In 1956, Astounding Science Fiction gushed about the wonders of a reactionless space drive invented in 1956 by Norman L. Dean. It could propel a converted atomic submarine into space, editor John W. Campbell wrote. He added, "The modern nuclear submarine is, in fact, a fully competent space-vehicle . . . lacking only the Dean Drive."

He chose a submarine of the Skate class for his thought experiment. With the reactionless space drive, the submarine would lift off the earth at a constant 1 g acceleration, which could be maintained nonstop for months, if necessary. There would be, as a consequence, no sense of free fall for the crew. Gravity would appear to be earth-normal. "In flight," Campbell wrote, "the ship will simply lift out of the sea, rise vertically, maintaining a constant 1,000 cm/sec/sec drive. Halfway to Mars, it would loop its course, and decelerate the rest of the way at the same rate." In adapting the submarine to space duty, he said. "There is one factor that has to be taken into account, however; the exhaust steam from the turbine has to be recondensed and returned to the boiler. In the sea, sea water is used to cool the condenser; in space no cooling water is available."

A huge bag-like balloon would be attached to the spaceship, silvered on one side, painted black on the other, and of whatever diameter needed to operate properly (unless it was elastic and self-adjusting). This would act as the condenser for the exhaust steam. "The tough part is the first hundred miles up from Earth; there air resistance will prevent use of the balloon condenser."


Campbell suggested that the ship carry along spare water in the form of ice. By the time it melted, the ship would be above the atmosphere. "Under the acceleration conditions described above, a ship can make the trip from Earth to Mars, when Mars is closest, in less than three days . . . It would have been nice if, in response to Sputnik I, the United States had been able to release full photographic evidence of Mars Base I."

The Dean Drive had been invented by a Washington, D.C., businessman, Norman L. Dean, as a hobby. He built several working models, none of which were able to lift themselves (and ones that allegedly did were claimed to have been destroyed in the process of testing).


Norman Dean

The Dean Drive, in converting rotary motion into a unidirectional motion, generates a one-way force, without any reaction. To do this, a pair of counter-rotating masses generated a nonreactive force. That is, in the case of Newton's law that for every action there is an equal but opposite reaction, for the Dean Drive there is an action without any reaction, equal or otherwise. Dean's data revealed that, neglecting losses due to friction, a 150-horsepower motor would develop 6,000 pounds of thrust.

Campbell and Dean and the machine

When John Campbell examined the device he admitted that "I do not understand Mr. Dean's theory very clearly; my personal impression is that he doesn't understand the thing in a theoretical sense, himself."

In the Drive, two counter-rotating masses (about 1/2 pound apiece) spun on shafts in a light frame. The complete model weighed about 3 pounds. Normally, with such device, a powerful oscillation would be produced. However, Dean changed the center of rotation of the masses as they spun. This point itself had no mass, so no energy was required to move it. "In the rotation of those counter-rotating masses," explained Dean, "there is a particular phase-angle such that the horizontal vectors are canceled, and the vertical vector is upward, and exactly equal to the weight of the two masses. At that instant, the light framework can be moved upward without exerting any force on the masses."

In the demonstration model Campbell saw, a small solenoid moved the frame carrying the rotating masses at the proper instant. The result of forcing the masses "to rotate about two different centers of rotation simultaneously" is "rectified centrifugal force." Dean maintained that during operation of the counter-rotating eccentrics the heart of the system was the intricate phasing relationship which must exist. The rigid connection between paired shafts and the counter-rotation of masses produced a cancellation of forces and reactions engendered in all directions except in the direction of the desired oscillation. This was always parallel to a plane perpendicular to the axes of rotation of the two masses. The result of the cancellation was an oscillation produced by the resultant forces which represented the sum of the components of all forces acting in the direction of a plane at right angles to the shaft axes. Thus, claimed Dean, such a freely suspended oscillating system was not subjected to any other reaction or force. The use of six properly phased pairs would produce an almost continuous thrust.

Western Gear Corp. ran tests on the Dean device and concluded that it couldn't work, although some computer simulations contradicted this. At the same time, rocket pioneer Alfred Africano recalled that several years earlier he had enjoyed a "ride" on a similar device developed on Long Island by Assen Jordanoff, the famed aviation expert. The 500-pound man-carrying vehicle attained a speed of 1/3 mph. It's important to point out, though, that this movement was horizontal, not vertical.

And twenty years prior to Dean, inventor S. J. Byrne devised, on paper at least, an antigravity method based on displaced inertial masses that he called the "planetary rotor." He did not believe that his invention duplicates Dean's, but rather complemented it and offered to join forces with the Washington inventor. (It is interesting to note that Ernst Mach, of Mach number fame, in his book Die Mechanik in ihrer Entwickling, 1883, and which was published in 1902 in the United States as The Science of Mechanics, with numerous reprints up to the 1960s, described and illustrated a machine very similar to Dean's. The young Robert Goddard also toyed with an idea similar to Dean's.

Ultimately, the Air Force Office of Scientific Research turned the device over to engineer Jacob Rabinow to assess. Rabinow concluded that the system "does not have any unusual properties" and that it "can not produce a unidirectional impulse." He did not even consider it an efficient vibrator or impact machine. The demonstration machine only gave the illusion of generating a force without an equal and opposite reaction by making use of the static friction of the load against the floor, similar to the way in which a person on roller skates can move across a floor by swinging his body to and fro. In the absence of static friction the machine did not perform as claimed.

Dean, of course, insisted that Rabinow's tests were improperly performed (and a number of Dean's modern supporters agree, many of whom are convinced inertial propulsion will work). "We are going to have to live with the Drive," he wrote, "whether we want to or not."