Speed of translation and rotation





Stroboscopic photographs relating to the measures of the speed of rotation and translation of the boomerang.

Photographs Strobe

To determine the kinematics of a boomerang, or the travel speed and the rotational speed of VT VR simultaneously, it is not possible in my opinion, to use another technique than that of stroboscopic photography. The measurements obtained are sufficiently precise and allow assessments particularly interesting about boomerang different weight and geometry as well as to various casting techniques.

Initially I had substantial doubts with regard to the timing between thrower and photographer, and in fact after two series of attempts rather disappointing, I was going to solve the problem by using a photoelectric device. However, in the third series of attempts to synchronize reached a good standard.

Obviously the photographer is a professional at the highest level and his equipment is top notch.

Some launches are purely demonstrative.

Following the launches were carried out with increasing power.

The travel speed VT has reached a value of about 36 m / sec

The rotation speed VR is between 9rps and 12rps

The best position is the one with the camera optical axis orthogonal to the second vertical line.

The accuracy of the measurements depends only on the distance of the trajectory with respect to the plan.

An interesting relief, I've noticed personally, however, for a long time with boomerang classic large enough, it is a transient that occurs at the time of the release: the boomerang passes from the rotation (planetary) imposed by the arm to that around the center of gravity. In practice, in all the sequences, the first boomerang photographed has not aligned with the center of gravity as it is for the following positions.

To achieve proper synchronization between the launches and photographic sequences, without using a photoelectric device, you have to run a good number of launches. Initially, the results are disappointing, but later, you reach broadly satisfactory results. Initially, we recommend a frequencyƬ of 20 Hz, then with the top one (40Hz)

Boomerangs used to strobe photos

Photo strobe

The distance between the vertical strips is 25cm

Launch demonstration of accuracy along the horizontal line

In the first frame of the sequence distance from the center line of gravity is greater than the following. It is evident that the transition occurs immediately after release. In the four frames following the centroids are aligned, or belong to a straight line.

VT: 18 m/sec

VR: 9 rps

VT: 20 m/sec

VR: 10 rps

Launch demo

VT: 20 m/sec

VR: 10 rps

VT: 30 m/sec

VR: 11,5 rps

VT: 36 m/sec

VR: 12 rps