It was said there was a total of 700 kg (1,540 lb) fitted, but it is unclear if this also included the self-sealing fuel tanks, bullet-proofed up to 12.7 mm (.50 in) rounds.

One noticeable difference was the twin tail, which gave a better field of fire to the dorsal gun, and helped to cope with the greater power and weight compared to the SM.79.

It was a theoretical improvement, though Scotti machine guns, even with a slightly higher rate of fire, were much less reliable than the Breda.

Another disadvantage was the inability of the turret to fire directly forward, through the propeller's blades, so the aircraft had no defence from frontal attacks.

With these engines, at full load the SM.84 was capable of:[8] Climb rates to: The maximum practical ceiling was 8,200 m (26,900 ft).

While the damage to Nelson was a success, the only one of this type that Italian torpedo bombers obtained, it was paid for by the loss of six aircraft, and almost all their crews, more than thirty men.

[11] During Spring and Summer 1942, 4° Gruppo Autonomo Bombardamento Terrestre flew bombing sorties against targets in Malta, suffering painful losses.

On 12 May, three SM.84 from 14a Squadriglia (plus four Junkers Ju 88), escorted by Italian and German fighters, attacked Ta' Qali airfield.

249 Squadron RAF managed to infiltrate the dense escort of the Axis fighters and to hit hard the Savoia-Marchettis (again, exchanged for CANT Z.1007), claiming all three shot down.

During that sortie, 4° Gruppo suffered two losses: a SM.84 crashed offshore, possibly the one piloted by Tenente Raffaele Notari, from 15a Squadriglia.

A second Savoia-Marchetti, piloted by Sergente Maggiore Romolo Cristiani, of the 14a Squadriglia, crashed on Ta' Garda.

[14] During Operation Pedestal in August 1942, 10 SM.84s used special Motobomba circling torpedoes to attack the convoy, losing two aircraft to enemy fighters.

The heavy German and Italian attacks, including those by SM.82s resulting in only five of the fourteen ships of the convoy reaching Malta, however their supplies were fundamental to saving the garrison, after the almost total failure of the previous operation.

While other groups were still receiving the aircraft, 36° and 7° Wing had stopped flying it by October 1942, while 32° went in action against North African targets.

The use of the aircraft with 8° Stormo to resupply troops in North Africa was a failure: despite having a far higher speed than the SM.82, the useful payload of the SM.84 was too small.

Overall, the SM.84 was a failed design (Francesco Pricolo called it a 'wrong aircraft', while Ettore Muti complained in 1941 about its awful handling and take off).

The SM.79bis, with improved engines was still lighter than the SM.84 and a better aircraft (with lower wing loading and better power-to weight ratio) for the role.

[16] It reports how this bomber wing performed its task, starting with bombing missions from Gioia del Colle on 13 July 1943.

Regia Aeronautica:[17] Data from World Encyclopedia of Military Aircraft[18]General characteristics Performance Armament