Dense cargo positioning
 

Suppose you have some very dense cargo to transport on a freighter plane. I mean really dense, think gold, tungsteen, marble blocks, something with which you will max out on weight way before you max out on volume. Where should you place it, in the belly or on the main deck? Does it have any implications on the plane behavior in-flight? I'm not talking about CG, it's obvious you need to mind that. I'm talking about the vertical component.

We used, regularly, to cart bullion around the country - Electra and B722. No different to other stuff (except for the artillery the police brought along for the trips).

(a) fuselage bending loads - the pallets were loaded centrally Really only feasible to main deck load due to handling considerations
(b) floor loading - no different to anything else
(c) doesn't have much of a vertical component - we could have played ping pong over the pallets
(d) no effect on handling as the mass is relatively concentrated near the aircraft CG

In the 747F, the load zones on the main deck over the center fuel tank/wing spars have higher load limits, so dense loads would be better placed there.

The main deck is divided into areas, each of which has a max load (kg). Over a given length of fuselage there is a linear limit (kg/m). There is an area limit (kg/m3). Appropriate use of spreaders may be needed. Overlaying all of this is the CG envelope.

HtH