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Could electric fans like the ones below lift a rocket? What is the amount of electricity needed to lift a interplanetary rocket?

Could a nuclear power plant provide enough electricity?

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https://en.wikipedia.org/wiki/Airbus_E-Fan

I added the pictures and link to show people who are not familiar with electric propellers and impellers an idea of what is available. I do wonder if these types of engines have enough thrust to vertically lift anything?

Which propelling device would be the most efficient for a space elevator?

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Tom Spilker
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Muze
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  • If you got a tower of 53 Km height, you dont need an electric turbine engine to lift a rocket, you may use an electric linear motor with better efficiency independent of the decreasing air pressure from ground to 53 km height. But we are not able to build a tower with 53 km height. – Uwe Sep 12 '18 at 20:17
  • @Uwe the tower is only strong enough to hold the power line. – Muze Sep 12 '18 at 20:18
  • It may have some horizontal stability and flexibility from mass. Full launch starts at ground full burn starts at the end – Muze Sep 12 '18 at 20:21
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    I, personally, have no idea what you are talking about. Can you explain this concept a little better? What does the tower do? – Organic Marble Sep 12 '18 at 20:27
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    Well, the Falcon Heavy has total takeoff thrust of 5,100,000 lbs with both boosters and the core running flat out. The GEnx jet engine puts out about 70,000 of thrust. So you would need 73 of them to equal the same thrust. The electric power requirements are going to be impressive. Each engine is about 20 megawatts, so you are going to need 1.5 gigawatts. At 100,000 volts you are going to need 14,600 amps. This will be difficult to deliver. Bottom line is this is impractical. – zeta-band Sep 12 '18 at 20:34
  • @OrganicMarble The tower is a power line/ mono rail. – Muze Sep 12 '18 at 20:34
  • @zeta-band impractical for 1 electric engine but reusable cleaner fuel saving? – Muze Sep 12 '18 at 20:35
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    A turbine extracts energy from a flowing fluid and it converts the energy to mechanical work--it turns a shaft. An engine releases energy by burning fuel, and converts the energy to mechanical work. What does "electric turbine engine?" mean. –  Sep 12 '18 at 20:39
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    Also, your questions keep referencing this magic number, 53km. What's so special about 53km? –  Sep 12 '18 at 20:41
  • @besmirched highest balloon – Muze Sep 12 '18 at 20:48
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    @Muze trying to do a sliding contact at 14,000 amps is going to give you arcs that will blast everything into plasma. Plus the 73 engines are going to weigh really a lot. You keep adding weight and complication to try to save a little fuel. It won't make things better. – zeta-band Sep 12 '18 at 20:53
  • Yes many engines it will have to lift up like a huge drone. – Muze Sep 12 '18 at 21:04
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    Very difficult to build electric jet engines to work with air pressures from ground to 53 km height. You need a fan that is efficient for such a broad pressure range and a cooling for the electric motor too. If cooling is not possible with very thin air, the motor will just melt. – Uwe Sep 12 '18 at 21:27
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    Why bring balloons in the equation when the subject is a plane... this affect negatively the readability and credibility of your questions. – Antzi Sep 13 '18 at 06:58
  • Please improve your question. 1. The pictures seem irrelevant. 2. Why are those links in there? 3. Answer the comment questions in the text –  Sep 13 '18 at 07:36
  • @OrganicMarble I have revised it – Muze Sep 13 '18 at 15:29
  • What do the pictures and Airbus link have to do with the question? I think you would want to explain those if you feel they are relevant. – JMac Sep 13 '18 at 16:22
  • @JMac I added the explanation and hope it helps. thanks – Muze Sep 13 '18 at 18:28
  • After all the edits it seems that your actual questions are: 1. Disregarding power consumption, could electric turbo engines be used to lift a rocket vertically? 2. How much power would be required; would a nuclear power plant supply enough energy? Is this correct? –  Sep 14 '18 at 07:51
  • @JanDoggen and will there be rainbows and sunshine? – Muze Sep 14 '18 at 08:53

1 Answers1

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Turbines don't work in the space, there is no air.

It might be usable as the first stage of an orbital, or suborbital vehicle.

The main problem with it is not the energy source, but that the size of the drives are too big.

The maximal lift mass of the largest plane ever built, the Antonov An-225, is 640tons. A Soyuz total mass is around 300 tons, more than half of it is its first stage.

However, the maximal speed of the Antonov is around 800 km/h, which is nowhere from the some km/s speed of a Soyuz after its burned out first stage.

To have a supersonic first stage is not impossible, mainly engineering reasons are avoiding it (it could work, but with rockets can go better). And note, we have very few technology to build large supersonic crafts. The largest is the Tupolev Tu160, a Russian strategic bomber, its maximal takeoff weight is 275 tons.

peterh
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    Add a problem of energy density. Hydrolox offers 15.8MJ/kg and is expelled as it burns. Best Li-ion batteries have 0.72MJ/kg and are a little too expensive (and dangerous) to drop the depleted ones throughout the flight. – SF. Sep 13 '18 at 09:03
  • doesn't use batteries direct electricity hypothetically – Muze Sep 13 '18 at 10:17
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    @Muze: How? Dragging wires behind? – SF. Sep 13 '18 at 11:03
  • wth?! nuclear cells are dangerous to carry around, especially in the case of an accident! – Aryan Sep 13 '18 at 11:32
  • @AryanBeezadhur: Primarily, RTGs provide very little momentary; something of order of 100W. They are great that they can provide it for years, but at a moment's notice? Useless. If you go with a fission reactor, you will have plenty of power... and need to expel the heat. You'd be better off with an NTR engine using the heat directly than going all the way around through steam, turbine, generator, electric motor, and the propeller. Or at least power the propeller with steam turbine directly, like in the nuclear jet. – SF. Sep 13 '18 at 14:36
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    @Muze you seemnto mix height and speed. For travelling to the moon, or other planets, you need speed. Imagine sitting in a giant soup bowl 200000 kilometers across. It has no friction, but it is huuuuge. To get out, you can bowl a ball really fast, and it will spiral out of the bowl eventually. The atmosphere is a teeny tiny patch in the middle of the bowl that has friction. Your tower, or a plane, will only move your bowling position halfway out of this patch, but give you virtually no help in accelerating the ball. All that energy for that titanic push still has to come from you (the rocket) – bukwyrm Sep 13 '18 at 15:04
  • @bukwyrm the goal is just to get the launch higher not speed. the rocket would blast off at a higher altitude – Muze Sep 13 '18 at 15:25
  • @Muze Some important data: To break through the atmosphere requires around 2km/s delta-v. It means, if the problem of the atmosphere wouldn't exist, the rockets would need to accelerate only 2km/s slower to go where they were intended to. In comparison, to leave the gravitational field of the Earth, requires 11.2km/s speed. (To go into orbit around the Earth, requires only 7.8km/s). – peterh Sep 13 '18 at 15:36
  • @peterh so if launch happened at 33 km or higher would that save combustible fuel or eliminate a stage? – Muze Sep 13 '18 at 15:40
  • the goal is just to get the launch higher not speed. the rocket would blast off at a higher altitude Do not change the goal posts! - Why is this not in your question? –  Sep 14 '18 at 07:53
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    @Muze: It wouldn't eliminate even 1/4 worth of a stage - replacing all the savings with a massively complex "electric fans" stage. It's like building 50 meters of escalator at the foot of Mt. Everest to make climbing it easier. – SF. Sep 18 '18 at 10:59