Prof. Laithwaite's Gyroscope Experiments Part IV

Video

Video of Part 4 ("The Jabberwock") from Professor Laithwaite's original 1974 Christmas lecture is at http://richannel.org/christmas-lectures/1974/1974-eric-laithwaite#/christmas-lectures-1974-eric-laithwaite--the-jabberwock

The "double-joint" experiment begins at about 33:30, and the system is shown briefly, twice, in its initial balanced state, at 33:50 and 34:06. The gyro does indeed rise as shown in the second image below.

Double-joint experiment — static balance

Double-joint experiment — finish

The "double-joint" experiment — computer modelling

A 30kg gyroscope and balance-weight on a jointed shaft, as in Professor Laithwaite's "double-joint" experiment.
The graphs show the height above ground level of the gyro wheel (red) and the balance-weight (dark blue).

The above image shows a gyroscope with an extra [single d.o.f. rotational] joint in its shaft, as in Professor Laithwaite's "double-joint" experiment shown above.

When the simulation is run on this model, the result is unlike either Prof. Laithwaite's Fig. 4.15, or the result achieved in his experiment. After some initial settling-down, [a force opposing the combined weight of all moving components is applied to the central axle, and there is a damper between that axle and the tower] the heights of both the gyro wheel and the balance-weight oscillate over time. The wheel is always lower than the balance-weight, as was expected from orthodox theory, but the angle of the joint is opposite from Fig 4.15.

The "double-joint" experiment — conclusion

Computer modelling of the double-joint experiment shows only orthodox behaviour, and fails to replicate the result demonstrated by Prof. Laithwaite. After having been exactly balanced initially, the modelled gyro wheel does not show any sign of transferring its weight any further back than the added shaft joint. The portion of the shaft carrying the wheel now has its center of mass at a greater radius, and presumably does not transfer its weight, which would explain why the wheel drops down below the balance-weight.

Of course, if there is even a very slight overall excess of weight on the balance-weight side when in operation with the wheel's weight transferred, the wheel does rise. In doing this, the system behaves essentially in the same way that a sensitive precision balance would behave. But in that case, at least in the computer model, the imbalance is obvious at the initial (static balance) part of the experiment.

My modelling so far cannot explain either the double-joint experiment, or more importantly, the apparent lack of weight that an experimenter feels when he first force-precesses, then lifts a heavy spinning gyroscope.

I have the building and testing of a heavy physical gyroscope on my "to-do" list.