The Flimsy AcceleroMeter: Principle of Operation

Joachim Köppen DF3GJ Kiel/Strasbourg/Illkirch Winter 2004

Design Philosophy

The FAM is a simple accelerometer which can be constructed with easily available material and which should give an indication of weightlessness rapidly enough and accurately enough to enable simple measurements in an indoor Drop Tower (drop of 2 m height). It is also capable of giving a rapid and easily visible optical indication when the weight is reduced below a certain value.

It is constructed from

The construction technique is soldering, as done in electronics, and some creative bending of wires...


The instrument described here is the 4th of a number of rather different designs, and has been verified to achieve the design goals.

Why and how it works

The weight (i.e. the gravitational acceleration) of a small mass M on a long arm L1 is counterbalanced by the elastic restoring force from two counteracting coiled springs S which acts on the short arm L2. This is essentially a spring balance, and the pointer P indicates the weight of the mass.

Some details:

However, some approximations had to be accepted:

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