XPost: sci.electronics.design, sci.physics, sci.space.policy   
      
   In sci.physics mike  wrote:   
   > On 11/7/2016 7:39 PM, jimp@specsol.spam.sux.com wrote:   
   >> In sci.physics mike  wrote:   
   >>> On 11/7/2016 1:46 PM, jimp@specsol.spam.sux.com wrote:   
   >>>> In sci.physics Phil Hobbs  wrote:   
   >>>>> On 11/07/2016 01:37 PM, jimp@specsol.spam.sux.com wrote:   
   >>>>>> In sci.physics Robert Clark  wrote:   
   >>>>>>   
   >>>>>>    
   >>>>>>   
   >>>>>>> If you know of a means to provide 50,000 V at *lightweight* then you   
   will   
   >>>>>>> have solved the problem of an independently flying lifter, using the   
   >>>>>>> macrosized wires currently used. You would need about a power to weight   
   >>>>>>> ratio for the power source of better than 1 watt per gram, while being   
   able   
   >>>>>>> to provide these ca. 50,000 V voltages.   
   >>>>>>>   
   >>>>>>>    Bob Clark   
   >>>>>>   
   >>>>>> Trivial; look at any camera flash unit built in the last several   
   decades.   
   >>>>>>   
   >>>>>> However you have totally missed the point; voltage and the weight of the   
   >>>>>> converter is irrelevant as it is the total power that determines the   
   >>>>>> weight of it all.   
   >>>>>>   
   >>>>>> BTW, here are some real world power to weight ratios:   
   >>>>>>   
   >>>>>> Boeing 777 engine 10 kW/kg   
   >>>>>    1985 Chevy Celebrity 300 W/kg <-- So for a 1000 kg car, that's 402   
   >>>>> horsepower?  Sign me up! ;)   
   >>>>>   
   >>>>> Cheers   
   >>>>>   
   >>>>> Phil Hobbs   
   >>>>   
   >>>> No, that is the power to weight ratio of the engine, not the power to   
   >>>> weight ratio of the car.   
   >>>>   
   >>>>   
   >>> Power is a red herring.  What's important is the total energy produced   
   >>> by the   
   >>> engine AND the fuel supply.   
   >>> It doesn't get the least bit interesting until the engine can lift   
   >>> itself and a FULL tank of whatever powers it AND the vehicle AND the   
   >>> payload to reach the destination.   
   >>> I can't imagine that ever happening 1000 feet off the ground on this ole   
   >>> earth at a cost anywhere near the cost of other forms of transportation.   
   >>   
   >> Are you trying to say airplanes aren't going to make it in the commercial   
   >> world?   
   >>   
   >>   
   > Yep, that's exactly what I'm saying: "Airplanes with ion drive are not   
   > going to make it in the commercial world."  Whatever technology can make   
   > that work will be FAR less costly applied to something that rolls along   
   > the roadway.   
      
   I doubt there is any technology that could ever make it work in an   
   atmosphere.   
      
   > But that misses the point that it's ENERGY that's the concern.  Doesn't   
   > matter how light or powerful the airplane engine is if it still can't lift   
   > enough fuel to reach the destination.  It takes a given amount of energy   
   > to get from here to there.  Changing the engine only affects the efficiency   
   > of the process that converts the available fuel source to whatever it takes   
   > to motivate the vehicle.  Maybe we'll see terrestrial ion engines, but   
   > the efficiency   
   > improvement won't be huge.   
      
   Aircraft engines don't lift anything.   
      
   > If we had an electric fuel source of sufficient energy/weight ratio,   
   > we'd already have electric airplanes.   
   >   
   > If you're gonna spend millions of dollars to fling an object into   
   > space at escape velocity, it makes sense to have a nuclear power   
   > source that applies tiny thrust for a long time using minimal reaction   
   > mass to continue the flight to places unknown.   
   > For a terrestrial flight to New York, not so much.   
   >   
   > So, what am I missing?   
      
   --   
   Jim Pennino   
      
   --- SoupGate-Win32 v1.05   
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