NASA's LEAPTech

[Weaver]

LEAPTech to Demonstrate Electric Propulsion Technologies
March 16, 2015

The arrival of a unique experimental demonstrator at NASA Armstrong Flight Research Center on February 26 may herald a future in which many aircraft are powered by electric motors. The Leading Edge Asynchronous Propeller Technology (LEAPTech) project will test the premise that tighter propulsion-airframe integration, made possible with electric power, will deliver improved efficiency and safety, as well as environmental and economic benefits. Over the next several months, NASA researchers will perform ground testing of a 31-foot-span, carbon composite wing section with 18 electric motors powered by lithium iron phosphate batteries.

The experimental wing, called the Hybrid-Electric Integrated Systems Testbed (HEIST), is mounted on a specially modified truck. Testing on the mobile ground rig assembly will provide valuable data and risk reduction applicable to future flight research. Instead of being installed in a wind tunnel, the HEIST wing section will remain attached to load cells on a supporting truss while the vehicle is driven at speeds up to 70 miles per hour across a dry lakebed at Edwards Air Force Base. Preliminary testing, up to 40 mph, took place in January at Oceano County Airport on California's Central Coast.

The LEAPTech project began in 2014 when researchers from NASA Langley Research Center and Armstrong partnered with two California companies, Empirical Systems Aerospace (ESAero) in Pismo Beach and Joby Aviation in Santa Cruz. ESAero is the prime contractor for HEIST responsible for system integration and instrumentation, while Joby is responsible for design and manufacture of the electric motors, propellers, and carbon fiber wing section.

The truck experiment is a precursor to a development of a small X-plane demonstrator proposed under NASA's Transformative Aeronautics Concepts program. Researchers hope to fly a piloted X-plane within the next couple years after removing the wings and engines from an Italian-built Tecnam P2006T and replacing them with an improved version of the LEAPTech wing and motors. Using an existing airframe will allow engineers to easily compare the performance of the X-plane with the original P2006T.

Each motor can be operated independently at different speeds for optimized performance. Key potential benefits of LEAPTech include decreased reliance on fossil fuels, improved aircraft performance and ride quality, and aircraft noise reduction.

LEAPTech is a key element of NASA's plan to help a significant portion of the aircraft industry transition to electrical propulsion within the next decade. According to Mark Moore, an aerodynamicist at Langley, "LEAPTech has the potential to achieve transformational capabilities in the near-term for general aviation aircraft, as well as for transport aircraft in the longer-term."

Peter Merlin, Public Affairs
NASA Armstrong Flight Research Center

From Here: http://www.nasa.gov/centers/armstrong/Features/leaptech.html#.VQiCJI7LIdU

[PR19_Kit]

Needs longer wings and more engines....... 

........Key potential benefits of LEAPTech include decreased reliance on fossil fuels........

So how do we generate the electricity to charge the plane's batteries in the first place?

[kerick]

Actually, having an engine in the fuselage driving a generator might be something to look at. Works for cars, locomotives and ships. Benefit would be a much smaller and lighter motor for cruise with stored battery power making up for take off high power demands. Weight will be an issue with a large number of batteries required for any kind of long range flight. Solar cells on the top of the wings may not power the entire flight but could extend the range. Interesting concept. Could lead to whiffing airliners with lots of tiny propellers.

[pyro-manic]

Needs longer wings and more engines....... 

........Key potential benefits of LEAPTech include decreased reliance on fossil fuels........

So how do we generate the electricity to charge the plane's batteries in the first place?

There's Solar Impulse for a start...

[maxmwill]

Ok, I can see a hybrid-electric type of operation, with a turboshaft of some sort spinning a generator, the engine/generator buried in the belly, powering as many electric motors in the wings as the manufacturer would care to afford to install.

I say turboshaft, because in order to have an acceptable  power-weight ratio, you need something powerful yet light in other to have the aircraft have any appreciable carrying capability(fuel-avionics-aircrew-pax), and a piston engine just wouldn't cut it.

An aside: weren't the Germans experimenting with this type of arrangement, not with turboshafts, but with a piston engine buried in the belly during the war?

[Weaver]

Needs longer wings and more engines....... 

........Key potential benefits of LEAPTech include decreased reliance on fossil fuels........

So how do we generate the electricity to charge the plane's batteries in the first place?

Thousands of environmentalists chained to treadmills? 

Since they say that one aim of the prototype is to compare efficiency with the standard aircraft, it would be logical for it to have the same engine, just driving a generator. For clean-sheet-of-paper designs, maxmwill's suggestion of a turboshaft generator makes more sense of course.

As kerick suggested, solar panels could help out too. You might imagine such an aircraft using it's turbo-generator to climb into a favourable jetstream and then shutting it down, using solar power to extend the glide as far as possible.

Whatever the power source, I've always been intrigued by the idea of a totally blown wing with lots of little props from root to tip. In one scheme, I imagined them powered by compressed air from a Pegasus-style engine(s) in the fuselage.

[Flyer]

I remember reading a American R/C magazine sometime in the 1990's that had a hints, tips and ideas section where someone suggested a micro turbine generator (whole unit not much bigger than a bank card) to replace or recharge on-board battery packs for electric model aircraft and drones to greatly increase flight duration, adding more generators in parallel or series for a bigger current or more power just like battery cells. As far as I know nothing has been done with it, but it is a good idea

Would a APU from a Dash-8 or similar be to heavy or even supply enough power to charge a flight battery?

[maxmwill]

Well, as far as weight is concerned, while I don't know the specific model of APU the Dash 8 has, the name of the game is power output and rotor speed(the faster the rpm of the rotor, the more electric power produced), so while you might have a certain dead weight of the unit itself, depending upon the size of the aircraft and the number of electric motors it drives, that weight would be compensated for by raw power output.