Happy New Year all. Now, anyone care to exlain this?
Many people have talked about the damage to the vent/exhaust structure on the alleged left engine trajectory - where it was said to be basically scraping the ground. Indeed, the damage lines up. ASCE:

For those who don't know this is it:

Locate that same spot in this photo, note also the angled 'doors' (I'm not sure what exactly) and you have a basic idea of the scale of the vent structurre - mostly recessed below ground level.

A later Ingersoll shot shows something like a camera or a light inside this thing - also note wall damage, and sloping lid-like edge, discussed below.

Here's an above shot during cleanup - things are moved around:

source:
DesmoulinsSome cite the back wall being gone as evidence the engine took it out entirely. I'm leaning towards there never was one. People had to get in their sometimes.
What's between the walls is less studied. We'll look at the 'doors' last. First the two intact structures on the left (as seen above): these are intact and in all photos. Cool. Boring.
Next: the one on the right, at the entry corner. In the overhead shot, it's gone - just a base. In early shots it's barely visible. I've looked everywhere and cannot see the top of it, just the edge. but it seems to be a panel/door, perhaps pushed down, definitely tilted at an angle relative to the walls, and bent at the corner nearest the engine entry point. Note also a large gap between these spots - something is missing.

Then the easternmost structure, top center in the overhead shot: again in later shots this is just a footprint, its top stuff removed. I propose this is where the angled 'doors' originally were, before being spun off to the left by something. Note in the overhead shot, where it's been moved and re-oriented, the right-hand door has a distinctive line of black stuff, and a missing corner.
Compare that to this, a cropped J. augustino photo.

Same grime, proportions, lip - and a corver curved on a scale of several feet. I'd guess this was right on a path between that retaining wall chip and the foundation damage.
Also note at left what I think Desmoulins labeled 'scorched metal' - its properties indicate ventialtion ducts.
See also my blog:
Vent Structure Damage