part5-5

History of Research in Space Biology and Biodynamics


- PART V -

Tolerance to Impact Forces (Task 78503): Research on the Daisy Track and Related



[73] Probably the most active of all the formal subdivisions of Project 7850 has been Task 78503, Tolerance to Impact Forces. Other tasks of the same project are concerned with impact forces, but usually with application to a particular set of operational problems. Task 78503, by contrast, seeks to compile basic research data on as broad as possible a range of short-duration g-forces.
The task objective has been stated as follows:³¹: Human, animal, and anthropomorphic dummy reactions to dynamic linear forces of 50 to 5000 g per second rate of onset, 10 to 200 g magnitude and durations of 10 to 100 milliseconds will be determined for all phases of body orientation.

Not all official statements have used these same figures, which are intended only to provide a rough frame of reference, and most of the high-speed track deceleration experiments fell within the limits set. However, those experiments were conducted as a "project-level" activity and were not looked upon as coming under any one task subdivision. The primary, though not the only, instrument for the research of Task 78503 has been the Holloman short track, or Daisy Track as it is usually called.
The Daisy Track was designed expressly for use by the Aeromedical Field Laboratory, was formally inaugurated in 1955, and is located immediately adjacent to the buildings of the laboratory complex. It consists of two rails five feet apart and 120 feet long. According to the original proposal made in 1953 by Colonel Stapp, who was then head of the laboratory, propulsion was to have been by compressed air catapult--hence the analogy with the popular Daisy air rifle which gave the track its name. As a result of administrative and funding complications, this propulsion device still is not in service, although it is currently on order and parts of the equipment have been delivered. In the meantime, propulsion is by powder-cartridge catapult. This system has been reasonably satisfactory even though it cannot offer quite the same precision or performance range.
Braking for deceleration was provided at first by a lead cone device, but this proved unsatisfactory in preliminary tests. A water braking system was then adopted instead and is still in use. The original sled used on the Daisy Track required the subject to lie on his side in a "seat" that could be rotated in all directions by fifteen-degree increments; in high-speed track sled experiments, by contrast, the subject had to assume one of two positions, forward-or backward-facing in an upright seat. Moreover, in the autumn of 1957 the Aeromedical Field Laboratory acquired another sled with upright seat suitable for use on...

[74] (MISSING GRAPHIC)
Anti-G Platform

[75]....the Daisy Track. Orientation of this seat can be changed by ten-degree increments through a full 360 degrees.³²
The one area of performance in which the Daisy Track simply cannot complete with the long track is sled velocity and thereby exposure to windblast. In deceleration, it is capable of producing g-forces as high as those that have been obtained in aeromedical tests on the long track, although it does not provide as long an exposure to decelerative force. The number of possible body orientations was a distinct advantage, and since the operation of the Daisy Track required less elaborate preparations, a greater number of experiments could be run in the same period of time. The Daisy Track provided more accurate and abundant measurements by means of "direct recording pickups with trailing cable leads" from the sled to a fifty-channel oscillograph. Last but not least, the Daisy Track was remarkably inexpensive to operate. Runs cost about one hundred or one hundred fifty dollars each, as against the usual several thousand dollars for a test on the high-speed rocket track.³³
The Daisy Track was completed in the summer of 1955, and the first actual sled run took place on 22 September 1955. This was only a preliminary test, and it was several weeks before a run was made with a live subject. There were various adjustments to be made first on the basis of preliminary testing, including replacement of the unsatisfactory lead cone braking device. The first chimpanzee subject tried out the new facility in mid-November; still more animal runs and engineering testing experiments, not to mention two dummy runs, were then held before the first human experiment on 17 February 1956. The original volunteer subject was Lieutenant Wilbur C. Blount, who at that time was task scientist for Task 78503.³⁴
The Daisy Track has remained one of the busiest of Holloman's specialized research facilities, despite some temporary interruptions. One such interruption occurred early in 1957 when the Center's Missile Test Track Division (now called Track Test Division), which has ultimate supervision over both long and short tracks, expressed fear that the one sled then available was unsafe as a result of the heavy loads it had sustained. The sled was taken out of commission for about a month while undergoing x-ray studies, and when these revealed no sign of cracks or metal fatigue the facility went back in operation. In September of the same year, the number of Daisy runs accomplished passed the two hundred mark, and by mid-October 1958 it stood at 390--as compared with less than a hundred aeromedical experiments on the long track from November 1953 to the present.³⁵
Animal experiments have figured less prominently in Daisy tests than on the long track. Most test configurations to date have not been of an order to cause serious injury, and therefore it has normally been possible to use human subjects. Nevertheless, chimpanzees did take part in some of the early tests and helped check out the facility for human use. On two later occasions, hogs, which have never been privileged to ride the long track, took part in preliminary experiments with a new test configuration and received spinal fractures from an impact force measured at less than thirty g's. This unfortunate result was due to the particular combination selected of g-forces and body orientation (forces parallel to spine), and to the nature of the hogs themselves, including the "virtual impossibility of properly restraining these animals" on the sled.³⁶
Bears, which joined the Aeromedical Field laboratory staff only in the fall of 1957, have also ridden the Daisy Track. The first instance occurred in connection with an automotive crash conference described below, but soon afterward runs were started in a test series "seeking correlation between spinal injury in bears and humans." Finally, rats served as subjects in tests of Doctor von Beckh's anti-g swinging platform on the Daisy Track. Runs have not been made expressly for the rats, but the anti-g platform is small enough to be mounted on the sled in tests scheduled primarily for some other research objective. It has been notably successful so far, increasing subject tolerance by holding longitudinal g-forces (as distinct from transverse) to insignificant values even on some relatively high-g runs.³⁷
Human tests, which have formed much the greatest part of research activity on the Daisy Track, started out with a series of low-g experiments mainly intended for subject indoctrination. Since then, most officers and enlisted men assigned to the Biodynamics Branch have taken part as subjects, naturally including Captain Eli L. Beeding, Jr., who succeeded Lieutenant Blount as task scientist in the latter part of 1956. Colonel Stapp likewise took part, although his three Daisy rides failed to attract the same attention as his earlier rides on the long track. His so-called "grounding" from high-speed track experiments in June 1956 did not, of course, apply to Daisy tests.

[76] (MISSING PHOTOS)
16 May 1958: Captain Beeding Absorbs 83 G's on the Daisy Track
(Below: Close-up of the Same)

[77] Test subjects on the Daisy Track have tolerated forces above thirty g's in the relatively unfavorable position that is standard for upward ejection from aircraft (g-forces parallel to spine). Still higher forces have been sustained without injury in other body positions. Total durations have been as low as .035 second and have seldom much exceeded one-tenth second--as compared with a plateau of more than twenty-five g's for 1.1 seconds recorded on Colonel Stapp's rocket sled ride of 10 December 1954. Physiological effects have varied with maximum force, duration, body position and restraints, and also individual tolerance, which is much higher for some persons than for others. But no test has ever produced more than temporary ill effects.³⁸
The all-time record among Daisy tests was a run of 16 May 1958, with Captain Beeding himself as test subject. Deceleration measured on Captain Beeding's chest was eighty-three g's, substantially more than the highest g-force previously experienced in any human experiment either at Holloman or at other research installations. Duration was one-tenth second and rate of onset calculated at 5000 g's per second; position was seated upright and backward-facing. After the run Captain Beeding gradually went into a state of shock, but he recovered in less than ten minutes. He entered the base hospital for treatment of sore vertebrae and detailed observation, but apparently suffered no permanent ill effects. On the other hand, Captain Beeding admitted that he considered eighty-three g's about the limit of voluntary human tolerance for the test configuration that was used. He pointed out further that his experience underscored the desirability of backward-facing seats in passenger aircraft; there is even some question whether he would have lived through the ordeal if his seat had been facing the other direction. It is interesting to note, finally, that Captain Beeding did not ride alone on 16 May 1958. His sled also carried Doctor von Beckh's anti-g platform, whose rat passenger did not go into a state of shock.³⁹
Since the aim of Task 78503 is to accumulate general research data on the physiological effects of impact force, test configurations on the Daisy Track are not necessarily determined by any one specific Air Force problem. However, the track has also been used to test particular items of equipment, such as integrated harness designs for B-52 and F-104 aircraft, and force-attenuating seat cushions. It has even been used to check out recording equipment for the Holloman high-speed test track. In the case of B-52 harness testing, runs had to be suspended before completion of the planned series because one test at thirty-five-g level caused hospitalization of the subject for two days. Arrangements were then made to have the harness equipment redesigned.⁴⁰
For that matter, data acquired on impact forces per se will be useful for study of a great many different problems. These include not only aircraft seating arrangements, but also stresses in catapult and rocket takeoff, and re-entry deceleration. Something has been said in a previous monograph concerning the importance of research on the Daisy Track for study of escape from aircraft. Even so, it is worth noting again here as one example that the tests in which men sustained over thirty g's in position for upward ejection and emerged unharmed appear to give more leeway-or at least a greater safety margin-to the designers of escape systems than was formerly thought possible.⁴¹
As stated before, the Daisy Track is the primary but not the only research tool for Task 78503. The Bopper, described in connection with aircraft crash experiments, is a fairly handy instrument for general study of impact forces as well, although naturally it is an instrument of much more limited performance than the Daisy Track. Still another device for study of impact forces is a swing seat prepared in mid-1955 especially for aeromedical research and located, like the Daisy Track, in the back yard of the Aeromedical Field Laboratory. The swing has a platform on which an aircraft or other type seat is installed, raised to desired dropping height by means of a crane, and then decelerated by aircraft cables attached to the back of the platform at the moment its fall places it perpendicular to the ground. Forces are applied for extremely brief duration-for example, twenty-three g's with the peak lasting just one millisecond. The swing seat is capable of greater g-forces than this, depending principally on the height from which the seat is dropped; but it has various limitations, and to some extent it has served simply to obtain rough parameters for the planning of other experiments. It has also been used in its own right for certain test series relating principally to Task 78507, Automotive Crash Forces, and it will be discussed further under that heading.⁴²
In June 1955, even before the inauguration of the swing seat, a more primitive variety of impact test was conducted.....

[78] Swing Seat with
a. Three-Inch-Wide Lap Belt.
b. Snub Cable Detector.

[79] in which a shot bag was simply dropped against an anesthetized hog "to determine the threshold of tissue damage by force transmissible through the abdomen wall...." This was an area of the body especially vulnerable to crash forces, so that the test procedure was of obvious interest for both aircraft and automotive crash research. The officer directly in charge of the shot-bag experimentation-Major Joseph V. Michalski, who technically preceded both Lieutenant Blount and Captain Beeding as task scientist of Task 78503-managed to conduct just one actual test before leaving Holloman in mid-1955 on permanent change of station. However, this was a forerunner of other impact tests with hog subjects on the swing seat that were held specifically under the auspices of the automotive crash program.⁴³
One final example of the concern of the laboratory's biodynamics program with all manner of impact forces is the effort spent on developing a nonpenetrating projectile which can be fired at close range "to produce concussion in animal subjects."⁴⁴ This effort was technically considered a part of Task 78503, but was assigned as a part-time additional duty to Captain (Doctor) John A. Recht, a trained veterinarian whose primary responsibility is to care for the Holloman laboratory's animal colony. Recht tested various types of rounds before finding one that seemed workable for research purposes. Because of limited time and resources, no serious testing has been conducted with this device, but potentially it could make a contribution not only to basic research on concussion but also to the study of specific crash problems such as the effect of collision with loose objects in an aircraft cockpit.⁴⁵