LOON LLC

Aspects of the technology relate to an apparatus and method for testing a material for use in a lighter-than-air craft deployable in the stratosphere. The apparatus and method may include and use a base plate and at least one ring component to attach to the base plate to secure a portion of the material. The at least one ring component has an elliptical shape including a minor radius having a first predetermined length and a major radius having a second predetermined length. The base plate receives a gas to inflate and pressurize the portion of the material. The first predetermined length and second predetermined length are selected to impart a stress ratio up to a predetermined maximum ratio onto the portion of the material through a predetermined temperature range when the portion of the material is inflated to a predetermined pressure.

The technology relates to health and lifetime estimation for a lighter-than-air (LTA) vehicle. An LTA vehicle health and lifetime estimation system may include a processor and a memory storing instructions executable by the processor to cause the processor to implement an estimation service for determining a remaining lifetime output and a simulator for simulating a terminal event based on the remaining lifetime output. The estimation service may include a thermal model configured to determine a gas temperature, a gas and air estimator configured to estimate a gas amount and an air amount remaining in a balloon of the LTA vehicle, a leak rate estimator configured to estimate a leak rate, and a zero pressure estimator configured to determine the remaining lifetime output based on the leak rate. The system also may include an air flow estimator configured to determine an air mass flow rate based on the air amount.

The technology relates to managing nighttime power for solar-powered vehicles. A system may include a sunrise estimator for estimating a time until a next sunrise, a battery state estimator for estimating a battery state, a critical battery estimator for determining a battery threshold, below which subsystems may be powered off, and an alert monitor to determine, and communicate to the solar-powered vehicle, a charge threshold and a restart charge threshold. A method may include operating a vehicle in an operational power mode, estimating a time until a next sunrise, estimating a battery state, determining a preservation battery threshold based on the estimated time until the next sunrise and the estimated battery state, determining a minimum charge threshold based on the preservation battery threshold, monitoring a battery charge level of the vehicle throughout the night, and if the battery charge level drops below the minimum charge threshold, implementing a preservation power mode.

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.

Aspects of the disclosure relate to an aerial vehicle. The aerial vehicle may include an envelope having a plurality of tendons and formed from a first plurality of gores. The aerial vehicle may also include one or more ballonets arranged within the envelope. An outer membrane may be arranged around at least part of the envelope and formed from a second plurality of gores. The outer membrane may include at least one panel attached at one side to the outer membrane between a pair of the second plurality of gores and attached at an opposite side to the envelope. The outer membrane may be arranged to improve aerodynamics of the envelope when the aerial vehicle is in flight.

The technology provides a launch rig structure capable of filling a very large balloon envelope while the balloon is arranged vertically. The filled balloon is capable of staying aloft in the stratosphere with its payload for months or longer. The launch rig structure is configured to rotate up to 360° in response to current wind conditions. It includes an integrated lifting boom and gas handling system to fill the envelope. A payload release assembly is configured to couple with a rigid connection member of the balloon, enabling the envelope to be filled while in a vertical orientation. The payload release assembly is part of a launch cart that is positioned within the interior space of the launch rig. A gripper assembly engages with the rigid connection member. Once the envelope is filled, the gripper assembly disengages from the connection member so that the balloon floats away from the launch rig.

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.

The technology described here relates to LTA vehicle launch configuration and in-flight optimization. A method for optimizing for an objective of an LTA vehicle launch may include receiving a desired objective, receiving known parameters of the LTA vehicle, including a pressure threshold, performing probabilistic calculations based on the desired objective and the known parameters, the probabilistic calculations configured to model setup parameters and to output probabilities for the setup parameters, the output indicating probabilities that a simulated vehicles would achieve the desired objective. The method also includes selecting a setup parameter value based on a high probability indicated in the output. Also described is an LTA vehicle launch configuration system implementing a thermal model, a physics model, and a fill and ballast tool, including an altitude range estimator, a gas-air estimator, and a pre-flight ballast model.

The technology described here relates to LTA vehicle launch configuration and in-flight optimization. A method for automated ballast dropping by an LTA vehicle in flight may include receiving, by an in-flight ballast model, an initial lift gas fill amount and an initial ballast amount, generating altitude ranges based on a remaining lift gas amount and a current system mass of the LTA vehicle to determine whether the remaining lift gas amount is within a ballast drop lift gas range, determining whether a convergence criterion for the remaining lift gas amount is met, the convergence criterion indicating a convergence between a remaining lift gas estimate and a remaining lift gas model, determining that dropping a ballast increment will not decrease an overall ballast amount below a target ballast amount corresponding to the remaining lift gas amount, and causing the LTA vehicle to drop the ballast increment.

The technology relates to a scalable power system. A scalable power system includes battery modules connected in parallel, a network of diodes, a battery management system that may be localized or centralized, a localized battery management system configured to control an individual battery module, a centralized battery management system configured to control all of the battery modules in the scalable power system. In a system with localized battery control, a parallelizing circuit board may connect battery modules to a system bus in parallel. The battery modules can be charged and discharged by the system bus. A method of adding a battery module to a scalable power system includes discharging a highest-charged battery module, then discharging a next highest-charged battery module until there are no remaining charged battery modules, then adding an additional battery module in parallel, and charging the connected battery modules in parallel.