Abstract: Aspects of the technology relate to propulsion systems for high altitude, long duration balloons, such as balloons that operate in the stratosphere for weeks, months or longer. A propeller assembly is used to provide lateral directional adjustments, which allows the balloon to spend more time over a desired region, reduce the return time to the desired region, reduce fleet overprovisioning, and increases the safety case by additional controls and avoidance abilities. A control assembly manages operation of the propeller assembly, including setting the pointing direction, speed of rotation and determining when to turn on the propeller and for how long. The propulsion system including the control and propeller assemblies is rotatable around a connection member of the balloon. Such rotation is independently adjustable from any rotation of the balloon's payload. The propeller blades may be made of plastic, which reduces weight and cost while providing sufficient speed at stratospheric altitudes.

Abstract: Aspects of the technology relate to lateral propulsion systems in lighter-than-air (LTA) platforms configured to operate in the stratosphere. One or more motor assemblies are used to actuate the lateral propulsion system and to make directional changes, for instance using one or more propellers. This can include a pointing axis motor assembly for orienting the lateral propulsion system along a particular heading, and a drive motor assembly for causing a propeller assembly or other propulsion mechanism to turn on and off Corrective actions may be necessary to adjust the alignment of the lateral propulsion system. A stepper motor control module may be used to control operation of the pointing axis motor assembly, for instance by causing it to rotate in a clockwise (or counterclockwise) direction. A motor current control approach may be used, in which the motor voltage is adjusted until a measured motor current reaches a selected current level.

Abstract: The technology relates to payload separation during descent of an aerial vehicle. A flight termination system (FTS) for a lighter than air (LTA) vehicle can include a first, a second, and a third mechanical actuation system. The first mechanical actuation system can be triggered in a first stage, causing an envelope and a payload of the LTA vehicle to separate. The second mechanical actuation system can be triggered in a second stage, causing a parachute to deploy from a component coupled to the payload. The third mechanical actuation system can be triggered in a third stage, causing a parachute to deploy from the envelope. In some cases, one or more of the mechanical actuation systems comprises a squib.

Abstract: The technology relates to a storm avoidance system for a lighter than air (LTA) vehicle. The storm avoidance system can include a mechanical actuation system, a balloon envelope comprising a ballonet, and a valve configured to allow air to escape the ballonet. When the storm avoidance system is engaged, the mechanical actuation system can open the valve, thereby allowing air to escape the ballonet and causing the LTA vehicle to ascend to an altitude above a storm altitude. In some cases, a state of the LTA vehicle can be detected, and the storm avoidance system can be engaged in response to the detected state. In some cases, a proximity of the LTA to a low population area can be determined, and the LTA vehicle can be caused to land in the low population area.

Abstract: Aspects of the technology relate to altitude control and lateral propulsion systems in lighter-than-air (LTA) platforms configured to operate in the stratosphere. For instance, an LTA platform may include an envelope filled with lift gas and a payload for providing telecommunication or video services. A fault or failure condition with one or more components of these systems, or with the envelope of the LTA platform itself, can prevent a high altitude platform (HAP) from operating as intended, or otherwise reduce its useful life. Onboard systems are configured to handle adverse conditions, such as a fault or failure of the envelope, an altitude control system component, or the lateral propulsion system. This may be done according to one or more ranked lists of adverse operational conditions. Different conditions may map to different corrective actions, which may be prioritized in importance, for instance to reduce the chance of catastrophic system failure.

Abstract: Aspects of the technology relate to propulsion systems for high altitude, long duration balloons, such as balloons that operate in the stratosphere for weeks, months or longer. A propeller assembly is used to provide lateral directional adjustments, which allows the balloon to spend more time over a desired region, reduce the return time to the desired region, reduce fleet overprovisioning, and increases the safety case by additional controls and avoidance abilities. A control assembly manages operation of the propeller assembly, including setting the pointing direction, speed of rotation and determining when to turn on the propeller and for how long. The propulsion system including the control and propeller assemblies is rotatable around a connection member of the balloon. Such rotation is independently adjustable from any rotation of the balloon's payload. The propeller blades may be made of plastic, which reduces weight and cost while providing sufficient speed at stratospheric altitudes.

Abstract: The technology relates to techniques for redundant power distribution and monitoring for lighter than air (LTA) vehicles. A power distribution and monitoring system for an LTA vehicle, can include two or more redundant controllers coupled to a multiplexer in a crossbar architecture. Each controller can control the multiplexer and inhibit the other controller in the case of a failure of the other controller. Each controller can control a power switch to direct power from a power source to an electronic component, and can monitor the power source. In some cases, a first controller receives a signal indicting a failure in a second controller, and the first controller inhibits the second controller and directs power from the power source to the electronic component.

Abstract: The technology relates to techniques for lighter than air vehicle redundant pressure sensor calibration. A lighter than air (LTA) vehicle can include a redundant pressure sensor calibration system, including a high precision pressure sensor onboard the LTA vehicle and two or more additional pressure sensors onboard the LTA vehicle, where the two or more additional pressure sensors are each redundant with the high precision pressure sensor. The two or more additional pressure sensors can be calibrated based on pressure measurements from the high precision pressure sensor and the two or more additional pressure sensors at two or more altitudes, wherein the high precision pressure sensor is calibrated before a flight of the LTA vehicle.

Abstract: The technology relates to techniques for a dynamic threshold for a pressure or altitude trigger for a lighter than air vehicle. A method of operating a system of an LTA vehicle can include setting a dynamic threshold of a system to a first value based on one or both of a first measured pressure altitude and a first measured absolute pressure, receiving an indication that the LTA vehicle has increased its altitude, and setting the dynamic threshold of the system to a second value based on one or both of a second measured pressure altitude and a second measured absolute pressure. A flight termination system for an LTA vehicle can include mechanical actuation systems configured to be triggered based on dynamic thresholds. A method of terminating the flight of an LTA vehicle can include triggering the mechanical actuation systems based on dynamic thresholds.

Abstract: Aspects of the technology relate to lateral propulsion systems in lighter-than-air (LTA) platforms configured to operate in the stratosphere. One or more motor assemblies are used to actuate the lateral propulsion system and to make directional changes, for instance using one or more propellers. This can include a pointing axis motor assembly for orienting the lateral propulsion system along a particular heading, and a drive motor assembly for causing a propeller assembly or other propulsion mechanism to turn on and off Corrective actions may be necessary to adjust the alignment of the lateral propulsion system. A stepper motor control module may be used to control operation of the pointing axis motor assembly, for instance by causing it to rotate in a clockwise (or counterclockwise) direction. A motor current control approach may be used, in which the motor voltage is adjusted until a measured motor current reaches a selected current level.

Abstract: Aspects of the technology relate to propulsion systems for high altitude, long duration balloons, such as balloons that operate in the stratosphere for weeks, months or longer. A propeller assembly is used to provide lateral directional adjustments, which allows the balloon to spend more time over a desired region, reduce the return time to the desired region, reduce fleet overprovisioning, and increases the safety case by additional controls and avoidance abilities. A control assembly manages operation of the propeller assembly, including setting the pointing direction, speed of rotation and determining when to turn on the propeller and for how long. The propulsion system including the control and propeller assemblies is rotatable around a connection member of the balloon. Such rotation is independently adjustable from any rotation of the balloon's payload. The propeller blades may be made of plastic, which reduces weight and cost while providing sufficient speed at stratospheric altitudes.

Abstract: Aspects of the technology relate to propulsion systems for high altitude, long duration balloons, such as balloons that operate in the stratosphere for weeks, months or longer. A propeller assembly is used to provide lateral directional adjustments, which allows the balloon to spend more time over a desired region, reduce the return time to the desired region, reduce fleet overprovisioning, and increases the safety case by additional controls and avoidance abilities. A control assembly manages operation of the propeller assembly, including setting the pointing direction, speed of rotation and determining when to turn on the propeller and for how long. The propulsion system including the control and propeller assemblies is rotatable around a connection member of the balloon. Such rotation is independently adjustable from any rotation of the balloon's payload. The propeller blades may be made of plastic, which reduces weight and cost while providing sufficient speed at stratospheric altitudes.