Actual ion drive aircraft...no joke!

Discussion in 'Hangar Flying' started by cluttonfred, Nov 21, 2018.

Help Support HomeBuiltAirplanes Forum by donating:

  1. Nov 24, 2018 #21

    lr27

    lr27

    lr27

    Well-Known Member

    Joined:
    Nov 3, 2007
    Messages:
    3,216
    Likes Received:
    463
    I doubt the voltage would get anywhere near this high, but here's a demo of how well a Faraday cage can protect a person. Two million volts, I think, and I don't know how many amps:
    https://www.youtube.com/watch?v=vheyKyV8vSA
    It's quite impressive and quite loud when seen in person. If memory serves, at one time the two terminals were separated, charged oppositely, and used for particle acceleration.
     
  2. Nov 24, 2018 #22

    Dan Thomas

    Dan Thomas

    Dan Thomas

    Well-Known Member

    Joined:
    Sep 18, 2008
    Messages:
    4,714
    Likes Received:
    1,946
    I'm well aware of all that, but there are positive and negative points on an ion-drive machine, and in an accident you might get between them. 30KV is enough to force plenty of current through you. If the two-ounce machine of de Seversky's needed 90 watts, I calculate that a thousand-pound machine would need 720,000 watts, or 24 amps at 30KV. That's 1600 times the typical 15 milliamps it takes to kill.

    And 720,000 watts is the equivalent of 965 hp. We will need some special magic to make this idea work.
     
    Joe Fisher and Norman like this.
  3. Nov 24, 2018 #23

    Pops

    Pops

    Pops

    Well-Known Member

    Joined:
    Jan 1, 2013
    Messages:
    6,683
    Likes Received:
    5,572
    Location:
    USA.
    Back in the early 1970's I worked on building a smoke stack at a coal fired power plant that was 1268' high. At the last of the construction we had to weld a stainless steel rain shield between the steel liner and the outside concrete stack on the very top. I welded scaffold brackets that hooked over the top of the concrete and we circled the top of the stack with two wide 12" wooded scaffold boards. While we were welding the unit was put on line with the smoke coming out of the stack. We used #8 wire to wire the wooden scaffold boards down to the scaffold brackets. The air hummed with static electricity at the top of the stack. You could take a short length of the #8 wire and hold it close to the air coming out to the stack and then point the other end to anything and it would discharge with a spark at least 2' long, or stand on the wooden boards and not touch anything and point your finger.
     
    Last edited: Nov 24, 2018
  4. Nov 24, 2018 #24

    Aerowerx

    Aerowerx

    Aerowerx

    Well-Known Member

    Joined:
    Dec 1, 2011
    Messages:
    4,620
    Likes Received:
    1,221
    Location:
    Marion, Ohio
    Yes, but there may be others reading this thread that do not know it.

    In order to be lethal you need enough voltage to break through your skin. And then enough power to provide the current.

    When you walk across your polyester carpet with your wool socks and touch a door knob, that is somewhere around 10-20kv. Enough to make your jump, but not lethal.

    On the flip side, did you know you can kill yourself with a flashlight battery if you know how? Cut a finger on each hand, then touch each cut to the ends of the battery.*

    --------
    *Legal disclaimer: The author of this post, or the host of this web site, is not responsible for the consequences if anyone is stupid enough to try this.:)
     
  5. Nov 24, 2018 #25

    pictsidhe

    pictsidhe

    pictsidhe

    Well-Known Member

    Joined:
    Jul 15, 2014
    Messages:
    5,922
    Likes Received:
    1,506
    Location:
    North Carolina
    Voltage doesn't kill, current does.
    If you want to get specific, a certain energy across the heart will disrupt it. But since the impedance vaies little, you can use current. A zillion volts at 1 microamp will barely tickle. 100volts with large, wet connections across the chest is going to be a round 2 amps. Do you have funeral cover?

    One of the nastier shocks I've had recently was while blowing cellulose (newspaper) insulation in my attic. In order to reach into the eaves, I taped a leaf blower tube and nozzle on the end of the hose. Worked great for 10 minutes, then 'crack' and I'm sat on my butt rather startled. Nastiest static discharge I've ever caught. I saw around 8" spark from the plastic nozzle back to me. I'd put it on a par with a good car ignition on the ouch scale. I was a lot more careful after that, but still caught two more zaps before I was done. I was a bit more ready for those, though.
     
  6. Nov 24, 2018 #26

    Aerowerx

    Aerowerx

    Aerowerx

    Well-Known Member

    Joined:
    Dec 1, 2011
    Messages:
    4,620
    Likes Received:
    1,221
    Location:
    Marion, Ohio
    As was said in post #18.
     
  7. Nov 24, 2018 #27

    Aerowerx

    Aerowerx

    Aerowerx

    Well-Known Member

    Joined:
    Dec 1, 2011
    Messages:
    4,620
    Likes Received:
    1,221
    Location:
    Marion, Ohio
     
    Last edited by a moderator: Mar 20, 2019
  8. Nov 24, 2018 #28

    lr27

    lr27

    lr27

    Well-Known Member

    Joined:
    Nov 3, 2007
    Messages:
    3,216
    Likes Received:
    463
    If you're doing stuff like that, it probably wouldn't hurt to have a grounded wire between you and the end of the nozzle. Maybe with a resistor in the thousands of ohms, maybe even millions. Or you could wrap the tube in paper if the humidity wasn't terribly low.

    I've had a zap from a Leyden jar made out of an 8 ounce plastic bottle. Probably only charged to 20,000 volts, but it was NOT a pleasant experience. I understand that if you have a coffee cup with a metallic coating on the outside, and you leave it near a van de Graaff, you can get a similar zap the next time you take a drink.

    On an ion drive aircraft, it might be good practice to discharge the terminals late in the approach and land deadstick. However, it's not clear to me the hazard is greater than that of gasoline.
     
  9. Nov 25, 2018 #29

    Dan Thomas

    Dan Thomas

    Dan Thomas

    Well-Known Member

    Joined:
    Sep 18, 2008
    Messages:
    4,714
    Likes Received:
    1,946
    You need both voltage and current to achieve anything at all. Ohm's Law says so. The wild cards in getting electrocuted are the resistance the voltage encounters and the current capacity of the source. If we have a low resistance (like the bleeding cut scenario) we can get plenty of current flow at low voltages.

    If we have a source that can only provide a very limited current (like the static charge from walking across the rug) we get a huge voltage drop as soon as we put a load on it. Think about trying to start your car with two 9-volt batteries wired in series to get 18 volts; ain't gonna happen. The current capacity is much too small and the voltage drops to pretty much zero when we place a resistance of about 0.05 ohms across it, about what we'd find in a typical starter. E=I x R.

    I've had some good jolts from 24 volts if I'm a bit wet. Think aircraft 24-volt systems, or welding something with damp gloves, maybe. Been there, done that. Ouch. I've also had some real dandies from fixing televisions in the days of the CRT, which had at least 20KV on the tube's anode. 20KV, maybe the same as the rug-generated static, but much more current available, making it more lethal.
     
    Last edited: Nov 25, 2018
  10. Nov 25, 2018 #30

    Aerowerx

    Aerowerx

    Aerowerx

    Well-Known Member

    Joined:
    Dec 1, 2011
    Messages:
    4,620
    Likes Received:
    1,221
    Location:
    Marion, Ohio
    At work (post office) they had strict rules on this stuff.

    For anything above 50 volts you had to wear protective gear. What protective gear depended on both the voltage and current capacity of the source. Don't remember the numbers now that I am retired and don't care any more:), but at some point they had to call a contractor to do the work.

    The post office must have been sued by OSHA at one point. They spent a lot of money buying the gear for everybody that might have to work on live equipment. I never wore mine---never had a need---except to demonstrate that I knew how.

    Interesting anecdote. One of the machines I had to baby sit was the "medium size package" sorter, which they also used to sort shrink wrapped bundles of junk mail. It consisted of a monorail system with rubber belts that kicked the packages off into bins. In the winter, when the air was dry...Well, can you say "Van de Graff Generator"? Just touch one of the metal bins after being charged by 100 shrink-wrapped bundles.
     
  11. Nov 25, 2018 #31

    Norman

    Norman

    Norman

    Well-Known Member

    Joined:
    Nov 29, 2003
    Messages:
    2,883
    Likes Received:
    907
    Location:
    Grand Junction, Colorado
  12. Dec 6, 2018 #32

Share This Page

arrow_white