The Design of test frames of all types owes a great deal to the pioneer work of the Structures Department, Royal Aircraft Establishment. This particular frame contains some novel features and has been subjected to some unusual overall calibration tests, particularly in relation to the entirely automatic and centralised control gear.

The choice of apparatus for testing large scale structural components may be influenced by many factors. In the present case, the choice of a test frame rather than other types of equipment was governed by the following considerations.

In an industrial establishment it is essential that test equipment should be put to maximum use. Unlike a central testing establishment such as the R.A.E., major strength tests are relatively infrequent and therefore the equipment should also be suitable for as much as possible of the development and research testing which cannot be undertaken on standard material testing machines.