Piaggio P.108B

Italy entered the Second World War with a bomber arm built mainly around twin- and three-engined aircraft such as the BR.20, CANT Z.1007 and S.79. They were useful within the Mediterranean, but none could give the Regia Aeronautica a sustained heavy-bomber capability. The Piaggio P.108B was the exception: the only four-engined heavy bomber to enter Italian operational service, designed for loads and distances beyond the normal reach of the country’s medium bombers.

Chief designer Giovanni Casiraghi had worked in the United States from 1927 to 1936 before joining Piaggio. His P.108 was an all-metal, low-wing monoplane with retractable landing gear and four engines—an ambitious answer to a 1939 requirement for a long-range bomber. The prototype first flew on 24 November 1939. That date made the design look timely; turning one prototype into a dependable combat force would prove far harder.

Four Piaggio P.XII RC.35 eighteen-cylinder radials, each rated at about 1,500 hp, powered an aircraft with a maximum take-off weight close to 29,900 kg. The P.108B could carry up to 3,500 kg of bombs, but payload and radius were inseparable: published figures give roughly 2,500 km with the maximum bomb load, while a much lighter load of about 600 kg allowed approximately 3,600 km. Its practical ceiling was only around 6,000 m.

These figures were respectable, not magical. The bomber was large, fuel-hungry and dependent on engines that suffered from reliability and maintenance problems during its long development. Production also demanded skilled labour and machinery already under wartime pressure. A heavy bomber can tolerate individual defects when hundreds of replacements, spare engines and trained crews exist behind it; with the P.108, every technical delay reduced an operational fleet that never grew beyond a small specialist unit.

The P.108B’s signature feature was its defensive system. Behind each outer engine sat a powered barbette carrying two 12.7mm Breda-SAFAT machine guns. Gunners did not occupy those nacelle mountings; they aimed them remotely from glazed sighting positions on top of the fuselage. Moving the guns away from the crew reduced the need for manned turrets in the airflow and gave the bomber four heavy machine guns covering much of its upper rear hemisphere.

The installation anticipated the idea of separating gun position from gunner, later developed far more comprehensively in aircraft such as the B-29. It was not the same centralized fire-control system, and it should not be described as one. The P.108B supplemented the nacelle barbettes with two more 12.7mm and two 7.7mm guns in other positions. Innovative hardware therefore existed alongside a conventional, labour-intensive defensive layout—and added another specialized system for ground crews to keep serviceable.

The Regia Aeronautica created the 274ª Squadriglia Bombardamento a Grande Raggio at Pisa on 1 June 1941 specifically for the P.108B. Its first commander was Captain Bruno Mussolini, Benito Mussolini’s son and an experienced military pilot. Aircraft deliveries were irregular, however, and the unit spent roughly a year working through conversion training, engine faults and the unfamiliar demands of operating a four-engined bomber before it was ready for combat.

On 7 August 1941, Bruno Mussolini was at the controls of a P.108 during an approach to Pisa when the aircraft lost height and struck a building. Mussolini and two other crewmen were killed. Beyond its political resonance, the crash exposed how little margin the programme possessed: the only future operational squadron had lost its commander while still learning the aircraft, and service introduction continued at the pace imposed by a small supply of machines and engines.

The P.108B’s defining operation began from Decimomannu, Sardinia, on the night of 28–29 June 1942. Five bombers took off for Gibraltar. One turned back with engine trouble; the other four reached the target and released 66 × 100 kg and six × 250 kg bombs—a combined load of approximately 8,100 kg. Reaching the British fortress demonstrated the range that had justified the entire programme, but the return flight revealed its operational limits more clearly than the bombing did.

Only one of the four attacking aircraft returned directly to Decimomannu. Short of fuel, three landed in Spanish territory: one was wrecked near Valencia, another was interned at Los Alcázares, and a third landed at Palma de Mallorca, refuelled and eventually flew back to Italy. Thus the P.108B’s first strategic raid put four aircraft over the target yet immediately removed two from the Italian order of battle. For a squadron measured in single digits, that was an unsustainable exchange.

The 274ª returned to Gibraltar with one to four aircraft at a time on 3 July, 24 September, 20 October and 21 October 1942. The small formations suited night operations but could not concentrate the destructive weight associated with an Allied heavy-bomber group. Mechanical failures, navigation over long sea routes and landing accidents remained as dangerous to the force as interception. The type also attempted maritime reconnaissance and anti-shipping work, roles for which such a scarce strategic bomber was an expensive instrument.

After the Allied landings in French North Africa in November 1942, surviving P.108Bs attacked targets in Algeria, including the Oran area, into early 1943. These missions gave Italy reach across the western Mediterranean, but not a sustained bombing campaign. Each operation depended on the few aircraft available that night, and each loss reduced future capacity. By the armistice of 8 September 1943, the bomber’s combat career had effectively ended without the unit ever possessing the mass needed to alter a campaign.

Piaggio adapted the airframe to other needs. The sole P.108A Artigliere carried a 102/40 cannon in the nose for anti-shipping trials but never entered operational combat. The pressurized P.108C passenger aircraft and unpressurized P.108T military transport used a broader fuselage; only one C and about twelve T aircraft were completed. After the Italian armistice, Germany took over surviving transports and unfinished airframes, employing P.108Ts with the Luftwaffe rather than trying to revive the bomber force.

Approximately 24 P.108B bombers were built, with minor differences between published totals depending on whether the prototype is counted. The aircraft itself was neither an absurdity nor a simple failure: it carried a useful bomb load, introduced an unusual remote-gun installation and completed genuine long-range operations. Its failure was systemic. Strategic bombing required reliable engines, navigation and training infrastructure, abundant fuel, spare aircraft and mass production. Italy produced an advanced bomber, but never the industrial force that could make it strategic.

• Chris Dunning, Courage Alone: The Italian Air Force 1940–1943 (Hikoki Publications).
• Jonathan W. Thompson, Italian Civil and Military Aircraft 1930–1945 (Aero Publishers).
• Giancarlo Garello, Piaggio P.108, Ali d’Italia No. 15 (La Bancarella Aeronautica, 2000).