Drone Aerial Refueling Project Progresses

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A flight test conducted at an altitude of 45,000 feet, during which a piloted Proteus test aircraft approached to within 40 feet of a NASA Global Hawk drone, was hailed as a success by engineers and is seen as another step closer to the goal of aerial refueling between unmanned aircraft. The approach of the Northrop Grumman Proteus to the Global Hawk tested its performance in the presence of wake turbulence, and although no actual refueling took placing during the flight test, the data gathered regarding flight control responsiveness and engine performance will prove invaluable in preparation for the real thing. Moreover, the two aircraft undertook simulated breakaway maneuvers essential for stealth surveillance tactics.

The Global Hawk, also manufactured by Northrop Grumman, is proving its value in high-altitude, long-endurance (HALE) flight, offering the science community the means to measure, monitor and observe remote locations unattainable previously. The Global Hawk currently boasts an 11,000 nautical mile range and 30-hour endurance. Aerial refueling will extend this capability tremendously, with the initial aim of remaining airborne for a week. As part of the $33 million Defence Advanced Research Projects Agency (DARPA) KQ-X project, the goal is to have successful aerial refueling between two Global Hawk drones by spring 2012.

From a military and defense point of view, having drones with HALE capabilities opens up the opportunities for surveillance beyond current capacity, while reducing the risk factor of piloted flights. From a science standpoint these aircraft make it possible to gather information relating to Earth System Science, defined as the study of global environmental changes involving interactions between land, water, atmosphere, ice, biosphere, societies, economies and technologies.

The Global Hawk is 44 foot long, with a wingspan of over 116 feet and a height of 15 feet. Powered by a single Rolls Royce AE3007H turbofan engine, its gross takeoff weight is 25,600 pounds including 2,000 pound payload capability. Northrop Grumman is working in conjunction with NASA Dryden and is responsible for the design and modification of the Global Hawk Aircraft. Other unmanned aerial vehicles (UAV) being developed at this time include the Phantom Eye by Boeing and Northrop Grumman’s X-47B and Fire-X.

Seagull Made of Metal

Joachim Huyssen, from the Nortwest University located in South Africa, started rethinking the principles and technologies that apply to aerodynamics and how to create an aircraft that was energy efficient. He began collaborating with Geoffrey Spedding, from the University of Southern California, and together they began creating an aircraft that now closely resembles a bird we often marvel at, namely the seagull. Nature is often looked at when it comes to aviation technology, although the men have confirmed that though their design resembles a seagull, it was purely by accident.

While Spedding was in South Africa, Joachim Huyssen approached him with his design ideas, which were extremely unconventional. Even though the design was unique in many ways, Spedding was intrigued by the new challenge and jumped on board as a collaborator. The new energy efficient and aerodynamic body of the aircraft is short, as well as the tail being best described as stubby. The fact that it does not have a conventional tail means that there is less drag on the aircraft and its bowed wings (gull wing configuration) are therefore the instruments that are moved to control pitch and stability. Most of the technology in regard to aviation has already been tried and tested, but when it comes to designing more fuel efficient aircraft, the challenge is still out there and there are new frontiers to be explored.

Spedding was quoted saying, “The most important point is that we may be wasting large amounts of fossil fuel by flying in fundamentally sub-optimal aircraft designs. At the very least, we can show that there exists an alternative design that is aerodynamically superior. One may argue that there is now an imperative to further explore this (and perhaps other) designs that could make a significant difference to our global energy consumption patterns.” As the fuel consumption and environmental crisis become more of a threat, there will be a greater need for more energy efficient forms of transportation, and currently, Spedding and Huyssen find themselves on the frontlines of new discoveries in regard to aviation. The new aircraft designed by them might be a familiar sight in our skies sooner than we might anticipate.

MIT-Designed Planes Aim for 70% Fuel Reduction

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With possible fuel shortages in the future being a very real cause for concern, coupled with dire observations on the damage fossil fuels are doing to our environment on a world-wide scale right now, much emphasis is being placed on developing alternative, ‘green’ energy sources, as well as finding ways to use the fuel we have in the most efficient way possible. In a project that forms part of a $2.1 million NASA grant, a team led by researchers from MIT’s Department of Aeronautics and Astronautics have come up with designs for commercial aircraft that will use up to 70 percent less fuel than airliners are currently using, while at the same time reducing noise and nitrogen oxide emissions. Referred to as an ‘N+3’ airplane, denoting three generations from now, its design will incorporate new technologies, such as advanced propulsion systems and innovative airframe configurations, in order to cut back drastically on fuel consumption.

Two designs have been developed by the MIT team: Model D 180-passenger series, which would replace the current Boeing 737 class of aircraft aimed at domestic flights; and the Model H 350-passenger series to replace the Boeing 777 class of aircraft used for international flights. Referred to as the ‘double bubble’ series, the Model D could burn around 50 percent less fuel than the current 737, however, using advanced technology and materials, fuel savings could be as high as 70 percent. Further beneficial features will be the use of bio-fuels as opposed to fossil-fuels, and a slimmer wing design along with a smaller tail resulting in reduced drag.

As the larger of the two models, the Model H makes use of a triangular-shaped hybrid wing body, creating a forward lift and eliminating the need for a tail to balance the airliner, thereby reducing drag. It is calculated that the Model H will also meet the 70 percent fuel reduction target set by NASA, with a reduction of 75 percent in nitrogen oxide emissions. Upon NASA’s approval of the project thus far, researchers will move ahead with the goal of having the new designs in commercial service by 2035, in an effort to meet increasing air travel demands.

Piper Commanche

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When Piper introduced the PA-24 Comanche in 1957, the company marketed it as a low-cost first-time buyer’s aircraft. The low-wing PA-24-180 Comanche with a 180 HP engine is somewhat more complicated to fly than a Cessna 172. As with the 172, the PA-24-180 Comanche is a four seat all-metal aircraft, but the gear is retractable and it uses a variable pitch propeller that requires more work on the pilot’s part than does a constant pitch propeller that never needs adjusting in flight. The same is true with the Comanche’s manually operated flaps. Piper manufactured 1,143 of the PA-24-180 Comanche airplanes.

Piper began selling the Comanche 250 in 1958. It had a 250 HP engine that provided more power than the earlier model. Carburetors were standard, but some planes came equipped with a fuel-injected engine. In later years, Piper included an optional 90-gallon auxiliary fuel system and replaced the hand brakes with toe brakes. Soon after, they also replaced the manually operated flaps with electrical flaps.

In 1965, Piper made the PA-24-260 available, most of which were fuel-injected. The company manufactured variations of the 260 until 1972, by which time they had sold 1,029 of the airplanes. Because of a larger, 260 HP engine and increase in propeller speed, the PA-24-260 is more powerful and faster than its predecessor, the Comanche 250.

Continuing with Piper’s desire to create ever more powerful aircraft, the Comanche 400 offered a 400 HP engine, a three-blade propeller, and greater fuel capacity for longer range and more power than earlier versions of the Comanche.

Piper sold 2,000 of the PA-30 Twin Comanche in its various forms. The first models were four-seat PA-30s that included minimal avionics and engine equipment. The PA-30B offered more, including third side windows and optional propeller and wing deicing equipment, a heated windshield, seating for six, and wing-tip fuel tanks. A turbo version (the PA-30B) came next, and though it had the same engines, they were manually controlled Rajay turbochargers, which when operated correctly, offered additional power. Operated by an unqualified or careless pilot, the engines were susceptible to sudden failure. Next from Piper came the PA-30C Twin Comanche. The turbo version of that aircraft was the fastest in the twin-engine line.

Piper then created the PA-39 C/R Twin Comanche with counter-rotating propellers. This was to correct the sometimes fatal control problems that occur when both engines’ propellers turn the same way. When the left, or critical engine, fails at a high angle of attack or at slow speed, the airplane will likely become uncontrollable.

Introducing Cessna’s Skyhawk TD

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After an extensive market survey and rigorous flight testing, Cessna Aircraft Company has made the announcement that, from mid-2008, the Skyhawk 172S airplane will be available fitted with a turbo diesel engine. The new Skyhawk TD (turbo diesel) will feature a Full Authority Digital Engine Control (FADEC) equipped Thielert Centurion 2.0 liter engine to drive a composite three-blade constant speed propeller. This DOHC (dual overhead camshaft) four-cylinder inline turbo-charged engine develops 155 horsepower, is liquid cooled and certified to run on Jet-A fuel.

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Boeing’s Development of the Fuel Cell Demonstrator Airplane

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Boeing has always strived to be in the forefront of developing aerospace products that will not harm the environment. At the Boeing Research and Technology Center such developments have been made in environmentally progressive technologies, which Boeing hopes to later apply to the field of aviation.

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The Need for Eco-Flying

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According to a recent report written by many of the world’s most respected scientists, carbon emissions, that nasty problem at the root of most climate change issues, is largely due to humans burning gas, oil, and coal. Airplanes alone generate two percent of the world’s carbon emissions. That amount is likely to increase substantially over the coming years as fare prices lower and more people can afford to fly. Already, airplanes are the fastest growing source of carbon dioxide in the United Kingdom and in several other countries around the world.

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Is 2007 the Year of the Very Light Jet?

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Several airplane manufacturers are expanding into the very light jet category, a type of plane that requires only one pilot and can transport between three and nine passengers. Even more companies are sitting on the fence without yet committing or walking away from the prospect of joining their competitors. Their wait-and-see attitude may be short-lived.

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More Than One Kind of Autopilot

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A Cessna 185 amphib lost power shortly after takeoff. Authorities determined that the pilot had selected Fuel Off instead of Fuel Both for tank selection. How did it happen? The fuel tank selector cover was broken which allowed full movement of the selector knob. The pilot relied on feel for sensing the knob’s location. The accumulator tank contained enough fuel for full operation of the plane until shortly after takeoff.

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