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Thread: The OT thread V1

  1. #1921
    Insider PBSteve's Avatar
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    Ever so many citizens of this republic think they ought to believe that the Universe is a monarchy, and therefore they are always at odds with the republic. -Alan Watts

    I work for the company building the Paragon

  2. #1922
    pewpewpew vijil's Avatar
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    It'll be interesting to see if there is ever a limit to how clean a gasoline engine can run.

    I'd like to see some gas microturbine range extended plugin EVs. 1000 miles + range seems likely.

    In fact I'd like to see how that combo would go in a personal VTOL.
    https://www.instagram.com/vijil/
    I draw guns and spaceships and bunnies

  3. #1923
    Insider Davros's Avatar
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    Lurker, That was fascinating.

  4. #1924
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    Micro-turbines are about 26% efficient right now. They burn clean enough to breathe in most cases.

    A gallon of gas has about 33kW of potential power. That means 8.6kW of energy from a micro turbine per gallon.

    A normal engine at 20% efficient produces (at best driving conditions mind you) produced about 6.6kW per gallon.

    Diesel has about 38kW per gallon. Lots of different numbers, but I have heard 30% better than gas to nearly twice gasoline. On a setup with 26% efficiency that leads to 9.9kW per gallon, if the turbine was used and was the same as the diesel.

    After that, it is mostly the CDa of the car, plus a few percentage points for rolling resistance.

    Play around here:

    http://ecomodder.com/forum/tool-aero...resistance.php

    Hence the low CDa of the Elio and 70+mpg claims.
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  5. #1925
    Insider Unfated33's Avatar
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    Skibbo, I've been streaming Good Place on Hulu for the past few months, but haven't seen the last two or three episodes yet. I was surprised by how much I enjoyed it, in light of the belief system in the premise not really being my thing. I credit it to Ted Danson, Kristen Bell, and William Jackson Harper all alternating playing the "straight man" in comedy to hilarious effect.

  6. #1926
    Insider new ion?'s Avatar
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    I've heard that at high rpm compression ignition is already a thing on some engines...

    Couple of the people I work with have advanced degrees in diesel & gasoline engine stuff.

    Also, speaking of work: my favourite thing in the world is when my damn USB ports don't work. My work computer is super unstable wrt USB, so I wind up having to reboot it and wait for the BSOD, then they might work. Oh and sometimes when I put it to sleep it just crashes (potentially causing further USB issues!). It's great!

  7. #1927
    Insider Unfated33's Avatar
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    How far out is your lease renewal on your work PC? (Hoping they lease and didn't buy that thing for you) If your company has a big enough IT department, you might be able to switch out quickly on those kind of errors. If it's a small company, that's bad news. Hopefully small means more agile and they can buy you a new one. The cost of dealing with that every day has got to be way more than a new PC.

  8. #1928
    Insider PBSteve's Avatar
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    Quote Originally Posted by vijil View Post
    It'll be interesting to see if there is ever a limit to how clean a gasoline engine can run.
    Yes? I mean it depends on what you mean by "clean". Modern catalytic converters do a pretty good job of cleaning up emissions.

    If you're talking about energy extraction, there is only so much available chemical energy, and there are fundamental thermodynamic limits on the efficiency of converting that energy to mechanical energy.
    Ever so many citizens of this republic think they ought to believe that the Universe is a monarchy, and therefore they are always at odds with the republic. -Alan Watts

    I work for the company building the Paragon

  9. #1929
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    I don't think turbines really have any structural advantages over good clean diesel piston motors. IIRC most of the efficiency gain comes from the superior pumping mechanism (less pumping losses). Josh's numbers seem to bear that out.

    http://www.roadandtrack.com/car-cult...toyota-engine/

    Steve and I were talking about utilizing harmonics in this style of engine (since it need only run at one speed) to further improve efficiency. The effective compression ratio could also be really high here, which means you don't need the added complexity of a turbo to boost Carnot.

    The thing that drive me crazy about quadcopters is how much efficiency they leave on the table. You could utilize a single ducted counter-rotating prop, along with a 4 zone angle of attack system to get similar maneuverability and stability but with far better lift to drag numbers due to the larger effective prop size. It's unclear to me that people really give a shit about drone battery efficiency for most applications, but since that's the driver of payload and effective range I fully expect someone to explore this space.
    "So you've done this before?"
    "Oh, hell no. But I think it's gonna work."

  10. #1930
    pewpewpew vijil's Avatar
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    To date I think it's been largely about mechanical simplicity. You can handle flight control entirely by relative rpm, so there are no complex linkages.

    Which is lighter per KW, diesel or microturbine? I suppose that may depend on fuel load (talking about which to use as a generator for a large drone, say)

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