Helmet Systems Research Articles

Determination of head/neck loads during manoeuvring acceleration

: Neck injury risk can increase when aircrew wear head mounted equipment while exposed to +Gz-loads. The effects of added weight and change in centre-of-gravity were determined during a centrifuge study using an instrumented manikin at Brooks AFB, Texas. Data included centrifuge Gz, head acceleration (three axes), and head and C7-TI pitch moment, compressive and shear forces. Helicopter (0.5G/s at +1.75 and +4Gz) and tactical aircraft (2Gk and 6GIs from +4 to 12Gz) accelerations were simulated (5s plateau at each level). Effect of added weights (up to overall 2.7kg) were measured in the forward pitch and lateral planes and tested using ANOVA. Seven real helmet systems were also tested. Head Gx and Gy increased with increasing +Gz-load, head weight, as CG shifted in the forward pitch plane, and onset rate. Head Gz was greatest when weight was distributed laterally. The resultant head and neck force and moment increased with increasing weight, pitch angle, and +Gz load. Neck forces and moments were significantly larger than those measured in the head.

U.S. Navy Head Anthropometry for Helmet Design

The U.S. Navy, like other organizations, requires a good anthropometric data base for the development of helmets and other head protective equipment. We develop a requirements list for an anthropometric data base for protective helmets, and then test four available data bases against it. Where existing data bases do not meet current and future needs, we recommend strategies for appropriate additional data collection. Specifically we propose the collection of 3D digital data sets which contain scans of heads without helmets, and scans of those same heads wearing current and prototype helmets. This approach allows the registration of the 3D data sets, and allows the calculation of a helmet-to-head transformation matrix. Such a matrix is critical for the successful design of well fitting new helmet systems.

Levels of carbon dioxide in helmet systems used during orthopaedic operations.

The use of isolation helmets has gained popularity as a method of possible protection of the operating-room personnel from diseases that can be transmitted during operative procedures. However, the use of these systems has been associated with a variety of symptoms, including fatigue, diaphoresis, nausea, headache, and irritability. These symptoms have often been attributed to the mental stress of the operative procedure or the physical discomfort of the helmet. As far as we know, no manufacturers include the measured levels of carbon dioxide or the rate of air exchange of their helmet system. A possible common cause of discomfort with helmet systems is the level of carbon dioxide to which the person wearing the device is exposed. We measured the levels of carbon dioxide in four helmet systems from three different manufacturers during light exercise designed to approximate the exertion during an orthopaedic operation. All but one unit failed to meet the exposure limits recommended by the National Institute for Occupational Safety and Health and the Occupational Safety and Health Administration regarding exposure to carbon dioxide. One unit, the Stackhouse Freedom Aire self-contained system, did meet these standards, but the levels of carbon dioxide in this helmet were more than 1000 per cent greater than the ambient levels in air (440 parts per million compared with 4939 parts per million). Isolation systems must be evaluated carefully not only for comfort but also for the physiological effects caused by exposure to elevated levels of carbon dioxide. Operating-room personnel who use such systems should be aware that many of the physical symptoms that they experience may be associated with elevated levels of carbon dioxide.

Tactical cockpits/spl minus/the coming revolution

A cockpit revolution is in the making. Many of the much ballyhooed, much promised, but little delivered technologies of the 70's and 80's will finally come of age in the 90's just in time to complement the data explosion coming from sensor and processing advances. Technologies such as helmet systems, large flat panel displays, speech recognition, color graphics, decision aiding and stereopsis, are simultaneously reaching technology maturities that promise big payoffs for the third generation cockpit and beyond. The first generation cockpit used round dials to help the pilot keep the airplane flying right side up. The second generation cockpits used multifunction displays and the HUD to interface the pilot with sensors and weapons. What might the third generation cockpit look like? How might it integrate many of these technologies to simplify the pilot's life and most of all: what is the payoff? This paper examines tactical cockpit problems, the technologies needed to solve them and recommend three generations of solutions.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Biodynamic Testing of Helmet Mounted Systems

New helmet mounted visually coupled systems (night vision devices and helmet mounted displays) which are designed to improve pilot performance may only increase the existing potential for neck injury during emergency escape due to the increase in head supported weight and altered center-of-gravity (CG). Designers need criteria for helmet system mass properties which will not increase the risk of injury above acceptable limits. A research study reviewed and analyzed accident statistics, current literature, and in-house laboratory data. Mass properties of various helmet systems were related to biodynamic responses of instrumented humans and manikins from impact tests conducted on the Armstrong Laboratory Vertical Deceleration Tower. Accident data revealed severe neck injuries are relatively rare in an operational setting. Laboratory studies of head/neck biodynamic response relating compression force at the occipital condyles to head supported weight indicate average forces exceed safe guidelines. The studies also suggest that helmet systems weighing less than 2.27 kg and having a center-of-gravity located only slightly above the anatomical axis origin of the head, will not induce severe neck injury during the catapult phase of ejection compared to current operational helmets.

Measurement of Mass and Cg Location of Helmet Systems

A procedure is described to measure the mass and CG location of helmet systems and relate these to head inertial properties. This procedure provides helmet mass properties data with respect to a consistent head coordinate system so that the mass properties of different helmet systems may be directly compared, allowing measurement of net head inertial property changes due to the addition of head mounted equipment. Relating helmet mass properties data to a consistent head coordinate system permits existing ejection safety criteria for head supported mass and CG location to be applied directly.

Human Factors in Design and Evaluation of Helmet Systems: An Overview

Human Factors in Design and Evaluation of Helmet Systems: An Overview

Integrated Flying Helmets

The addition of vision enhancement, display and control functions to aviator's headgear is operationally attractive. Fast jets and helicopters currently under development call for headgear with a combination of these novel facilities. This paper reviews the recent history of such helmet systems, which demonstrate admirably the inventiveness of the design teams. However, there are attendant perceptual and operational concerns and the addition of extra components invariably compromises basic ergonomic qualities. It is suggested that a new design philosophy, which emphasizes functional integration rather than the incorporation of compatible sub-systems, has become essential. This will be assisted significantly when key optical and electro-optical technologies become mature.

Evolution of coronal helmets during the ascending phase of solar cycle 20

The principal polar-crown coronal helmet structures were selected from nearly three years (May, 1965–January, 1968) of K-coronameter observations made at Haleakala and Mauna Loa, Hawaii. Six isolated and long-lived helmet systems were found at latitudes of 45° and above. Their developments are compared with underlying chromospheric and photospheric activity and a simple phenomenological model is presented showing that a coronal system is formed over an active region. Thereafter the center of gravity of the system gradually drifts poleward with the trailing unipolar magnetic region (UMR), and it becomes a high latitude coronal helmet, arched over a polar crown filament.