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Complete aerodynamic design and characterization of ascent as well as descent phases of ReusableLaunch Vehicle-Technology Demonstrator (RLV-TD) have been obtained through thousands of wind tunnel tests, flow simulations using various computational fluid dynamic codes and tailor-made engineering codes. The evolution of the ascent and descent designs, aerodynamic characterization and flight performance is presented in this article. The flight data comparison of aerodynamic coefficients, control surface loads, pressure distribution and external acoustic levels with preflight data is good and therefore, providing confidence in using the ground-based data generation techniques along with defined dispersion bands. Some of the minor deviations in the performance observed in flight were resolved/understood in the post-flight analysis, whereas few effects observed in flight need further understanding.

The improper use of artificial light causing skyglow is detrimental to many types of wildlife and can potentially cause irregular human sleeping patterns. Studies have been performed to analyze light pollution on a global scale. However, light pollution data on a local scale is not of ten available and the effects at local scale have rarely been studied. Herein, a new custom-designed autonomous light assessment drone (ALAD) is described for evaluating light pollution at local scale. The ALAD is designed and equipped with a sky quality meter (SQM) to measure skyglow and a low-cost illuminance sensor to measure light from artificial sources. Outdoor field tests are performed at a remote site in central Utah and the measured results are validated against data from lightpollution-map.info. The SQM measurements are in agreement with the estimates from the light pollution map, and the initial results demonstrate feasibility of the ALAD for local-scale skyglow assessment.

Wind-tunnel tests in the Mach number range of 0.18-2.5 showed the reattachment of shear layer from the strap-on boosters onto a point on the canted nozzles of a multibooster launch vehicle model. Such a reattachment can cause dynamic side loads on the nozzles and the associated gimbal actuators. A mean flow model of the forcing function was construed based on qualitative studies. The forcing function associated with the external excitation up to 550 Hz was quantified using specially designed strain-gauged nozzles that had a natural frequency of more than 700 Hz. With gimbaling, magnitudes of mean moments at the simulated location of the gimbal actuator were found to increase while the fluctuations decreased. Simple passive "load alleviation devices," which prevent local flow separation, deflect the trajectory of the separating shear layer and avoid reattachment on the nozzle were found to substantially reduce the flow-induced mean moments. A short semicircular segment that envelopes the boat tail of the strap-on boosters was found to be the most effective device for reducing the mean moments, as well as flow-induced unsteadiness on the nozzles at the location of gimbal actuators. The nozzle response indicates occurrence of discrete frequencies of about 103 and 466 Hz in the forcing function.