Savoia-Marchetti SM.89

Savoia-Marchetti

Industry	Aerospace, defense
Founder	Alessandro Marchetti

The Savoia-Marchetti SM.89 was an attack aircraft conceived by Alessandro Marchetti and constructed by Savoia-Marchetti. Only a single prototype, designated MM.543, was ever completed.

Although sometimes classified as a "bomber," the aircraft's main firepower consisted of two 37 mm cannons with a barrel length of 54 calibers. This armament aligns it more closely with contemporary ground attack and maritime strike planes such as the Bristol Beaufighter or Douglas A-26 Invader.

The prototype's maiden flight occurred in September 1941 at Vergiate, piloted by Lieutenant G. Algarotti.

Development

The SM.89 was developed to fulfill a bomber/attack role comparable to that of the Junkers Ju 88. While showcasing notable features, the design was not entirely new but rather an evolution of the earlier SM.84. It retained much of the SM.84’s wings, rear fuselage, and mixed-material construction, but introduced a completely redesigned nose section. The fuselage framework consisted of steel tubing, sheathed in a combination of duralumin and wood up to the dorsal turret, with the remainder constructed from wood and fabric. The wooden wings incorporated three spars and were covered with plywood. Control surfaces included slats, flaps, and partially drooped ailerons used alongside flaps to enhance lift.

A key distinction between the SM.84 and SM.89 lay in the forward fuselage design. The cockpit accommodated only a single pilot, followed by a radio operator/gunner and an additional gunner, reducing the crew size by half compared to the SM.84. This tandem seating arrangement resulted in a more confined fuselage space, which also decreased the need for extensive protective armor.

Unlike many Italian aircraft of its time, the SM.89 did not feature a nose-mounted engine. Instead, it employed two engines mounted on the wings, leaving the nose available for armament installation. The nose was short, rounded, and sharply angled to provide excellent visibility during surface attack missions. Its primary weapons were two 37 mm (1.46 in) Breda cannons intended for anti-tank and anti-ship engagements. Additionally, three 12.7 mm (.50 in) Breda machine guns were installed in the nose area. Defensive armament included one Breda machine gun in the dorsal turret and another in a novel remote-controlled ventral turret.

For ordnance capacity, the aircraft could carry either 700 bomblets or up to 1,400 kg (3,090 lb) of bombs or torpedoes mounted beneath the fuselage. It could also be equipped with air brakes designed for dive bombing operations. Its speed allowed potential use as a bomber interceptor; however, no radar system was ever installed.

The initially planned Piaggio P.XI engines proved insufficiently powerful for this airframe, leading to adoption of two Piaggio P.XII RC.35 powerplants producing 1,119 kW (1,500 hp) each at takeoff. These engines featured a more compact arrangement than those used on the Piaggio P.108 or CANT Z.1018. Fuel capacity totaled 2,700 L (710 US gal) stored in self-sealing fuel tanks, enabling an operational range of approximately 720 km (450 mi).

The SM.89 incorporated substantial armor protection: 300 kg (660 lb) shielded the front and windscreen areas, another 300 kg (660 lb) safeguarded the engines, while an additional 80 kg (180 lb) reinforced the rear fuselage. The aircraft was also likely equipped with a CO²-based fire extinguisher system for enhanced safety during combat operations.

Operational service

Although the aircraft first took to the skies in 1941, it was only in September 1942 that it underwent evaluation trials at Guidonia. It officially entered service in March 1943, fulfilling roles such as anti-tank operations among others. Its combat effectiveness was notable, with firepower surpassed only by the P.108A.

The primary challenge facing the S.89 was its engine power and dependability. The installed engines delivered 2,237 kW (3,000 hp), which proved insufficient for the aircraft's weight of 12,600 kg (27,780 lb). Plans existed to equip the aircraft with Piaggio P.XV or Alfa Romeo 135 engines, but these upgrades were never realized.

Pilots reported that handling the aircraft was problematic: it exhibited nose heaviness, limited maneuverability, sluggish speed, and presented difficulties during landing. Maintaining altitude required flying at a higher angle of attack. Eventually, the aircraft was neglected and transferred to Foligno in July 1943. Following the events of 8 September 1943, it fell into German hands and subsequently disappeared.

The aircraft might have achieved greater success if it had carried fewer weapons or less armor; the combined load caused its weight to exceed 12,000 kg (26,460 lb). Attempting to fulfill both attack and interception roles compromised its reliability and flight characteristics even more than those of the already underwhelming S.84.

Specifications (S.89)

File:SM89Riss.jpg

Sources

• Lembo, Daniele, i distruttori della Regia, Aerei nella Storia n.46, pp. 9–11.