Accurate and effective bombing is the ultimate purpose of your entire airplane and crew. Every other function is preparatory to hitting and destroying the target.
That's your bombardier's job. The success or failure of the mission depends upon what he accomplishes in that short interval of the bombing run.
When the bombardier takes over the airplane for tbe run on the target, he is in absolute com-mand. He will tell you what he wants done, and until he tells you "Bombs away," his word is law.
A great deal, therefore, depends on the understanding between bombardier and pilot. You expect your bombardier to know his job when he takes over. He expects you to understand the problems involved in his job, and to give him full cooperation. Teamwork between pilot and bombardier is essential.
Under any given set of conditions—ground-speed, altitude, direction, etc.-there is only one point in space where a bomb may be released from the airplane to hit a predetermined object on the ground.
There are many things with which a bombardier must be thoroughly familiar in order to release his bombs at the right point to hit this predetermined target.
He must know and understand his bomb-sight, what it does, and how it does it.
He must thoroughly understand the operation and upkeep of his bombing instruments and equipment.
He must know that his racks, switches, controls, releases, doors, linkage, etc., are in first-class operating condition.
He must understand the automatic pilot as it pertains to bombing.
He must know how to set it up, make any adjustments and minor repairs while in flight.
He must know how to operate all gun positions in the airplane.
He must know how to load and clear simple stoppages and jams of machine guns while in flight.
He must be able to load and fuse his own bombs.
He must understand the destructive power of bombs and must know the vulnerable spots on various types of targets.
He must understand the bombing problem, bombing probabilities, bombing errors, etc.
He must be thoroughly versed in target identification and in aircraft identification.
The bombardier should be familiar with the duties of all members of the crew and should be able to assist the navigator in case the navigator becomes incapacitated.
For the bombardier to be able to do his job, the pilot of the aircraft must place the aircraft in the proper position to arrive at a point on a circle about the target from which the bombs can be released to hit the target.
Consider the following conditions which affect the bomb dropped from an airplane:—
1. ALTITUDE: Controlled by the pilot. Determines the length of time the bomb is sustained in flight and affected by atmospheric conditions, thus affecting the range (forward travel of the bomb) and deflection (distance the bomb drifts in a crosswind with respect to airplane's ground track).
2. TRUE AIRSPEED: Controlled by the pilot. The measure of the speed of the airplane through the air. It is this speed which is imparted to the bomb and which gives the bomb its initial forward velocity and, therefore, affects the trail of the bomb, or the distance the bomb lags behind the airplane at the instant of impact.
3. BOMB BALLISTICS: Size, shape and density of the bomb, which determines its air resistance. Bombardier uses bomb ballistics tables to account for type of bomb.
4. TRAIL: Horizontal distance the bomb is behind the airplane at the instant of impact. This value, obtained from bombing tables, is set in the sight by the bombardier. Trail is affected by altitude, airspeed, bomb ballistics and air density, the first 2 factors being controlled by the pilot.
5. ACTUAL TIME OF FALL: Length of time the bomb is sustained in air from instant of release to instant of impact. Affected by altitude, type of bomb and air density. Pilot controls altitude to obtain a definite actual time of fall.
6. GROUNDSPEED: The speed of the airplane in relation to the earth's surface. Ground-speed affects the range of the bomb and varies with the airspeed, controlled by the pilot.
Bombardier enters groundspeed in the bombsight through synchronization on the target. During this process the pilot must maintain the correct altitude and constant airspeed.
7. DRIFT: Determined by the direction and velocity of the wind, which determines the distance the bomb will travel downwind from the airplane from the instant the bomb is released to its instant of impact. Drift is set on the bomb-sight by the bombardier during the process of synchronization and setting up course.
The above conditions indicate that the pilot plays an important part in determining the proper point of release of the bomb. Moreover, throughout the course of the run, as explained below, there are certain preliminaries and techniques which the pilot must understand to insure accuracy and minimum loss of time.
Prior to takeoff the pilot must ascertain that the airplane's flight instruments have been checked and found accurate. These are the altimeter, airspeed indicator, free air temperature gauge and all gyro instruments. These instruments must be used to determine accurately the airplane's attitude.
The Pilot's Preliminaries
The autopilot and PDI should be checked for proper operation. It is very important that PDI and autopilot function perfectly in the air; otherwise it will be impossible for the bombardier to set up an accurate course on the bombing run. The pilot should thoroughly familiarize himself with the function of both the C-l autopilot and PDI.
If the run is to be made on the autopilot, the pilot must carefully adjust the autopilot before reaching the target area. The autopilot must be adjusted under the same conditions that will exist on the bombing run over the target. For this reason the following factors should be taken into consideration and duplicated for initial adjustment.
1. Speed, altitude and power settings at which run is to be made.
2. Airplane trimmed at this speed to fly hands off with bomb bay doors opened.
The same condition will exist during the actual run, except that changes in load will occur before reaching the target area because of gas consumption. The pilot will continue making adjustments to correct for this by disengaging the autopilot elevator control and re-trimming the airplane, then re-engaging and adjusting the autopilot trim of the elevator.
Setting Up the Autopilot
One of the most important items in setting up the autopilot (see pp. 185-188) for bomb approach is to adjust the turn compensation knobs so that a turn made by the bombardier will be coordinated and at constant altitude. Failure to make this adjustment will involve difficulty and delay for the bombardier in establishing an accurate course during the run—with the possibility that the bombardier may not be able to establish a proper course in time, the result being considerably large deflection errors in point of impact.
Uncoordinated turns by the autopilot on the run cause erratic lateral motion of the course hair of the bombsight when sighting on target. The bombardier in setting up course must eliminate any lateral motion of the fore-and-aft hair in relation to the target before he has the proper course set up. Therefore, any erratic motion of the course hair requires an additional correction by the bombardier, which would not be necessary if autopilot was adjusted to make coordinated turns.
USE OF THE PDI: The same is true if PDI is used on the bomb run. Again, coordinated smooth turns by the pilot become an essential part of the bomb run. In addition to added course corrections necessitated by uncoordinated turns, skidding and slipping introduce small changes in airspeed affecting synchronization of the bombsight on the target. To help the pilot flying the run on PDI, the airplane should be trimmed to fly practically hands off.
Assume that you are approaching the target area with autopilot properly adjusted. Before reaching the initial point (beginning of bomb run) there is evasive action to be considered. Many different types of evasive tactics are employed, but from experience it has been recommended that the method of evasive action be left up to the bombardier, since the entire antiaircraft pattern is fully visible to the bombardier in the nose.
EVASIVE ACTION: Changes in altitude necessary for evasive action can be coordinated with the bombardier's changes in direction at specific intervals. This procedure is helpful to the bombardier since he must select the initial point at which he will direct the airplane onto the briefed heading for the beginning of the bomb run.
Should the pilot be flying the evasive action on PDI (at the direction of the bombardier) he must know the exact position of the initial point for beginning the run, so that he can fly the airplane to that point and be on the briefed heading. Otherwise, there is a possibility of beginning to run too soon, which increases the airplane's vulnerability, or beginning the run too late, which will affect the accuracy of the bombing. For best results the approach should be planned so the airplane arrives at the initial point on the- briefed heading, and at the assigned bombing altitude and airspeed.
At this point the bombardier and pilot as a team should exert an extra effort to solve the problem at hand. It is now the bombardier's responsibility to take over the direction of flight, and give directions to the pilot for the operations to follow. The pilot must be able to follow the bombardier's directions with accuracy and minimum loss of time, since the longest possible bomb run seldom exceeds 3 minutes. Wavering and indecision at this moment are disastrous to the success of any mission, and during the crucial portion of the run, flak and fighter opposition must be ignored if bombs are to hit the target. The pilot and bombardier should keep each other informed of anything which may affect the successful completion of the run.
HOLDING A LEVEL: Either before or during the run, the bombardier will ask the pilot for a level. This means that the pilot must accurately level his airplane with his instruments (ignoring the PDI). There should be no acceleration of the airplane in any direction, such as an increase or decrease in airspeed, skidding or slipping, gaining or losing altitude.
For the level the pilot should keep a close check on his instruments, not by feel or watching the horizon. Any acceleration of the airplane during this moment will affect the bubbles (through centrifugal force) on the bomb-sight gyro, and the bombardier will not be able to establish an accurate level.
For example, assume that an acceleration occurred during the moment the bombardier was accomplishing a level on the gyro. A small increase in airspeed or a small skid, hardly perceptible, is sufficient to shift the gyro bubble liquid 1° or more. An erroneous tilt of 1° on the gyro will cause an error of approximately 440 feet in the point of impact of a bomb dropped from 20,000 feet, the direction of error depending on direction of tilt of gyro caused by the erroneous bubble reading.
HOLDING ALTITUDE AND AIRSPEED: As the bombardier proceeds to set up his course (synchronize), it is absolutely essential that the pilot maintain the selected altitude and airspeed within the closest possible limits. For every additional 100 feet above the assumed 20,000-foot bombing altitude, the bombing error will increase approximately 30 feet, the direction of error being over. For erroneous airspeed, which creates difficulty in synchronization on the target, the bombing error will be approximately 170 feet for a 10 mph change in airspeed. Assuming the airspeed was 10 mph in excess, from 20,000 feet, the bomb impact would be short 170 feet.
The pilot's responsibility to provide a level and to maintain a selected altitude and airspeed within the closest limits cannot be over-emphasized.
If the pilot is using PDI (at the direction of the bombardier) instead of autopilot, he must be thoroughly familiar with the corrections demanded by the bombardier. Too large a correction or too small a correction, too soon or too late, is as bad as no correction at all. Only through prodigious practice flying with the PDI can the pilot become proficient to a point where he can actually perform a coordinated turn, the amount and speed necessary to balance the bombardier's signal from the bombsight.
Erratic airspeeds, varying altitudes, and poorly coordinated turns make the job of establishing course and synchronizing doubly difficult for both pilot and bombardier, because of the necessary added corrections required. The resulting bomb impact will be far from satisfactory.
After releasing the bombs, the pilot or bombardier may continue evasive action—usually the pilot, so that the bombardier may man his guns.
The pilot using the turn control may continue to fly the airplane on autopilot, or fly it manually, with the autopilot in a position to be engaged by merely flipping the lock switches. This would provide potential control of the airplane in case of emergency.
REDUCING CIRCULAR ERROR: One of the greatest assets towards reducing the circular error of a bombing squadron lies in the pilot's ability to adjust the autopilot properly, fly the PDI, and maintain the designated altitude and airspeeds during the bombing run. Reducing the circular error of a bombing squadron reduces the total number of aircraft required to destroy a particular target. For this reason both pilot and bombardier should work together until they have developed a complete understanding and confidence in each other.
THE RADIO OPERATOR
There is a lot of radio equipment in today's B-17's. There is one man in particular who is supposed to know all there is to know about this equipment. Sometimes he does, but often he doesn't. And when the radio operator's deficiencies do not become apparent until the crew is in the combat zone, it is then too late. Too often the lives of pilots and crew are lost because the radio operator has accepted his responsibility indifferently.
Radio is a subject that cannot be learned in a day. It cannot be mastered in 6 weeks, but sufficient knowledge can be imparted to the radio man during his period of training in the United States if he is willing to study. It is imperative that you check your radio operator's ability to handle his job before taking him overseas as part of your crew. To do this you may have to check the various departments to find any weakness in the radio operator's training and proficiency and to aid the instructors in overcoming such weaknesses.
Training in the various phases of the heavy bomber program is designed to fit each member of the crew for the handling of his jobs. The radio operator will be required to:
1. Render position reports every 30 minutes.
2. Assist the navigator in taking fixes.
3. Keep the liaison and command sets properly tuned and in good operating order.
4. Understand from an operational point of view:
(a) Instrument landing
and other navigational aids equipment in the airplane.
5. Maintain a log.
In addition to being a radio operator, the radio man is also a gunner. During periods of combat he will be required to leave his watch at the radio and take up his guns. He is often required to learn photography. Some of the best pictures taken in the Southwest Pacific were taken by radio operators. The radio operator who cannot perform his job properly may be the weakest member of your crew—and the crew is no stronger than its weakest member.
Size up the man who is to be your engineer. This man is supposed to know more about the airplane you are to fly than any other member of the crew.
He has been trained in the Air Forces' highly specialized technical schools. Probably he has served some time as a crew chief. Nevertheless, there may be some inevitable blank spots in his training which you, as a pilot and airplane commander, may be able to fill in.
Think back on your own training. In many courses of instruction, you had a lot of things thrown at you from right and left. You had to concentrate on how to fly; and where your equipment was concerned you learned to rely more and more on the enlisted personnel, particularly the crew chief and the engineer, to advise you about things that were not taught to you because of lack of time and the arrangement of the training program.
Both pilot and engineer have a responsibility to work closely together to supplement and fill in the blank spots in each other's education.
To be a qualified combat engineer a man must know his airplane, his engines, and his armament equipment thoroughly. This is a big responsibility: the lives of the entire crew, the safety of the equipment, the success of the mission depend upon it squarely.
He must work closely with the copilot, checking engine operation, fuel consumption, and the operation of all equipment.
He must be able to work with the bombardier, and know how to cock, lock, and load the bomb racks. It is up to you, the airplane commander, to see that he is familiar with these duties, and, if he is hazy concerning them, to have the bombardier give him special help and instruction.
He must be thoroughly familiar with the armament equipment, and know how to strip, clean, and re-assemble the guns.
He should have a general knowledge of radio equipment, and be able to assist in tuning transmitters and receivers.
Your engineer should be your chief source of information concerning the airplane. He should know more about the equipment than any other crew member—yourself included.
You, in turn, are his source of information concerning flying. Bear this in mind in all your discussions with the engineer. The more complete you can make his knowledge of the reasons behind every function of the equipment, the more valuable he will be as a member of the crew. Who knows? Someday that little bit of extra knowledge in the engineer's mind may save the day in some emergency.
Generally, in emergencies, the engineer will be the man to whom you turn first. Build up his pride, his confidence, his knowledge. Know him personally; check on the extent of his knowledge. Make him a man upon whom you can rely.
The B-17 is a most effective gun platform, but its effectiveness can be either applied or defeated by the way the gunners in your crew perform their duties in action.
Your gunners belong to one of two distinct categories: turret gunners and flexible gunners.
The power turret gunners require many mental and physical qualities similar to what we know as inherent flying ability, since the operation of the power turret and gunsight are much like that of airplane flight operation.
While the flexible gunners do not require the same delicate touch as the turret gunner, they must have a fine sense of timing and be familiar with the rudiments of exterior ballistics.
All gunners should be familiar with the coverage area of all gun positions, and be prepared to bring the proper gun to bear as the conditions may warrant.
They should be experts in aircraft identification. Where the Sperry turret is used, failure to set the target dimension dial properly on the K-type sight will result in miscalculation of range.
They must be thoroughly familiar with the Browning aircraft machine gun. They should know how to maintain the guns, how to clear jams and stoppages, and how to harmonize the sights with the guns.
While participating in training flights, the gunners should be operating their turrets constantly, tracking with the flexible guns even when actual firing is not practical. Other airplanes flying in the vicinity offer excellent tracking targets, as do automobiles, houses, and other ground objects during low altitude flights.
The importance of teamwork cannot be overemphasized. One poorly trained gunner, or one man not on the alert, can be the weak link as a result of which the entire crew may be lost.
Keep the interest of your gunners alive at all times. Any form of competition among the gunners themselves should stimulate interest to a high degree.
Finally, each gunner should fire the guns at each station to familiarize himself with the other man's position and to insure knowledge of operation in the event of an emergency.
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