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The downturn in planetary exploration funding during the s had one welcome consequence: JPL began to seek other kinds of spaceflight tasks. This led the Lab into astronomy and Earth science.
One of JPL's technology development efforts in the mids had been research on improving charge-coupled detectors CCDs for use in space. This work was intended for the Galileo camera system, but also resulted in the Laboratory being awarded the Hubble Space Telescope's Wide Field and Planetary Camera in Intended to be the observatory's primary imaging instrument, WFPC operated flawlessly when the telescope was finally launched in WFPC also helped pinpoint a manufacturing flaw in the telescope's primary mirror.
It had been polished to just slightly the wrong shape. The error made Hubble a hugely expensive laughing stock shortly after launch, but JPL scientists realized they could rescue the mission by installing corrective optics in an updated camera.
JPL developed the camera, WFPC2, which was installed on Hubble by astronauts in , and operated until removed during a servicing mission in JPL was the U. Seasat-A was an ocean remote-sensing satellite, with experimental instruments for measuring surface temperature, sea surface height and wind velocity. The satellite also carried a synthetic aperture radar for both ocean and land surface studies.
Spare equipment from the synthetic aperture radar experiment also flew on the second space shuttle mission in During the s, as NASA was developing its space shuttle, the agency had also begun to develop an Earth Observing System concept to advance understanding of our planet's processes. Launched between and , the missions were still operating as of JPL entered the program with an ingenious mission to map the movement of water and melting ice by proxy, through changes in the gravitational pull of shifting masses on orbiting satellites.
JPL also won a cloud research mission, CloudSat, launched in , as well as a series of atmospheric carbon dioxide measuring missions, the Orbiting Carbon Observatories, and the Aquarius sea surface salinity mission. Many of these missions are aimed at tracking Earth's changing climate but contribute to other needs, too. And several missions improve weather forecasts. JPL's first planetary mission approval after Galileo's in was the approval of the Magellan radar mapping mission to Venus.
It was followed by approval of a series of low-cost planetary missions called "Planetary Observers," starting with Mars Observer.
Like Magellan, Mars Observer was intended to fly on the space shuttle, but following the Challenger tragedy the spacecraft launched on a Titan III rocket in While Magellan enjoyed a very successful mission to map most of Venus' surface via radar, Mars Observer disappeared shortly before it was to go into orbit around Mars.
With Mars Observer went the Planetary Observer line of missions—no more were built. Magellan's approval built momentum for the Cassini-Huygens mission to Saturn, a more complex and difficult political effort. But the sudden dissolution of the Warsaw Pact and the Soviet Union over the next few years resulted in NASA's budget unexpectedly shrinking, and Congress threatened to terminate Cassini in and again in The international commitment to the mission saved it, though a budget cut forced the cancellation of Cassini's instrument scan platform — ironically increasing the mission's operating cost over its very long life.
The Cassini-Huygens mission left Earth on Oct. Huygens recorded the most distant planetary landing to date, and operated for 72 minutes on the moon's frozen surface before its batteries failed. The Cassini orbiter continued to study Saturn, its rings and moons until Sept. Cassini circled Saturn for nearly half of the giant planet's Among its many discoveries was super-low temperature volcanism "cryovolcanism" on the tiny moon Enceladus, with the spacecraft even flying through a plume of gas and dust to sample it.
The plume contained chemicals that could fuel microbial life, exciting scientists interested in the search for life off Earth. Cassini flew through Saturn's rings and atmosphere during its final scientific campaign, returning data on their composition and structure until the moment it disintegrated. The Mars Surveyor program eventually flew all of Mars Observer's experiments, though on smaller spacecraft.
The Mars Surveyor program came to an end in , after the failure of two missions launched in , the Mars Climate Orbiter and the Mars Polar Lander. Mars Observer's loss also helped enable NASA to gain approval for another planetary mission program, known as Discovery. The Discovery Program required NASA centers and university-based scientists to submit proposals to competitions that were to be held every few years.
To get the program going, the first two Discovery missions were assigned. JPL was awarded Mars Pathfinder. The Mars Pathfinder mission introduced what has become a powerful technology for planetary exploration: the planetary rover. The USSR had landed robotic rovers on the Moon, and it had tried to land a miniature rover on Mars in the s but had failed.
Mars Pathfinder's micro-rover, named Sojourner, for abolitionist Sojourner Truth, in became the first robotic rover to explore the Red Planet. Mars Pathfinder also pioneered a new policy of releasing imagery to the public in almost real time, via the newly public World Wide Web. Finally, Mars Pathfinder was also inexpensive, and justified an agency drive to reduce the cost of planetary missions even further.
The two were equipped for robotic geology, looking for signs that liquid water having ever existed on the surface. They operated until and , respectively, roving nearly nearly 33 miles 53 kilometers between them. Among their many spectacular findings: at some time in Mars' deep past, water had flowed on the surface.
NASA also approved a large orbiter to help discover suitable landing sites for a future Mars sample return project. That orbiter mission became the Mars Reconnaissance Orbiter, launched in The next rover, eventually named "Curiosity," was equipped for even more detailed investigation of Mars' ancient minerals and geology. It arrived on Mars on Aug. It was launched July 30, Instead of mineralogy, it will specialize in astrobiology and look specifically for signs of past life on Mars.
Perseverance is also designed to collect and store rock samples on the Martian surface for retrieval by a future Mars sample return mission, formally approved by NASA in Perseverance also hosts a robotic helicopter named Ingenuity, a technology demonstration mission that will attempt powered flight on another planet.
The Stardust mission collected particles from comet Wild-2 in , while the Genesis mission returned some particles from the solar wind in The Deep Impact mission launched a kinetic impactor at Comet Tempel 1 to assess its structure and composition in Its mission was to measure martian seismic activity and the heat flow coming from Mars' interior. JPL's next Discovery mission, Psyche, is being designed to explore the unusual main belt asteroid 16 Psyche during the late s.
The InSight lander after placing its seismometer and heat probe instruments on the Martian surface in NASA used the successes of the Discovery program to initiate another program of competed missions, New Frontiers, focused on larger, higher cost efforts.
Unlike Galileo, which had focused much of its data gathering on the Jovian moons, Juno was focused solely on Jupiter. Juno entered a polar orbit on July 4, , and was still operating in In the decades it has led the nation's planetary exploration program, JPL has honed several skills and areas of innovation, including deep space navigation and communication, digital image processing, imaging systems, intelligent automated systems, instrument technology, microelectronics and more.
Digital compression algorithms JPL used to help return Galileo data from Jupiter are widely used in digital recording and transmission now. A JPL spacecraft, Deep Space 1, demonstrated the use of solar electric propulsion for interplanetary missions as well as autonomous space navigation.
The Laboratory has also been active in developing CubeSat technology to reduce mission costs. Its first planetary CubeSats, MarCO 1 and 2, were launched with the InSight mission to Mars and provided data relay services during the probe's landing. Skip to main content. Who We Are. Executive Council. Annual Reports. Virtual Tour. From rockets to missiles In late , the team began tests near Leach Spring in the Mojave desert of small unguided missiles, named Private, that reached a range of about 11 miles nearly 18 kilometers.
Corporal E Round 31 launch at the U. Army anti-aircraft missile model in JPL's supersonic wind tunnel, May Launch of Explorer 1, January 31, Other methods include catapult-launching, using an elastic bungee cord.
The newer "discus" style of wingtip hand-launching has largely supplanted the earlier "javelin" type of launch. Also using ground-based power winches, hand-towing, and towing aloft using a second powered aircraft.
Gliders sustain flight through exploitation of the wind in the environment. A hill or slope will often produce updrafts of air which will sustain the flight of a glider. This is called slope soaring , and when piloted skillfully, radio controlled gliders can remain airborne for as long as the updraft remains.
Another means of attaining height in a glider is exploitation of thermals , which are columns of warm rising air created by differences of temperature on the ground such as between an asphalt parking lot and a lake. Heated air rises, carrying the glider with it. As with a powered aircraft, lift is obtained by the action of the wings as the aircraft moves through the air, but in a glider, height is only gained by flying through air that is rising faster than the aircraft is sinking relative to the airflow.
Sailplanes are flown using thermal lift. As thermals can only be indirectly observed through the reaction of the aircraft to the invisible rising air currents, skill is required to find and stay in the thermals. Hang gliders are composed of rigid frame from which the fabric skin is attached, much like a triangular sailboat sail. The payload and crew are suspended or hung from the frame, and control is exercised through the movement of the harness in opposition to a control frame,.
Paragliders use a special type of steerable parachute for a wing. Control is exercised through lines that deform the trailing edge of the airfoil or the wing's end regions.
Walkalong gliders are lightweight model airplanes flown in the ridge lift produced by the pilot following in close proximity. In other words, the glider is slope soaring in the updraft of the moving pilot see also Controllable slope soaring. Powered models contain an onboard powerplant , a mechanism powering propulsion of the aircraft through the air. Electric motors and internal combustion engines are the most common propulsion systems, but other types include rocket , small turbine , pulsejet , compressed gas, and tension-loaded twisted rubber band devices.
It is the most widely used powerplant for model aircraft, found on everything from children's toys to serious competition models. The elastic motor offers extreme simplicity and survivability, but suffers from limited running time, and the fact that the initial high torque of a fully wound motor drops sharply before 'plateauing' to a more steady output, until finally declining as the final turns unwind.
Using this torque curve efficiently is one of the challenges of competitive free-flight rubber flying, and variable-pitch propellers, differential wing and tailplane incidence and rudder settings, controlled by an on-board timeswitch, are among the means of managing this varying torque and there is usually a motor weight restriction in contest classes.
Even so, a competitive model can achieve flights of nearly 1 hour. Stored compressed gas, typically carbon dioxide CO 2 , can also power simple models in a way similar to filling a balloon and then releasing it.
A more sophisticated use of compressed CO 2 is to power a piston expansion engine, which can turn a large, high-pitch propeller. These engines can incorporate speed controls and multiple cylinders, and are capable of powering lightweight scale radio-controlled aircraft.
Gasparin and Modela are two recent makers of CO 2 engines. CO 2 , like rubber, is known as "cold" power because it becomes cooler when running, rather than hotter as combustion engines and batteries do. Steam, which is even older than rubber power, and like rubber, contributed much to aviation history , is now rarely used.
Hiram Stevens Maxim later showed that steam can even lift a man into the air. Samuel Pierpont Langley built steam as well as internal combustion models that made long flights.
Baronet Sir George Cayley built, and perhaps flew, internal and external combustion gunpowder -fueled model aircraft engines in , , and These had no crank, working ornithopter -like flappers instead of a propeller. He speculated that the fuel might be too dangerous for manned aircraft. All internal combustion engines generate substantial noise and engine exhaust and require routine maintenance. For larger and heavier models, the most popular powerplant is the glow engine.
Glow engines are fueled by a mixture of slow burning methanol , nitromethane , and lubricant castor oil or synthetic oil , which is sold pre-mixed as glow-fuel. Glow-engines require an external starting mechanism; the glow plug must be electrically heated until its temperature can trigger fuel-ignition, upon which the engine's combustion-cycle becomes self-sustaining. The reciprocating action of the cylinders applies torque to a rotating crankshaft , which is the engine's primary power-output.
Some power is lost in the form of waste-heat. Vendors of model engines rate size in terms of engine displacement. Common sizes range from as small as 0. Under ideal conditions, the smallest.
The simplest glow-engines operate on the two-stroke cycle. These engines are inexpensive, yet offer the highest power-to-weight ratio of all glow-engines, but can often generate a great deal of noise, requiring substantially-sized expansion chamber mufflers to reduce their noise output, of both tuned exhaust and non-tuned varieties.
Glow engines which operate on the four-stroke cycle , whether using ordinary poppet valves or occasionally rotary valves offer superior fuel-efficiency power-output per fuel-consumption , but deliver less power than two-stroke engines of the same displacement — yet, often because the power they deliver is more suited to turning somewhat larger diameter propellers for lighter weight, more drag-producing airframe designs such as biplanes and scale aircraft models of pre-World War II full-scale subjects, four-stroke model engines, fueled either with methanol or gasoline fuels are slowly increasing in popularity from their generally lower noise output when compared to similar displacement two-stroke engines, and are available for larger displacement, multi-cylinder four-stroke engines in opposed twin and radial engine layouts.
Internal combustion IC engines are also available in upscale and up-price configurations. Variations include engines with multiple-cylinders, spark-ignited gasoline operation, and carbureted diesel operation. The term "diesel" is in fact a misnomer, as such engines actually operate by compression-ignition. The compression-ratio is controlled by an adjustable threaded T screw on the cylinder head, bearing onto a contra piston within the cylinder bore.
Diesels are preferred for endurance competition, because of their fuel's higher energy content, a mixture of ether and kerosene with lubricating oil. They have higher torque, and for a given capacity, they can usually "swing" a larger propeller than a glow engine. Early "jet" style model aircraft utilized a multi-blade and high pitched propeller fan inside ductwork, usually in the fuselage of the aeroplane. The fans were generally powered by 2 stroke piston engines that were designed to operate at high RPM.
Early brands of these units were the Kress, Scozzi, and Turbax, among others. They generally used 0. This basic fan-in-tube design has been adopted very successfully for modern electric powered "jet" aircraft and are now quite popular.
Glow engine powered ducted-fan aircraft are now relatively uncommon. A major development is the use of small jet turbine engines in hobbyist models, both surface and air. Model-scale turbines resemble simplified versions of turbojet engines found on commercial aircraft, but are in fact new designs not based upon scaled-down commercial jet engines. The first hobbyist-developed turbine was developed and flown in the s by Gerald Jackman in England, but only recently has commercial production from companies such as Evojet in Germany made turbines readily available for purchase.
Turbines require specialized design and precision-manufacturing techniques some designs for model aircraft have been built from recycled turbocharger units from car engines , and consume a mixture of A1 jet fuel and synthetic turbine engine or motorcycle-engine oil.
These qualities, and the turbine's high-thrust output, makes owning and operating a turbine-powered aircraft prohibitively expensive for most hobbyists, as well as many nations' national aeromodeling clubs as with the USA's AMA requiring Jet Planes Landing Upload their users to be certified to know how to safely and properly operate the engines they intend to use for such a model.
The extremely noisy pulsejet offers more thrust in a smaller package than a traditional glow-engine, but is not widely used. A popular model was the "Dynajet". Due to the noise, the use of these is illegal in some countries. Rocket engines are sometimes used to boost gliders and sailplanes, the earliest being the s model rocket motor called the Jetex engine.
This uses solid fuel pellets, ignited by a wick fuse; the casing is reusable. These days, flyers can also mount single-use model rocket engines to provide a short less than 10 second burst of power. In some countries, government regulations and restrictions initially rendered rocket-propulsion unpopular, even for gliders; now, though, their use is expanding, particularly in scale model rocketry. Self-regulation of the sport and widespread European availability of single use 'cartridge' motors seemed to ensure a future, but in recent years the cartridges known as "Rapier" units have become difficult to obtain, due to a reclassification from "smoke producing devices" to "fireworks".
In electric-powered models, the powerplant is a battery -powered electric motor. Throttle control is achieved through an electronic speed control ESC , which regulates the motor's output. The first electric models were equipped with brushed DC motors and rechargeable packs of nickel cadmium cells NiCad , giving modest flight times of 5—10 minutes.
A fully fueled glow-engine system of similar weight and power would likely provide double the flight-time. Later electric systems used more-efficient brushless DC motors and higher-capacity nickel metal hydride NiMh batteries, yielding considerably improved flight times.
The recent development of cobalt -content lithium polymer batteries LiPoly or LiPo now permits electric flight-times to approach, and in many cases [ example needed ] surpass that of glow-engines — however, the increasing popularity of the much more rugged and durable, cobalt-free lithium iron phosphate -celled batteries is increasingly attracting attention away from LiPo packs.
In June a record of 48 hours and 16 minutes was established in California for this class. Electric-flight was tested on model aircraft in the s, but its high cost prevented widespread adoption until the early s, when falling costs of motors, control systems and, crucially, more practical battery and electric power technologies, with the increasing adoption of brushless motors powered with better battery chemistries and controlled with an electronic speed control in place of a throttle servo came on the market.
Electric-power has made substantial inroads into the park-flyer and 3D-flyer markets. Both markets are characterized by small and lightweight models, where electric-power offers several key advantages over IC: greater efficiency, higher reliability, less maintenance, much less messy and quieter flight.
The 3D-flyer especially benefits from the near-instantaneous response of an electric-motor. Starting around the year the entry of Chinese direct-to-consumer suppliers into the hobby market has dramatically decreased the cost of electric flight. It is now possible to power most models weighing less than 20 lb with electric power for a cost equivalent to or lower than traditional power sources. This is the most rapidly developing segment of the hobby as of end of year , along with the increasing popularity of FPV radio control aeromodeling , most often with electric-powered model aircraft, especially multirotor designs.
Most powered model-aircraft, including electric, internal-combustion, and rubber-band powered models, generate thrust by spinning an airscrew. The propeller is the most commonly used device. Propellers generate thrust due to the angle of attack of the blades, which forces air backwards. For every action there is an equal and opposite reaction, thus the plane moves forwards.
As in full-size planes, the propeller's dimensions and placement along the fuselage or wings are factored into the design. In general, a large diameter and low- pitch offers greater thrust and acceleration at low airspeed, while a small diameter and higher-pitch sacrifices thrust for a higher maximum-airspeed.
In model aircraft, the builder can choose from a wide selection of propellers, to tailor the model's airborne characteristics. A mismatched propeller will compromise the aircraft's airworthiness, and if too heavy, inflict undue mechanical wear on the powerplant. For example, a 5x3 propeller has a diameter of 5 inches mm , and a pitch of 3 inches 76 mm.
The pitch is the distance that the propeller would advance if turned through one revolution in a solid medium. Additional parameters are the number of blades 2 and 3 are the most common.
Ducted fans are propellors encased in a cylindrical housing or duct, designed to look like and fit in the same sort of space as a model jet engine but at a much lower cost.
They are available for both electric and liquid-fuelled engines, although they have only become widely used with the recent improvements in electric-flight technology for model aircraft. It is possible to equip a model jet aircraft with two or four electric ducted fans for much less than the cost of a single jet turbine or large petrol or methanol engine, enabling affordable modeling of multi-engine planes, including military bombers and civilian airliners. The fan-unit is an assembly of the spinning fan a propellor with more blades , enclosed inside a shaped-duct.
Compared to an open-air propellor, a ducted-fan generates more thrust per crossectional-area. The shaped-duct often limits installation to recessed areas of the fuselage or wings.
Ducted fans are popular with scale-models of jet-aircraft, where they mimic the appearance and feel of jet engines, as well as increasing the model's maximum airspeed. Speeds of up to mph have been recorded on electric-powered ducted fan airplanes, largely due to the high amount of RPMs produced by ducted fan propellors. But they are also found on non-scale and sport models, and even lightweight 3D-flyers. Like propellors, fan-units are modular components, and most fan-powered aircraft can accommodate a limited selection of different fan-units.
With ornithopters the reciprocating-motion of the wing structure imitates the flapping-wings of living birds , producing both thrust and lift. World competitions are organised by the FAI.
There are the following classes:. Free flight models are flown without any form of mechanical or radio control over the model in flight.
There were contests in , and For many years after the First World War there was no contest. The original trophy had been lost and so in the Society of Model Aeronautical Engineers SMAE approached Lord Wakefield and were offered a new larger silver trophy for international competition.
This trophy is the present Wakefield International Cup and was first awarded at a competition in Also referred to as U-Control in the US, it was pioneered by the late Jim Walker who often, for show, flew three models at a time. Normally the model is flown in a circle and controlled by a pilot in the center holding a handle connected to two thin steel wires.
The wires connect through the inboard wing tip of the plane to a mechanism that translates the handle movement to the aircraft elevator, allowing maneuvers to be performed along the aircraft pitch axis. The pilot will turn to follow the model going round, the convention being anti-clockwise for upright level flight.
For the conventional control-line system, tension in the lines is required to provide control. Line tension is maintained largely by centrifugal force. To increase line tension, models may be built or adjusted in various ways. Rudder offset and thrust vectoring tilting the engine toward the outside yaw the model outward. The position where the lines exit the wing can compensate for the tendency of the aerodynamic drag of the lines to yaw the model inboard.
Weight on the outside wing, an inside wing that is longer or has more lift than the outside wing or even no outside wing at all and the torque of a left rotating propeller or flying clockwise tend to roll the model toward the outside. Wing tip weights, propeller torque, and thrust vectoring are more effective when the model is going slowly, while rudder offset and other aerodynamic effects have more influence on a fast moving model.
Since its introduction, control line flying has developed into a competition sport. There are variations on the basic events, including divisions by engine size and type, skill categories, and age of model design. The events originated largely in the United States, and were later adapted for use internationally.
World Championships are held semiannually throughout the world, most recently in in France, with a limited slate of events — special varieties of Racing F2C or "Team Race" , combat F2D , and speed F2A , all limited to engines displacing 0. A pilot and a mechanic compete as a team to fly small grams; 13 ounces 65 cm Lines are Three pilots, plus mechanic teams, compete simultaneously in the same circle, and the object is to finish the determined course as fast as possible.
Tank size is limited to 7 cc, thus 2—3 pitstops for refueling are needed during the race. The mechanic stands at a pit area outside the marked flight circle. The engine will be started and the model released at the start signal.
Ground time of a good pitstop is less than three seconds. The race course is 10 km, corresponding to laps. Line pull due to centrifugal force is 85 N 17 lb. A faster model will overtake by the pilot steering it above the slower one while he moves his handle with lines over the opponent pilot's head. After two rounds of elimination heats, the 6, 9 or 12 fastest teams enter two semifinal rounds, and the three fastest teams in the semifinals go to the final, which is run over the double course.
Maximum engine size is 2. Diesel, i. They are single cylinder two-stroke, designed for this purpose. At the world championship level it is not uncommon that the competitors design and build their own engines. Their output power is approaching. This time it is two, each with two mechanics on the ground. The aircraft are light in weight and very short from nose to tail so as to maneuver quickly in the air. Each has a 2,5 meter crepe paper streamer attached to the rear of the aircraft by a 3 meter string.
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