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: A system for an unmanned aerial vehicle can include an altitude control system 320, which further includes a compressor assembly 400, a valve assembly 500, and an electronics control assembly 600. The compressor assembly may include a compressor housing 410 that includes a compressor inlet 402, an outlet 202, and a cavity 414 extending therethrough and joining the inlet to the outlet. A diffuser 408 may be coupled to the compressor housing. A motor housing 407 may be disposed within the central cavity at the inlet of the compressor housing, and a compressor motor 406 may be disposed within the motor housing. An impeller 412 disposed within the compressor housing may be coupled to a driveshaft 444 for rotation therewith. The valve assembly may be coupled to an opening 416 of the compressor inlet. The valve head 502 may be configured to move into and away from the inlet opening so as to change a size of the circumferential area of the inlet opening.

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 a braking assembly for a lateral propulsion system of a high altitude platform (HAP) configured to operate in the stratosphere. Power is supplied to a propeller assembly as needed during lateral propulsion so that the HAP can move to a desired location or remain on station. When lateral propulsion is not needed, power is no longer supplied to the propeller assembly and it may slowly cease rotating. However, in certain situations, it may be necessary to cause the propeller assembly to stop rotating as soon as possible. This can include an unplanned descent. Rapid braking can avoid the propeller blades from entangling in the envelope, parachute or other parts of the HAP. A reusable brake is employed to prevent uncontrolled rotation of the propeller on descent, or otherwise to prevent the propeller from spinning freely when not being used to propel the HAP laterally.

Abstract: A system for an unmanned aerial vehicle can include an altitude control system 320, which further includes a compressor assembly 400, a valve assembly 500, and an electronics control assembly 600. The compressor assembly may include a compressor housing 410 that includes a compressor inlet 402, an outlet 202, and a cavity 414 extending therethrough and joining the inlet to the outlet. A diffuser 408 may be coupled to the compressor housing. A motor housing 407 may be disposed within the central cavity at the inlet of the compressor housing, and a compressor motor 406 may be disposed within the motor housing. An impeller 412 disposed within the compressor housing may be coupled to a driveshaft 444 for rotation therewith. The valve assembly may be coupled to an opening 416 of the compressor inlet. The valve head 502 may be configured to move into and away from the inlet opening so as to change a size of the circumferential area of the inlet opening.

Abstract: Aspects of the technology relate to a braking assembly for a lateral propulsion system of a high altitude platform (HAP) configured to operate in the stratosphere. Power is supplied to a propeller assembly as needed during lateral propulsion so that the HAP can move to a desired location or remain on station. When lateral propulsion is not needed, power is no longer supplied to the propeller assembly and it may slowly cease rotating. However, in certain situations, it may be necessary to cause the propeller assembly to stop rotating as soon as possible. This can include an unplanned descent. Rapid braking can avoid the propeller blades from entangling in the envelope, parachute or other parts of the HAP. A reusable brake is employed to prevent uncontrolled rotation of the propeller on descent, or otherwise to prevent the propeller from spinning freely when not being used to propel the HAP laterally.

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: 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 a braking assembly for a lateral propulsion system of a high altitude platform (HAP) configured to operate in the stratosphere. Power is supplied to a propeller assembly as needed during lateral propulsion so that the HAP can move to a desired location or remain on station. When lateral propulsion is not needed, power is no longer supplied to the propeller assembly and it may slowly cease rotating. However, in certain situations, it may be necessary to cause the propeller assembly to stop rotating as soon as possible. This can include an unplanned descent. Rapid braking can avoid the propeller blades from entangling in the envelope, parachute or other parts of the HAP. A reusable brake is employed to prevent uncontrolled rotation of the propeller on descent, or otherwise to prevent the propeller from spinning freely when not being used to propel the HAP laterally.

Abstract: Aspects of the technology relate to a braking assembly for a lateral propulsion system of a high altitude platform (HAP) configured to operate in the stratosphere. Power is supplied to a propeller assembly as needed during lateral propulsion so that the HAP can move to a desired location or remain on station. When lateral propulsion is not needed, power is no longer supplied to the propeller assembly and it may slowly cease rotating. However, in certain situations, it may be necessary to cause the propeller assembly to stop rotating as soon as possible. This can include an unplanned descent. Rapid braking can avoid the propeller blades from entangling in the envelope, parachute or other parts of the HAP. A reusable brake is employed to prevent uncontrolled rotation of the propeller on descent, or otherwise to prevent the propeller from spinning freely when not being used to propel the HAP laterally.

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: A system for an unmanned aerial vehicle can include an altitude control system 320, which further includes a compressor assembly 400, a valve assembly 500, and an electronics control assembly 600. The compressor assembly may include a compressor housing 410 that includes a compressor inlet 402, an outlet 202, and a cavity 414 extending therethrough and joining the inlet to the outlet. A diffuser 408 may be coupled to the compressor housing. A motor housing 407 may be disposed within the central cavity at the inlet of the compressor housing, and a compressor motor 406 may be disposed within the motor housing. An impeller 412 disposed within the compressor housing may be coupled to a driveshaft 444 for rotation therewith. The valve assembly may be coupled to an opening 416 of the compressor inlet. The valve head 502 may be configured to move into and away from the inlet opening so as to change a size of the circumferential area of the inlet opening.