Could electricity power a rocket? Feedback appreciated!

[joey13]

Hi! I'm a high school physics student. I really, really love physics, especially rocket science, and I had an idea about a rocket design, but I don't know how feasible it is. I was hoping you guys could give me some feedback.

So I was learning about electricity, and as far as I know, electric explosions can produce lots of energy. So I wondered, would it be possible to harness this energy to, say, produce thrust for a rocket, or would it be too destructive? What do you guys think?

Thank you for your feedback!

P.S. I wasn't sure if this is the right place to post this, apologies if it isn't!

 

[fresh_42]

Hello and !

What do you mean by an electric explosion?

 

[sophiecentaur]

electric explosions can produce lots of energy.

The energy available from a Chemical source is actually much more convenient and potentially greater - if you want an "explosion". That's not to say a projectile can't be launched at great speed with an electromagnetic system.

Read this link about railgun.

 

[anorlunda]

I don't know about explosions. But search for ion rocket propulsion. NASA is already using it on some space probes.

Ion propulsion uses electricity to accelerate particles.

 

[DaveE]

The problem with electric propulsion, in cars and rockets, is that we don't have really good light weight devices to store large amounts of electricity (batteries et. al.). This is in contrast to chemical energy storage (rocket fuel, etc.). So, in the situation where you want to store a bunch of energy to use later, chemistry just works better, for now. Other methods are also better for storage, depending on your requirements, like pumping water uphill, flywheeels, etc.

However there are promising electric propulsion methods that can help transform energy using electricity in spacecraft . For example, you may collect energy from the sun with solar cells to power low thrust electric engines. Or, you may have an onboard radioactive energy source that can do the same.

So, you need to split up the problem into pieces and find the best solution for each. Energy generation, energy storage (if required), and propulsion.

 

[kuruman]

How much do you know and understand about momentum conservation? Any idea you may have about a rocket must address how the momentum of the rocket that is zero relative to the Earth will be increased. Your idea is to harness an "electric explosion to produce lots of energy". Energy is not the point. The point is to produce lots of momentum change per unit time in a given direction a.k.a. thrust, that will accelerate the rocket.

So you need to explain what you mean by electrical explosion and then have some idea how the released energy might be channeled into thrust. You have to flesh out at least that much; we cannot do it for you.

 

[sophiecentaur]

Energy is not the point. The point is to produce lots of momentum change

I half agree and Momentum is often forgotten about. Energy is actually very important too. You need to convert sufficient energy in the fuel into KE of the craft but the way the momentum is transferred affects the efficiency of the operation. Rockets are very inefficient during the first few seconds of takeoff; the faster they are going, the better use is made of the fuel - as long as the ejecta is leaving fast enough.

 

[kuruman]

I half agree and Momentum is often forgotten about. Energy is actually very important too. You need to convert sufficient energy in the fuel into KE of the craft but the way the momentum is transferred affects the efficiency of the operation. Rockets are very inefficient during the first few seconds of takeoff; the faster they are going, the better use is made of the fuel - as long as the ejecta is leaving fast enough.

Sure. Energy is important too. If one could come up with a more efficient way to convert energy into momentum, one has a better design. I am not a rocket scientist, but I am sure that rockets are characterized by some figure of merit regarding this. My concern was that OP was not aware of the importance of momentum. Let's wait and hear from OP.

 

[jbriggs444]

I am sure that rockets are characterized by some figure of merit regarding this.

Normally, the best use of fuel is to extract all of its energy and use that energy to hurl it out the back -- the spent fuel becomes the reaction mass.

If that approach is used, the relevant figure of merit is exhaust velocity. Sometimes it is expressed as "specific impulse": the length of time for which the rocket can hover in Earth's gravity while using an amount of fuel equal to its own mass.

 

[sophiecentaur]

The specific impulse may be zero for a perfectly useable rocket if it is not bound be the Earth’s surface gravity. The term is very useful but not for every rocket engine.