Track Recorders

Anyone know what Track Recorders looked like? The text below is a brief description from "How the RAF Works" from 1941

Yet another device for bombing instruction is the track
recorder, also used in conjunction with an aeroplane fitted
with a light connected to the bomb-lever. It is operated
by two men and the course of the bomber is followed
through two telescopes set at right-angles. As they turn
handles to keep the aeroplane in their sight its course is
recorded on a strip of paper, and when the light flashes
the spot is marked on the paper by an automatic pencil.
The accuracy of the aim can then be computed by means
of a scale which has already been worked out.

I think it has been simplified as it sounds very "Heath Robinson" and probably not fully explained due to wartime restrictions. I am trying to work out if it has any relevance to bombing ranges as it seems to be somewhere between the Camera Obscura and the Hills Mirror, both of which were relevant.

Also here

AVIA 18/1192 - Royal Aircraft Establishment flight track recorder: tests. (1934).
Yes TNA has much info embedded in unrelated files and relies on researchers finding them. Not the TNA's fault but the original compiler.
I will take a look at AIR 10/2600, although the Olympics will make travel on public transport a nightmare (if predictions are correct) so it will have to wait until that annoyance is over.

Finally got around to looking at Track Recorders. This device was designed to replace the Camera Obscura, which had its limitations, in the mid 1930's. Like the Camera Obscura it was used for practice bombing and wind direction and speed. Early designs by RAE at Farnborough were to be operated by a single person who attempted to keep the crosshairs in the telescope on the target aircraft by turning an elevation wheel and an azimuth wheel. Whilst this was being done a pen was marking a paper every second or two to allow the track to be followed. Bomb release was signalled by flashing a Sashalite in the aircraft and the operator caused a mark to appear on the paper. Plotting the actual bomb strike was similar to the Camera Obscura and relied on accurate height data and timings. This early version was only successful when operated by an experienced operator and it was easy to lose sight of the aircraft. Later versions required two operators, one for elevation tracking and one for azimuth. This is where the two telescopes came in and the were at right angles to the line of sight for ease of operation and corrected to line of sight via a prism. Tracking was by a stylus on waxed paper and was on a 30" disc table, enabling multiple plots to be recorded. There was only one track recorder and its ideal siting was at the target, any other location required an offset calculation to identify the actual bomb strike. As far as I can see the trail for the fall of the bomb was set to zero on the bombsight and terminal velocity set to infinity so that impact would have been dircectly below the bomber. The Track Recorder co-existed for many years and the track recorder was certainly used during the war but no idea when it was dropped from training.

The optics included line of sight open sights to get things close enough to use the telescopes. These were mounted on top of the optical sight. The early tests found that users struggled to find the target through the telescopes, especially in slightly cloudy condidtions - a failing with all optical based tracing. It's bad enough with reasonably powerful binoculars moving freely but to do this with turning wheels as well!

Those Cinetheodolites look similar in operation but more modern looking than the wartime version.

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