Talk:Jet propulsion

Jet engines

The article currently states that jet engines include "turbojets, turbofans, rockets, ramjets, pulse jets and pump-jets." It is being proposed at Talk:Jet engine#Rockets - really? that there is a significant difference between jet propulsion and jet engines, and that rockets and pump-jets are not types of jet engine. Contributions to the discussion are invited. — Cheers, Steelpillow (Talk) 09:59, 26 June 2018 (UTC)

Plasma engines and ion thrusters

The article on the plasma propulsion engine appears to assume that it is a type of rocket engine, where it refers to "other types of rocket engine". Plasma rocket already redirects to it. The phrase "plasma rocket" is popular on the Internet too:[1]. Should the recently-added subsection on it be merged into the section on the rocket engine? — Cheers, Steelpillow (Talk) 17:37, 16 July 2018 (UTC)

Just what we need; another "how many angels can dance on the head of a pin?"-type issue. :-) I'm inclined to not mix them in with rockets; note Electrically powered spacecraft propulsion calls them "rocket-like reaction engines". They are radically different from the conventional rocket, and as noted are no good for launch applications as they are high impulse, low thrust. I guess the real question is, does that popular internet usage rise to the level of common usage? JustinTime55 (talk) 18:49, 16 July 2018 (UTC)

Nuclear rockets also work very differently from chemical rockets, but nobody says they are not rocket engines. Given that the popular Internet usage of "plasma rocket" includes sites like PhysOrg, New Scientist and the NASA archives, I would say yes. We find it too in Bittencourt's Fundamentals of Plasma Physics. Whether you heat the working fluid by chemical reaction, a nuclear furnace or microwaves or you simply pressurise the air behind it as in the water rocket, it is still a jet of fluid coming out the back and therefore a rocket. But if you know of more authoritative and weighty RS to the contrary, then I would be happy to stand corrected. — Cheers, Steelpillow (Talk) 19:45, 16 July 2018 (UTC)

Also, a stream of ions is not a fluid and an ion thruster is therefore not a form of jet propulsion, according to the definition used here. It is however a form of reaction engine. I have therefore reverted that particular addition. — Cheers, Steelpillow (Talk) 18:24, 16 July 2018 (UTC)

Reading ion thruster, it wasn't entirely clear to me whether a stream of ions can be considered a fluid or not (since a plasma is also a stream of ions (of both charges) and is recognized as a fluid). I just guessed the ion stream could be considered fluid, especially since the article says the engine mixes the electrons back into the exhaust after electrostatically accelerating the cations in order to keep zero net charge on the environment. If you think the answer is no, then I'm OK with omitting the ion thruster, but the short description of the plasma thruster should be restored. JustinTime55 (talk) 18:49, 16 July 2018 (UTC)

I suspect there is a lot of editorial bias in that article, but it is either a fluid and therefore a rocket engine or not a fluid and therefore not a form of jet propulsion. Sources may well differ. Either way, I think some representative sources need to be sounded out before adding unsourced claims to the article. — Cheers, Steelpillow (Talk) 19:45, 16 July 2018 (UTC)

Having said all that, I feel that I have done enough in bringing these issues to your attention, and I leave it to you and others to carry on from here as you see fit. — Cheers, Steelpillow (Talk) 19:48, 16 July 2018 (UTC)