull projects out
horizontally a matter of several feet beyond the side of the cockpit. An
ordinary outboard mounting is therefore out of the question. The camera
must either be held out at arm's length or else mounted on a long
bracket (Fig. 186). The usual place for carrying the camera is in the
front cockpit with its magnificent all-round view. Obliques can, too, be
taken in great comfort from the side windows behind the wings, as shown
in Fig. 185. The possibility of cutting a hole in the bottom of a flying
boat to take care of a vertical camera is not entertained in British and
American naval circles. Nevertheless it is the regular practice in the
Italian service, with their small high ceilinged flying boats. In them a
round hole is cut in the floor, stopped with a plug and rubber gasket.
After the boat rises into the air the hole is opened, and the regulation
Italian camera is set securely in a frame on the floor over the hole
(Fig. 187). Photographs are taken to the capacity of the camera, and if
it is desired another camera is put in its place, till all its plates
have been exposed, and then even a third. Before coming down the hole
must of course be closed again. Sliding doors have been designed to
close this aperture, but have not proved sufficiently water-tight,
although such a device could undoubtedly be worked out.
[Illustration:
FIG. 187.—Italian flying boat with camera mounted on the floor.]
With its space for five or more passengers, and with its low speed, the
modern flying boat affords an excellent craft for photographic work.
There is ample room for any size of camera, and for any style of
mounting, if we assume that there is no objection to an opening in the
bottom. The low ceiling of these ships, however, prevents their use for
certain forms of aerial photography which should be of the greatest
importance. Operations against shore stations—harbors, docks, shipyards,
ships at anchor, and fortifications—cannot be undertaken for fear of
anti-aircraft guns and hostile land planes. The solution of the problem
of carrying and launching fast high flying planes from ships will
immediately extend the usefulness of aerial photography to coastal work.
In the recent war, such of this as was done, along the Belgian coast—the
shore batteries, and the results of naval operations at Zeebrugge and
Ostend—was done by land planes from territory held by the Allies. The
photographic equipment of sea planes of the type suggested will of
course present special problems, but the apparatus used will be apt to
approximate closely to that of the land planes.
VII
THE FUTURE OF AERIAL PHOTOGRAPHY