Designed by Gianni Caproni and Dino Giuliani, this six-engine biplane was the largest landplane in the world.
The Caproni Ca.90 made its maiden flight on October 13, 1929 - two weeks before the 7th anniversary of Fascist takeover. It had an unusual layout, with two tandem pairs of 1,000hp Isotta Fraschini Asso engines above the 46.6 m (153 ft) lower wing and one more pair mounted above the fuselage. Upper wing had a span of 34.90 m (114 ft 6 in). Its dimensions are roughly comparable to those of the German WWI R-planes, save the height: the Caproni was significantly taller, 10.80 m (35 ft 5 in) against Zeppelin-Staaken R.VI's 6.3 m (20 ft 8 in). Add to this 15 ft of extra length. Impressive, uh?
The giant airplane was not just another Caproni folly, but a purpose-built heavy bomber, an embodiment of then-fashionable Douhet doctrine. Giulio Douhet, an Italian general, envisioned a fleet of "flying dreadnoughts" capable of destroying enemy "vital centers". So the C.90 was designed to carry a load of 8,000 kg bombs - enough to bring substantial damage to Toulon, Alexandria or Gibraltar. On the other hand, its range (with full load) - 1,290 km / 802 mi - was not sufficient to attack these targets and return home. And some important targets were still out of reach (for example, the distance between Napoli and Gibraltar is 1779.93 km / 1106 miles, one way). The six-engine monster boasted only a mediocre top speed - 205 km/h. Besides, the Caproni superbomber was a disaster from the aerodynamical point of view.
Nevertheless, the C.90, introduced to the public at the Milan Trade Fair, set at least two world records. Here is a quote from the Flight magazine, April 1930, p.361:
The Royal Aero Club has received particulars of the following International Records granted by the F.A.I.: <...>
Useful Load: 10,000 kg.; Duration: 1 h. 31 m. Altitude: 3,231 m. Italy. Cav. Domenico Antonini, on biplane Caproni "Ca 90," six engines Isotta-Fraschini Asso, 1,000 h.p., at Cascina Malpensa, on February 22, 1930. <...>
Record of the largest load transported to a height of 2,000 m. : Italy. Cav. Domenico Antonini, on biplane Caproni "Ca 90" six engines, Isotta-Fraschini Asso, 1,000 h.p., at Cascina Malpensa, on February 22, 1930, 10,000 kg.
There was nothing to modernize, nothing to improve - the C.90, obsolete before it started to fly, remained a sole prototype. Until 1934, it served with 62nd Experimental Heavy Bomber Squadron (I wonder if there were other experimental heavy bombers in this unit), and then was written off and scrapped.