Back in the mid-60s that prestigious journal POPULAR MECHANICS ran an article on a new propulsion system being developed by the Sikorsky aircraft people. This was a lifting-body system with no moving parts: lift is provided by ionizing air, which is then forced downward. A working model had been created, and was photographed in flight.
(Note that this is an in-atmosphere propulsion system, not the “ion drive” of spacecraft.)
“Neato-jet!” I exclaimed, and waited for the first full-scale craft to take, er, wing. I’m still waiting.
Obviously the basic idea “works.” Anyone know wha hopp?
Check out this search on “ion lifters” for all the latest details. The upshot is that it works on small models, but scaling it upward to large vehicles is unfeasible and would required huge amounts of electricity to make it work. It has been discussed here on the SDMB several times, just search for “lifters”.
I couldn’t say with any real answer concerning that particular engine/drive, but there’s plenty of reasons that something like that would never make it past the experimental stage.
Things like fuel efficiency- if it takes more energy to achieve the same lift as a conventional engine, where’s the benefit?- and max thrust- if the engine can only, due to physical constraints, put out just so much power, then it will be limited in application.
There’s also construction costs, especially when combined with either of the above- why pile cash into ceramics and carbon fiber to have an engine that puts out less power while consuming more fuel?- or material lifespans; an “ion” engine uses a plasma jet, as I recall, which means exotic materials are needed to resist the temps involved. Even some ceramics eventually erode at 5,000 and 6,000 degrees.
I’m not sure how the Sikorsky system worked, but I can’t imagine “ionized” air providing a great deal of lift. I would imagine if a small scale model had an umbilical to an off-board power supply, it could indeed fly, but that system doesn’t necessarily scale up adequately to full size craft.
What is it, double the weight of the plane and you have to quadruple the area of the wing?
Right. Wing area scales only by the square of the linear dimension, but mass scales by its cube. Double the length and you’ll quadruple the wing area but octuple the weight, thereby doubling the wing loading.
Ionizing thrusters do have applications on spacecraft, though.
I’ll have to do a little more research on previous SDMB discussions of this, but a cursory look at the “ion lifters” cites tells me that there’s some real confusion as to what I’m talking about.
The Sikorsky device was not a Bifeld-Brown device, did not involve unbalanced capacitors, and had nothing to do with antigravity. Though I, in my unwashed naivete, would term it an “ion wind” effect, I’m not sure it’s quite the same thing as the phenomena mentioned elsewhere under that label.
The Sikorsky device consisted of a lightweight rigid framework mainly composed of a horizontal metal screen–like a window flyscreen–with several short vertical metal “spikes” extending upward from its top-facing surface. When current was fed into these spikes, charge was emitted into the surrounding air. The charged-up air (I think just a very small percentage of the total volume of local air) then rushed downward, attracted to the opposite charge on the screen below, knocking forcefully against other air molecules along the way and creating a substantial downward flow. The moving air then passed on through the open screen, depositing its excess charge along the way.
Though the article doesn’t make it too clear, I gather that upward thrust comes from (a) the negatively-charged emitter-spikes being repelled upward by the negatively-charged mass of air below it; and (b) the positively-charged screen being attracted upward by that same air-mass, which is above it. I don’t think comparisons to scaling-up wing area, etc, really apply to something like this.
The photo of the model in operation showed it fairly high in a hangar. “Ground-effects” do not seem to be involved. As I recall, it was about a yard square.
What I’d really like to find out about is what happened to, specifically, the Sikorsky project, which was being pushed by Igor Sikorsky himself (then a very old man). Maybe a good biography of IS would supply my answer, hmm?
De Seversky, huh. No wonder “Sikorsky” looked wrong.
So: anyone know of a good De Seversky biography, or other source of info on what happened? (Or didn’t?)
(It occurred to me that, if the “ionocraft” really worked, it could be used to accelerate payloads thru the atmosphere and into orbit. Tom Swift and His Atomic Ionocraft, anyone?)