А давайте я попробую показать в английской книжке 1943 года.
Там: rear main spar и front main spar- аж целых два!
Ещё добавлю оттуда-же по крылу:
The wing is a one-piece wooden cantilever with built-up spars having laminated spruce flanges and plywood birch webs. The ribs between the spars have spruce booms and plywood webs.
In the wing covering the Mosquito differs somewhat from the Comet and Albatross. The lower covering is plain birch plywood, except for the doors over the tank bay. The top skin, however, is diiferent in that there are two skins, spaced some distance apart, and instead of the balsa wood packing between them, as used in the fuselage, they have stringers running spanwise. These stringers are fairly closely spaced and serve to stabilise the two skins. Otherwise the outer skin, being further from the neutral axis, would take a greater load than the inner. Generally speak ing, the leading edge is built as a separate unit and screwed on when the various leads, controls, etc., have been mounted on the front face of the front spar.