Hackaday Links: August 30, 2015

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A month ago, we ran a post about [Jim]’s rare and strange transparent microchips. He’s back at it again, this time taking a look at the inner workings of MOSFETs

The Unallocated Space hackerspace is moving, and they’re looking for a few donations to get the ball rolling.

Yes, it’s a Kickstarter for a 3D printer, but the LumiPocket is interesting, even if only on the basis of the engineering choices. It’s a UV laser resin printer, and they’re using a SCARA arm to move the laser around. They’re also doing a top-down resin tank; it requires more resin, but it seems to work well enough.

Around DC or northern Virginia? We’re going to be there on September 11th through the 13th. We’re holding a Hackaday Prize Worldwide meetup at Nova Labs in Reston, Virgina. Sign up now! Learn KiCAD with [Anool]! Meet [Sudo Bob]! It’ll be a blast.

Not around DC or NOVA? This Wednesday we’ll be hosting another chat on .io.

The GEnx is one of the most beautiful and advanced engines in the world, and that means [Harcoreta] oven on the RC groups forums has made one of the most beautiful electric ducted fans in the world. On the outside, it looks like a GEnx, including reverse thrust capabilities, but inside it’s pure electronics: a brushless motor rotates a 100mm, 18-blade fan. He’s hoping to mount it on a Bixler (!). We can’t wait for the video of the maiden.

21 thoughts on “Hackaday Links: August 30, 2015

  1. Back when I was in college for my EE degree Motorola had given the school a whole set of all their chips in clear plastic like that. we even had a motorola 68000 in clear plastic.

  2. Electric fans are the future of air travel, Musk thinks supersonic flight at 80,000 feet with electric fans is the way to go. As much as I hate to agree with him he is probably right.

    I can’t believe this guy printed all that on a prusa i3 not to mention he drew it all, a truly skilled individual.

    1. Sadly fans that would work at that altitude would be ridiculously large, and the batteries of today don’t have anywhere near the energy density required to replace jet fuel and a modern turbo-fan engine. Sorry Musk.

          1. Turbo fans aren’t used because the air density is too low at altitudes over 50,000 feet to be useful. Not because of a lack of oxygen. P&W J57 / J58 turbine engines have been used at altitudes of over 80,000 feet reliably for decades.

          1. And the cycle life of most battery chemistries is so low (compared to the life of an aircraft), that no commercial airline would adopt it. The new battery pack would be more than half the total cost of the aircraft.

          2. But then you are back to the fans with ridiculously large dimensions required to operate at 80K feet. If you have a liquid fuel for the APU’s, then a simpler (and therefore more reliable) system would use the fuel directly for propulsion.

          3. @Brian Not disagreeing, but I like to point out as an interesting note that actually a surprisingly large number of planes are leased rather than bought by the airliners.

          1. Jet engines are about 50% efficient at speed.

            The energy density of jet fuel is actually around 10 kWh per kg, whereas batteries operate at 0.2 kWh per kg and 0.5 kWh/kg for some special versions, so there’s still a 10x advantage for simply burning the fuel versus the best available batteries.

            The additional problem is that the higher the energy density of the battery, the fewer charge cycles they can manage, because the battery chemistries become increasingly unstable. The most powerful batteries can only be recharged a dozen times before the capacity diminishes, and because they are unstable they are very prone to catching fire and blowing up, which jet fuel simply doesn’t do.

  3. [Harcoreta] created a thing of beauty.
    Was the sound generated or actually recorded relying only on the turbofans of the scale engine? I see the mic on the stand in the background. It just seems too real.
    What materials were used for the fans, the ducts and the shroud?
    So much work went into that engine I’d be afraid to fly it.

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