hp at take-off, around 20% heavier than early B-17s). Engines and performance Piaggio was one of the few Italian aviation companies that had the capability to develop both aircraft and engines; their P.XII engines, although unreliable, were among the most powerful of their time. Fiat was a much larger company that also designed and manufactured airframes and powerplants, but limited its production to aircraft like the BR.20 Cicogna, a conventional medium bomber. The P.108 was equipped with four air-cooled 18-cylinder P.XII radial engines, which suffered from reliability problems, but produced 1,010 kW (1,350 hp) at 3,000 m (9,800 ft), with 1,120 kW (1,500 hp) at takeoff, and drove three-blade constant-speed Piaggio propellers. The P.XII was two Piaggio P.X engines in tandem, which were versions of the French Gnome-Rhône 9K Mistral made under license, themselves being derived from the license-built Bristol Jupiters. Alfa Romeo also lacked a powerful, modern engine, and its 1,010 kW (1,350 hp) AR.132s were two Bristol Mercurys in tandem. 12 self-sealing fuel tanks could hold around 12,000 L (3,100 US gal), and eight oil tanks, two for each engine, held a total of 350 L (90 US gal). The combination of a heavy airframe and powerful engines resulted in high fuel consumption, and the P.108's performance at high altitude was mediocre, with a practical ceiling of about 6,000 m (19,700 ft) and a theoretical 8,000 m (26,300 ft). By comparison, the B-17C was capable of attaining a 3,000 m (9,840 ft) higher ceiling. The figure for the Italian bomber was comparable to contemporary bombers; the ceiling for the RAF's best bomber, the Avro Lancaster was similar, while the USAAF's B-17, B-24 and later B-29 were unusual in being able to gain such altitudes. This was due to their installed turbochargers, as well as doctrinal differences in high altitude precision bombing advocated by the United States Army Air Forces. The P.108 could reach speeds of 420 km/h (260 mph) at 4,300 m (14,100 ft), which was slower than several types of biplane. Whereas the B-17C was capable of 515 km/h (319 mph) at over 7,000 m (23,000 ft), even if its range and bombload, 3,220 km (2,000 mi) with 1,800 kg (4,000 lb), were slightly inferior to those of the P.108's 3,335 km (2,070 mi) with 2,000 kg (4,400 lb). The aircraft could fly 2,500 km (1,600 mi) with a bombload of 3,500 kg (7,700 lb), and 3,600