19d • General discussion
The Pendulum Test
In the early days of space commercialization, Arthur Dula was recognized as the world's foremost authority on space law. (Of which there are now many). I talked to Art on the phone back in the '80's, in his alternative capacity as a patent attorney. He told me: "The test of an Inertia Prime Mover is that it will deflect a pendulum".
This term 'pendulum' has been subjected to a significant amount of misconception and misunderstanding. Various builders on YouTube have demonstrated their devices with a so-called "pendulum test". Usually, the device is suspended on a tether, hanging straight down at the bottom, with the expectation that the 'plumb bob' will be pulled out to the side a little ways and stay there. Invariably, the device's momentum will add to its thrust, causing it to swing out further than its thrust alone would take it. This movement is directly in line with gravity's reverse acceleration. So, as the 'thruster' settles back to its effective deflection angle, this reverse movement couples with gravity, which changes its operation. (Just as a drawing on a piece of paper will change when the paper is moved). The result is that, even with a unidirectional thrust impulse, the suspension line still moves back past the straight down position.
At this point, a laser spot, or some background reference line, is added, to convince the observers that the tether vibrates further on one side than the other. This test is neither convincing nor conclusive.
Fundamentally, a plumb bob is NOT a pendulum. A pendulum is something which swings back and forth, while a plumb bob just hangs there. (An unsteady line will hang straight and plumb if it is bobbed up and down a few times; hence the name).
To understand the true Pendulum Test, we must consider what happens the instant the pendulum reaches the highest point in its swing. (Or anywhere up to that point). Here, gravity is acting to move the swinging mass back towards the bottom. However, gravity has no sideways effect whatsoever on a mass which isn't at the bottom. Therefore, any amount of unidirectional thrust applied perpendicular to the swinging direction will change the pendulum's swing angle. If the applied thrust is not unidirectional, or missing altogether, the pendulum's swing will not be "deflected", remaining in its normal plane of movement.
A fundamental Principle of Inertia states: "If something changes direction by ninety degrees, its previous motion disappears". (The plumb bob effect). If a thruster being tested has enough force to pull the swinging tether completely out to the side, it will orbit the bottom point, with the swinging motion completely replaced. Any less thrust - including even a tiny amount - will leave some, or much of, the pendulum's original momentum. In this instance, the pendulum will be "deflected" into a more or less flattened orbit.
If the applied thrust is unidirectional, the pendulum's swing angle will be deflected into a curving motion. If the pendulum isn't deflected, the device will have failed the test.
The is the accepted scientific TEST of an emissionless thruster - accepted by both those having Skill in the Art, as well as, convincingly, by a casual observer.
-Jerry Volland
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The Pendulum Test
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