This method has been designed to give all necessary performance data, concerned with the take-off and landing of aircraft, in a cheap and efficient manner. The complete path of the machine from the start of the take-off run to beyond the screen is recorded on a single photograph and from it the reduction of the data is done readily and simply. In the case of a take-off the data obtainable is as follows :

1. (a) Take-off run.

2. (b) Nature and length of the transition.

3. (c) Height at any screen.

4. (d) Distance, velocity and acceleration at any point from the start.

5. (e) Angle of climb.

6. (f) Rate of climb.

7. (g) Any irregularities in the flight path.

Similar data can be obtained in the case of a landing. Any information may be extracted independently and the photographic negative filed for future reference.

The camera used is simple and inexpensive, both in construction and subsequent use. Four persons at present form the total ground staff and with an improved camera now under construction one of these is eliminated.

The accuracy obtainable with the present apparatus is sufficient to fix the position of the aircraft to within ± 2 feet. Once the initial work has been carried out on any aerodrome, future use of this method has been found to be simple, quick and sufficiently accurate for all normal requirements.