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Presented is an introduction to the basic principles of the Advancing Blade Concept (ABC) rotor and a review of the related experimental and analytical research conducted in support of the Sikorsky ABC helicopter program. The ABC helicopter is comprised of two coaxial, counter‐rotating rotors having blades rigidly attached to the hub except for feathering freedom. The blades are significantly stiffer than conventional rotor Blades and are capable of supporting large moments without excessive tip deflections. Improved forward flight efficiency and the elimination of retreating blade stall results from the ability of the ABC rotor to utilize to a large extent the lifting potential of the advancing blades—a capability not present in conventional single rotors. Results of various small‐scale wind tunnel experiments are presented along with summaries of several analytical investigations which were conducted to provide information concerning rotor performance, blade dynamics, vibration, and stability and control

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Introduction The Critical Care Air Transport Team (CCATT) Advanced course utilizes fully immersive high-fidelity simulations to train CCATT personnel and assess their readiness for deployment. This study aims to (1) determine whether these simulations correctly discriminate between students with previous deployment experience (“experienced”) and no deployment experience (“novices”) and (2) examine the effects of students’ clinical practice environment on their performance during training simulations. Materials and Methods Critical Care Air Transport Team Advanced student survey data and course status (pass/no pass) between March 2006 and April 2020 were analyzed. The data included students’ specialty, previous exposure to the CCATT Advanced course, previous CCATT deployment experience, years in clinical practice (<5, 5–15, and >15 years), and daily practice of critical care (yes/no), as well as a description of the students’ hospital to include the total number of hospital (<100, 100–200, 201–400, and >400) and intensive care unit (0, 1–10, 11–20, and >20) beds. Following descriptive analysis and comparative tests, multivariable regression was used to identify the predictors of passing the CCATT Advanced course. Results A total of 2,723 surveys were analyzed: 841 (31%) were physicians (MDs), 1,035 (38%) were registered nurses, and 847 (31%) were respiratory therapists (RTs); 641 (24%) of the students were repeating the course for sustainment training and 664 (24%) had previous deployment experience. Grouped by student specialty, the MDs’, registered nurses’, and RTs’ pass rates were 92.7%, 90.6%, and 85.6%, respectively. Multivariable regression results demonstrated that deployment experience was a robust predictor of passing. In addition, the >15 years in practice group had a 47% decrease in the odds of passing as compared to the 5 to 15 years in practice group. Finally, using MDs as the reference, the RTs had a 61% decrease in their odds of passing. The daily practice of critical care provided a borderline but nonsignificant passing advantage, whereas previous CCATT course exposure had no effect. Conclusion Our primary result was that the CCATT Advanced simulations that are used to evaluate whether the students are mission ready successfully differentiated “novice” from “experienced” students; this is consistent with valid simulation constructs. Finally, novice CCATT students do not sustain their readiness skills during the period between mandated refresher training.