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  1. lengould

    Airscraft Propulsion by Compressed Air

    The application is actually a (relatively) low-speed (max. 150 kmhr) air-propelled ground-effect vehicle using low-pressure industial compressor powerplant, primarily because of other requirements for the compressed air aside from propulsion. My question relates to "eg. if I already have 33% of...
  2. lengould

    Airscraft Propulsion by Compressed Air

    Am I missing any law of physics which makes this a lot less efficient per unit input power than a propellor? Pechez les vaches.
  3. lengould

    Airscraft Propulsion by Compressed Air

    Actually i haven't missed the sarcasm, or the absence of creativity. Thanks anyway. Pechez les vaches.
  4. lengould

    Flywheel structural questions

    My only experience with flywheel failure was when a kid driving a Camaro missed a shift on the street in front of our house one night about 3AM. There was a crash, and we went into our livingroom to find a significant chunk (about 1/4 or less) of his engine's flywheel smoking on the carpet in...
  5. lengould

    Airscraft Propulsion by Compressed Air

    So do I take it that eg. 1000 shaft kw into an air compressor operating at eg. 50 psi, resulting airstream directed into a venturi volume multiplier will produce propulsive effect just as efficiently as 1000 shaft kw driving a propellor? No objection? Pechez les vaches.
  6. lengould

    Airscraft Propulsion by Compressed Air

    I'm sure this is a long-sorted issue, but was just wondering about relative efficiency issues. What would be the relative power efficiency of using eg. 3 barg compressed air as propulsion? Assuming of course that a) The wieght of the compressor machinery would be a non-issue. b) A venturi...
  7. lengould

    Oil-free compressor piston/ring design

    Thanks all, especially dcasto, who's tip earns a star. Pechez les vaches.
  8. lengould

    Oil-free compressor piston/ring design

    I'm working on designing a piston / cylinder / ring assembly for a large (eg. up to 6" bore) medium-high-pressure (eg. 30 bar) compressor requirement. Anyone know of available technology capable of doing this (eg. rings). Alternatively, looking for someone capable of designing this. Payment...
  9. lengould

    Texas Blackouts

    The "6 parallel AC lines for minimum interconnect" sounds about correct. Advantage of DC ties is they don't require synchronizing, can just leave ERCOT isolated in frequency whatever it wants. Makes it an obvious choice for a continantal super-grid. Pechez les vaches.
  10. lengould

    Texas Blackouts

    Right-of-way should be simplified a lot just by following freeways and railways with extra-tall poles similar to wing generator towers, in fact in good wind areas would make sense to extend the towers another 30 meters and put wind generators on top of them. Pechez les vaches.
  11. lengould

    Texas Blackouts

    Agreed on AC ties. Too expensive now. What Texans should start supporting now is a large continental DC super-grid. Give Texas a 10 GW dc link west to CA, a 10 GW dc link North to Wyoming (coal), and another 10 GW east into Florida and all the issues go away. It could have been completed...
  12. lengould

    Texas Blackouts

    Ah, that makes sense. CNN wasn't clear of that distinction, though they did mention something about 80% of Texas, now I recall they stated "affected ERCOT area, which manages 80% of grid." They did say the blackouts affected omly/mainly 3 large cities which they named so I should have picked...
  13. lengould

    Texas Blackouts

    Dotty Roark (ERCOT). 7:22pm CST, CNN. 1050 pre-agreed interruptible. 1000 mw of firm load. Are a lot of peakers still in winter layup or what? Pechez les vaches.
  14. lengould

    Texas Blackouts

    Anybody have any detailed information? Just heard on CNN about rolling blackouts inititated by the grid manager covering 80% of state. 15 min intervals. Seems afully early in the year. Pechez les vaches.
  15. lengould

    Cable Heating From Using Steel Conduit Elbows?

    Heating due to induction should be entirely a function of amperage, voltage should not be a factor in what temperature the elbows come to, though it may be a factor in whether the resulting heat breaks down the insulation. Likely the lower voltage runs can put up with the added heat load for...
  16. lengould

    Voltage Reduction for Energy Saving

    One possible area where overvoltage can cost you money is in power factor penalty. A motor designed to put out 10 hp at 460V and connected to a load which requires 10 hp will still draw about the same total power to do the job at 480V but will do it at a significantly worse power factor. Check...
  17. lengould

    Cable Heating From Using Steel Conduit Elbows?

    If there's any way to make a longitudinal cut in the elbows-in-place, you might not need to remove them. Requires that they not be touching each other, and have no magnetic or conductive contact with each other. The cut needs to be wide enough to ensure that eg. backfilling etc. won't force...
  18. lengould

    Multiple A/C Units_Share Service

    It might save you money to put in a control system which can shut down or cycle the heaters in sequence to ensure that only eg. 60% are running at any one time. Provided some addurance, the code will allow you to then derate. Might cost more than just uprating the service though, and on the...
  19. lengould

    Cable Heating From Using Steel Conduit Elbows?

    One minor addition might be that a contributing cause to "the failure always occuring at the elbows" is that that's the (only/best) conductive path to ground or another phase, the rest of the run having the individual conductors enclosed in pvc and even if badly stripped would stand up longer...
  20. lengould

    POWER, TELEPHONE AND CABLE, ALL IN ONE CONDUIT

    Just from memory, but doesn't the code require that all conductors in a conduit must be insulated with a rating equal to the highest voltage in the conduit? Will be very difficult to find TV cable with any voltage rating, therefore the electrical run should fail inspection. For 208V...

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