Detonation and Autoignition : Some Considerations on Methods of Determination
This is a 1937 NASA technical report on detonation and autoignition in engines, a scientific paper of the NACA era produced for engineers and researchers. The two pictures are a blurred high-speed photograph of a detonating combustion flame front and a line graph comparing cylinder pressure against crank angle for diesel and spark-ignition engines, with a horizontal auto-ignition threshold marked. A designer could take from them the stark, grainy look of early engineering photography and the clean, minimal line-graph style with dashed and solid curves.
