Prime reason for greater sales of civil DC-10, over L.1011, was structure weight. L10 Hull had belly bilge, 2 skins. Good when you are sitting there under max. pressurisation, not so hot as dead weight. Gunk from galleys/lavs slurched around and caused corrosion. DoD choice of K-10 was presented as superior fuel transfer capacity, but was actually US Protectionism v.limey power.