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NASA Unveils Plans For Electric-Powered Plane (techcrunch.com)
An anonymous reader quotes a report from New York Times: A new experimental airplane being built by NASA could help push electric-powered aviation from a technical curiosity and pipe dream into something that might become commercially viable for small aircraft. At a conference on Friday of the American Institute of Aeronautics and Astronautics in Washington, Charles F. Bolden Jr., the NASA administrator, announced plans for an all-electric airplane (Warning: source may be paywalled) designated as X-57 and nicknamed "Maxwell," part of the agency's efforts to make aviation more efficient and less of a polluter. "The X-57 will take the first giant step in opening a new era of aviation," Mr. Bolden declared. Maxwell is equipped with 14 electric propeller-turning motors located along the wings, which will all be used to create sufficient thrust during take-off and landing. Only two large motors on the tips of the wings will be used once it's up in the air. The plane is a result of NASA's "New Aviation Horizons" initiative: a 10-year program to create a new generation of X-planes that will make use of greener energy, use half as much fuel, and be half as loud as commercial aircraft in use today.
The issues with electric planes have been beat to death here, this NASA plane appears to have no solution for any of them.
In two days .
12 engines as deadweight and dragging props, that doesnt seem very efficient ? Even with foldable props, they will induce a significant drag. I am sure NASA can come up with a better solution for extra power needed for takeoff.
So they have 12 extra motors/props just for takeoff, that add both weight and drag? Why don't they just use one motor and drive one of the wheels against the ground?
The Russians are't going to do shit. They have nothing like technology to do this - the Chinese are far more likely and are closer. The Russians plod on with steam-era rockets, which are practical but are a fallback to pre-V2-technoliogy. They aren't advancing any states of any arts.
You're forgetting that with the extra props across the wing, you need a much much smaller wing, and can have a wing with much higher aspect ratio*. The reduction in wing area and increased aspect ratio more than offsets any drag from the multiple (folded) props during cruise.
*Those props aren't there for thrust, they are for increasing flow velocity over the wings.
"There are a dozen opinions on a matter until you know the truth. Then there is only one." - CS Lewis (paraprhase)
RTFA. Max speed is 175KT, not exactly "high speed". NASA also admits this won't be viable for commercial service, basically a hobbyist plan for short flights with very little payload.
Bottom line though is that NASA is and has always been a PR machine. An all electric plane is a warm fuzzy story for people to read.
The distributed motors are a feature, not a bug. With current designs, manufacturers can't go with more smaller engines due to efficiency losses. The engines installed on aircraft now are used to provide thrust and the resulting wind across the airfoil from that forward movement is what provides lift.
This design is different because the smaller motors have higher efficiencies and are able to direct air over the airfoil directly instead of relying solely on forward thrust to provide the same wind. That adds to lift, which reduces takeoff distance, which reduces friction losses from the wheels.
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Musk, not being an engineer or scientist of any sort, is probably used to people telling him things are impossible. Most of the time, engineers in the current day tend to immediately jump to "impossible" based on their experiences trying to make something of fix something simple due to crushing bureaucracy that they assume everything is impossible. When someone tells a management type something is impossible, they just don't believe the engineer any more, because the engineers are usually overstating the difficulties.
Lots of tradeoffs. Airflow over the wings helps takeoff performance, but the disrupted airflow from the props in cruise is likely top reduce efficiency. Generally for low speed aircraft you want as few total propeller blades as you can use in order to reduce the losses from blade tip vortices. (practical effects like prop diameter will often force you to more props and more blades).
The Russians plod on with steam-era rockets, which are practical but are a fallback to pre-V2-technoliogy.
That's a pretty ridiculous and insulting exaggeration.
Up until SpaceX announced the Merlin 1C less than a decade ago, Russia was the unquestioned leader in Kerosene-Oxygen engine technology. There's a good reason that United Launch Alliance selected the Russian RD-180 for the Atlas V. More generally, Russian technology is competitive with (I do not say equal to) that of the West in many areas, such as rocketry, jet engines, airframes, avionics, weaponry, etc.
Dismissing all of that as "pre-V2 technology" is nonsensical propaganda: facing off against a military limited to actual pre-V2 tech, the Russian military would absolutely dominate.
The article states that the Maxwell X plane is a hybrid and goes on to detail it is electric propulsion and battery powered. That doesn't sound like a hybrid to me. I can only guess they either used the term in error or were think of future concepts.
Interesting I would guess pure electric aircraft make up the majority if you include hobby quadcopters in that definition. I mention that as I think the takeaway from the article is that electric aircraft are practical in some niche areas and NASA's work will widen those niches. The changes need for EV cars to replace ICE are evolutions in batteries and is already close to the tipping point, but It is going to take some truly impressive breakthrough in battery technology before your will see traditional commercial jets like the A320, 737, 767 or A380 replaced. My guess we are are years, not decades, away from cars going all electric but for aircraft we are probably still talking decades.
My guess is the props on the takeoff motors fold in when cruising to reduce drag. Even if they do I would still worry about the remaining drag and the extra weight.
But then again it is an X plane. That is why you build them, to see how good or bad the ideas are in the real world.
Building a supersonic electric airplane is certainly ambitious, but far from impossible.
On the other hand, building a practical and economically useful supersonic electric airplane with current technology is impossible. Hydrocarbon-powered supersonic planes still run out of fuel quickly, even after hundreds of billions of dollars of investment in the concept. A battery-powered model will certainly not have useful endurance.
> GP also ignorantly fails to understand that props efficient in
> high speed flight are inefficient at low airspeed and vice versa,
> so stowing climb props is a very good choice for an electric airplane.
Howsabout variable pitch propellors??? They've been around since the 1920's, and have been in practical use since the 1930's https://en.wikipedia.org/wiki/...
Rev up 2 or 4 engines (admittedly a bit inefficient) for takeoff, and then back off to more efficient speed for cruising. 2 or 4 larger engines are cheaper and more efficient than 14 smaller ones. A bonus feature is that many "variable pitch propellors" can change pitch to *REVERSE* thrust. This is useful for backing up out of a hangar, as well as providing braking during landing on short airstrips.
I'm not repeating myself
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