BODY SIZE IN MILITARY AIRCRAFT AND
Randall, Albert Damon, Robert S. Benton, and Donald I. Patt
AAF Technical Report No. 5501
Army Air Force
Air Materiel Command
Wright Field, Dayton, OH
10 June 1946
THE FOLLOWING ARE EXTRACTS.
"The functional aircraft must include its crew members. The flight potential of an aircraft can never exceed that of its crew members.
The present report deals with the relation of human body size to military aircraft and equipment. It contains the necessary data and instructional material to guide the designers of aircraft and associated flying equipment in the proper use of anthropometry, as it applies to AAF flying personnel. The functional man is fully described and the spatial requirements of his personal equipment are evaluated. Finally, the complete functional man is considered in his air crew position and as an integral part of the functional aircraft."
I - INTRODUCTION
"From the time the Wright brothers constructed their first airplane and flew it in 1903, the problem of adapting aircraft design to all the high technical requirements has met with unlimited attention. The requirements established by air flow characteristics, by air speeds, altitudes, temperatures, as well as the other mechanical problems which must be considered, such as the size of instruments, the stress of metals and other materials, have occupied almost to the fullest extent the attention of designers. With all due credit to the highly developed techniques which have been, and continue to be, applied to aircraft design, it is the purpose of the data presented on the following pages to try to aid in some degree the consideration of the designers in so far as the problems presented by human body size are concerned.
The concept of writing specifications on the man, which are as definite and demanding as any of those written on any type of material or equipment otherwise used in an airplane, has been attempted many times. It is certainly realized by any sincere designer that his potential airplane is not really complete until a man actually enters the plane and engages it in flight. It should be quite apparent that the operational behaviour of an airplane of unlimited potentialities is actually no better than the behaviour characteristics imposed upon it by the physiological capabilities of the human being involved. It has been the experience of the Army Air Forces during the progress of World War II that many problems relating to inefficiencies on the part of the flight personnel could have been eliminated had the designers of the planes been fully cognizant of some of the implications of human biology.
The data discussed later in this report are not presented in an effort to try to sell engineers on the idea that an airplane should be considered only from the standpoint of the human being, but rather that it should be considered as a functional unit combining both the aircraft and the human being under flight conditions. Therefore, it shall be constantly stated that these data are actually specifications and should receive as much attention as do those specifications relating to any other type of equipment.
One of the most interesting historical facts which has been brought to our attention has been the one of the condition in which the original flights were made. It will be recalled that these occurred with the pilot flying in what is termed the "prone" position and that our so-called conventional positions for the pilot now are actually the opposite, historically speaking. It would be interesting to speculate upon what progress aircraft would have made had the man been retained in his original prone status. Recent developments along this line which are usually considered radical, are actually a continuation of stories which the Wright brothers initiated, and we shall gain much information from flight tests which will be conducted on this position. Aerodynamically it is probably the best possible position in which the pilot can be installed in the aircraft because it permits the minimum thickness to be designed into the plane.
The first Army Air Forces attempt made to write a specification on the human being for use in aircraft was made about 1926, at which time Mr. Hugh Lippman constructed from meager data available a profile scale manikin which was used up to the time Captain (now Colonel) Harry G. Armstrong prepared data derived from Randolph Field Aviation Cadets in such a manner as to illustrate that the Medical Corps and Air Corps physical size requirements were permitting acceptance of unnecessarily large individuals. At that time 6’'7" and 250 pounds were acceptable. It was Armstrong's recommendation that these maximum limits be dropped to 6'4" and 200 pounds, and that almost as large a population would be obtained inasmuch as only a very small percentage of individuals falls above that value. It was also Armstrong's recommendation that fighter pilot sizes should be limited to 70" and 180 pounds, in order to gain as much performance as possible from fighter aircraft. This recommendation was accepted with certain reservations. For some period the fighter stature was held at 5'8" instead of the 5'10" recommended by Armstrong. This acceptance limit was adequate so long as peacetime requirements remained. However, with the advent of stepped-up military requirements in 1942, such a large number of men was required for pilot training that a 5'8" limit actually prevented full use of the potentials available. The greatest defect which appeared in this regard was due to the fact that the fighter-type aircraft available for military use at that time had been designed around the 5'8" average and, without due regard to this fact, the limits were stepped up to 5'10" again, irrespective of the abilities of the planes to accommodate these higher statures.
This situation would not have been too disastrous had the original design requirements remained in use. That is to say, that these aircraft had been designed to fly not more than 3 and 1/2 hours. However, it is easily recognizable that this situation did not remain, inasmuch as long range requirements entered in and wing tanks and belly tanks were added to these same aircraft to enable them to fly as much as seven to eleven hours. There could be no modifications of the cockpit to provide any comfortable conditions for the pilots of the large stature who would be trained to fly these planes. This situation subsequently developed into probably the most difficult problem from the human operational standpoint encountered in World War II. The fact that high priorities were assigned by Army Air Force Headquarters to every aspect of problems relating to the alleviation of fatigue of pilots is alone sufficient proof of its importance. Therefore, from the standpoint of operational requirements of the Army Air Forces, every preliminary design should incorporate to the fullest extent the consideration of the size of human beings, and, also, that every consideration should be made in a cockpit design to provide for every eventuality possible regarding the possible ranges of this aircraft. It will, therefore, be the purpose of all the discussions to follow to try to instruct the designers in the best known way to provide adequate functional and comfort installations in cockpit designs in such a manner that the aircraft will not be limited in its performance by the poor functioning of the human beings involved."
CHAPTER I I -
THE FUNCTIONAL MAN
"The concept of the functional man is of such a nature as to complicate the entire picture in the design of aircraft. Historically, the man has been regarded too frequently as a constant and a more or less static piece of equipment. This is probably the factor which has contributed more than anything else to the failures in operational aircraft so far as the performance of the human being is concerned. It will be well to keep in mind the general problems presented in this concept.
. . . the "man" is not of a single size. . . . In fighter air craft the stature is allowed to vary from 5'4" to at least 6', and in some cases actually exceeds this value. The weight may vary from 120 to 180 pounds. In bombardment type aircraft commissioned officers may vary from 5' to 6'4", and in weight from 120 to 200 pounds. . . .
In addition, functionally speaking, this "man" may vary in the amounts of equipment worn, from very light clothing, including a small quick-attachable parachute, to the large bulky total of the equipment consisting of heavy flying clothing, emergency survival vests, life rafts, flak suits. and heavy parachutes. . . . This total amount of equipment may in certain conditions add as much as 117 pounds of weight to the nude weight of the individual. . . .
Next, and of no less importance, is the factor involved in the space requirements of the aircrew as they go through the motions of performing their duties. Minimum dimensions will avail us nothing if they must be greatly exceeded in the operational requirements of the individual. . . .
. . . In addition to the engineering requirements which are imposed by the human being and which can be adequately met if early consideration is given to them, there is a strong indication that the actual work of the flight surgeons and the Medical Corps in general would be reduced considerably if the man received a greater amount of attention.
Let us begin then with the nude man in the more or less static sense of the word and develop him throughout the whole range of requirements which have been established for his use in aircraft. . . . This is the man sent to the aircraft for installation from a training center. He already has certain inherent characteristics in him which can in no way whatsoever be modified. . . . He must be taken as he stands upon "delivery" and installed effectively in an airplane. It is the responsibility of the designer and the manufacturer to have provided tolerances in the plane in order to insure efficient installation of the equipment.
We can well imagine the difficulties which are encountered in some subassemblies when one item has been delivered with certain fixtures which are over-sized compared to their original requirements. It takes little time in the ordinary processes to see that this matter is corrected, yet it has been common procedure to ignore equally glaring inadequacies and tolerances in con ditions involving the man. . . ."
CHAPTER III - PERSONAL EQUIPMENT
CHAPTER IV - AIRCREW POSITIONING
PRINCIPLES OF COCKPIT SEATING
Stick Type Control
The Center of Gravity of the Seated Fighter Pilot
Body Size Considerations for Ejection Seats
"In fighter-type aircraft, and possibly in certain type of heavier planes,
it must be kept in mind that speeds in excess of three hundred and fifty miles
per hour render emergency escape very dangerous, and consideration must be given
to the provision of ejection of the man under some form of power other than his
own. The Germans attained this by providing a charge of powder which would eject both the seat and the man, following which the man could release the seat
and proceed through the ordinary parachute maneuvers.
Attempts have been made to modify existing aircraft in such a manner as to incorporate installation of an ejection-type seat, but it has been found extreme ly difficult to gain fully satisfactory means. Therefore, the designer should make every effort to incorporate the full installation for his aircraft before the mock-up stage is reached.
The primary requisite for the consideration of the human body as it relates to the cockpit is the degree of assurance which can be guaranteed for the positioning of the body in the seat. A definite example will serve to demonstrate this point.
In the type of seat figured, it will be seen that the toes of the feet serve to define the maximum [fore and aft dimensional] requirement. The position of the instep in relation to the hip will also define the extent of radius through which the thigh must go to attain a fixed position. It may be that lower dimensional requirements might be attained if pans rather than stirrups could be provided, perhaps holding the toes down and back from their present position. However, the degree to which this could be attained will be determined by the clearances offered when the seat is at full-down adjustment. In addition, if there is a possibility that the feet might slip off the stirrups. the thighs might very well be describing a radius as the knees pass the windshield, and thereby present a maximum dimensional requirement of about 28 inches, even with the feet falling farther back.
There are certain aerodynamic requirements which must be considered if deviations from the 13° angle used by the Germans on this particular seat are indicated. They went to great length to design the head rest in such a manner as to protect the face in the slip-stream, and . . . that the relative position of [the top of] this head rest will change from a position somewhat in line with the top of the head of a tall man, down to a position about level with his ears if the angle of ejection is dropped back to 30° from the vertical. If the ejection angle should be this great, the head rest must be elongated and this elongation may require such an increase in the sitting position of the seat structure, at 13°, that it will be too long to fit under the canopy of the aircraft.
If ejection at angles in excess of 13° is considered, the man must be moved from the 13° back to the ejection angle, requiring time. If he is not moved back, but stays at the 13°[stet] while ejection is occurring, then the difference in angles may be sufficient to apply transverse "g" to the man's head and produce instability in amounts great enough to break the neck. A small difference may be inconsequential, but extreme care should be taken to insure this before full installation is considered.
Frontal areas must also be considered in relation to the angles of ejection and the trajectories which must be maintained to clear the rudder. . . . The total frontal area drops from 5.0 sq. ft. at 13° down to 4.5 sq. ft. at 30°, so may offer some advantage to compensate for the lower trajectory inherent in ejection at the 30° angle.
Finally, in consideration of frontal areas, it is absolutely imperative that no less than 25 inches be provided laterally for clearances at the shoulders and elbows."
Anthropometry in the Design of Aircraft Gun Turrets
CHAPTER V - EMERGENCY EXITS
CHAPTER VI - CREW WEIGHTS
CHAPTER VII - MOVEMENT OF THE HEAD AND EYE IN SIGHTING
CHAPTER VIII - APPENDIX
Male Body Dimensions
Female Body Dimensions
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