The Nuclear Salt Water Rocket - Possibly the Craziest Rocket Engine Ever Imagined.

An other quite interesting concept (also a little less "out there" and actually, successfully tested) is the NERVA engine, also linked at the bottom of the article[1]. It uses a nuclear reactor to heat up a single propellant (liquid hydrogen) which then rapidly expands as it goes out the nozzle at the end, resulting in quite high specific impulse and is more efficient than a chemical rocket. If we want to go really far out in terms of crazy rocket designs, there is also the concept of the nuclear salt-water rocket[2][3]. This one uses enriched plutonium or uranium salts, dissolved in water, inside a neutron-absorbent fuel tank design. The water is pushed out through a pipe, where an uncontrolled chain reaction starts. If it goes fast enough, it explodes right inside the engine bell, pushing the rocket. The proposed design in the original paper is supposed to generate hundreds of gigawatts of thermal power. This is comparable to the Chernobyl reactor #4 when it exploded, but unlike Chernobyl (which only exploded once) or the pulsed Orion engine, it could run continuously . [1] link [2] link [3] Obligatory Scott Manley video: ▶ this video

Can we develop a nuclear salt water rocket already? link Scott Manley video on the subject: ▶ this video Basically a controlled thermo nuclear reaction blasting out the back. "One design would generate 13 meganewtons of thrust at 66 km/s exhaust velocity (or 6,730 seconds ISP compared to ~4.5 km/s (450 s ISP) exhaust velocity for the best chemical rockets of today)." You certainly wouldn't want to use this to take off from Earth. But we could use it for deep space travel.

For those interested: As absurd as it sounds nuclear powered aircraft engines are a thing.[1] They have also been proposed for spacecraft, Scott Manley does a great video talking about nuclear rocket engines[2]. [1] link [2] ▶ this video