FWIW I did measurements of air pressure in the props slipstream to see if I could learn anything about thrust, cowling, and possible drag. I used an 049 engine mounted on a test stand.

I found that the areas of greatest pressure were almost exactly in the center of the prop's semi-span and extended behind the prop disk about the length of the prop raduis. Pressures fell off sharply to ambient pressure outside this area.

I was surprised to find that I saw negative pressure readings directly behind the prop tips and near the hub. Pressures in front of the prop showed only slight negative readings generally equal along the blade length and then only in very close proximity to the prop.

If air pressure was related to thrust, it seemed that the area generating the greatest amount of thrust was about half way along the blade length. To me that seemed the area with the greatest need for concern when designing a cowl.