Well, one thing I am not is a rocket scientist.  David Wright has a nice review of some of the pieces of debris, though sadly he finished it before several more images (like the engine, above) hit the press.

Here are the images, along with an invitation to continue our discussion:

This looks like one or two (crushed) engines of the four engines in the first stage. For reference.

Gas tanks to pressurize the propellant tanks. For reference see similar Scud tanks.

An o-ring, possibly from the area between the oxidizer and fuel tanks.

What appears to be section of the rocket with the oxidizer tank.

An end view of the forward end of the section containing the oxidizer tank.

Another shot of the section containing the oxidizer tank.

The section containing the oxidizer tank showing four outlets.

What I said before.

I guess we now know the North Koreans put the oxidizer tank forward. I referred to the first bit of debris as the fuel tank, prompting Tal Inbar to suggest the section was for the oxidizer.  (I was trying not to take sides; I should have said “a propellant tank.”) We had some debates about this in the past, but it seems pretty clearly the larger tank (for oxidizer) was forward.

Anyway, I’ve decided to spend some considerable time on learning to identify components of rockets, including engines.  I am looking for advice!  I am starting with Sutton, Rocket Propulsion Elements.  What I really need are recommendations to read and, more importantly for the way I learn, historical collections to see.  I am already planning a trip to the collections at Udvar Hazy, which are nice.  But if you know of others worth visiting, especially on the Best Coast, please let me know.