Abstract: A tailsitter aircraft for deploying a tow line includes an airframe having wings with pylons extending therebetween and a thrust array attached to the airframe, the thrust array including propulsion assemblies configured to transition the airframe between a forward flight orientation and a VTOL orientation. The tailsitter aircraft includes an attenuation spool coupled to the airframe and an attenuation cable having a first end coupled to the attenuation spool and a second end coupled to the tow line, the attenuation cable partially or fully wound around the attenuation spool. The tailsitter aircraft also includes a spool sensor to detect movement of the attenuation spool and a flight control system implementing a tow line tension monitoring module in communication with the spool sensor to determine a tow line tension parameter and a tow line tension reaction module to initiate an aircraft response based on the tow line tension parameter.

Abstract: A method for reducing form drag on a tailsitter aircraft during at least one of takeoff or landing includes vertically taking off from the ground in a tailsitter orientation. The method also includes determining an actual pitch of the tail sitter aircraft in the tailsitter orientation. The method also includes determining a difference between the actual pitch and a predetermined pitch. The method also includes adjusting a heading of the tailsitter aircraft based on the difference to minimize a pitch angle to reduce the form drag on the tailsitter aircraft.

Abstract: A tailsitter aircraft includes an airframe, a thrust array attached to the airframe and a flight control system. The thrust array includes propulsion assemblies configured to transition the airframe from a forward flight orientation to a VTOL orientation at a conversion rate for an approach to a target ground location in a forward flight-to-VTOL transition phase. The flight control system implements an adaptive transition system including a transition parameter monitoring module configured to monitor parameters including a ground speed and a distance to the target ground location. The adaptive transition system includes a transition adjustment determination module configured to adjust the conversion rate of the airframe from the forward flight orientation to the VTOL orientation based on the ground speed and the distance to the target ground location such that the airframe is vertically aligned with the target ground location in the VTOL orientation of the forward flight-to-VTOL transition phase.

Abstract: A combustion reactor which includes a reactor housing having an interior chamber, an inlet port at a top end of the housing and an outlet port at a bottom end thereof. The interior chamber has a circular cross-section, the diameter of which continuously increases from the inlet port to an intermediate level and then continuously decreases to the outlet port. A gas inlet conduit opens into the interior chamber adjacent to the inlet port at a location and in a direction tangent to a notional circle whose center lies on the axis of the interior chamber. By directing a high velocity flow of gas containing oxygen into the chamber tangent to the interior surface thereof and initially a combustible gas, upon ignition of the combustible gas and feeding into the inlet port combustible material, combustion of the fuel material takes place as the latter progresses from the inlet to the outlet.