Bow Wave Effect in Probe and Drogue Aerial Refuelling

U. Bhandari, Peter R. Thomas, S. Bullock, T.S. Richardson, ‘Bow Wave Effect in Probe and Drogue Aerial Refuelling’, paper presented at the AIAA Guidance, Navigation and Control Conference, Marriott Boston Copley Place, Boston, United States, 19-22 August, 2013.A wide range of UAV applications has been identified in the last decade, both for civil and military use. An autonomous AAR capability is perceived as an advantage to future support and deployment of mid-large scale UAV to meet operational requirements. Despite drawing a lot of attention and research, bow wave effects in an AAR scenario has not received enough attention. Some existing works have discussed and attempted to model the effect of the bow wave from a comparatively large receiver (B-2, C-17) onto the tanker (KC-135) during boom refuelling. However the effects of bow wave from the receiver aircraft onto the drogue in a probe and drogue refuelling system has received very little attention. This paper analyses the effects of the bow wave and results suggest that a solution to the bow wave effect is not only desirable but essential for a successful AAAR refuelling. This paper considers the use of an offset which is used by human pilots to compensate for the drogue movement resulting from the receiver's bow wave. This simple yet effective solution was found to restore the loss in performance in the AAAR simulation which results from the bow wave interaction. This work forms part of the ASTRAEA programme in the UK.Non peer reviewe

Phase II dose-ranging trial of the early bactericidal activity of PA-824

PA-824 is a novel nitroimidazo-oxazine under evaluation as an antituberculosis agent. A dose-ranging randomized study was conducted to evaluate the safety, tolerability, pharmacokinetics, and early bactericidal activity of PA-824 in drug-sensitive, sputum smear-positive adult pulmonary-tuberculosis patients to find the lowest dose giving optimal bactericidal activity (EBA). Fifteen patients per cohort received oral PA-824 in doses of 50 mg, 100 mg, 150 mg, or 200 mg per kg body weight per day for 14 days. Eight subjects received once-daily standard antituberculosis treatment with isoniazid, rifampin, pyrazinamide, and ethambutol (HRZE) as a positive control. The primary efficacy endpoint was the mean rate of decline in log CFU of Mycobacterium tuberculosis in sputum incubated on agar plates from serial overnight sputum collections, expressed as log 10 CFU/day/ml sputum (± standard deviation). The mean 14-day EBA of HRZE was consistent with previous studies (0.177 ± 0.042), and that of PA-824 at 50 mg, 100 mg, 150 mg, and 200 mg was 0.063 ± 0.058, 0.091 ± 0.073, 0.078 ± 0.074, and 0.112 ± 0.070, respectively. Although the study was not powered for testing the difference between arms, there was a trend toward significance, indicating a lower EBA at the 50-mg dose. Serum PA-824 levels were approximately dose proportional with respect to the area under the time-concentration curve. All doses were safe and well tolerated with no dose-limiting adverse events or clinically significant QTc changes. A dose of 100 mg to 200 mg PA-824 daily appears to be safe and efficacious and will be further evaluated as a component of novel antituberculosis regimens for drug-sensitive and drug-resistant tuberculosis. Copyright © 2012, American Society for Microbiology. All Rights Reserved