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posted by martyb on Sunday May 10 2015, @03:55PM   Printer-friendly
from the next-up:-a-very-long-and-lightweight-extension-cord dept.

NASA has tested the Greased Lightning GL-10, a 10-motor drone which can take off vertically like a helicopter and fly efficiently like an airplane. They also envision a scaled-up version which could carry 1-4 people:

The GL-10 is currently in the design and testing phase. The initial thought was to develop a 20-foot wingspan (6.1 meters) aircraft powered by hybrid diesel/electric engines, but the team started with smaller versions for testing, built by rapid prototyping.

"We built 12 prototypes, starting with simple five-pound (2.3 kilograms) foam models and then 25-pound (11.3 kilograms), highly modified fiberglass hobby airplane kits all leading up to the 55-pound (24.9 kilograms), high quality, carbon fiber GL-10 built in our model shop by expert technicians, " said aerospace engineer David North.

"Each prototype helped us answer technical questions while keeping costs down. We did lose some of the early prototypes to 'hard landings' as we learned how to configure the flight control system. But we discovered something from each loss and were able to keep moving forward."

During a recent spring day the engineers took the GL-10 to test its wings at a military base about two hours away from NASA Langley. The remotely piloted plane has a 10-foot wingspan (3.05 meters), eight electric motors on the wings, two electric motors on the tail and weighs a maximum of 62 pounds (28.1 kilograms) at take off.

"During the flight tests we successfully transitioned from hover to wing-borne flight like a conventional airplane then back to hover again. So far we have done this on five flights," said Fredericks. "We were ecstatic. Now we're working on our second goal — to demonstrate that this concept is four times more aerodynamically efficient in cruise than a helicopter."

Here is a 4m45s video of a test flight.

 
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  • (Score: 1) by Katastic on Monday May 11 2015, @09:33PM

    by Katastic (3340) on Monday May 11 2015, @09:33PM (#181656)

    In what part of your ass do you find people to support your even more vague assertions?

    I didn't get a degree in Mechanical Engineering to have some armchair warrior tell me I don't know how to design machinery.

    I said four, not two, engines very specifically because four capture all possible thrust vectors that those ten would. Two front, two rear, everything can swivel, and the engines can still use different thrusts to impart rotation. Look up "degrees of freedom." You can't magically add more engines to the same, non-jointed section, and get new moments of rotation.

    A laymen analogy. Want to know why there aren't more than four wheels on most vehicles? Because three wheels leaves you with a triangle of stability--once the center of mass goes outside the triangle it falls over. Four wheels give you a rectangle. Six wheels? Do nothing for stability--it's still a rectangle. They also do nothing for acceleration/braking, because friction (from the wheel turning against the ground) depends on weight--not number of wheels. The only time you add wheels is for redundancy, additional weight bearing, and occasional use with off-road vehicles which operate in a constant slip condition.

    Now, the equivalent scenario applies to airplanes. Put one engine on the center of a uniwing plane. It moves forward. Put two engines at any equal distance from the centerline, it still moves forward. Throttle the engines unequal amounts and you can create a moment and turn that wing. Now what happens when you add a third engine? It goes in the center. It can pull you forward more, but it can't help you turn faster. Go four or ANY even amount of equally spaced engines: You can turn that wing faster, but if they're all pointing the same direction you can't do anything new. But wait, four engines are equal to two double power engines. Now eight engines! Eight engines, can't go new directions, and they're equivalent to two 4X powered engines.

    So more engines on the same wing aren't giving you anything agility wise. Moreover, 8 engines are very often heavier than 2 engines (with 4X the power output) because of all of the replicated parts.

    So my point still stands: What are the ten engines for other than cheap, ease-of-scaling for a prototype?

    Moreover, "less stress"? The biggest stress is where the wing joints to the body of the airplane because if you're pulling a unit of thrust, it doesn't care how many engines you have to spread the load. Once that load hits the body, it's got an entire moment arm trying to rip it off.

    You may be able to get away with your pseudo-science bullshit here, but when you walk into a engineering forum we're going to tell you to shut your bitch mouth.

  • (Score: 2) by wonkey_monkey on Monday May 11 2015, @10:26PM

    by wonkey_monkey (279) on Monday May 11 2015, @10:26PM (#181676) Homepage

    Jesus, what's with the attitude?

    Your first post adopted a sneering attitude towards this design simply - as far as I can tell - because you couldn't determine the reasoning behind the ten props, and also because, for some reason, you decided they were "advertising" this feature as if it was some great advance in aviation design. Which they are not doing. It's merely factually descriptive.

    Yes, my "maybe" was an uninformed guess. I didn't claim it to be anything but. deadstick [soylentnews.org] ("This arrangement will reduce the bending load at the wing root, allowing a lighter structure.") seemed to think I might have a point, but maybe he's not an engineer either. If I'm wrong, couldn't you just calmly explain why instead of going apeshit?

    What are the ten engines for

    I still don't know, and neither, it seems, do you. So why are you adopting such a condescending attitude towards them for doing so?

    other than cheap, ease-of-scaling for a prototype?

    What's wrong with that as a reason? How does it in any way conflict with the way they have presented their information?

    You may be able to get away with your pseudo-science bullshit here, but when you walk into a engineering forum we're going to tell you to shut your bitch mouth.

    I'd be far more inclined to listen to what you have to say if you'd at least attempt to be civil. Being rude just makes you people think you're stupid, even when you're not.

    --
    systemd is Roko's Basilisk
  • (Score: 0) by Anonymous Coward on Tuesday May 12 2015, @07:18AM

    by Anonymous Coward on Tuesday May 12 2015, @07:18AM (#181838)

    ...Six wheels? ... They also do nothing for acceleration/braking, because friction (from the wheel turning against the ground) depends on weight--not number of wheels.

    Tire-road friction/grip depends on a lot more than weight. And since grip is nonlinear with load, spreading the same load over more wheels will typically result in a higher friction coefficient (accel/decel capability) for the vehicle.