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Boeing's Hybrid Electric Airliner of the Future
fergus07 writes "Borne out of the same NASA research program that gave birth to MIT's D 'double bubble,' Boeing's Subsonic Ultra Green Aircraft Research (SUGAR) Volt concept is a twin-engine aircraft design notable for its trussed, elongated wings and electric battery gas turbine hybrid propulsion system — a system designed to reduce fuel burn by more than 70 percent and total energy use by 55 percent. The goal of the NASA supersonic research program is to find aircraft designs that will significantly reduce noise, nitrogen oxide emissions, fuel burn and air traffic congestion by the year 2035."
All the coolest technology is always now()+25 years away.
The other planes....I just imagined the airline packing those suckers and having more than one middle seat. And you know they'll be charging extra for the window or the isle seat.
RIP America
July 4, 1776 - September 11, 2001
You say you want to save massive amounts of energy, and then you show me a design that is not a flying wing. Slashdot, you have some aerospace engineers lying around, so help me out: what gives?
I had 'jet fuel' as on my list of things that wouldn't ever likely get replaced with electric storage, and now this reduces the list a bit. Can we just start putting up some modern nuclear reactors and get out of the Middle East then? We've got plenty of sources here for real oil needs.
No one has died of a radiation-related accident in the history of the U.S. civilian nuclear reactor program. but 10,000 or so Americans have died so far as a result of making war in the Middle East.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
Jet engines are already de-facto propeller engines. If you call it a "Fan" it doesn't sound as scary as "Propeller." In a high bypass turbofan engine such as those found in most modern aircraft, most of the thrust is produced by the fan part of the turbofan. For example, the CF-34 jet engine has a bypass ratio of 80% or better. This means 80% of the thrust is produced by spinning a fan. Newer designs like the Rolls-Royce Trent 800 get 84% thrust from the bypass fan. Basically, anything that can create radial motion can be use to turn that fan. Electric, steam, compressed air, .... {insert physics here}.
This is a boring sig
LH2 tanks require more insulation (meaning more weight). The planes can only carry so much fuel by volume. The maximum fuel capacity for a 737-NG is 26,000 liters. The density of Jet A at 15C is about 800g/L. The density of liquid hydrogen is 71g/L at 20K. At these densities, you get masses of about 21,000kg of Jet A and 1900kg of LH2. The specific energy of Jet A is about 43MJ/kg, and 143MJ/kg for LH2. At those levels, you get total stored energy of about 1.1 million MJ for Jet A, and only 270,000 MJ for LH2.
The numbers just don't work, and these don't consider the complicating factors from dealing with cryogenic fuels.
You can never go home again... but I guess you can shop there.
The bypass ratio refers to the mass of air moved around the core to the mass moved through the core, not the ratio of thrust. For any given mass of air being put through the core, it will produce more thrust than the same ratio outside the core because it gets hotter/faster.
They tried building a hydrogen powered spy plane back in the 70s or something. LH2 is kind of a nightmare to deal with compared to jet fuel. For one thing, its a cryogenic. The US Air Force decided that playing with LH2 was a) too dangerous and b) too much of a logistics headache. And even with LH2, your energy density is still significantly lower than jet fuel. They had a nightmare trying to get the range required on that spy plane. Wiki-link for you: http://en.wikipedia.org/wiki/Lockheed_CL-400_Suntan. If you're interested, try finding Ben Rich's Shunkworks. He spends a chapter talking about trying to build this thing (and all the wonderful fun they had playing with LH2... they apparently went ahead and did all the usual Liquid Nitrogen fun stuff... except with LH2).
Jet engines are, by definition, not fans. They produce thrust by the acceleration of a jet of combustion products exiting the rear of the engine through a nozzle. Rockets are jet engines; but the term jet engine usually implies air-breathing and rockets are assumed to carry their own oxidizer. Propellers/fans produce thrust pushing air back by rotation of the fan blades/fan wheels/propellers .
Fans can be propellers or otherwise. When talking about aircraft it's usually meant that a prop is un-ducted but a fan is ducted.
Pure jet engines are efficient at high speeds, but very inefficient at low speeds like at takeoff where fans can be a big help. That's one of the main reasons fans are included in the "jet engines" found on most commercial aircraft. (Unducted) Props don't work very well at the high cruising speeds of most airliners because the velocity of the propeller tip gets added (vector-wise) to the airspeed of the plane, which result in velocities near or above the speed of sound. The ducting can be designed to slow down the air and somewhat mitigate that issue.
Commercial airliners usually use combination fan/jet engines.
obscure?
Definitely obscure. "Ecological" cars and airplanes? Carbon-powered? Obscure motivations? Trains are 100% electric, infinitely safer, more spacious, smaller footprint than roads, etc. On short routes, they can be faster than flying, after factoring taxis and airport waits. And, there are bar-cars. -- http://gizmodo.com/5434582/the-fastest-train-in-the-world
Build your own energy sources from scratch. http://otherpower.com/
The press release is devoid of details, but a google search turns up that they're decoupling the jet engine (which generates the power) from the bypass fan (which generates most of the thrust).
For those not up to speed on jet engine technology, modern turbofans are essentially ducted propellers. The engine itself occupies a small section in the center. It burns fuel and throws the air it consumes out the back at a higher speed. This generates about 20% of the total thrust. The rest of the energy goes into spinning the bypass fan blades. Just like a propeller, they grab large chunks of air which never goes through the combustion chamber, and push it out the back at higher speed to generate about 80% of the thrust.
In current engine designs, the blades of the two are locked together (although some of the compressor blades inside the engine may rotate at a different speed). For the bypass fan blades to be spinning, the engine must also be on and spinning. The idea behind this hybrid is to decouple them so they can operate independently of each other. The bypass fan would be spun using an electric motor. I don't know the numbers involved, but theoretically that would mean you could always run the jet engine at its most efficient RPM to generate electricity, and even turn it off if there's little thrust required and the batteries have enough juice to run the bypass fan (e.g. descent).