Graham Hoyland has written a tremendously enjoyable narrative around the development of the Rolls Royce Merlin engine (a 27 litre supercharged monster) - the crankshaft starts as a 500lb chrome moly steel forging, machined by hand, heat treated and nitride hardened. Continuous improvement means a large number of models sprung from the original - the supercharging was steadily improved, going to two stages with intercooling to get more and more power.
Graham introduces a lot of interesting side notes (except they do not appear as side notes, they are cleverly woven into the whole story) eg, speaking about the Battle of Britain (June 1940):
The RAF fielded 754 single seat fighters and 149 two seat fighters. Horsepower was crucially important to the British, both to climb up to meet the incoming bombers and to evade the protecting fighters. This where the RR Merlin excelled. By using the newly introduced 100 octane fuel, the supercharger boost could be increased from 6 and 1/4 psi to 12 psi for five minutes, giving a max combat power of 1,310 hp at 9000 feet. The pilot pushed aside an emergency boost override top at the end of the throttle and used everything the Merlin could give for five minutes. Any longer than this would risk overheating of crucial components such as exhaust valves and piston crowns, but plenty of pilots during interceptions just rammed through the boost override and let the engine take its chance, a practice the Merlin engine took remarkably well.
Significantly, the German pilots were not allowed to override their boost controls with impunity. Examination of downed German aircraft revealed that clockwork devices were attached to the throttles of some aircraft which only allowed a three or four minute period of full boost. It then cut out and prevented re-engagement until a further two or three minutes had passed. This may have saved overstressing the engine, but left the pilot vulnerable to British fighters whose access to full boost was left to the discretion of the pilot. Once this information was passed the the RAF squadrons, they could seek opportunities of forcing the enemy to use full power and wait for the cut-out period. They could then pounce.
Starting with early attempts at flight and early attempts at the internal combustion engine. Charles Manly made a jewel of a 9 litre 5 cylinder engine which was put into Professor Langley's "Aerodrome" aircraft - an altogether imperfect plane with no control surfaces as such and very weak structure - tried to fly in Oct 1903, and flopped - Dec 1903 Wilbur and Orville Wright conducted successful flights near Kitty Hawk, NC. Sideline about the politics of the Arab revolt and T E Laurence and "Squadron number 2 of Rolls Royces (boilerplate armoured, with rotating gun turret fitted) sent to Egypt" and how incredibly sturdy the cars were in the desert (the "40/50" engine used here was the basis of the first RR aero engine) - with Rolls's account of a desert race between two RRs when they reach nearly 70mph, not bad for four tons of boilerplate and only 80hp. The engines were paragons of reliability and power.
Much interesting detail about the elliptical winged Spitfire (inner wing set at higher angle of attack than at the outer, meaning stalling started at the wing root rather than the tip, giving the pilot early warning of a stall), the de Havilland Mosquito (largely made of wood, light and hugely maneuverable), the Avro Manchester (a disaster, underpowered with the RR Vulcan which was prone to throwing con rods), the four (Merlin) engined Avro Lancaster (a beauty of a plane, relatively easy to control, fast and maneuverable.