Altitude control system

Abstract

Various aspects of the disclosure generally relate to an altitude control system that may be used with lighter-than-air (LTA) aircraft. The altitude control system may include a motor and propeller. In one aspect, the motor may spin the propeller, directing thrust opposite to gravity, which may cause the LTA aircraft to descend. The LTA aircraft may be a balloon with the balloon / control system used in one aspect as a weather balloon gathering atmospheric data.

Description

Docket No. SORC-OOIWO PATENT APPLICATIONALTITUDE CONTROL SYSTEMCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 742,420, filed January 6, 2025, entitled Altitude Control System for a High-Altitude Balloon, which is hereby incorporated by reference in its entirety.BACKGROUNDField of the Disclosure

[0002] Aspects of the disclosure relate to control systems for lighter-than-air (LTA) aircraft.Description of Related Art

[0003] Aerostatic balloons are a specific lighter-than-air (LTA) aircraft that rely on buoyancy to maintain flight at a desired altitude. Unlike a traditional latex party balloon, they will ascend to an altitude and remain at level flight, not popping. These balloons are a component of systems that are used for scientific research, weather observation, and communication technologies, for example.

[0004] Assisting in weather forecasting, sensor packages attached to a high-altitude latex balloon are called "radiosondes." Many are launched per day from sites across the globe, capturing data on their way up to ~80, 000ft where they pop and return to earth under parachute. The data (temperature, wind velocity, pressure, etc) they transmit is fed into forecasting computers to produce weather forecasts. Radiosonde launches may be restricted to ground based stations, missing data over oceans and rural / under developed regions. Less than 5% are recovered - the rest are still out in the world as trash.

[0005] Current altitude control mechanisms for high-altitude balloon systems can be grouped into two categories: consumable and non-consumable. Consumable systemsDocket No. SORC-OOIWO PATENT APPLICATIONrely on valves to release lift gas, lowering the balloon, and dropping ballast / weights, raising the balloon.

[0006] Consumable systems may be simpler and can be scaled down to relatively small packages. They require minimal power and have been used for decades. Because they rely on finite medium (lift gas and ballast) they typically only remain aloft for a few weeks depending on usage. Once consumable systems exhaust their consumable medium they can no longer control altitude.

[0007] Non-consumable systems typically rely on air compressors to compress outside air or lift gas, increasing the system's mass. Due to the high operating altitudes, these air compressors typically run at tens of thousands of RPMs to compress the little air left in the upper atmosphere. Large, complex support systems and significant power onboard are typical aspects of these systems. These systems are typically several hundred pounds, but can remain aloft for long periods of time. In practice, they typically see lifetimes of 6-12 months. These systems are relatively expensive.

[0008] What is needed is an altitude control system with an endurance greater than that available to consumable systems, but without the cost, complexity and weight of non-consumable systems.SUMMARY

[0009] The systems, methods and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein

[0010] In one aspect, an altitude control system may include a propeller and a motor that is coupled to the propeller. The propeller may be configured to generate thrust when spun by the motor. A controller may be coupled to the motor and configured to change the thrust of the propeller. The controller may be coupled to a computer readable medium storing instructions for execution by the controller, the instructions when executed by the controller causing the altitude control system to perform theDocket No. SORC-OOIWO PATENT APPLICATIONfollowing: process an altitude modification order; increase the thrust generated by the propeller; and decrease altitude as a direct result of the increase in thrust.

[0011] The computer readable medium may further store instructions causing the altitude control system to decrease the thrust generated by the propeller, and increase altitude as a direct result of the decrease in thrust.

[0012] The computer readable medium may further store instructions causing the altitude control system to modulate the thrust generated by the propeller between positive values and maintain a descent rate from 0.5 meters / second to 10 meters / second.

[0013] The computer readable medium may further store instructions causing the altitude control system to reverse the spin of the motor, produce negative thrust with the propeller, and increase a rate of ascent with the negative thrust.

[0014] The computer readable medium may further store instructions causing the altitude control system to transmit telemetry, the telemetry from the group consisting of location, time, battery state of charge, and motor data.

[0015] The altitude control system may further comprise a sensor coupled to the controller, with the computer readable medium further storing instructions causing the altitude control system to transmit sensor data from the group consisting of air temperature, pressure, humidity and wind velocities.

[0016] The altitude control system may further comprise a hollow shaft connecting the motor and the propeller, a sensor cable coupled to the controller, the sensor cable extending through and exiting the hollow shaft, and a sensor coupled to the sensor cable.

[0017] In one aspect, a balloon system may comprise a balloon configured to generate buoyancy when filled with a lighter-than-air gas. An altitude control system may be coupled to the balloon, the altitude control including a controller, a motor coupled to the controller, and a propeller coupled to the motor. The propeller may be configured to generate thrust when rotated by the motor, such that, when the balloon is in flight, a majority of the thrust is in the direction of buoyancy.Docket No. SORC-OOIWO PATENT APPLICATION

[0018] The balloon may comprise a super-pressure balloon (SPB).

[0019] The thrust of the balloon system may be sufficient to overcome buoyancy and cause a descent of the balloon while in flight.

[0020] The altitude control system of the balloon system may comprise a sensor coupled to the controller, the sensor selected from the group consisting of air temperature sensor, pressure sensor, humidity sensor, wind velocity sensor.

[0021] The balloon system may further comprise a hollow shaft connecting the motor and the propeller, a sensor cable that is coupled to the altitude control system, with the sensor cable extending through and exiting the hollow shaft, and a sensor coupled to the sensor cable.

[0022] The sensor of the balloon system may be selected from the group consisting of temperature sensor, pressure sensor, humidity sensor, location sensor, solar radiation sensor and electrical conductivity sensor.

[0023] The balloon system may further comprise a transceiver coupled to the altitude control system, the transceiver configured to receive an altitude modification order and to transmit telemetry.

[0024] The altitude modification order may be selected from the group consisting of change the altitude, change an operating state of the motor, change a speed of the motor, change the pressure.

[0025] The balloon system may further comprise a battery coupled to the altitude control system and a photovoltaic (PV) system coupled to the battery and configured to charge the battery.

[0026] In one aspect, for a balloon system including a balloon configured to generate buoyancy when filled with a lighter-than-air gas, and an altitude control system coupled to the balloon, the altitude control system including a controller, a motor coupled to the controller, and a propeller coupled to the motor, the propeller configured to generate thrust when rotated by the motor, the propeller oriented, when the balloon system is in flight, such that a majority of the thrust is in the direction of buoyancy, a transceiver coupled to the altitude control system, there may be a method of adjusting altitude ofDocket No. SORC-OOIWO PATENT APPLICATIONthe balloon system as follows: transmit an altitude modification order resulting in an increase in thrust, and receive data indicating a decrease in balloon system altitude.

[0027] The method may further include transmit an altitude modification order resulting in a decrease in thrust, and receive data indicating an increase in balloon system altitude.

[0028] The method may further include receive sensor data, the sensor data selected from the group consisting of atmospheric temperature, pressure, humidity, location and wind speed.

[0029] The method may include the sensor data corresponding to a plurality of locations with a decreasing altitude followed by a plurality of locations with an increasing altitude.

[0030] The foregoing has outlined rather broadly the gestures and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of this disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purposes of illustration and description, and not as a definition of the limits of the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0031] So that the above-recited features of the disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for theDocket No. SORC-OOIWO PATENT APPLICATIONdescription may admit to other equally effective aspects. The same reference numbers in different drawings may identify the same or similar elements.

[0032] FIG. 1 is a simplified environmental perspective illustrating one aspect of an altitude control system.

[0033] FIG. 2 is a block diagram of one aspect of the altitude control system from FIG. 1.

[0034] FIG. 3 is a block diagram of one aspect of the altitude control system from FIG. 2.

[0035] FIG. 4 is a perspective view illustrating a balloon system.

[0036] FIG. 5 is a block diagram illustrating the balloon system from FIG. 5.

[0037] FIG. 6 is a simplified environmental perspective illustrating one aspect of a communication and navigation network for balloons.

[0038] FIG. 7 is a block diagram illustrating a method of adjusting altitude for a balloon system in flight.DETAILED DESCRIPTION

[0039] Various aspects of the disclosure are described more fully herein with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based at least in part on the teachings herein, one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented, or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. Any aspect of the disclosure may be embodied by one or more elements of a claim.Docket No. SORC-OOIWO PATENT APPLICATION

[0040] FIG. 1 is a simplified environmental perspective illustrating one aspect of altitude control system 100 attached to balloon 110 and carrying optional payload 120 (indicated with dashed lines for payload 120), in flight. Altitude control system 100 includes various components, electronics, a motor and a propeller, and may be attached to a class of craft that are lighter-than-air (LTA) aircraft. LTA aircraft include balloons, airships, and hybrid airships that derive buoyancy with a gas (e.g. hydrogen, helium and heated air) or gas mix. The amount of buoyancy (or aerostatic lift - as used herein, the term "buoyancy" is synonymous with "buoyancy force") for the LTA aircraft depends on the gas and the amount of air displaced by the LTA aircraft. Altitude control system 100 is applicable to all LTA aircraft, including but not limited to balloon, airship, dirigible, blimp, zeppelin, etc. This disclosure primarily references balloons and FIG. 1 is illustrated with a balloon, however altitude control system 100 is applicable to other LTA aircraft as well. Payload 120 may be a separate component hanging apart from altitude control system 100 (payload 120 is illustrated in FIG. 1 below altitude control system 100) but one of ordinary skill in the art will understand that payload 120 may be above (or to the side of) altitude control system 100 or may be separately attached to balloon 110. In one aspect, payload 120 may be integrated with altitude control system 100 or may be absent (hence being optional as illustrated in FIG. 1).

[0041] When a gas or gas mix is added to an LTA aircraft, for example balloon 110, air is displaced and buoyancy is created by the atmosphere due to the displaced air. The buoyancy (upward force) on the balloon is equal to the weight of the displaced air. The weight of the displaced air decreases as the balloon rises, because atmospheric density decreases as the altitude increases. The buoyancy (force pushing the balloon upward) diminishes with altitude and at some particular altitude, the upward force equals the weight of the balloon. With a sufficient amount of gas or gas mix, the buoyancy is enough to overcome the weight of balloon 110. Additional gas or gas mix may overcome the weight of altitude control system 100 and payload 120, causing all of them (balloon 110, altitude control system 100 and payload 120) to rise above the ground. Based on how much air is displaced, atmospheric conditions, the total weight (in one aspect, theDocket No. SORC-OOIWO PATENT APPLICATIONweight of balloon 110, altitude control system 100 and payload 120), balloon 110 (along with altitude control system 100 and payload 120) will rise to an unadjusted altitude. The unadjusted altitude may change over time and correlates to atmospheric conditions and buoyancy (which may vary if gas is added or lost from balloon 110, or the volume of balloon 110 changes, for example). The unadjusted altitude may change over time due to other factors that affect weight, for example ice build up, precipitation, etc.

[0042] Altitude control system 100 may cause a change in altitude by spinning the propeller (see later Figures for further description). Altitude control system 100 is configured such that, while in flight, the rotational plane of the propeller is roughly parallel to the ground and the thrust from the spinning propeller is directed up, or perpendicular to the ground. In one aspect, the direction of thrust is roughly parallel to the direction of buoyancy. When spinning the propeller, altitude control system 100 is "flying" downward. In contrast, conventional LTA aircraft (dirigible and Zeppelin, for example), may use one or more propellers whose rotational plane is parallel to the direction of buoyancy, and direction of thrust is perpendicular to the direction of buoyancy. These conventional LTA aircraft use their propellers to direct thrust parallel to the ground (or horizontally), and change altitude by changing the amount of buoyancy, or applying other aerodynamic forces (elevators, for example). Further conventional aircraft, for example fixed-wing airplanes, may use a propeller to pull (or push) an aircraft through the air and roughly parallel to the ground (depending on flight attitude), causing air to flow over the wings and resulting in aerodynamic lift. Another class of aircraft, rotary wing aircraft, also have a propeller (main rotor) whose rotational plane is parallel to the ground, but the direction of thrust is in the direction of gravity, the result being that the propeller counteracts and works in opposition to gravity in order to create aerodynamic lift and enable flight.

[0043] For altitude control system 100, the spinning propeller causes thrust, which in combination and working with gravity, overcomes the buoyancy and causes balloon 110 to descend (altitude control system 100 decreases the altitude of itself, balloon 110 and where applicable, payload 120). The spinning propeller of altitude control system 100Docket No. SORC-OOIWO PATENT APPLICATIONdoes not create buoyancy, rather, it overcomes buoyancy resulting in a descent. One of skill in the art will recognize that the amount of thrust can vary and be used to control the descent rate as well as control the ascent rate. In one aspect, the amount of thrust is proportional to the rotational speed of the propeller (typically in rotations per minute -RPM). A higher RPM, or faster spin, results in more thrust. In one aspect, the amount of thrust is proportional to the pitch of the propeller (for a variable-pitch propeller). A steeper pitch on the blades of a variable-pitch propeller results in more thrust (as well, a steeper pitch on one fixed pitch propeller may result in more thrust than compared to a less-steep pitched propeller, other factors being equal). In one aspect, either pitch or RPM of the propeller may be altered to change thrust. In one aspect, both pitch and RPM of the propeller may be altered to change the thrust. One of ordinary skill in the art will recognize that a variable or fixed pitch propeller may be used to create thrust.

[0044] "Thrust" as used herein is referenced as being in the same direction as buoyancy. One of skill in the art will recognize that reversing the spin of the propeller (or, with a variable pitch propeller, keeping the same direction of spin while angling the blades of the propeller in the opposite direction) will result in thrust in the opposite direction, i.e. in the direction of gravity. This "negative thrust" would have the effect of assisting buoyancy and potentially increasing a rate of ascent beyond what buoyancy alone is capable of providing. In one aspect, "negative thrust" may be used to ascend more rapidly through storm cells, thunderclouds, icing conditions, etc.

[0045] In one aspect, the thrust created by the spinning propeller is enough to bring balloon 110 to ground level. In one aspect, the thrust is not sufficient to bring balloon 110 to ground level. When altitude control system 100 either stops creating thrust with the propeller, or decreases the thrust sufficiently, balloon 110 may ascend (or maintain a new altitude as an adjusted altitude depending on buoyancy, weight, atmospheric conditions and thrust). In one aspect, when altitude control system 100 stops rotating the propeller, balloon 110 may return to an unadjusted altitude (which may be the same altitude as prior to the thrust, or may be a different and new, unadjusted altitude). In one aspect, altitude control system 100 may spin the propeller in order to maintain aDocket No. SORC-OOIWO PATENT APPLICATIONcertain altitude (or altitude range, for example within 10 meters of a certain altitude, or 15 meters, or 23 meters, and so on) (working with gravity to overcome buoyancy that would otherwise result in an unadjusted altitude, rather than maintaining the certain altitude / altitude range). Balloon 110 may reach an unadjusted altitude from the ground up to 14 kilometers, or up to 30km, or other unadjusted altitudes as dictated by the amount of buoyancy.

[0046] In one aspect, balloon 110 is a super-pressure (superpressure or SPB) balloon that, when combined with altitude control system 100 may be a long-duration atmospheric observation platform designed for numerical weather prediction and atmospheric research. Multiple, daily sensor readings (either from altitude control system 100 or payload 120) may result in vertical profiles of temperature, pressure, humidity, and wind (with mission durations of weeks to months), comparable to conventional radiosondes. A super-pressure balloon is a type of aerostatic balloon where the volume of the balloon is kept relatively constant as ambient pressure outside the balloon changes, and as the temperature of the gas inside the balloon changes. This allows the super-pressure balloon to keep a more stable altitude in contrast to variable-volume balloons, which are either only partially filled with lifting gas or are made with more elastic materials. The volume of a super-pressure balloon is more constrained, so the volume of air displaced by it tends to be more consistent. As a result, the balloon remains stable in a narrower altitude range. A super-pressure balloon may be made with stronger materials than non-pressurized types of balloons (for example, variable volume balloons). A super-pressure balloon may be referred to as an ultra long distance balloon (ULDB) or pumpkin balloon (the sealed balloon envelope has a pumpkin-shape at flight altitude). One of skill in the art will recognize that balloon 110 may be a variable-volume balloon or any other LTA aircraft.

[0047] Advantages of altitude control system 100 over conventional systems may include increased longevity (time aloft) given operational costs, decreased manufacturing and operating cost, decreased weight, increased freedom of navigation, and aircraft using altitude control system 100 is yaw / rotation agnostic. Other advantagesDocket No. SORC-OOIWO PATENT APPLICATIONof altitude control system 100 include freedom from the ballast and gas needs of some conventional LTA aircraft. An LTA aircraft using altitude control system 100 for altitude control does not need to carry (or compensate for) extra ballast (that is dropped for altitude control) or extra gas (to replenish gas that is purposefully vented for altitude control).

[0048] FIG. 2 is a block diagram illustrating one aspect of altitude control system 100 from FIG. 1. In FIG. 2, altitude control system 200 includes propeller 210, motor 220, controller 230 and computer readable medium 240. Controller 230 may represent one of more circuits, from a group of discreet components including resistors, capacitors, diodes and transistors, metal-oxide-semiconductor field-effect transistor (MOSFET), for example, to integrated circuits, which may include operational amplifiers, field programmable gate array (FPGA), application specific integrated circuits (ASICS), microprocessors, microcontrollers, etc, as well as other electrical or electronic components. Computer readable medium 240 includes a medium that is readable by controller 230 and may include various forms of non-transitory memory, for example read-only memory (ROM), random access memory (RAM), flash, and other suitable short or long-term instruction storage mechanisms.

[0049] Computer readable medium 240 may include instructions for various operations that when executed by controller 230 cause altitude control system 200 to perform associated operations. Included in the instructions may be those for processing an altitude modification order, increasing or decreasing thrust provided by propeller 210, checking battery status, checking digital elevation / terrain model (DEM) for proximity to the ground, checking for ice build-up, polling sensors for data, transmitting sensor data or telemetry. Computer readable medium 240 may have other instructions for operating altitude control system 200 with an LTA aircraft, for example with a super-pressure balloon as an atmospheric observation platform.

[0050] In one aspect, altitude control system 200 may process an altitude modification order, for example: an order to descend (or ascend) to a certain altitude; an order causing motor 220 to spin propeller 210 at specific or various RPM; an order to vary theDocket No. SORC-OOIWO PATENT APPLICATIONpitch of propeller 210; an order to generate a certain amount of thrust (generally, a set amount, a variable amount, or where the amount of thrust is zero); or an order causing motor 220 to run for a certain amount of time, or until a certain battery level is reached or some combination thereof. Any one of the altitude modification orders may be processed, or multiple orders. One of skill in the art will recognize that other orders, not previously listed, may be an altitude modification order if the result is a change in altitude for altitude control system 200 during flight. One source for an altitude modification order is from a mission control system (not illustrated in FIG. 2, see FIG. 7), either through direct wireless communication to altitude control system 200, or through a satellite, or through another altitude control system (not separately illustrated). In one aspect, the mission control system may communicate with altitude control system 200 through a transceiver (not illustrated in FIG. 2, see FIG. 3). Altitude control system 200 may receive one or more altitude modification orders from the mission control.

[0051] In one aspect, computer readable medium 240 may include altitude modification orders stored therein (for example, programming that results in processing orders to modify altitude, absent input from a mission control). In one aspect, altitude control system 200 may include sensors and systems for terrain monitoring (for example, a DEM) or other terrain proximity alert, or to monitor atmospheric conditions that could be a risk, for example icing. Despite receiving an amplitude modification order from the mission control, for example, and processing that order, altitude control system 200 may countermand that order by processing another altitude modification order resulting from those conditions (terrain and icing, for example). The second order may originate from within altitude control system 200.

[0052] In one aspect, altitude control system 200 includes instructions for altitude modification orders to be executed over a prolonged time period, the instructions contained within computer readable medium 240. Rather than receive altitude modification orders from the mission control, altitude control system 200 operates independently from a mission control, using instructions stored in computer readableDocket No. SORC-OOIWO PATENT APPLICATIONmedium 240. Altitude control system 200 may operate independently for days, weeks or months.

[0053] Upon processing an altitude modification order, altitude control system 200 may respond by increasing the thrust generated by propeller 210. As discussed with respect to altitude control system 100, thrust may be generated by rotating propeller 210 and spinning propeller 210 in a certain RPM range, at a certain pitch angle (for a variable pitch propeller, for example), or a combination thereof. In one aspect, controller 230 modulates motor 220 and propeller 210 in order to affect a descent rate from 0.5 meters / second (m / s) to 10 m / s, or from 0.5 m / s to 9 m / s, or from 0.5 m / s to 8 m / s, or from 0.5 m / s to 7 m / s, or from 0.5 m / s to 6 m / s, or 0.5 m / s to 5 m / s, or 0.5 m / s to 4 m / s, or 0.5 m / s to 3 m / s, or 0.5 m / s to 2 m / s, or about 2 m / s. For example, in order to affect a descent rate between 1.8 m / s and 2 m / s, propeller 220 may begin spinning at a certain RPM that gradually increases as altitude control system 200 descends to lower altitudes. Depending on conditions, the RPM may change over the course of the descent to the new altitude, keeping the descent rate within a certain range by sometimes increasing RPM, sometimes decreasing RPM, or holding RPM (in this example, for a fixed pitch propeller - for a variable pitch propellerthe pitch angle of the blades may also change, with a narrower change in RPM).

[0054] Upon reaching the altitude called for by the altitude modification order (previously referenced as adjusted altitude), altitude control system 200 may process another altitude modification order, for example turning off motor 220, or decreasing the thrust of propeller 220 to allow altitude control system 200 to ascend, or decreasing the thrust or propeller 220 to hold at the adjusted altitude (within some tolerance range, for example + / - 200 meters, for example).

[0055] In one aspect, motor 220 may be a wound brushless motor powered by a battery (see FIG. 3).

[0056] In one aspect, propeller 210 may be made with carbon. Propeller 210 may be designed as a blade-element model (BEM) tuned to reduce mass, raise Reynolds number, and reduce induced profile losses during operation. To reduce profile losses, aDocket No. SORC-OOIWO PATENT APPLICATIONcustom airfoil may be used with a panel method flow solver. For this airfoil, a thin, cambered profile may be used, and a polished carbon fiber surface that induces a transition to turbulent boundary layer flow, delays trailing edge separation at Reynolds numbers of Re = 104 to 3*104, reduces profile drag and improves efficiency. Tuning of twist may be carried out to improve the load distribution profile, reduce spanwise flex, and improve stiffness. In one aspect, the leading and trailing edges may be altered in the 3D geometry to improve manufacturability.

[0057] In one aspect, propeller 210 may include a foam core with a single-ply carbon construction to create a lightweight, but stiff propeller. In one aspect, propeller 210 has a diameter of 654 mm and a pitch of 300 mm. It may have a mass of 26 g. At a speed of 1 m / s and thrust of 1 N, the efficiency may be ~0.1N / Watt while at altitude.

[0058] In FIG. 2, altitude control system 200 is illustrated absent an LTA aircraft or a payload. One of skill in the art will recognize that altitude control system 200 may be connected to an LTA aircraft, such as a balloon (as discussed in FIG. 1 with altitude control system 100) and optionally a payload. In one aspect, a payload may be separately attached to altitude control system 200 (see FIG. 3), or may be integrated with altitude control system 200.

[0059] In one aspect, altitude control system 200 may process an order to produce negative thrust (as described with respect to FIG. 1), such that the direction of thrust is the same as the direction of gravity. This may cause altitude control system 200 to increase a rate of ascent over what would otherwise occur, without the negative thrust. Examples of orders to produce negative thrust include: reverse the spin direction of motor 220 in order to spin propeller 210 in that direction; reverse a pitch of the blades of propeller 210; reverse at a particular RPM, and so on.

[0060] FIG. 3 is a block diagram illustrating one aspect of altitude control system 200 from FIG. 2. In FIG. 3, altitude control system 200 further includes transceiver 300, battery 310 and photovoltaic (PV) system 320, all of which may be connected to controller 230. Transceiver 300 may be an electronic device that is a combination of a radio transmitter and a receiver. Transceiver 300 may both transmit and receive radioDocket No. SORC-OOIWO PATENT APPLICATIONwaves using an antenna, for communication purposes. Transceiver 300 may be separate discrete components or an integrated subsystem and configured to communicate wirelessly with a ground station through direct radio communication or through indirect communication (for example, through relays such as satellites or other altitude control systems).

[0061] Battery 310 may be any type of battery suitable for the power and voltage needs of altitude system 200, for example lithium-ion rechargeable batteries. Battery 310 may be recharged with photovoltaic (PV) system 320, which may include photovoltaic cells and a charge controller (not illustrated). In one aspect, photovoltaic cells may be located on top of altitude control system 200. In one aspect, photovoltaic cells may be located to the side or attached below. In one aspect, controller 230 may monitor the charge level of battery 310 and regulate operations of altitude control system 200 based on battery level. In one aspect, charge level may be monitored by a mission control (not illustrated) and an altitude modification order sent only when the battery charge level is high enough for descent to an adjusted altitude as well as continued operation of altitude control system 200.

[0062] In one aspect, altitude control system 200 includes sensors. Sensors may be integrated into a main body of altitude control system 200, for example above propeller 210 and alongside controller 230 and the other electrical components of altitude control system 200. Sensors may be configured to provide information about location, time, battery state of charge, motor operation / health, air temperature, air pressure, humidity, wind velocity, solar radiation, electrical conductivity, and so on. Sensors may all be in the same general area (for example above propeller 210, alongside controller 230 and the other electrical components of altitude control system 200), or the sensors may be in different areas. For example, sensors related to telemetry may be above propeller 210. Telemetry sensors 330 may relate to location, time, battery state of charge, motor operation / health. Sensors related to atmospheric data may be below propeller 210. Atmospheric sensors 340 may relate to air temperature, air pressure, humidity, wind velocity, solar radiation and electrical conductivity. Sensors 340 may be connected toDocket No. SORC-OOIWO PATENT APPLICATIONcontroller 230 by sensor cable 350, which may be an electrically conductive support cable routed through hollow shaft 360 in motor 220. In one aspect, sensors 340 may be optional payload 120. One of skill in the art will recognize that components other than sensors 340 may be located in payload 120, or that sensors 340 may be located above propeller 210 and alongside controller 230. In one aspect, sensor cable 350 may hold payload 120 from 8 to 12 meters below altitude control system 200, or from 9 to 11 meters below, or about 10 meters below. In one aspect, physical separation of sensors 340 from altitude control system 200 may benefit some sensor readings by reducing influence from the altitude control system or a potential balloon. In one aspect, no separation of sensors 340 from altitude control system 200 may benefit altitude control system 200 by creating a more compact unit and simplifying manufacturing, deployment and if applicable, retrieval.

[0063] Computer readable medium 240 may include instructions that cause controller 230 to gather telemetry and sensor data, and to transmit that data with transceiver 300. In one aspect, telemetry may be transmitted at some regular interval.

[0064] FIG. 4 is a perspective view illustrating balloon system 400. Balloon system 400 may include aerostatic balloon 410 and altitude control system 420. Altitude control system 420 may be one aspect of altitude control system 100 from FIG. 1. Altitude control system 420 may include a controller (not illustrated in FIG. 4, see FIG. 5), motor 430 and propeller 440. The controller may be one aspect of controller 230. Motor 430 may be one aspect of motor 220. Propeller 440 may be one aspect of propeller 220. Balloon 410 and altitude control system 420 are not illustrated to scale.

[0065] Balloon system 400 is illustrated as it may appear in flight. Aerostatic balloon 410 may be filled with a lighter-than-air gas that displaces air, resulting in buoyancy, which is roughly opposite the direction of gravity. As previously discussed, when enough air is displaced from aerostatic balloon 410, buoyancy will overcome the effect of gravity on balloon system 400 and it will ascend to an unadjusted altitude.

[0066] While in flight, in one aspect motor 430 may rotate propeller 440, which may be configured to generate thrust in the same direction as buoyancy (or upward, andDocket No. SORC-OOIWO PATENT APPLICATIONopposite gravity). Reciting the Third Law of Motion, for every action there is an equal and opposite reaction, resulting in that upward thrust from propeller 440 causes balloon system 400 to descend (decrease in altitude), with a direction of travel in the same direction as gravity. As previously discussed, with a given level of thrust, balloon system 400 will eventually stabilize at an adjusted altitude (other factors staying constant). Keeping the thrust constant, altitude control system 420 may keep balloon system 400 at the adjusted altitude. In one aspect, altitude control system 420 may decrease the thrust such that buoyancy causes balloon system 400 to ascend. A further decrease in thrust may allow a more rapid ascent. Altitude control system 400 may control altitude by varying the thrust from zero to maximum, resulting in ascent (at various rates depending on thrust), descent (at various rates depending on thrust), or an altitude hold (at various altitudes, depending on thrust).

[0067] In one aspect, aerostatic balloon 410 may be a super-pressure balloon (SPB). With a suitable balloon, balloon system 400 may be an operational, long-duration atmospheric observation platform for weather prediction and atmospheric research. With a super-pressure balloon and suitable sensors, vertical profiles of temperature, pressure, humidity, and wind that are comparable to traditional radiosondes may be collected. Balloon system 400 may have a mission duration of weeks or months, operating between the ground and an altitude of approximately 14 kilometers above mean sea level (depending on atmospheric conditions). In one aspect, balloon system 400 may have an additional payload of roughly 300 grams.

[0068] In one aspect, balloon system 400 may produce negative thrust (as described with respect to FIG. 1), such that the direction of thrust is the same as the direction of gravity. This may cause balloon system 400 to increase a rate of ascent over what would otherwise occur, without the negative thrust. Negative thrust may result when the direction of spin (or rotation) for motor 430 with propeller 440 is reversed. In one aspect, with a variable pitch propeller, the direction of spin may stay the same, but the pitch of the blades of propeller 440 may be reversed.Docket No. SORC-OOIWO PATENT APPLICATION

[0069] FIG. 5 is a block diagram illustrating one aspect of balloon system 400 from FIG.4. In FIG. 5, altitude control system 420 further includes transceiver 500, battery 510 and photovoltaic (PV) system 520, all of which may be connected to controller 530.Transceiver 500 may be an electronic device that is a combination of a radio transmitter and a receiver. Transceiver 500 may both transmit and receive radio waves using an antenna, for communication purposes. Transceiver 500 may be separate discrete components or an integrated subsystem and configured to communicate wirelessly with a ground station through direct radio communication or through indirect communication (for example, through relays such as satellites or other altitude control systems).

[0070] Battery 510 may be any type of battery suitable for the power and voltage needs of altitude system 420, for example lithium-ion rechargeable batteries. Battery 510 may be recharged with photovoltaic (PV) system 520, which may include photovoltaic cells and a charge controller (not illustrated). In one aspect, photovoltaic cells may be located on top of altitude control system 420. In one aspect, photovoltaic cells may be located to the side or attached below. In one aspect, controller 530 may monitor the charge level of battery 510 and regulate operations of altitude control system 420 based on battery level. In one aspect, charge level may be monitored by a mission control (not illustrated) and commands sent only when the battery charge level is high enough for descent to an adjusted altitude as well as continued operation of altitude control system 420.

[0071] In one aspect, altitude control system 420 includes sensors. Sensors may be integrated into a main body of altitude control system 420, for example above propeller 440 and alongside controller 530 and the other electrical components of altitude control system 420. Sensors may be configured to provide information about location, time, battery state of charge, motor operation / health, air temperature, air pressure, humidity, wind velocity, solar radiation, electrical conductivity, and so on. Sensors may all be in the same general area (for example above propeller 440, alongside controller 530 and the other electrical components of altitude control system 420), or the sensors may be in different areas. For example, sensors related to telemetry may be above propeller 440. Telemetry sensors 540 may relate to location, time, battery state of charge, motorDocket No. SORC-OOIWO PATENT APPLICATIONoperation / health. Sensors related to atmospheric data may be below propeller 440. Atmospheric sensors 550 may relate to air temperature, air pressure, humidity, wind velocity, solar radiation and electrical conductivity. Sensors 550 may be connected to controller 530 by sensor cable 560, which may be an electrically conductive support cable routed through hollow shaft 570 in motor 430. In one aspect, sensors 550 may be optional payload 120. One of skill in the art will recognize that components other than sensors 550 may be located in payload 120, or that sensors 550 may be located above propeller 440 and alongside controller 530. In one aspect, sensor cable 560 may hold payload 120 from 8 to 12 meters below altitude control system 420, or from 9 to 11 meters below, or about 10 meters below. In one aspect, physical separation of sensors 550 from altitude control system 420 may benefit some sensor readings by reducing influence from the altitude control system or a potential balloon. In one aspect, no separation of sensors 550 from altitude control system 420 is beneficial to balloon system 400 by creating a more compact unit and simplifying manufacturing, deployment and if applicable, retrieval.

[0072] FIG. 6 is a simplified environmental perspective illustrating one aspect of a communication and navigation network for weather balloons. In one aspect, the weather balloons of FIG. 6 may include altitude control system 100 of FIG. 1 with atmospheric sensors, telemetry sensors, transceivers, battery, photovoltaic systems and other necessary equipment, each one held aloft with a super-pressure balloon.Illustrated in FIG. 6 are two balloon systems, weather balloon 600a and weather balloon 600b (collectively referred to as weather balloons 600). Communication between weather balloons 600 and mission control (not illustrated) may be facilitated by ground antennae 610 or satellite 620, or a combination of both. In one aspect, weather balloons 600 may communicate with each other.

[0073] In one aspect, weather balloon 600a may be at an unadjusted altitude, for example, of 14 kilometers. A wind from the right is moving weather balloon 600a to the left in the illustration. Weather balloon 600a may be transmitting telemetry at some interval, for example 10 minute increments, while its battery recharges from aDocket No. SORC-OOIWO PATENT APPLICATIONphotovoltaic system. Weather balloon 600a may also transmit sensor data (atmospheric data from sensors) at some interval, for example 15 minute increments. Weather balloon 600a may be transmitting to satellite 620 or antennae 610, or it may be generally transmitting to whichever platform best receives a signal. During this mode when weather balloon 600a has zero thrust from its propeller, it may collect and transmit wind speed and direction at the unadjusted altitude.

[0074] I n this example, weather balloon 600b is at a lower altitude than weather balloon 600a. Separating weather balloon 600a from weather balloon 600b is a vertical wind shear at which the wind direction reverses, now blowing from left to right in the illustration. Therefore, weather balloon 600b is moving to the right. Weather balloon 600b is transmitting data at regular intervals, which may be time based or may be based on altitude increments, for example 100 meter changes. Weather balloon 600b is illustrated in several stages (two descending stages, one final adjusted altitude, and two ascending stages, all of which are part of "sounding mode" or a "sounding"), each stage represented in FIG. 6 by one of an encircled numbers 1-5. Each stage shows weather balloon 600b at a different location (both horizontally and vertically), illustrating the effect of wind in combination with the altitude control system adjusting the altitude of weather balloon 600b. During a sounding (including both descent and ascent), sensor data may be transmitted more frequently than otherwise, while telemetry may be transmitted less frequently, for bandwidth and power preservation.

[0075] In descending stage 1, the altitude control system for weather balloon 600b is decreasing the altitude of weather balloon 600b by rotating the propeller. Sensors may gather data, for example air temperature, atmospheric pressure, relative humidity, wind speed, direction, geolocation (including altitude). Weather balloon 600b may transmit a packet of sensor data to mission control, each packet polled from the sensors at 100 meter vertical increments.

[0076] In descending stage 2, weather balloon 600b continues descending under power and transmitting sensor data. Descent rate for weather balloon 600b may be around 2 meters / second. In descending stage 2, weather balloon 600b is nearing an end to itsDocket No. SORC-OOIWO PATENT APPLICATIONdescent. In one aspect, onboard systems may monitor conditions that could affect performance, for example icing and battery level. These may also be monitored by mission control. In one aspect, weather balloon 600b may have a digital elevation / terrain model (DEM) and may compare its current altitude and location to the DEM to avoid coming too close to the ground. In one aspect, weather balloon 600b may have other terrain avoidance systems that, when appropriate, may prevent it from completing instructions from mission control before ascending.

[0077] At final adjusted altitude stage 3, weather balloon 600b has reached the bottom of this sounding. The altitude may be nearly ground level (when conditions allow), or within 100 meters of the ground, or 200 meters, or 300 meters, or 400 meters, or 500 meters, and so on, depending on atmospheric conditions, telemetry and location. The amount of time taken to descend from an unadjusted altitude to this final adjusted altitude may be from 1 to 1.5 hours, with sensor data polled at 100 meter vertical increments (as an example - larger and smaller increments may be used). At final adjusted altitude stage 3, the altitude control system of weather balloon 600b may change the thrust produced by the propeller, reducing it to a lower level, or to zero, and begin an ascent for balloon 600b. Total horizontal movement of weather balloon 600b from the beginning of the descent to the final adjusted altitude may reach 150 kilometers, for example.

[0078] In ascending stage 4, weather balloon 600b may continue gathering sensor data at regular vertical intervals and transmit that data to mission control. In all of stages 1-5, weather balloon 600b is experiencing wind from left to right, so is moving to the right.

[0079] In ascending stage 5, weather balloon 600b may continue gathering and transmitting sensor data. The ascent portion of the sounding from the final, adjusted altitude to the unadjusted altitude may take 1-1.5 hours. The total sounding time (a complete round trip of descent and ascent) may take from 2 to 3 hours, with each weather balloon 600 performing 2-4 soundings per day. In one aspect, mission control may determine when and where a sounding is taken. In one aspect, weather balloons 600 may be programmed in advance with a mission, removing the need for input fromDocket No. SORC-OOIWO PATENT APPLICATIONmission control. In one aspect, weather balloons 600 may be out of range from antennae 610 or satellite 620, resulting in sensor data being transmitted from a weather balloon outside the sounding. Based on the sensor data from the sounding (or from multiple soundings), mission control may generate an atmospheric profile.

[0080] Navigation for weather balloons 600 may be accomplished based on winds aloft and altitude, such that weather balloons 600 ascend, descend or hold at an adjusted altitude to be moved along by a particular wind to a more desirable location. One of skill in the art will recognize that with a network of weather balloons mapping different wind currents and the ability to move weather balloons to different altitudes and take advantage of the wind currents, a mission control may direct a network of weather balloons

[0081] FIG. 7 is a block diagram illustrating a method of adjusting altitude for a balloon system (not illustrated) in flight. In one aspect, blocks in FIG. 7 may be applicable to a mission control (not illustrated, but one of skill in the art will recognize that a mission control may have electronics and communication components useful in carrying out blocks in FIG. 7) in communication with a balloon system including a balloon configured to generate buoyancy when filled with a lighter-than-air gas. An altitude control system, in one example altitude control system 100 from FIG. 1, may be coupled to the balloon, the altitude control system including a controller, a motor coupled to the controller, and a propeller coupled to the motor. The propeller may be configured to generate thrust when rotated by the motor, with the propeller oriented, when the balloon system is in flight, such that a majority of the thrust is in the direction of buoyancy. A transceiver may be coupled to the altitude control system.

[0082] In block 700, a mission control may transmit an altitude modification order resulting in an increase in thrust. In one aspect, an altitude modification order may include an order to descend to a certain altitude, or descend in general, or increase the thrust of the propeller (either generally, or to spin the propeller at a certain RPM, or for a certain amount of time, etc.), or to descend to a certain pressure level, and so on.Docket No. SORC-OOIWO PATENT APPLICATION

[0083] Following and because of block 700, in block 710 the mission control may receive data indicating a decrease in balloon system altitude.

[0084] In block 720, a mission control may transmit an altitude modification order resulting in a decrease in thrust. In one aspect, an altitude modification order may include an order to stop descending (hold altitude), to begin ascending to a particular altitude, or descend in general, or change the thrust of the propeller (either generally, or to spin the propeller at a lower RPM, or decrease the thrust, etc.). The altitude modification order in block 720 may be sent because the bottom of a sounding is reached, or because conditions such as icing have changed the weight of the balloon system, or the balloon system is too close to ground or is approaching restricted airspace, and so on.

[0085] Following and because of block 720, in block 730 the mission control may receive data indicating an increase in balloon system altitude.

[0086] In block 740, mission control may receive sensor data, the sensor data selected from the group consisting of atmospheric temperature, pressure, humidity, location and wind speed. In one aspect, sensor data received in block 740 may be part of a sounding, including sensor data from a powered descent (the propeller providing thrust) over a period of time to an adjusted final altitude, followed by un unpowered ascent (the motor not spinning the propeller).

[0087] The aspects and features mentioned and described together with one or more of the previously detailed examples and figures, may as well be combined with one or more of the other examples to replace a like feature of the other example or in order to additionally introduce the feature to the other example.

[0088] Examples may further be or relate to a computer program having a program code for performing one or more of the above methods, when the computer program is executed on a computer or processor. Steps, operations or processes of various above-described methods may be performed by programmed computers or processors. Examples may also cover program storage devices such as digital data storage media, which are machine, processor or computer readable and encode machine-executable,Docket No. SORC-OOIWO PATENT APPLICATIONprocessor-executable or computer-executable programs of instructions. The instructions perform or cause performing some or all of the acts of the above-described methods. The program storage devices may comprise or be, for instance, digital memories, magnetic storage media such as magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. Further examples may also cover computers, processors or control units programmed to perform the acts of the above-described methods or (field) programmable logic arrays ((F)PLAs) or (field) programmable gate arrays ((F)PGAs), programmed to perform the acts of theabove-described methods.

[0089] The description and drawings merely illustrate the principles of the disclosure. Furthermore, all examples recited herein are principally intended expressly to be only for pedagogical purposes to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventor(s) to furthering the art. All statements herein reciting principles, aspects, and examples of the disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0090] A functional block denoted as "means for . . . " performing a certain function may refer to a circuit that is configured to perform a certain function. Hence, a "means for something" may be implemented as a "means configured to or suited for something", such as a device or a circuit configured to or suited for the respective task.

[0091] Functions of various elements shown in the figures, including any functional blocks labeled as "means", "means for providing a sensor signal", "means for generating a transmit signal.", etc., may be implemented in the form of dedicated hardware, such as "a signal provider", "a signal processing unit", "a processor", "a controller", etc. as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which or all of which may be shared. However, the term "processor" or "controller" is by far not limited to hardware exclusively capable of executing software but may include digital signal processor (DSP) hardware, network processor, application specificDocket No. SORC-OOIWO PATENT APPLICATIONintegrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage. Other hardware, conventional and / or custom, may also be included.

[0092] A block diagram may, for instance, illustrate a high-level circuit diagram implementing the principles of the disclosure. Similarly, a flow chart, a flow diagram, a state transition diagram, a pseudo code, and the like may represent various processes, operations or steps, which may, for instance, be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown. Methods disclosed in the specification or in the claims may be implemented by a device having means for performing each of the respective acts of these methods.

[0093] It is to be understood that the disclosure of multiple acts, processes, operations, steps, or functions disclosed in the specification or claims may not be construed as to be within the specific order, unless explicitly or implicitly stated otherwise, for instance for technical reasons. Therefore, the disclosure of multiple acts or functions will not limit these to a particular order unless such acts or functions are not interchangeable for technical reasons. Furthermore, in some examples a single act, function, process, operation or step may include or may be broken into multiple sub-acts, -functions, -processes, -operations or -steps, respectively. Such sub acts may be included and part of the disclosure of this single act unless explicitly excluded.

[0094] Furthermore, the following claims are hereby incorporated into the detailed description, where each claim may stand on its own as a separate example. While each claim may stand on its own as a separate example, it is to be noted that--although a dependent claim may refer in the claims to a specific combination with one or more other claims--other examples may also include a combination of the dependent claim with the subject matter of each other dependent or independent claim. Such combinations are explicitly proposed herein unless it is stated that a specific combination is not intended. Furthermore, it is intended to also include features of aDocket No. SORC-OOIWO PATENT APPLICATIONclaim to any other independent claim even if this claim is not directly made dependent on the independent claim.

Claims

Docket No. SORC-OOIWO PATENT APPLICATIONCLAIMSWhat is claimed is:

1. An altitude control system comprising:a propeller;a motor coupled to the propeller, the propeller configured to generate thrust when spun by the motor;a controller coupled to the motor and configured to change the thrust of the propeller; anda computer readable medium storing instructions for execution by the controller, the instructions when executed by the controller causing the altitude control system to:process an altitude modification order;increase the thrust generated by the propeller; anddecrease altitude as a direct result of the increase in thrust.

2. The altitude control system of claim 1, the computer readable medium further storing instructions causing the altitude control system to:decrease the thrust generated by the propeller; andincrease altitude as a direct result of the decrease in thrust.

3. The altitude control system of claim 2, the computer readable medium further storing instructions causing the altitude control system to:modulate the thrust generated by the propeller between positive values; and maintain a descent rate from 0.5 meters / second to 10 meters / second.

4. The altitude control system of claim 3, the computer readable medium further storing instructions causing the altitude control system to:reverse the spin of the motor;produce negative thrust with the propeller; andDocket No. SORC-OOIWO PATENT APPLICATIONincrease a rate of ascent with the negative thrust.

5. The altitude control system of claim 3, the computer readable medium further storing instructions causing the altitude control system to:transmit telemetry, the telemetry from the group consisting of location, time, battery state of charge, and motor data.

6. The altitude control system of claim 3, further comprising:a sensor coupled to the controller, the computer readable medium further storing instructions causing the altitude control system to:transmit sensor data from the group consisting of air temperature, pressure, humidity and wind velocities.

7. The altitude control system of claim 3, further comprising:a hollow shaft connecting the motor and the propeller;a sensor cable coupled to the controller, the sensor cable extendingthrough and exiting the hollow shaft; anda sensor coupled to the sensor cable.

8. A balloon system comprising:a balloon configured to generate buoyancy when filled with a lighter-than-air gas; andan altitude control system coupled to the balloon, the altitude control system including a controller, a motor coupled to the controller, and a propeller coupled to the motor, the propeller configured to generate thrust when rotated by the motor, such that, when the balloon is in flight, a majority of the thrust is in the direction of buoyancy.

9. The balloon system of claim 7, wherein the balloon comprises aDocket No. SORC-OOIWO PATENT APPLICATIONsuper-pressure balloon (SPB).

10. The balloon system of claim 7 wherein the thrust is sufficient to overcome the buoyancy and cause a descent of the balloon while in flight.

11. The balloon system of claim 9, the altitude control system of claim 9 further comprising a sensor coupled to the controller, the sensor selected from the group consisting of air temperature sensor, pressure sensor, humidity sensor, wind velocity sensor.

12. The balloon system of claim 9 further comprising:a hollow shaft connecting the motor and the propeller;a sensor cable coupled to the altitude control system, the sensor cable extending through and exiting the hollow shaft; anda sensor coupled to the sensor cable.

13. The balloon system of claim 12, the sensor selected from the group consisting of temperature sensor, pressure sensor, humidity sensor, location sensor, solar radiation sensor and electrical conductivity sensor.

14. The balloon system of claim 10 further comprising:a transceiver coupled to the altitude control system, the transceiver configured to receive an altitude modification order and to transmit telemetry.

15. The balloon system of claim 14, the altitude modification order selected from the group consisting of change the altitude, change an operating state of the motor, change a speed of the motor, change the pressure.

16. The balloon system of claim 15, further comprising:Docket No. SORC-OOIWO PATENT APPLICATIONa battery coupled to the altitude control system; anda photovoltaic (PV) system coupled to the battery and configured to charge the battery.

17. A method of adjusting altitude of a balloon system in flight, the balloon system including a balloon configured to generate buoyancy when filled with a lighter-than-air gas, and an altitude control system coupled to the balloon, the altitude control system including a controller, a motor coupled to the controller, and a propeller coupled to the motor, the propeller configured to generate thrust when rotated by the motor, the propeller oriented, when the balloon system is in flight, such that a majority of the thrust is in the direction of buoyancy, a transceiver coupled to the altitude control system, the method comprising:transmitting an altitude modification order resulting in an increase in thrust; and receiving data indicating a decrease in balloon system altitude.

18. The method of claim 17, further comprising:transmitting an altitude modification order resulting in a decrease in thrust; and receiving data indicating an increase in balloon system altitude.

19. The method of claim 17, further comprising:receiving sensor data, the sensor data selected from the group consisting of atmospheric temperature, pressure, humidity, location and wind speed.

20. The method of claim 19 wherein the sensor data corresponds to a plurality of locations with a decreasing altitude followed by a plurality of locations with an increasing altitude.

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