The Impulse Drive Experiment - IPD v1.0
Created on February 25th, 2001 - JLN Labs - Updated on February 9, 2002
All informations in this page are published free and are intended for private/educational purposes and not for commercial applications

This experiment is the replication of the Henry Bull's Impulse engine demontrated in 1935. This experiment has also been conducted successfully by Alexander Frolov in Russia and presented during the International Conference in St Petersburg in 96, see "Collection of Lectures" by Alexander V.Frolov, published in Proceeding of International Conference New Ideas in Natural Sciences, 1996

<< The theory is that a large weight with a low velocity ( if stopped by springs ) will yield more foot pounds of energy than a small weight with a high velocity being stopped by impact, even though both were given the same initial force. A simple illustration: Let us assume you are in the centre of a room in space. One wall is elastic and the opposite one solid. In your hands are two balls one heavy and the other light and you throw them with the same force at the same time. The heavier one hits the elastic wall with an impulse and a large amount of energy is given to the room in that direction. The lighter one having the same energy hits the solid wall but its energy is dissipated in heat and distortion. If there could be found a method whereby the kinetic energy of the lighter ball could be effectively utilised the room would move in the other direction.
It depends upon the difference in effectiveness of two ways of transmitting energy, which can be termed impact and impulse. If a weight is thrown against a solid wall, it is stopped by impact, and much of its energy is wasted in distorting the weight and the wall and in producing heat. However, if the weight is thrown against a spring fastened to the wall, it is stopped by impulse, the spring conserving the energy of the moving weight and transmitting the resulting force, with little loss, to the wall. Tests have shown a weight will yield three times more force by impulse than by impact. >> has said Henry Bull in an article published in Popular Science in January 1935.

This is a very simple and cheap experiment that you can do by yourself, the material required is :

You need very few and cheap material for conducting yourself this experiment

The Impulse Drive is now ready for testing, compress the spring and attach a nylon wire between the small hooks,
use a lighter for cutting the nylon wire and thus releasing the sping. ( see the animation below )

Impulse drive specifications :
  • Total weight = 188 g
  • Weight of the moving masses: M=M1+M2+spring = 84 g
  • Weight of the support = 104 g

Test Results : When spring is released by the burning of the nylon wire, the Impulse Drive ( its support ) moves 5 mm from the left to the right but the internal moving mass M has shifted 6 mm from the right to the left, and we have : 84 g x 6 mm ~ 104 g x 5mm.

Conclusion : Today, I am able to confirm the effect observed in the Bull's Impulse engine with this simple experiment: After that the spring is released the device has translated 5 mm in one direction.

But, after a short analysis of the photos above you will notice that there is no motion of the center of mass in spite of the apparent motion of the device. This is only a 'one-shoot' experiment because the device needs to be resetted before each test, the net impulse in the Bull's device sums to zero over a complete cycle ( when the moving masses return to its initial position at the end the cycle ).

Now in 2002...we can go further :

In 1935 it was not possible to build a reactionless drive based on the Henry Bull's device by simply using a mechanical apparatus. Today, its seems now conceivable to build a spacedrive by using this kind of principle with a soliton wave or a transient mass fluctuation ( the Woodward experiment which uses the Mach's principle ) instead of the old Bull's moving masses.
Some projects are currently in study by the
NASA Breakthrough Propulsion Physics Workshop such as the BPP task #1 : "Independent test of Woodward’s transient inertia effect" by the Dr. John Cramer, Univ. of Washington, Seattle WA ( completion due: March 2001 ).
See the Woodward experiment detail at :

See the tests independant report :
AIAA-2001-3908 : Tests of Mach's Principle with a Mechanical Oscillator
by J. Cramer, Univ. of Washington, Seattle, WA

Method and apparatus for generating propulsive forces without the ejection of propellant
No. Publication (Sec.) :US6098924
Date de publication :2000-08-08
Abrégé :
Mach's principle and local Lorentz-invariance together yield the prediction of transient rest mass fluctuations in accelerated objects. These restmass fluctuations, in both principle and practice, can be quite large and, in principle at least, negative. They suggest that exotic space time transport devices may be feasible, the least exotic being "impulse engines", devices that can produce accelerations without ejecting any material exhaust. Such "impulse engines" rely on inducing transient mass fluctuations in conventional electrical circuit components and combining them with a mechanically coupled pulsed thrust to produce propulsive forces without the ejection of any propellant. The invention comprises a method of producing propellant-less thrust by using force transducers (piezoelectric devices or their magnetic equivalents) attached to resonant mechanical structures. The force transducers are driven by two phase-locked voltage waveforms so that the transient mass fluctuation and mechanical excursion needed to produce a stationary thrust are both produced in the transducer itself.
Analysis of Woodward's Piezoelectric Capacitor Thruster by Steve Burns ( PDF document )

Animated photo about the Frolov's Impulse drive experiment
( Photos courtesy of Alexander Frolov )

<< In this case we are working with asymmetry of entropy: in one side of the system we have produced heat that is realted to microimpulses of particles (that is more entropy) and in other side of the system we have produced elastic interaction with minimum heat but with max kinetic macro impulse transfer. So, after the spring become free and masses were interated with the body of the system, total impulse of the system should be constant and it is true. But in one side of the system the part of the impulse is transformed in microimpulses of elemental particles, i.e. in heat energy. By that way we can produce macroimpulse of the experimental system. >> Alexander Frolov

See the Frolov web site at :

See the video of the JLN's Impulse Drive experiment

Download the Video of the test ( size 108 kb )

To see this video, the free downloadable RealPlayer is required

Stick-Slip drives Vs Reactionless drives, be carefull... by J-L Naudin

See : The Stellar Drive Engine project from Robodyne Cybernetics

Email :

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