# What prevents the use of electric engines to assist with spacecraft launches? (Space Shuttle Booster Supplement)

Much power is used to get rocket off the platform on the initial launch? Could electric engines used like booster rockets work similar in the way they launch planes of an aircraft carrier? The electric turbines would disconnect at the top of the launch platform that could also be made taller. Could it save fuel by creating lift for the first 1000 ft or so?

supplement

• By "electric turbine engine" do you mean an electric motor? Also, after reading your other question on Physics SE, it is still not clear what you mean by "will it work?". How fast does it need to go? How much force does it need to generate? These are all things you need to figure out. Please add more details or ask more questions on the site if you need more information on engineering topics Sep 7 '16 at 19:38
• @BarbalatsDilemma An engine that moves air using a turbine and electricity instead of jet fuel. Will it work as a whole?
– user4139
Sep 7 '16 at 20:14
• just as a matter of terminology if you had an electric powered device that pushed air it would not be called a turbine. it would be called a fan, propellor, compressor, or perhaps pump. a turbine by definition extracts power from the fluid. Dec 5 '16 at 3:10
• Muze, I tried to edit your question so that it is a bit more clear what you are looking for. I hope I have properly captured your intent. Dec 6 '16 at 17:47
• reviewing the energy density of whatever fuel you like with whatever battery technology you like should put this question to rest. en.wikipedia.org/wiki/Energy_density. Even knocking fuel values in half to account for carrying oxidizer for a rocket application the numbers are not even close. Dec 7 '16 at 16:18

# Electric turbine engines

First off, "electric turbine engines" don't really exist. What you're probably thinking of is an electric version of the jet turbine engine, which is a type of combustion engine (it burns fuel). Air is sucked in the front, compressed by a compressor, then mixed with fuel and burned in a combustion section. A turbine extracts some of the energy from the air and uses it to power the compressor, while the rest of the air shoots out the back of the engine to provide thrust. The important thing to understand is that the turbine is extracting energy from the air, not generating thrust. The burning fuel adds energy to the air which is converted into thrust by the structure of the jet engine. The turbine is just a way of making the jet engine more compact, so it doesn't need a separate power source for the compressor.

The closest electric engine equivalent that I could find would be something like the Airbus E-Fan (see also the Airbus website). It uses an electric motor to spin a fan, providing thrust. It does not use a turbine, it's more like a fancy propeller.

Apparently Airbus is hoping to use the E-Fan on commercial passenger jets in the future, albeit using a gas-powered generator to provide electricity, so it might be able to provide enough thrust to launch a small rocket.

# Will this work for your application? (Edit: Space Shuttle booster replacement)

There are two problems with replacing the solid fuel booster rockets of the space shuttle with electric fans:

1. The booster rockets generate 13,800 kN of thrust each at liftoff, for a total of 27,600 kN. By comparison, the E-Fan only produces 750 N, therefore you would need 37,000 electric engines to get the same thrust.

2. The booster rockets burn for 2 minutes and are ejected when the shuttle reaches an altitude of 46 km. At that height the atmosphere is so thin that an E-Fan wouldn't be able to produce any thrust. In fact, since the E-Fan works by "pushing" air through its duct, its performance would decrease as the atmosphere thinned, whereas the solid boosters do not need air to operate.

# Conclusion

You can't replace the space shuttle solid rocket boosters with electric fans/engines, even if you could solve the battery/fuel problem. The electric fans simply do not produce enough thrust. Even if they did they still require an atmosphere to work properly, but the space shuttle needs its boosters to take it most of the way out of the atmosphere. Neat idea, but I'm afraid it just won't work.

• I'm hoping this can eliminate the need for booster rockets on the space shuttle.
– user4139
Sep 7 '16 at 23:13
• @Jen Ok, cool idea. I will update my answer, could you please add that information to your question? Sep 7 '16 at 23:27
• parking the shuttles in musems has completely eliminated the need for boosters Sep 8 '16 at 3:50
• @Jen I'm not sure what you mean by your stealth bomber comment. 50,000 ft $\approx$ 15 km, i.e. a third of the height that the booster rockets reach. As for making the rail longer, consider that the maximum height a high-altitude balloon can reach is somewhere around 37 km, at which point it wouldn't have any buoyancy left to support a rail. At this point, I would suggest you look into space elevators, since they accomplish more or less what you want and may be more feasible than a balloon-held launch rail Sep 8 '16 at 14:58
• I just used the stealth bomber as a general reference point for modern technology and doesn't fit this question.
– user4139
Aug 5 '17 at 1:11