1
$\begingroup$

Is it possible to step up the notch and create the lift effect used in airplanes and helicopters without moving parts? By "moving parts" I mean helicopter blades moving at high speeds to create pressure difference (often misunderstood as caused by "differences in speed" but caused by length of travel of airflow) or wings in airplanes, that must move with the plane at high speed to create lift.

Wouldn't it be possible to create a similar effect by somehow making the air above a disk(?) conductive(I know this is hard) and moving it with electric currents to create the pressure difference?

I suppose vibration( a form of pressure) alone does not work, otherwise we'd have flying machines made with subwoofers

$\endgroup$
  • $\begingroup$ Unlikely, with current technology, given that MHD propulsion hasn't taken off even for salty water boats (arguably a much easier setting). $\endgroup$ – stafusa Sep 15 '17 at 12:25
  • $\begingroup$ Yeah but MHD was focused on using an electrified fluid as thrust. What I am saying is create a disruption to create the pressure difference, and let atmospheric pressure produce the lift $\endgroup$ – Pinhead Sep 16 '17 at 0:45
  • $\begingroup$ Your second paragraph describes a MHD system. Look, whatever is done, it has to cause a downflow of air with sufficient momentum per second to support the weight of the craft. That's how all heavier-than-air craft work. $\endgroup$ – Mike Dunlavey Sep 18 '17 at 17:41
1
$\begingroup$

It's probably quite unpractical, if possible at all.

The Original Post (OP) seems to mean something like moving the air "out of the way" from above the disk. In order to keep a significant pressure difference between the upper and lower parts of the disk, we'd have to maintain an extremely large sideways flow to compensate the atmosphere rushing to the lower pressure region. We'd be better off directing this flow downwards to create lift, in a version of the magnetohydrodynamic propulsion that has been called MHD aerodyne.

With current technology, MHD propulsion hasn't taken off even for salt water boats, an arguably much easier setting (the required propellant speed is inversely proportional to the propellant density for the same thrust, and salt water is not only much denser than air, it's also already conductive).

On the other hand, MHD propulsion in tandem with traditional turbojet engines is being considered for hypersonic and space access flight: The MHD-controlled turbojet engine: an alternate powerplant for acsess to space (Blankson & Schneider 2014 - DOE/NETL MHD Workshop); The Effect of Magnetohydrodynamic (MHD) Energy Bypass on Specific Thrust for a Supersonic Turbojet Engine (Benyo 2010 - NASA/TM—2010-216734, AIAA–2010–232). It's also being touted as a solution to problems beyond propulsion, such as shock wave control: MHD hypersonic flow control for aerospace applications (Petit & Geffray 2009), though some of the main author positions, in particular on UFOs are controversial.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.