Dr Zarkoff
Long before Turner quit being a sheepman and the Santa Fe, Galton, with the help of Westinghouse made several experiments on various British Railways ca 1878. WAB reprinted the papers in the 1890s under Galton's title 'The Effects of Brakes on Railway Trains'
GW built the speed recorder and had his hand on nearly every aspect of the test wagon and the test runs.
The information from those experiments is still germane
for example
Don't slide the wheels- sliding friction is less than rolling friction
For a given shoe pressure braking force is inversely proportional to wheel speed
This has been worked around by the Composite Brake shoe to replace cast iron
but it was/is a key to high speed braking
You are correct that air from a broken pipe must exit at the break- however, the wave propagation from the pressure change is what sets the other brakes in the train.
Otherwise the action would be incredibly slow in a long train- like that of straight air,
and the shocks at the rear end would be lethal
You are incorrect in saying emergency action in the QA exhausted to the air.
Or perhaps I mis stated. In the QA the principal was not to exhaust into the air, but to use that air to add to the braking force- a 20% increase [in emergency] over that attained by simply exhausting it to the air. NYAB challenged WAB from about 1890, and WAB met each by winning infringement case in court, until the late 1890s.
NYAB won because it abandoned the use of exhaust air and simply let it go. The NYAB official position was ' We never said it is as good as WAB, but it is legal and it is cheaper'.

TUrner and Dudley were very valuable inventors and researchers. However their tenures were much later than key WAB experiments.
Those were done at Burlington IA 1886-1887. In 1892 other tests were done vs NYAB ending with the head-to-head runs at KArner NY. Westinghouse had already turned to finding solution to the braking of high speed trains.
Dudley is best known for the hispeed tests on the West Jersey and Seashore which culminated in the UC brake.
Turner Was a heavy contributor to the K brake. He was also a great thinker and lecturer on the subject of brakes and what they can accomplish, such as reducing the headways on NY transit services by braking, rather than increasing speed
regards