Abstract: An inner middle rotor is rotated while an inner front rotor, an inner back rotor, and an outer rotor are not rotated. The inner middle rotor is surrounded by the inner front rotor, the inner back rotor, the outer rotor, and a fuselage. After rotating the inner middle rotor while not rotating the inner front rotor, the inner back rotor, and the outer rotor, the inner middle rotor, the inner front rotor, the inner back rotor, and the outer rotor are simultaneously rotated.

Abstract: A multi-modal aircraft recovery system is disclosed. In various embodiments, the system includes a first aircraft recovery parachute having a first set of physical attributes optimized for a first set of conditions and a second aircraft recovery parachute having a second set of physical attributes optimized for a second set of conditions different from the first.

Abstract: A commanded control signal is compared against an adaptive control signal in order to detect a rotor strike by a rotor included in an aircraft, wherein the adaptive control signal is associated with controlling the rotor and the adaptive control signal varies based at least in part on the commanded control signal and state information associated with the rotor. In response to detecting the rotor strike, a control signal to the rotor is adjusted in order to reduce a striking force associated with the rotor.

Abstract: A system for adjusting a load on a tethered aircraft is disclosed. The aircraft is tethered to a payload. The system determines a new position for the tethered aircraft in the event that due to environmental effects, e.g., the aircraft is flying upwind or downwind, the load experienced by the tethered aircraft is not optimal.

Abstract: A set of one or more desired forces or desired moments associated with an aircraft having a plurality of rotor modules is received. A plurality of health metrics associated with the plurality of rotor modules is received. A plurality of commands for the plurality of rotor modules is determined based at least in part on the set of desired forces or desired moments and the plurality of health metrics. The plurality of commands is sent to the plurality of rotor modules where each rotor module in the plurality of rotor modules is configured to perform a corresponding command in the plurality of commands.

Abstract: A distance sensor and a measured object are positioned at a known distance from each other. A measured distance between the distance sensor and the measured object is obtained from the distance sensor, where the distance sensor uses a plurality of signals at a plurality of angles to generate the measured distance. The known distance and the measured distance are compared in order to test the distance sensor and produce a test result.

Abstract: A plurality of sensor datasets is received including: (1) an interference sensor dataset which is associated with interference between airflow from a first rotor in a multicopter and airflow from a second rotor in the multicopter, (2) a first and a second isolated sensor dataset which are associated with isolated airflows from the first rotor and the second rotor, respectively. A generalized flow model associated with a generalized rotor is received and an altitude for the multicopter is generated based at least in part on the plurality of sensor datasets and the generalized flow model, including by using a non-linear filter that builds a consolidated probability function associated with altitude that reconciles the plurality of sensor datasets with the generalized flow model.

Abstract: In an embodiment, a system for air cooling in a wet environment includes a propeller coupled to a vehicle capable of at least one of: taking off from and landing on water. The system includes a battery configured to power the propeller, a float configured to hold the battery, and a flap in the float. The flap is configured to open in response to air pressure to permit airflow into the float to cool the battery.

Abstract: In an embodiment, a system to deploy a plurality of parachutes includes a plurality of parachute canopies each packed in a canister, a plurality of rockets adapted to extract an associated canopy from the canister, and a controller. The controller is configured to determine that an aircraft is at least one of: in a hover mode of operation and a forward flight mode of operation. In response to the determination that the aircraft is in the hover mode of operation, the controller applies a hover deployment sequence including by instructing the plurality of parachutes to deploy substantially simultaneously. In response to the determination that the aircraft is in the forward mode of operation and above a threshold airspeed, the controller applies a forward deployment sequence including by instructing the plurality of parachutes to deploy in a predefined sequence.

Abstract: A battery ejection system is disclosed. The battery ejection system comprises a pressure vessel, a battery submodule positioned at least partway in the pressure vessel and configured to release gas into the pressure vessel, and a seal of the pressure vessel configured to release in the event a pressure level in the pressure vessel exceeds a threshold pressure level. The battery submodule is configured to be ejected from an electrical connection in the event the seal is released.

Abstract: A propeller includes a blade free to rotate. A first stop is positioned to mechanically engage one or both of a first portion of the blade and a first structure coupled to the blade when the blade is in a first position at a first end of the rotational range of motion. A second stop is positioned to mechanically engage one or both of a second portion of the blade and a second structure coupled to the blade when the blade is in a second position at a second end of the defined rotational range. The blade rotates to the first position against the first stop when the propeller is rotated in a first direction and to the second position against the second stop when the propeller is rotated in a second direction.

Abstract: An automated aircraft recovery system is disclosed. In various embodiments, the system includes an interface configured to receive sensor data; and a control mechanism configured to: perform automatically a recovery action that is determined based at least in part on the sensor data. In various embodiments, the control mechanism may determine an expected state of an aircraft, determine whether a state of the aircraft matches the expected state, and in the event the state of the aircraft does not match the expected state, perform the recovery action.

Abstract: A tilt rotor system, comprising: a pylon portion that includes: an upper protrusion that is configured to be in contact with an upper surface of a wing and a lower protrusion that is configured to be in contact with a lower surface of the wing; and a rotor portion that includes a rotor, wherein the rotor portion is able to move between: (1) a first position that is associated with a vertical flight mode and (2) a second position that is associated with a forward flight mode. The pylon portion further includes an air intake vent, a horizontal surface, a rotor controller, and a heat sink.

Abstract: A parachute deployment system is disclosed. In various embodiments, the system includes an interface configured to receive sensor information; a parachute load limiting device; and a parachute load limiting device state controller. The parachute load limiting device state controller sets a state of the parachute load limiting device to a state associated with a corresponding amount of load based at least in part on the sensor information.

Abstract: A system includes a first battery in a vehicle. The vehicle is capable of being coupled at least temporarily with a second, removable battery and is powered by at least one of the first or the second battery. The system also includes a controller in the vehicle which is configured to estimate an amount of travel-related charge based at least in part on a pickup and drop off location. It is decided whether to charge the first battery using the second battery based at least in part on the amount of travel-related charge and a measured amount of stored charge in the second battery. If it is decided to do so, the first battery is charged using the second battery.

Abstract: A selection is made between single stage and multistage parachute deployment for a vehicle based at least in part on vehicle state information. In the event multistage parachute deployment is selected, a drogue parachute is deployed during a first deployment stage and afterwards, a main parachute is deployed during a second deployment stage. In the event single stage parachute deployment is selected, at least the main parachute is deployed in a single stage where in the event the drogue parachute is deployed during the single stage, the drogue and main parachute are deployed simultaneously.

Abstract: A plurality of port-side tilt rotors and a plurality of starboard-side tilt rotors are configured to rotate between a first rotor position and a second rotor position. The port-side tilt rotors are coupled to a trailing edge of the fixed and forward-swept wing on the port side and the starboard-side tilt rotors are coupled to the trailing edge of the fixed and forward-swept wing on the starboard side. The aircraft also includes a fuselage. When the port-side and starboard-side tilt rotors are in the first rotor position, at least some of a lift to keep the aircraft airborne comes from thrust output by the rotors at least some of the time. When in the second rotor position, at least some of the lift to keep the aircraft airborne comes from aerodynamic lift on the fixed and forward-swept wing at least some of the time.

Abstract: A parachute deployment system is disclosed. In various embodiments, a parachute is tethered to an aircraft. A self-propelled projectile is tethered to the parachute. The self-propelled projectile is configured to be launched in a trajectory away from the aircraft. Once launched, the self-propelled projectile pulls the parachute taut in one dimension.

Abstract: A flight-time variable associated with an aircraft is determined including by determining the flight-time variable while the aircraft is flying. It is determined whether the aircraft is airworthy based at least in part on the flight-time variable. In response to determining that the aircraft is not airworthy, the aircraft is automatically landed.

Abstract: Thrust values for motors in an aircraft are generated where each flight controller in a plurality of flight controllers generates a thrust value for each motor in a plurality of motors using an optimization problem with a single solution. Each flight controller in the plurality of flight controllers passes one of the generated thrust values to a corresponding motor in the plurality of motors, where other generated thrust values for that flight controller terminate at that flight controller. The plurality of motors perform the passed thrust values.