Transcriber’s Note: Italic text is enclosed in _underscores_; boldface
text is enclosed in =equals signs=. Subscripts are actual subscript
characters.
[Illustration: (cover)]
BALLOON OBSERVATION
and INSTRUCTIONS
on the subject of
WORK IN THE BASKET
❦
_Issued by the_
Division of Military Aeronautics
U.S. Army
¶ A free translation of the French booklet
“Instructions au sujet du Travail en Nacelle,”
and an added discourse on Balloon Observations
[Illustration]
WASHINGTON
GOVERNMENT PRINTING OFFICE
AUGUST, 1918
PART I.
BALLOON OBSERVATION.
INTRODUCTORY NOTE.
In this pamphlet will be laid down the general principles and also the
limitations which govern observation from balloons. Balloon observation
includes more than actual artillery observation. (See “Employment of
Balloons.”)
The details of cooperation between balloons and artillery are issued
from time to time by the General Staff in the form of pamphlets.
Whatever the system ordered at the time, there are certain principles
which do not change.
In artillery observation it can not be emphasized too strongly that
success depends both on--
1. The efficiency of the balloon observers, including an intimate
knowledge of the ground within view.
2. An intimate knowledge by artillery commanders of the possibilities
and limitations of balloon observation.
The limitations of balloon observation are--
1. Distance from the target.
2. Height of observer.
3. Visibility.
Distance from the target is inevitable, but can be lessened by advanced
positions and winch tracks. During active operation it has sometimes
been possible to approach balloons within 4,500 meters (4,921 yards) of
the line.
The low height of the balloon compared with an aeroplane is a drawback,
as it brings a question of dead ground and exaggerated perspective.
Visibility is the determining factor of the balloon’s usefulness.
In very high winds, very misty or cloudy weather, observation is
impossible, and owing to its stationary nature the balloon can not, by
any special effort on the part of its observers, overcome unfavorable
conditions in the same way as is possible in the case of aeroplane
observation.
On the other hand, a balloon flying at a height of 1,500 meters (1,640
yards) and 7,000 meters (7,651 yards) from the line, under favorable
weather conditions, combines in a marked degree many of the advantages
of air and ground observation.
In the first place, glasses can be used. Secondly, the balloon observer
can converse direct with the battery commander by telephone. Apart,
therefore, from ease and certainty in reporting observations, the
telephone system enables an elastic program of work to be drawn up and
admits of personal conversation between the battery commander and the
observer, often permitting mistakes or misunderstandings to be cleared
up during shoot instead of afterwards.
Finally, owing to the continuous nature of his observation from the
same spot, the balloon observer is able to learn his country in the
greatest detail and can keep a close watch on suspected roads or areas
of country.
LIAISON BETWEEN BALLOONS AND ARTILLERY
The work of balloons is principally with the artillery, and close
liaison between these two branches is indispensable if the best results
are to be obtained. This close liaison should be promoted on the
following lines:
(_a_) Balloon companies should each, as far as possible, be allotted
specific artillery organizations. This facilitates telephone
communication, prevents duplication of liaison work, and leads to a far
more intimate and personal liaison than does any other method.
(_b_) Balloon observers must visit batteries frequently, and sometimes
be attached for short periods. Shoots should be discussed, especially
if unsuccessful. Observers should prepare and take with them when
visiting batteries a list of targets which are clearly visible from the
balloon and on which they can observe effectively. Similarly, artillery
commanders should let balloon observers know of any further targets
which they especially wish to engage, as work previously prepared on
the ground saves time and gives better results.
(_c_) Artillery officers should visit the balloon and make ascents.
They will thus become acquainted with the extent of view from the
balloon and the ability and difficulties of the observers.
EMPLOYMENT OF BALLOONS.
In view of the above, the work most suitable for balloons is as follows:
GENERAL SURVEYANCE OF ENEMY’S ACTIVITIES.
(_a_) Reporting modifications of enemy defensive organization;
detecting movements of convoys and trains. Their importance and
itineraries, locating infantry signals, and all other activities such
as revealed by fires, smokes, dust, trails, etc.
(_b_) Spotting active hostile batteries and reporting hostile shelling.
Reporting hostile shelling is a duty for which balloons are especially
suitable, as they are favorably situated to observe both the flash of
the gun and the fall of the shell. From this information it is possible
to direct not only neutralizing fire on the hostile battery, but often
also to establish the caliber of the guns and the arc of fire of the
battery.
RANGING AND ADJUSTING OF FIRE.
(_a_) Observing fire for destruction on all targets, counterbattery, or
bombardment.
(_b_) Reporting fleeting targets and observing fire on them.
(_c_) Observing for registration fire.
(_d_) Observing fire on the enemy’s communications.
(_e_) Cooperation with aeroplanes.
PART II.
WORK IN THE BASKET.
[Translation of French document, “Instructions au sujet du Travail en
Nacelle,” a publication of French G. Q. G., 1918, by Lieut. Kellogg.]
The rapidity and precision of the work in the basket depend not only on
the natural gifts of the observer, but also very largely on his methods
of work.
The object of the following instructions is to tell the student
observers the general methods they should follow and to explain the use
of these methods.
The principal operations which they must be able to execute rapidly are
as follows:
1. Orientation and general reconnaissance of the terrain.
2. Spotting points on the ground seen on the map and points on the map
seen on the ground.
3. Observation of fire.
CHAPTER 1.
ORIENTATION AND GENERAL RECONNAISSANCE OF THE TERRAIN.
This is the operation which the observer executes on his first
ascension in a new sector; this is how it should be conducted.
1. _Rapidly look over the terrain around the ascensional point in order
to orient the map._
This is done by finding in some direction from the ascensional point a
line giving an easily identified direction (a road, an edge of woods,
etc.). Orient the map so as to make this line on the map parallel to
the line on the ground.
The map can also be oriented by means of the compass.
2. _Locate the horizontal projection of the balloon._
The observer may know already the winch position, but the balloon is
carried off horizontally from the winch sometimes as much as 400 or
500 meters (436 to 545 yards). Thus it is essential not to confuse the
winch position with the horizontal projection of the balloon. If this
is done, errors will be made in the operations which we are going to
discuss later, where we make use of this known point.
It is pretty hard to materialize definitely the vertical line passing
through the basket. The effect of the wind and the movements of the
balloon make it impossible to use a plumb line. The observer has to
find his projection on the ground by leaning first from one side of
the basket and then from the other in order to diminish the chances of
error. An approximation of 25 or 50 meters is sufficiently accurate for
the general reconnaissance which it is necessary to make.
3. _Leaving the region beneath the balloon, acquaint yourself, step by
step, with the most prominent points in different directions--masses of
woods, villages, etc._
There are two methods--by the process of cheminement or tracing
landmarks and by the process of direct alignment.
The process of “=cheminement=” or tracing consists in following
outlines, such as roads, streams, or hedges, identifying as you go
along details of the terrain which these lines pass through or near.
On account of the deformations due to the effect of perspective and
to the unevenness of the ground, and particularly on account of the
deformation of angles, if it is a winding road, this method often leads
to errors; it should be employed only in certain cases defined below:
The process of “=direct alignment=” consists of studying the terrain by
following successive directions from the balloon position.
We call the “alignment” of a point the trace, on the terrain, of the
vertical plane passing through this point and through the eye of the
observer; in perspective vision, when the observer determines the point
in question, this alignment would appear to him a vertical line. On the
map it is nothing more than the straight line joining the point under
consideration to the vertical projection of the balloon.
The method of alignment, then, consists in first identifying the most
prominent points near the balloon and finding, by cheminement or
tracing, the lines running from these points. =A point found directly
by cheminement should not be considered as definitely determined until
its alignment has been verified.=
This first reconnaissance is not to study the terrain in all its
details, but only to fix in the memory a certain number of prominent
points scattered throughout the sector in order to facilitate later
work.
These points should be very distinct, visible to the naked eye, and
of characteristic forms, so that there will be no danger of confusing
them with others--masses of woods, important villages, etc. Roads
with borders of trees, large paths for hauling supplies, when taken
together, are very valuable for quickly finding others.