MOTION SIMULATION STUDIES

A study by Wilcoxon and Davy (10), in 1954, described an experimental investigation of the effectiveness of rough air simulation in basic instrument and radio range procedure troining. The tongh air simulation consisted of mild pitching and rolling movements in two flight trainers: the Link 1.CA-2 SNJ Operational Flight Trainer (OFT) and the Link 1-CA-i Navy Basic Jnstrument

-iLv •

Figure 28. Nrvy 'k€ Instrument Trainer, Unk I-CA-I (Nay AIT)

Trainer (Nay BIT). The OFr subjects received rough air during all syllabus periods or during only one basic instrument and one radio procedure period. The NavBIT subjects received only the rough air schedule. The control groups for both trainers received no rough air simulation. The rough air simulation did not contribute to greater proficiency in either the trainers or in the SNJ aircraft. The rough air simulation seemed to add more realism to the training situation which re-sultcd in a more favorab!e student attitude toward the trainers. The authors concluded that while rough air simulation is considered to be unnecessary, the inclusion of tie simulation may be justi-fie because of its "face validity."

A motion platform of tht Grumman Motion Research Simulator, shown in figure 29, was de-scribed by Ruocco, Vitale, and Benfari (107). Three hydraulic servos position the points A. B.

and C in a plane. Foints A and B move differentially for roll, point C moves for pitch, and all three move simultaneously for vertical motion and any combination of pit h, roll, and ileave can be achieved within the mechanical limitations of the motion platform.

A study by Townsend (109), 1955, indicated that the addition of motion is a desirable simu-lator feature. The ME-1 Link trainer used in the elevation was capable of a maximum cockpit

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movement of 5.5^° of pitch with no roll, and 8.50 of roll with no pitch. Pilots' opinions, which were not supported by experimental evidence, indicated that the motion capability increased the value of the trainer above all others that they had flown.

Vomaske, Sadoff, and Drinkwater (80) reported a National Aeronautics and Space Adminis-tration (NASA) study based on pilots' opinions on adverse and favorable aileron-induced yawing moments at various Dutch-roll damping levels. The authors concluded that the results of the fixed-base shnulator test were about the same as for the actual flight results. Therefore, the absence of motion cuaes (in the simulator) did not markedly affect pilot opinion, possibly because of the strengthened visual cues presented.

A C

Another NASA study by Creet, Steward, Merrick, and Drinkwater (53) distinguishes between what they call a mandatory stimulus and a desirable stimulus. The authors conclude that for cer-tain aircraft characteristics, some form of motion must be provided if realistic simulation is to be achieved. On the other hand, there are various re.sponse characteristics for which fixed-base simu-lation should be sufficient.

Brown, Johnson, and Mungall (48), 1960; Federsen (58), 1962; and Ruocco, Vitale, and Ben-fari (107), 1965, found that the incorporation of motion in simulators enhanced performance.

However, Brown, Kuehnel, Nicholson, and Futterweit (49), 1960, reported that work with a fixed-base simulator provides as good a basis for the prediction of pilot performance as do investi-gations using a centrifuge.

Research by NASA, compared the capabilities of test pilots in flight over a wide range of conditions under six degrees of motion with those on various fixed-base and moving-base simu-lators. In general, the conclusions indicate that motion cues in simulators are necessary only

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Figure 30. The Unk Trulan, MU-i

when they improve control of the vehicle or interfere with satisfactory perfox mance. The studies emphasize that there is a distinction betweeu mandatory and desirable cues. Thus, it seems that motion cues might be classified as "need to have" and 'nice to have." These studies were sum-marized by Rathert, Cretr, and Douvillie-' (73), 1959; Ratheit, Creer, and Sadok (74), 1961.

Caro and Isley (34) reported a study in which the Whirlymite Helicopter Trainer was used.

This device differed from other flight trainers in that it used real worli visual, auditory, and prc,-prioceptive stimuli associated with actual contact flight. The performance of the experimental group was superior to the control group in the actual helicopter.

The demand for centrifuge facilities has continually increased over the past decade because of the advanced developments in aerospace systems. These developments in supersonic aircraft and qpace vehicles have increased the need for research on man's tolerance to flight stress. The results of the research may then be used as a basis for both vehicle and personnel equipment development. In addition, the centrifuge may be a valuable tool in aerospace systems tests by permitting tests of pro'cedures, life support, control, restraint, escape, aircrew compartment con-stnction, and instnmentation display during exposure to dynamic force environments. These motion simulators permit training of crew members to develop manual and mental skills which may increase the probability of app!opriate responses to the performance requirements of a mission. Seven centrifuge studies (49, 51, 52, 61, 62, 71, 77) are included in the annotated bibli-ography of this section.

The Aerospace Medical Research Laboratories' human centrifuge with four cantilever trusses is shown in figure 31. The superstniciure and cab were constructed by S. Morgan Smith Company, York, Pennsylvania. This centrifuge was 'retired" in 1962 after 13 years of continuous service. It

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has been replaced by the Dynamic Escape Simulator, shown in figure 32, which was constructed by the Franklin Institute, Philadelphia, Pennsylvania under thf, sponsorship 6f the Aerospace Medical Research Laboratories. The Dynamic Escape Simulator is basically a human centrifuge, designed to produce as closely as possible, the complex accelera ion profiles of flight and emer-gency escape from present and proposed aerospace vehicles. It can be used as a simple centri-fuge, escape simulator, disorientation device, six degrees of freedom simulator, and also for multi-stress tests.

Figure 31. Humca Centrfuge - Aeroopac Medical Research tabeqtmories

Human centrifuge research is also conducted at the U. S. Naval Air Development Center (NADC), Johnsville, Pennsylvania. The centrifuge facility at the Aviation Medical Acceleration Laboratory contains a centrifuge which consists of a 50 ft. arm with a 10 ft. by 6 ft. oblate sphe-roid gondola mounted at the end.

Although airborne simulators are not considered to be within the scope of this report, several studies (64. 65, 66, 76) are included in the annotated bibliography as topics of related interest.

The need for this flight-testing tool is based on the design iequirement! for modern high perform-ance aircraft. A test airplane may be used to con~duct research in the design of cockpi, controls as well as the aicraft's response to the controls. For example, the control system of a jet trainer may he modified to pennit simulation of more advanced aircraft. Thus, the airborne simulators may be used to acquaint pilots with the control characteristics of newly developed fighter aircraft.

CONCLUSIONS

In normal flight, the pilot uses both visual and motion cues while controlling the aircraft;

however, the need for simulating these cues in flight trainers often has been questioned. External visual displays are only a part of flight training and the effectiveness of these devices may be as much a function of the fidelity of the simulator with which they are used as it is a function of the

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Figure 32. 1h. Dynamic Escalso Centrifuge -Aerospace Medical Research 9aberatorles

SYSYSTEM TTRONICS

ERVOS PILOT

TEST ENGINEETER CONSOL

FEELSYSTEM-Figure 33. Layout of General Purpose Airborne Simulator Systems 31

visual displays. Also, the value of contact displays may depend upon the quality of instruction, attitudes toward the trainer, and other variables. The factors which should be considered in the design of a visual device are shown below: