[sci.space] April 1st : entertaining and tantalising PUZZLE

andrew@nsc.nsc.com (andrew) (04/02/89)

			UFO TECHNOLOGY

Consider the properties of the following object. A superconducting current
loop is created inside a shape formed by the slicing of a cube, with a
square hole in the centre. It's thus a square, thin, single-turn coil.
Create a rectangular superconducting, hollow box of depth greater than half 
the coil (nondiagonal) dimension. Embed the coil inside the box such that
the coil and box main axes are orthogonal, and such that the lower half of
the coil is inside the box. Put a lid on the box (in some way) so that the
lower half of the coil is now totally enclosed, and the lid does not make
electrical contact with the coil (insulated slots, or whatever).

Apply an external magnetic field to the system parallel to the coil axis.
Is there a net translational force on the coil? Two sides cancel, while
the third side produces a net force. Therefore, in the earth's magnetic
field a decrease in weight will be observed (unless you have it upside
down!). Wow.

Notes
1. Superconductors are perfect shields of magnetic fields; ergo
2. The bottom half of the coil is "invisible" to the external field
3. The flux in the coil is quantised and may not change; ergo
4. Energy is supplied from the external field.

Who needs fusion? ....come fly with me, let's play among the stars....

			CHEAP UFO TECHNOLOGY - UPDATE

Problems were experienced lifting the large Whirlpool super-refrigerator,
as room temperature superconductors could not be found, so Deuterium fusion
was harnessed instead using dissipative conductors - good ol' copper.
The same old box and coil was used, but due to the enormous power:weight
ratio of the "Mr. Fusion" unit, liftoff was still achieved, despite the
lack of Meissner effect assist. Now the energy came from the power source,
not the external field. This was a relief to owners of compasses. The hot
magma circulation was gradually slowing down, and the North Pole now lay
somewhere in Tuscaloosa.

Assuming:		B (earth's mag)   = 1E-5 wb/m**2
(round numbers)		g (earth's grav)  = 10 m/s**2
			r (spec res Cu)   = 1E-8 ohm.m
			d (density Cu)	  = 1E4 Kg/m**3

We need, for liftoff, 	B*I*L > M*g,	which cranks into
			W/M > 1E8	watts/Kg (no form factor dependence)

The Mark I fusion unit provided about 20W/cc (2E3 watts/Kg : Pons &
Fleischmann) but enhancements of order 1E5 better power:weight ratio
did the trick. Performance in space with the solar wind gave
acceptable acceleration levels even with the Mk I fusion unit.
				...on Jupiter or Mars...
=====
Andrew Palfreyman 		USENET: ...{this biomass}!nsc!logic!andrew
National Semiconductor M/S D3969, 2900 Semiconductor Dr., PO Box 58090,
Santa Clara, CA 95052-8090 ; 408-721-4788 		there's many a slip
							'twixt cup and lip