Soft cover. Condition: Good. This undated collection of technical notes on aircrarft engines comes just after the transformation of the Royal Flying Corps into the Royal Air Force, during the First World War or just after, as there are RFC notes which are virtually identical.The engines described are as Follows: 110Hp Clerget, 80 HP Gnome, 100 HP Monosoupape, 200 HP RAF 3a, 80 HP Le Rhone, Siddeley Puma Engine,120 HP Beardmore, 90 HP RAF 1A. It is a very dog-eared and grubby copy, its fragile thin card cover with tears and much creasing. Tthe pages, which are undamaged, are held in place with two large brass fold-back staples. Rare.