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- 12/07/2014, 14:49 #1
- 01 feb, 09
Pruebas ATR 42-600 hibido
No habia oido nada de esto, no se si lo conocíais, parece que la NASA anda estudiando la posibilidad de aviones híbridos.
Recently there has been a shift in paradigm and now science is doing its best to go green. We have come to realize how our inventions have affected the nature and are doing our best to undo those harmful effects and to be more and more environment friendly. One such project was ERO robot that recycles concrete and Project Zero Electric Plane. This was the reason behind NASA’s project known as Environmentally Responsible Aviation (ERA). The ERA’s goals were to reduce aircraft emissions, noise and fuel consumption. This is what inspired the engineering students from the University of Virginia into focusing their time and energy into the simulation of an environment friendly plane. The result of this work is a simulation that employs a hybrid electric plane which is capable of flight with 50 passengers aboard. The team was led by aerospace engineering students; Sohail Ahmad and Kelly Thomas and these undergraduates used Flight Optimization System (FLOPS) to evaluate a number of designs which were based on propulsions systems and airplanes which are already in use. The whole study was carried out to find out if a hybrid – internal combustion engine and electric motor – was feasible for being a passenger aircraft.
Hybrid Plane 3The team decided, to make use of the batteries while takeoff and landing since they take place in congested areas and the internal combustion engine (ICE) would be in charge during the rest of the flight. The ICE would be charging the batteries for the landing part too. The test plane was chosen to be ATR 42-600 which is a twin turbo propeller commercial aircraft that can carry 48 persons. The team wanted to see if converting this model would result in a feasible hybrid solution to the problem. Two methodologies were employed; series and parallel. In a series system; ICE works to charge the batteries and powers an electric generator which in turn runs the motor. However, for the parallel system; the propeller is capable of being powered by either the ICE and/or electric motor. Their final conclusion was that the parallel system was more efficient for their design and project.
The batteries are a crucial part of this system and they had to consider a number of factors including the power to weight ratio and life of battery. The modeling they did in FLOPS gave them specifics for the battery they needed. Accordingly they needed energy enough to provide them with a thrust of more than 6,000 lbs at a speed of 368 km/hr. This came down to be 1500 kW per engine. Their final choice of battery was a Lithium polymer battery which ended in a total weight of batteries equaling less than 13,000 lbs.
Hybrid PlaneThe final conclusion from the team tells us that in the coming years using this modification approach for an aircraft designed to work ICE would be much more fuel efficient for distances of up to 300 miles and holds a promise for the environment. However, retrofitting the current technology won’t prove to be very fruitful. But they are confident that using the current technology to design an aircraft specifically for the hybrid propulsion system would do the trick. Research is in progress and we wish them good luck. This sure is a work of wonderful engineering.
- See more at: NASA Tests A Hybrid Plane That Works Like A Toyota Prius
NASA Plans Tests Of Distributed Electric Propulsion
Light aircraft are early targets for the efficiency and safety benefits touted for electric propulsion
Jul 10, 2014 Graham Warwick | Aviation Week & Space Technology
A version of this article appears in the July 7 edition of Aviation Week & Space Technology.
Aviation did not enter the Jet Age overnight, and a decades-long journey to the next propulsion paradigm may already be underway. At NASA, the exploration has begun with plans for ground and flight tests to determine whether hybrid and distributed electric propulsion could be the next disruptive shift in civil aviation.
A wing carried high above a truck racing across the dry lakebed at Edwards AFB, California, in November could provide the first validated data to prove that distributed electric propulsion can offer the promised benefits. The 31-ft.-span wing will carry 18 small electrically driven propellers, and is a precursor to a small X-plane demonstrator proposed under NASA’s new Transformative Aeronautics Concepts program.
Modifying the wing on a Technam P2006T light twin would directly compare distributed electric and conventional propulsion. Credit: NASA
In parallel, over the next five years, the agency wants to develop technology for compact, high-power-density electric motors generating 1-2 megawatts—sufficient to power an all-electric general-aviation aircraft or helicopter, a hybrid turbine-electric regional airliner or a large transport with many small engines distributed around the aircraft in ways that make it safer and more energy-efficient.
The sweet spot for a first generation of electric-powered aircraft seems to be between 1 and 2 megawatts, says Ruben Del Rosario, NASA Fixed Wing program manager. But the agency also sees an intersection of unmanned and personal air vehicles around electrical propulsion and increasing autonomy, beginning this spiral exploration with small unmanned aerial systems (UAS) (see page 20) and light aircraft.
“What problems are we trying to solve in general aviation?” Mark Moore, advanced concepts engineer at NASA Langley Research Center, reflects. His answer is many, and they encompass the low efficiency; poor safety, emissions and ride quality; and high operating costs of some light aircraft and helicopters.
Distributed electric propulsion promises dramatic increases in aerodynamic and propulsive efficiency, and reductions in noise and energy costs. “It is not just about general aviation, but they are earlier adopters at a smaller scale, faster and cheaper,” Moore says.
Electric propulsion is not without its penalties. Energy-storage weights are far worse than those of aviation fuel, and battery-pack costs are high. But electric motors are more efficient than turbines or pistons across a wide rpm range, and power-to-weight ratios are higher; they are quiet, compact and reliable, with zero emissions and energy costs that are much lower than for aviation fuel. And, crucially for aircraft design, efficiency and power-to-weight are independent of size.
“You can have multiple small electric motors with the same output as a large one without much penalty. You can put them anywhere around the aircraft, versus heavy piston engines that can only go in one or two places,” says Joby Aviation’s Alex Stoll, chief designer of the Lotus small UAS and two-seat S2, both vertical-takeoff-and-landing designs using distributed electric propulsion. “You can use them to make a personal air vehicle practical, versus an expensive, noisy, unsafe helicopter.”
To test the premise that the tighter propulsion-airframe integration possible with electric power will deliver efficiency, safety and environmental and economic benefits, NASA has partnered with Empirical Systems Aerospace (ESAero) and Joby to propose the Leading Edge Asynchronous Propeller Technology (LEAPTech) demonstrator as an X-plane testbed for distributed electric propulsion.
A traditional light aircraft needs a large wing to meet the low stall-speed requirement for certification, but this is inefficient in cruise. LEAPTech replaces the big wing with one that is one-third the size for lower drag, and has three times the wing loading for better ride quality. Cruise lift-to-drag ratio at 200 mph is greater than 20, versus 11 for a comparable Cirrus SR22, NASA estimates.
To achieve the required 61-kt. stall speed with such a small wing, LEAPTech mounts an array of small propellers along the leading edge. These accelerate airflow over the wing, increasing dynamic pressure at the leading edge and more than doubling the maximum lift coefficient (CLmax) at low speed. “In computational fluid dynamics, we have seen lift coefficients of 5.5. We need 4.5 for a 61-knot stall,” says Stoll. Unblown, with full-span Fowler flaps deployed 40 deg., CLmax is 2.7, says Moore.
Runway tests of a truck-mounted wing will measure the lift augmentation from a leading-edge propeller array at 61-kt. stall speed. Credit: NASA Concept
Optimized for low speed, the small-diameter, high-solidity propellers have low tip speeds, around 450 ft./sec. compared with an SR22’s 919 ft./sec., for reduced noise. In addition, they all operate at slightly different speeds to spread the frequencies and reduce the annoyance. The props blow the wing for takeoff and landing, but fold back to reduce drag in cruise, at which point wingtip propellers optimized for high speed provide propulsion, operating inside the wingtip vortices to increase efficiency.
The intent of LEAPTech is to modify a Tecnam P2006T light twin with the new wing, to provide a direct comparison between conventional and distributed-electric propulsion. But the first step is the Hybrid-Electric Integrated Systems Testbed (Heist), a truck-mounted rig that will enable NASA to ground-test a full-scale wing at the 61-kt. stall condition at lower cost than a wind-tunnel test.
“NFAC [National Full-Scale Aerodynamics Complex wind-tunnel facility] would have cost more than the entire budget [for Heist],” says Moore. “And we need to get to this scale to have reasonable data.” The wing will float on an airbag system in the truck to minimize vibration from the lakebed, and the remaining noise will be removed during post-processing to obtain lift measurements with less than 5% error, he says.
ESAero is the prime contractor for Heist. Joby Aviation is building the test rig, wing, motors and props. Combined, the 18 propellers will generate 300 hp and the wing will provide 3,500 lb. of lift. ESAero will conduct shakedown tests on a paved runway before the lakebed tests in November. “We will get ground vibration . . . [but] are confident we can get clean data on lift, drag and pitching moment,” says NASA Armstrong Flight Research Center project engineer Sean Clark.
In parallel, NASA is beginning fundamental research to understand and overcome the challenges of electric propulsion. Now taking shape at Armstrong, the Airvolt test stand will be used to characterize each element of a single-string propulsion system, from batteries to propeller. A year from now, this will be upgraded to the Airvolt Hybrid, with a Rolls-Royce M250 turboshaft, electric motor/generator and enlarged batteries. This will be arranged so that both the gas turbine and electric motor can drive the propeller, and will be used to look at power-transfer stability issues with parallel hybrid propulsion.
In February 2016, NASA Armstrong plans to begin the Heist power management and distribution (PMAD) ground demonstration. This will be a static propulsion test stand co-located with Airvolt and used as a long-term research platform. NASA plans to evaluate stability issues inherent in parallel-hybrid electric bus architectures, characterize aggregate thrust control of many motors, investigate algorithms for thrust-augmented yaw control and to assess power generation and consumption problems such as catastrophic load shedding, says Clark.
“We will take the wing off the truck, put it on a static test stand and start to do power distribution studies,” he says. These will include shifting between batteries and turbine-driven generator feeding the distributed power bus, and stabilizing the high-frequency electrical loads from the motors. “We will study how to schedule power for yaw control, and how to integrate prognostic health monitoring,” including sensors on the motors, Clark says.
A distributed propulsion electronic controller will translate thrust targets input by the pilot into individual thrust commands for each of the propulsors, while managing the balance between power generation, storage and consumption. A control algorithm will manage the loading of the generator, real-time capacity of the energy storage buffer and power demand from the collection of propulsors. Another algorithm will synthesize individual propulsor commands based on total thrust targets and generator- and stored-power availability.
Heist will use 100-120-volt electrical systems. “That’s not optimal, but it allows us to do [Heist] within a year, and we do not care about weight,” says Andrew Gibson, ESAero business-development president. NASA plans to move to a 600-volt system to reduce distribution wiring weight. “It’s the sweet spot; [there are] no arcing concerns and components are available today,” says Clark.
To follow PMAD, NASA plans hardware-in-the-loop tests to integrate flight-like electric propulsion hardware with simulated aircraft flight controls. Next up will be aircraft-in-the-loop “iron bird” tests with real controls surfaces, flight-ready control system and flight-like energy storage components. The iron bird would test systems for a kilowatt-class distributed electric propulsion X-plane, the LEAPTech, and a 1-2 megawatt hybrid-electric flight demonstrator, notionally one of NASA’s Northrop Grumman RQ-4 Global Hawk unmanned aircraft.
Clark says the iron bird will be used to assess actual electric-propulsion implementation effects such as real-world volume and weight constraints, to address failure modes and recovery strategies, identify and resolve interdependencies between propulsion and other systems, validate aero-propulsive efficiency gains and demonstrate realistic performance benefits from propulsion-airframe integration.
While it seems futuristic, distributed electric propulsion is on the near horizon for light aircraft. Companies such as Joby and secretive Zee.aero are designing personal aircraft around the concept, knowing they must wait for batteries and motors to improve. Joby plans to fly the S2 in 1-2 years and certificate it in “a few years,” says Stoll, who believes “by 2020 electric aircraft will fly 500 miles at 200 mph.”
Moore believes electric propulsion, coupled with autonomy, will spark a breakthrough in on-demand aviation and that the technology will move up to larger aircraft over time, because, just as “the PC came before the Internet, transformative vehicles lead transformative capabilities,” he says. “As you go up in size, the benefits decrease because larger aircraft are already more efficient. But it is still compelling.”Distinguir a un aerotrastornado es fácil, en medio de una multitud cuando oiga el sonido de un avión surcando los cielos. Levantara la mirada hasta establecer contacto visual con el avión, da igual el numero de veces que lo haya visto.
- 14/07/2014, 13:37 #2
- 31 may, 07
Ojala en pocos años podamos ver turbohelices hibridos de pasajeros y aviacion ligera electrica, la revolucion podria ser brutal para la aviacion al reducir la dependencia del petroleo sin lugar a dudas.
Me impresiona ver como esta avanzando la tecnologia en este aspecto, mas rapido incluso que con los coches electricos (que han tenido mas años para desarrollarse)."SPANAIR 1986-2012 , Una de las mejores aerolineas europeas de la historia "
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