First Flight of Ion-Drive Aircraft

choi

(1) On Nov 21, 2018 Nature published three on the topic:
(a) Editorial: First Flight of Ion-Drive Aircraft; A remarkable machine propelled by ionic wind could signal a future with cleaner aeroplanes. Nature, 563: 443.
https://www.nature.com/articles/d41586-018-07477-9
("A News and Views article delves into the technical details and the challenges that must be addressed to scale up the prototype plane. Is such a goal achievable? Conventional wisdom would say probably not. But then it also said that aircraft with ion-drive, or electroaerodynamic, engines — which create thrust by using electrical forces to accelerate ions in a fluid to form an ionic wind — would never fly at all")
, which is available to the public but there is no need to read it.
(b) This is written for the public:

Franck Plouraboué, Flying with Ionic Wind. Aeroplanes use propellers and turbines, and are typically powered by fossil-fuel combustion. An alternative method of propelling planes has been demonstrated that does not require moving parts or combustion. Nature, 563: 476 (in the "News and Views" section).
https://www.nature.com/articles/d41586-018-07411-z

Quote:

"In Xu and colleagues' plane, an electric field is applied to the region that surrounds a fine wire called the emitter (Fig 1a). The field is strong enough to induce a chain reaction: free electrons in the region collide heavily enough with air molecules to ionize them, producing more electrons that then ionize more molecules. These electron cascades give rise to charged air molecules in the vicinity of the emitter — a phenomenon called a corona discharge. Finally, the charged molecules drift away from the emitter and generate a propulsive ionic wind as they are accelerated by the electric field towards a device called the collector (Fig. 1b). This process occurs only in gases, and not in liquids, justifying the authors' use of the term 'electro-aerodynamics.'

"The optimization technique [by Barrett group] found a feasible design at a wingspan of 5 metres, with a mass of 2.5 kilograms, a flight velocity of 4.8 metres per second and a power requirement of 600 watts. The authors built a full-scale plane based on this design (see Fig 1b of the paper [which is (1)(c) and listed below).

(i) Plouraboué is senior researcher at the Institute of Fluid Mechanics of Toulouse (French acronym: IMFT), University of Toulouse and CERN.
https://en.wikipedia.org/wiki/Ce ... herche_scientifique
(ii) Do not worry if you can not understand quotation 1. The notion will be explained in (3) below.
(iii) Fig 1(a) is viewed from (a person who is at) the collector toward the emitter. So outside the circle (marked with "corona-discharged region") the pink circle (marked with "+" inside) and the grey circle (labeled with "Neutral air molecule") are flying toward (but not necessarily at) the collector.
(iv) What is the orientation of Fig 1(b) relative to the plane (or unmanned aviation vehicle (UAV)?  Plouraboué did not say; I figure out that the left of Fig 1(b) faces the front , and right does the rear of the plane.  See (2) below.

(c) Xu et al, Flight of an Aeroplane with Solid-State Propulsion. Nature, 563: 532 (in the Letters section).
https://www.nature.com/articles/s41586-018-0707-9
("a fixed-wing aeroplane * * * All batteries and power systems, including a specifically developed ultralight high-voltage (40-kilovolt) power converter, were carried on-board. * * * We provide a proof of concept for electroaerodynamic aeroplane propulsion")
is locked behind paywall.
(i) The corresponding author, Steven Barrett, is an associate professor with MIT's Department of Aeronautics and Astronautics.
(ii) I am stumped by the term "solid-state propulsion." (Judging from the context of MIT's own press releases and the following news reports, the term appears to mean "no moving parts.") Beyond this burst of publicity (around Nov 21), the only two other use of this term are found in
(A) solid-state fan
https://en.wikipedia.org/wiki/Solid-state_fan
(in toto: "is a device used to produce an airflow with no moving parts. Such a device may use the principle of electro-aerodynamic pumping, which is based on corona discharge")

It has advantages over mechanical fans such as that it is noiseless and more reliable")
(B) a company name Digital Solid State Propulsion, Inc (based in Reno, Nevada.  Compare solid-state physics (semiconductor, in contrast with vacuum tube) and solid-state storage/solid-state drive.

choi

(2) None of MIT press releases or news reports detailed the precise look of the plane, except three:
(a) I do not know whether or how to upload a picture that does not have an URL.

Here is the news report
Star Trek-style 'ionic wind' plane hailed as most significant advance in flight since the Wright brothers. Telegraph, Nov 21, 2018.
Just search images.google.com with the title, and the first picture is it.
(b)
(i) Silent Plane with No Moving Parts Makes 'Historic' Flight. France24, Nov 21, 2018 (figure only, no text).
https://www.france24.com/en/2018 ... kes-historic-flight
(ii) Steve Hanley, Solid-State Airplane With No Moving Parts Takes Flight. Clean Technica, Nov 22, 2018
https://cleantechnica.com/2018/1 ... parts-takes-flight/
(view TOP of figure only)

(3) ionic wind explained.
How Ion Propulsion Works (Lifters, Ionocraft, Ion Wind). Rimstar.org, undated.
https://rimstar.org/science_elec ... _ion_wind_works.htm

The "corona discharge" mentioned in both (1)(b)(iii) and (1)(c)(ii)(A) is just
https://en.wikipedia.org/wiki/Corona_discharge
("is often seen as a bluish (or other color) glow in the air adjacent to pointed metal conductors carrying high voltages, and emits light by the same property as a gas discharge lamp whose example includes neon signs]" )
View its photos.

(4) Park S, Cvelbar U, Choe W and Moon SY, The Creation of Electric Wind Due to the Electrohydrodynamic Force. Nature Communication, 9: 371 (Jan 25, 2018)
https://www.nature.com/articles/s41467-017-02766-9

Quote:

"Abstract[:] this mechanism remains unclear.

"Introduction[:] Collisional coupling (that is momentum and energy exchange) between charged particles and neutral particles (c–n) * * * the first observation of c–n coupling by F Hauksbee in the 1700s

(a) This article concluded that electrons, rather than the positive ions, play the major part in creating the wind. I do read but fail to understand the entire article.
(b) Wonho Choe ("Choe W" in the citation above) is the corresponding author. The professor is with Department of Physics, Korea Advanced Institute of Science and Technology (KAIST) at Daejeon 大田廣域市.
https://en.wikipedia.org/wiki/Daejeon
(i) Korea Advanced Institute of Science and Technology 韓國科學技術院 (1971- ; a national university)
(ii) 崔 "is most often anglicized Choi, and sometimes also Choe."  en.wikipedia.org for "Choi (Korean surname)"
(b) Cvelbar  works in Slovenia.
(c) "Francis Hauksbee * * * made the earliest report of electric wind in 1709."  en.wikipedia.org for "ion wind" (which opens by stating that "ion wind, ionic wind, coronal wind or electric wind" all mean the same).  That is Francis Hauksbee the Elder (1660–1713). Another English scientist, Francis Hauksbee the Younger, was the Elder's nephew (not son).
(d) This article used "ionic wind" just once (paragraph 1 of the Introduction). The rest of the article uses "electric wind" -- the preferred term of Choe.