Naval Air Warfare Center Aircraft Division Research Articles

Evaluating the Challenges and Potential Complications of Breastfeeding in Naval Aviation.

Active duty flight crew plays a critical role in military operations. The occupational demands of the flying environment require a certain level of medical suitability. Additionally, such an environment could be more hazardous for certain populations. While the Centers for Disease Control and Prevention, the American Academy of Pediatrics, and the World Health Organization strongly support exclusive breastfeeding for the health benefit of both the mother and the child in the first 6 months of life, the aeromedical implications of lactating are not widely discussed. Breastfeeding is inherently challenging for many women, in part because of the frequent emptying required to maintain breastmilk supply and avoid complications such as engorgement, clogged ducts, and mastitis. This pilot study evaluated the experiences of individuals concurrently breastfeeding while on active duty Naval flying status to (1) assess whether these individuals experience frequent challenges or complications associated with lactating and (2) establish the need for future expanded studies. This survey-based, retrospective, descriptive study evaluated the experiences of 17 lactating individuals on active duty Naval flying status. Women were recruited using word of mouth and social media platforms. Responses were tabulated and summarized from the survey, which included yes/no questions and free-response sections regarding flying position, breastfeeding history, and breastfeeding challenges. This trial was approved by the Naval Air Warfare Center Aircraft Division (NAWCAD) Institutional Review Board (Protocol Number NAWCAD.2021.0004-IR-EP7). Of the 27 women who received study materials after expression of interest, 17 individuals completed the informed consent and survey protocols. Although limited by sample size and the demographics of respondents, the results highlight that the active duty flying environment did impact the breastfeeding experiences of the participants, with 88% of respondents reporting some difficulty or complication associated with breastfeeding and the operational flying environment. Difficulty in maintaining breastmilk supply, engorgement, and the need for supplementation were some of the concerns discussed. This study hypothesizes that occupational demands associated with aviation result in a decreased ability to maintain exclusive breastfeeding, an increased risk for engorgement and clogged ducts, and a higher likelihood of early weaning among Naval aviators. It included only the perspectives of Naval officers, thereby lacking the input of enlisted aircrew on flight status, who comprise a large population of active duty flyers. The responses, although limited by a lack of controls and survey limitations, indicate that a future study to expand understanding of the aeromedical implications on lactating individuals would be valuable for improving workplace support and the ultimate success of lactating women in meeting their breastfeeding goals.

Comparative study: Flow-induced noise on underwater acoustic pressure, particle velocity, and intensity sensors

A neutrally buoyant underwater acoustic p-u intensity probe contains discrete sensors for direct measurement of acoustic pressure and particle velocity [J. A. McConnell and G. C. Lauchle, J. Acoust. Soc. Am. 103, 2755(A) (1998)]. Intensity is calculated from the cross spectrum between these two quantities. Thus a single probe can be categorized as a compound sensor capable of independently measuring acoustic pressure, particle velocity, and intensity. Using this probe, a comparative study concerning the measurement of all three quantities in the presence of mean flow and an independent sound source was performed. Bias errors, which result from the flow-induced noise generated by towing the sensor (e.g., a cylindrical body) in cross flow at low speeds through a channel of water, are presented. Other parameters of interest include analysis of experimental pressure–pressure and pressure–velocity correlation functions. The effect of body geometry (e.g., variation in aspect ratio) on the measured bias errors and correlation functions is also presented. [Work supported by the Office of Naval Research, the Naval Submarine League, and the Acoustics Technology Branch of the Naval Air Warfare Center—Aircraft Division, via the DoD Small Business Innovation Research Program.]

Development of a compact suspension system for a neutrally buoyant underwater acoustic intensity probe

Practical use of neutrally buoyant underwater acoustic intensity probes requires a suspension system to position them in some preferred orientation with respect to an acoustic field of interest. However, since these probes typically contain a moving coil geophone to facilitate particle velocity measurements, the design of such suspension systems is not trivial. On one hand, theory mandates that the dynamics of the geophone will not be adversely affected by the suspension as long as the mass-spring system created by the probe and the elastic members has a low-resonance frequency and high quality factor relative to that of the geophone. However, by meeting these two design criteria, wave effects (e.g., flexural resonances) in the elastic members can become a limiting factor in the performance of the device, particularly at high frequencies. This paper presents theoretical and experimental results of an effort to design a compact suspension system that embodies the aforementioned design considerations, but has relatively low susceptibilty to flexural resonances. [Work supported by the Acoustics Technology Branch of the Naval Air Warfare Center—Aircraft Division, via the DoD Small Business Innovation Research Program.]