3 ms·

I think the issue would be weight. You'd need an alternator capable of absorbing some 20000+ HP (~15000 kW). And then the electric motors and associated fans an

by jcoby 11y ago

I think the issue would be weight. You'd need an alternator capable of absorbing some 20000+ HP (~15000 kW). And then the electric motors and associated fans and housings and mount points. And then the cabling to handle distributing the current. And if you're going to cross route you'd need the switches and associated stuff to drive it.

hinkley 11y ago
Not to mention the wiring. How much wire and shielding do you need to keep that sort of current safely contained? Especially since the gas tanks are in the wings too?
- ars 11y ago
  It's not that bad. Use 300 volts and it's only 50amp. That kind of amperage is routinely used by oven/stove/ranges. And 300 volts is not considered high voltage. If they upped the voltage to 1,500v (which is the limit before you need much more complicated stuff) it's only 10amp - a simple thin wire would do it.
  - jcoby 11y ago
    I think you are off by 3 orders of magnitude unless you are planning on putting 1000 motors on each wing. I said 15000 kW. That's 15 MW. 300v @ 50A is only 15000 W or roughly 20 HP (actually a bit less when you consider the power factor).
    - ars 11y ago
      Yes, I misread kW for W :( :( They'll actually need some very high voltages to make this work. That's going to be an enormous challenge - even simple motor windings, what will you insulate them with? 15MW? That's some serious power, are you sure about that number?
      - jcoby 11y ago
        There really isn't a good way to rate turbines to hp. I did find this article [1] that says a 747 uses some 87000 hp in cruise across all 4 engines. That's approx 20000 hp per. It also says that's only 1/4 of the rated thrust it's capable of. I have no idea if you can say each of those engines is capable of 87000 hp or not since it's entirely dependent on speed. If you watch agentjayz on YouTube he rebuilds turbojets that have been converted to become gas generators for power plants and some of those are easily capable of generating 30000 hp using tech from the 60s. It really is phenomenal how much power turbine engines can make. There is a thread on the Concorde [2] that goes through a q&a session with the people who operated it. In that thread it says that the engines at idle consumed some 5 metric tons of fuel per hour per engine. 1: http://www.aerospaceweb.org/question/propulsion/q0195.shtml http://www.aerospaceweb.org/question/propulsion/q0195.shtml 2: http://www.pprune.org/tech-log/423988-concorde-question.html http://www.pprune.org/tech-log/423988-concorde-question.html
iSnow 11y ago
High-Tc superconducting cables?

by jcoby 11y ago

hinkley 11y ago

Not to mention the wiring. How much wire and shielding do you need to keep that sort of current safely contained? Especially since the gas tanks are in the wings too?

ars 11y ago
It's not that bad. Use 300 volts and it's only 50amp. That kind of amperage is routinely used by oven/stove/ranges. And 300 volts is not considered high voltage. If they upped the voltage to 1,500v (which is the limit before you need much more complicated stuff) it's only 10amp - a simple thin wire would do it.
- jcoby 11y ago
  I think you are off by 3 orders of magnitude unless you are planning on putting 1000 motors on each wing. I said 15000 kW. That's 15 MW. 300v @ 50A is only 15000 W or roughly 20 HP (actually a bit less when you consider the power factor).
  - ars 11y ago
    Yes, I misread kW for W :( :( They'll actually need some very high voltages to make this work. That's going to be an enormous challenge - even simple motor windings, what will you insulate them with? 15MW? That's some serious power, are you sure about that number?
    - jcoby 11y ago
      There really isn't a good way to rate turbines to hp. I did find this article [1] that says a 747 uses some 87000 hp in cruise across all 4 engines. That's approx 20000 hp per. It also says that's only 1/4 of the rated thrust it's capable of. I have no idea if you can say each of those engines is capable of 87000 hp or not since it's entirely dependent on speed. If you watch agentjayz on YouTube he rebuilds turbojets that have been converted to become gas generators for power plants and some of those are easily capable of generating 30000 hp using tech from the 60s. It really is phenomenal how much power turbine engines can make. There is a thread on the Concorde [2] that goes through a q&a session with the people who operated it. In that thread it says that the engines at idle consumed some 5 metric tons of fuel per hour per engine. 1: http://www.aerospaceweb.org/question/propulsion/q0195.shtml http://www.aerospaceweb.org/question/propulsion/q0195.shtml 2: http://www.pprune.org/tech-log/423988-concorde-question.html http://www.pprune.org/tech-log/423988-concorde-question.html

iSnow 11y ago

High-Tc superconducting cables?