Savoia-Marchetti SM.81 Pipistrello

The Savoia-Marchetti SM.81 Pipistrello (Italian: bat) was a three-engined bomber/transport aircraft serving in the Italian Regia Aeronautica during World War II. Despite being too slow to remain competitive as a bomber, it was one of the most flexible, reliable and important aircraft of the Regia Aeronautica from 1935 to 1944, and adapted to second line duties in performing a wide range of tasks.

Design and development

The SM.81 was a militarised version of Savoia-Marchetti's earlier SM.73 airliner, having cantilevered wings, three engines and a fixed undercarriage. The origins of this version were in pursuit of the interests of Italo Balbo, a brilliant exponent of the Fascist regime (but nevertheless "exiled" in Lybia by Mussolini), who required a fast and efficient aircraft that was capable of serving the vast Italian colonies in Africa.

The SM.81 had wings that were roughly similar to those of the double-fuselage SM.55, but had a much simpler fuselage. Around 6 months after the SM.73s first appearance, the SM.81 prototype (MM.20099) first flew from Vergiate, near Varese, on 8 February 1935, controlled by test pilot Adriano Bacula. The first serie, ordered in 1935, was for 100 aircraft and was quickly put into production as a result of the international crisis and the embargo caused by the war in Ethiopia. The first examples were sent to 7 Wing, Lonate Pozzolo.

Although it was quickly superseded as a first line bomber, the SM.81 continued to serve as a transport aircraft by virtue of its wide fuselage, which allowed it to accommodate a wide range of armament. Apart from its speed, it was generally superior to the SM.79 Sparviero as a bomber and multirole aircraft.

Overall characteristics

The SM.81 was a robust, three-engined monoplane, with large aerodynamically-shaped fixed main undercarriage gear, and had a crew of five. The aircraft was of mixed construction: the fuselage had a framework of steel tubes with a metallic-covered aft portion, while the rest was wood- and fabric-covered. It had a relatively large fuselage, an unnecessary characteristic for a bomber, which determined its future as a transport aircraft. Since the engines were quite small, the fuselage did not blend well with the nose engine, even less so than the SM.79. Many windows were present, giving the impression that it was a passenger aircraft, but these were to provide light for the fuselage interior.

The all-wooden wing had three spars to provide the necessary support, whereas the semi-elliptical tail surfaces were fabric-covered metal. The cockpit had several engine- and the flight instruments: three oil-temperature guages (one for each engine), three pressure guages, two rev. counters, a 1,000 m. altimeter, an 8,000 m altimeter, a climb-meter, compass, clock, and five other sundry indicators, accommodated in three panels. The pilot and co-pilot were seated side-by-side with the radio-operator/gunner behind. The bomb bay was behind the cockpit, together with a passage which linked the mid and aft fuselage, where there were three further defensive positions.

The bomb-aimer's position was located just below the cockpit, and differed with that of the SM.79, being larger, in a location which was more favourable for communicating with the crew, and provided excellent visibility (also for the pilot) thanks to the glazed panel. Both this position and the cockpit had escape hatches, but for normal entry and exit there was a door in the left, mid-fuselage, and one in the aft fuselage. Equipment included an RA 350I radio-transmitter, AR5 radio-receiver, and a P63N radiocompass (not always fitted), while other systems comprised an electrical generator, fire extinguishing system, and an OMI 30 camera (in the gunner's nacelle).

Weaponry

As typical for a bomber of these times, there were both offensive and defensive weapons.

As defensive systems there were two retractable turrets, dorsal-aft (just behind the pilot's seats) and ventral-aft, with two 7,7 mm machine-gun each. These motorized turrets were effectively an heavy weapon set for a 1935 aircraft. They were also retractable when not necessary, so the aircraft had less drag. This was a particular of not much importance, given the cruise speed of around 270 km and the presence of a massive fixed undercarriage, but still this aircraft had retractable turrets, with a manual mechanism. The rotation was due to a Riva-Calzoni hidraulic system, that functioned simply pushing the weapons to the left or the right:The elevation was only manual, and there was a manual back-up also for rotation,if the motor wasn't in function. For the aiming there was a reticle external, posed between the weapons. Even if it gave some drag, it was in the best position to help the gunner to aim. When retracted in the fuselage, upper turret leaved outside, in vertical, the barrel's weapons, with the reticle in between, and to reduce the drag the weapons were leaved with the barrels one after the other, that gave the impression that there was a sort of radio antennas. Because the reach of some simplicity there was the possibility to host inside the fuselage also of the weapons.

One of the odd things about the armament was the ventral turret. It is unclear how it was manned by the gunner, because there was not space for enter in it (as happened with B-17s one). Ventral turrets were always troublesome (with configurations projected in ball, dustbin or tele-command) and never too effective, but this S.81s turret wasn't with any of this concept: apparently, the gunner sit in the fuselage and with the head down in the turret actioned it. Perhaps also because this (Piaggio P.108 had a turret 'dustbin' style, with a man inside), the further Savoias were leaved without ventral turrets, but still, S.81 continued to have it. As the dorsal turret, the only exception was the S.79s, seen that their utility was well clear.

Another one, then two machine-guns were in the flank positions, there were at least initially the old Vickers guns with the characteristic round magazine. All these weapons, up to six, were not only an heavy armament, but for the four in the turrets, were also reliable, even if not very fast-firing weapons, models made by Breda. The amount of ammunition, 500 cartridges for each weapon, was also reasonably good and roughly standardized with other aircraft.

As offensive weapons there was a bomb bay with horizontal or vertical stored bombs. This bomb bay was divided in two parts, with a passage between, used to link aft and mid fuselage. The weapons load was much varios, with ordnance from 1 to 500 kg.

• 4x500 kg. (stored horizontal)
• 4x250 kg.(idem)
• 16x100 (stored vertical, as all the smaller ones), true weight around 130 kg.
• 28x50 kg.(real weight, around 70 kg.)
• 56x31 kg. or 24 kg., or 20 kg. or 15 kg.
• 1008x2 kg.(real weight, around 1,7 kg.)
• Incendiary bombs
• Some examples, two torpedoes

The command for the launch was in the pointer's nacelle, in the right side. There were possible many combinations of these weapons, to optimize the load to the necessities.

The S.81, thanks to the space of the fuselage, quite wide, was capable to carry more weapons and defensive turrets than the successor, the S.79 Sparviero, that relied mainly on speed to survive. Effectively, the Sparviero was more survable than Pipistrello, but this was, in its limits, armed quite well at least to face '30s fighters, and with an heavy bomb load: Sparvieros can held only two 500 kg bombs, or 5x250 kg or 12x100 kg, so except with 250 kg bombs it had much less load capability. Seen that the civil version (S.73) of this project had 18 seats compared to the 8 of the Sparviero's project, this is well understandable. The problem was about the power of the engines and the fuel available with the maximum payload.

Propulsion

S.81 had a tree engine configuration, but differently than Sparviero it had since the beginning a wide range of engines:

• Alfa Romeo 125 RC.35, 580 hp (or 680, dependig by the source)at take-off, 650 at 3,500m.(1,740-1,950 hp)
• Gnome et-Rhone K14C, 650 hp at take-off, 740 at 3,000m.(1,950-2,220)
• Piaggio P.X R.C.15, 670 hp at take-off, 700 at 1,500m.(2,010-2,100)
• (possible) Piaggio P.IX RC40, 780 hp at take-off (2,340-?)
• Alfa Romeo 126 RC.34, 680 hp at take-off, 750 at 3,400m.(2,040-2,250)

This latter set was the same of the S.M.79 Sparviero in its early versions. This wide range of engines,with differents motor rings, gave obviousely different performances. The propellers were 3 blades, metallic (duralluminium blades, the center in steel to maximize the resistance with reduced weight) and with 3,4 or 3,5 m diameter. The fuel tanks, as standard for Italian multiengine aircraft, were metallic but also 'semapized', that means self-sealing tanks,with a special materials made by SEMAPE, the specialized manifacturer. Eight tanks were fitted. Six were in the central wing, 4x150l., and two of 1,140l. each. In the wings there were also other two tanks, 370l. each, or 780 with G.R.14 engines. This gave the overall capability of 3,620 or 4,400l.

Standardizing the engines was necessary for all the aircraft, on basis of geographic displacement. So, the Italians and Spanish S.81s had Alfa 125/126, the lybians had K.14s, the Eastern Africa ones had Piaggios. The S.81 was one of the 'standards' for the colonies and mainland, a trade mark for Regia Aereonautica everywhere it was involved.

AS the performances, with a complessive amount of 1,750-2,350 hp the S.81 were quite good served, even if they had engines with unitary power not so high. The maximum speed with AR.125 was 340 km/h, with the others was 320-347 km/h, cruise speed at its best was 260 km/h, but are reported values up to 330 (maximum cruise speed). The extra power of many engine-set was valuable in high and hot conditions, but their diameter was sometimes bigger enough to not allow higher maximum speed. With the same or even greater fuel load of S.79s, the S.81 nevertheless had less range, a maximum of 2,000 km endurance in normal condition, and a range, with bombs, of only 450-640 km. The ferry range to Spain, in 1936, was an hugely example of the relatively short range of the aircraft, perhaps caused (as the low speed as well) by the drag. The range with 2,000 kg max ordnance was 460 km, and the endurance with this load was 640 km (this mean that the return part, emptied by bombs, of 460 km, was equal to fly another 180 km with them, as fuel consumption). Given the 3,799 kg useful load, with the maximum fuel on board (2,400 kg) the bomb-load was around 1000 kg, giving a range of around 600-700 kg, depending also by the type of engines. Even so, this aircraft was faster than Ju-52, the most direct equivalent, because the structure more draggier and heavier (being total metallic) of the German aircraft.

About the performances of the tree engine versus two engines aircraft, it must be said that both the solutions had positive and negative sides. The real problem was the availability of a reliable engine. Italian project were usually or reliables but underpowered or powerful but much less reliable. As reliability, overall, it's obvious that the tree engine solution, with the power obtained from tree quite reliable engines, was better than having the same output made by only two more powerful but less reliable engines, for several reasons: if one engine was shut down or damaged (in military aircraft it' prevedible), with two engine solution there is an asymmetric thrust, that make the handling of the aircraft much difficult. With tree engines, if one is shut-down the aircraft has still a not dramatically asymmetric thrust or even no asymmetry if the engine is the one on the nose. Obviously, if the two engines remained are also quite reliable and better placed in the aircraft, the possibilities that aircraft return to home is much better. Moreover, the lost in power is only 1/3. If the aircraft with two engines lost one, it lost half power, it had asymmetrical thrust and the only engine remained is less reliable on itself. Moreover, the speed falls and the struggle for the survived engine, already less reliable, is bigger, and with the risk to overheat (with emergency power and a modest airflow) and break it as well.

This is a good explanation of why tree-engine machines were so liked by Italians. The shortcoming is that tree engines are more heavy, more costly and more complex that one.

As aerodinamical side, tree engines are usually draggier than one. But this is only partial true. In fact, the less powerful engines often had also smaller diameter, and so, less drag. This drag could had been reduced with carenatures on the propellers and tight engine rings, thanks to the lower termic emissions (less need to a bigger airflow) and so, giving a modest drag overall. If the aircraft had one small engine in the nose, drag could be not so dramatically bigger than having a free nose. But the diameter of powerful engines in the wing is bigger than smaller ones, so the overall drag of fuselage+wings is not necessarily lower for twin (big)engined than tree-(small) engined aircraft, while the total power output of 3 engines could be higher and obtained with much more reliability both as single engine and as overall architecture. All this explain quite well why S.M.79 (3x760 hp) was as fast if not faster than BR.20 (2x1000), and much more powerful, agile and reliable. At lower speed, as climbs and manoeuver, an aircraft with the same speed but draggier and so, with more power (to reach these speeds), had an advantage in P/W ratio, so while BR.20 was competitive with S.79 in horizontal speed, but nowhere in agility and climb (climb at 6,000 m was 25' compared to 17' at 5,000). The S.79 had a 15% more power with only a minimal increment of the weight.

The tree engine configuration was superseed essentially when engines both reliable and powerful became availables, but still Z.1007ter whipped C.1018 overall, even if slower (when the speeds became higher the difference of design are more importants than at lower ones, because mainly drag is attrition and so is related to the quadre of speed).

Operational history

Overwiev

The SM.81 first saw combat during the Second Italo-Abyssinian War, where it showed itself to be versatile serving as a bomber, transport and reconnaissance plane. SM.81s also fought in the Spanish Civil War with the Aviazione Legionaria and were among the first planes sent by the fascist powers to aid Francisco Franco.

Despite obsolescence, by 1940, when Italy became involved in the Second World War, more than 300 (290-304 dependig the source)SM.81s were in service with the Regia Aeronautica. Its low speed and vulnerability to fighter aircraft meant that during daytime, it was restricted to second line duties, finding use as a transport. At night the SM.81 was an important bomber, particularly in the North African theatre.

Most SM.81s were withdrawn by the time of the Italian armistice of 1943, though some remained in service for both the Italian Social Republic and the Italian Co-Belligerent Air Force.

Several examples survived the war and went on to serve the Aeronautica Militare Italiana, but by 1950 these had all been retired.

Beginnings

The first 100 machines were delivered to 7 Wing, then 9 Wing, 13 and 15 Wing. This machine was less capable than S.79 Sparviero, but it was, in those years, almost the same chronology, with just one year between these two aircraft, basically both born in the mid '30s.

These aircrafts were used firstly in Ethiopia, mothballed and delivered with ships in that far east territory. In that war these aircraft were used for every kind of task, resulted quickly an almost ideal aircraft for this theatre. These machines were used for bombing, strafing, but also refogements, air support, recognition. The lack of air opposition, except some 20 mm Oerlikon guns and light fire arms, made the things better for these machines than they deserved. The bombings included also the use of chemical weapons, utilized in this fierce war to interdict some areas over the direct use against enemy troops and animals. The Fosgene and Yprite were used without any respect to international convenctions, but this and many other war crimes were committed without any problem, not only by Italians but also by abyssinians. In every case this was cleary an aggression war set up by Italian regime against the old adversaries, that defeated at Adua Italian expedition corps in 1896.170 bombers Ca.133 (less powerful but rugged and simples) and S.81 were delivered for Ethiopia war, included in two groups of 9 Wing, a cloned unit (called 'bis') because the former 9° was still in Italy.

After having 'ufficially' whipped the Negus with the entry in Addis Abeba, during 1936, Italians must face an opposition fierce and dangerous for many months if not years. Mrsc. Graziani was badly wounded by an attack made by locals, and there was a cruel repression in all the country. Only about 1937 the situation was stabilized, that was also by the support of the aviation, the real decisive weapons of Italians against an enemy extremely dangerous in such difficult and wild terrains. 36 S.81 with Piaggio engines remained after the end of 'ufficial' hostilities to perform 'colonial policy duties' and support of any kind to Italian troops, including air supplies and transport. The small arm fire was a danger in such missions, flew at low levels, but usually the damages were not enough to shot down the aircraft, even if they had no protection except the fuel tanks.

In the meanwhile, S.81s were sent to 8 (Bologna),10(Bresso),11(Ferrara),12(Guidonia), 14 and 16(Vicenza), 30,32 and 33Wing (Napoli). This expansion of Regia Aereonautica was impressing in this time, especially the bomber force. 15°,with anti-sand filters and K14 engines S.81s was sent in Lybia.

Spain

But the real start of main career of S.81 was started on 28 July 1936, a day in wich 12 S.81s taken off from Elmas, near Cagliari, directed in Spain. The ferry flight was around 1,200 km but several problems occurred. This mission was dedicated to support gen.Franco and his 'alzamiento' against republican govern. 63 men were involved in this mission, led by col. Bonomi. They weared civil vests and ufficially the aircraft were officially bought by a Spanish citizen.

This journey should had been flown in less 4,5 hours (260-270 km/h), but strong winds blowing in contrary sense were an heavy hostacle for the 12 S.81s flyng at 1,000, so they climbed at 3,500, the best cruise altitude with Alfa AR.125s, but after 5 hours there was still an hour to Melilla, Marocco, the final destination. The aircraft were flown also Ettore Muti, one of the most important protagonist of fascist regime. Some sources says that the aircrfats were fitted with one 100 kg bomb, helping to explain why aircraft capable of at least 1,800 km ferry range were unable to make this mission. Tryng to maintain tight formations despite the mushrooms was also fuel-costly, with non linear flight. At the end of the ferry journey,11,35, only 9 aircraft managed to land at Melilla. One fallen in the sea (pil.Angelini), another crash landed in Algeria and a third force landed without damages, but still in Algeria. The rest of the aircraft had only an average of 130l. in the tanks (maximum, 200 for an aircraft sent to research the missing aircraft, that were effectively found). This amount of fuel, not much even for a fighter, was enough for just few minutes of flight, being only 3% of the total fuel capacity. This meant that, with only a slight stronger wind, all the Savoias could had been lost or force landed in Algeria.

This could had been catastrophic for the Franco troops. Savoias were an valuable resources. They were soon used as transport troops, and bombers, so the troops of Marocco, mainly fedels to Franco, were sent in Spain with 4 merchant ships, in 6 August. The treath of the Savoias and their bombs, once reforged by ship RM Morandini, kept away the Spanish fleet, that could had been enough to forbid to any franchist convoy to reach Spain. Instead, the bombers helped to kept away the fleet, mainly fedel to republicans. They were also used as trasnport aircraft. After the first batch of 12 S.81s, the most unlucky but also the most important of all (the Franco's Marocco troops were foundamentals to raise the fortunes of the 'alzamiento', mainly whipped by republicans). The republican fleet was not too active and daring, and the things worsened when 9 August S.81s fired the fuel and ammunition reserves of the Spanish Navy, forced the fleet to go to northern bases, outside of this treath. This stopped the trials to forbid the sea transport of ispano-maroccon forces.

After this exploits, S.81s were reinforced by many others: four squadrons, 213,214,215,216 in two Groups (XXXIV and XXXV), and other two 251, and 252 for XXV Group 'Pipistrelli'. For all the war the S.81s were used as bombers and even attack aircfats, used often by night when Polikarpov I-15 and 16 arrived in Spain. At this point S.81s were already delivered but the original 9 machines, only 7 stil efficients, already released 210t. bombs and contribuited to the trasport of maroccon troops with 868 flight (toghever with Ju-52s). The missions started to became more and more made by night.

Despite this there were bombing missions with CR.32 as escorts, and even day missions without escort, thanks to the thigt formations with the machine guns firing all around, and the instrumental capability to fly inside the mushrooms, a thing more dangerous for single-seat fighters.

after thousands of huors flown, the survivors of at least 64 S.81s were leaved to Spain, at the end of 1938, in the G-12 Group. The losses of S.81s are not known, but almost at the end of the war this aircraft had a catastrophic incident, when one of them was lost fully of high officiers, that were all killed.

Further developements

Even if this aircrafts were used in many tasks and by many units, soon the modest speed of the S.81s suggested to leave them by first line and replaced them with S.79s. The flight with S.81 was easy: it was a docile and stable aircraft, with low wingload and not trascurable power available. One of the model developed was a two engine version, with 2 Isotta Fraschini Asso, an inline, liquid cooled engine with 840 hp. But the performances, theorically interesting given the reduced drag and the almost as powerful propulsion system, were quite disappointings, including 330 km/h maximum speed, so the modiphic had no success.

Another version was a tanker aircraft (for fuel trasport, not air refuelling), made in few examples.

A command version was made with a powerful radio equipment, used as well in few examples.

The VIP version was used in some numbers. Mussolini had one, that piloted this aircfat personally. It was called 'Turtle', meaning the slow speed it was capable. Another nickname of the S.81s was 'Lumache', also telling about the slowness of this aircraft. But the wide fuselage was more comfortable than the 'fast bombers' like Sparviero. An innovative feature was the new Caproni-Lanciani turret, armed with a 12,7 mm heavy machine-gun. This was considered better than two 7.7 mm but the reliability of Scotti machine gun leaved a lot to desire.

Another example was experimented as anti-magnetic mines aircraft: it was called Saturno, because it had an immense steel ring with high voltage, to set the trigger of magnetic mines, the most dangerous of all the mines. The weight of the gear was too high and so it had not success at the beginning. But it was modiphied with an aluminium alloy ring, much lighter and the results were acceptable. But only this aircraft was made and used in La Spezia port. It was used as the Vickers Wellington in one of its many versions.

Another task for the S.81 was the torpedo-bomber. Already in 1936 there were experiments with up to two torpedoes. But even with one the aircraft was much slow and so not ideal to the task, also because there was S.79 available. In every chase, Hampden, G3Ms and Wellingtons had not so better performances to display, and still were used as torpedo as well. Some S.81 had the torpedo racks under the wings, but never this option was seriously considered.

But the main task for this aircraft will been the trasport, as this machine after all, was meant in its original design. Designed S.81T they were ordered in 1941, when their first line employ, as first line bomber, was almost ended. They were fitted with Caproni-Lanciani turret and AR 126 engines. From 1942 they were delivered from 28 November 1942, when they were quite obsolete at any level. It's strange that, despite the presence of the bigger S.82, still many S.81 were ordered, because they had almost nothing to offer except a less big target for the enemy and a more economical construction, but not much because they were made in non-strategical materials as structure and had the same engines of the bigger Marsupiales, that can hold the twice of payload. Even so, S.81 were almost as fast as C-47, and had a defensive weapon set, while the range and payload was almost equal, with only a slight inferiority on installed power and speed.

The late '30s and World war two

S.81s began the most diffused multi-engine aircraft of Regia Aereonautica in the second half of '30s. It was a pleasant and reliable aircraft to fly, even if obviousely it was too slow with flyght commands to be a manouvrable aircraft as the S.79. It gave a good impression, also, in the pre-war exercises, with these big aircraft aligned on the ground or flyng in 3-planes formations. Several complex manoeuvers were performed, but the reality, apart the propaganda's regime, was that Regia lagged behind in training and tactics, except for a punch of very experienced flyers, that were much superior than the average, often with air raids or world records.

With the Albany's occupation the S.81s were used (37 and 39 Wing) as trasport aircraft over Adriatic sea, sending quickly soldiers over Albania, in a much publicized operation that showed the 'efficiency' of Italian armed forces. In Lybia, already in 1938 a whole parachadutist bataloon was launched when the King went on a ufficial visit to Balbo's colony.

The production was: SIAI, 237; Piaggio, 60; Macchi,76;CRDA,36;Breda,36;CMSA,58;AerUmbra,20; Caproni,8. Total, 530 and the bi-engine example (SIAI). This production program was so involving almost all the Italian aeronautic industry, but still, it produced less than the half of S.79s and even less than S.82.

When the war broke, Regia had still 293-304 machines on charge, with 37 Wing (Lecce) and 40Group of 38 Wing. The other 38 Wing group, the 39°, was in Albanya. The Egeum aereonautic, a small and almost indipendend military entity of RA, had 39Wing, Lybia had 14 and 15 Wing and finally 5 Groups in Ethiopia were present with this aircraft in strength. (at those time, there were apparently 14 wings with S.79, at least one of these groups, 4 with BR.20s and two C.1007 in a total of 25 Wings).

S.81s fought initially in first line, with anti-ship attacks and missions over Alexandria. 37, 38 and 39Wings fought at Punta Stilo, and others fought at battle of Capo Spada, still with modest success. Alexandria was attacked for the first time 7 July, with 11 machines. This long range missions were repeated 16, 25 July, 26 August, 8 and 21 September and finally, 5 October. All these missions,excpecially those against ships were only modest successfully.

Greece was attacked in the fall, also with the use of 37 (Valona) and 39 (Lecce) Wings, that were involved also in air reforgements and air attacks. When faced with RAF, the S.81s suffered in according.

In Eastern Africa, S.81s were 59, so every group had around a squadron of aircrafts. Despite the presence of the most modern S.79s this war saw the Pipistrello as main Italian bomber. When Gladiators and Hurricanes made the things difficults, the S.81s were used less and less. Initially of the 59 aircrafts there were 43 ready to use. They were involved in several bombing, generally made by night. The S.81s were used also to bomb a big British convoy, without losses but many aircraft were damaged. Already in 13 June, four bomber were sent in Aden, the main British base, and two of them were shot down. In 30 days, without replacements, 9 aircraft were shot down, 10 were destroyed on the ground, and 18 were heavily damaged, two-thirds of the total. On February 10, there were only 10 serviceable aircraft, and only 3 in March. These are small numbers, but the decline of S.81s force was very important for the battles there fought.

Another S.81 was sent in the area: a S.81 with A.130/AR.8 long range radio, that landed at Kirkuk in the spring 1941. It was the command aircraft for the expedition made, too late, by Italian forces (toghever with Germans) to help the iraqui 1941 raising. But iraquis were already defeated by British, despite their equipmente was quite powerful, and the Axis mission was not successfull. So, of the 12 CR.42s of the 'Squadriglia Irak', only seven returned claiming 2 Gladiators.

In the meanwhile, S.81s in North Africa and Italy where used more and more as night bombers, quickly leaving the anti-ship and day bombings but not before the first year of war. 145 Group delivered until the end of January 1941, 11,600 men and 1,140t. of varios materials, in 3,200h flyng hours, and this happened in a very critical peridod for Italians North Africa troops.

For Operation C3, Malta invasion, S.81s of 18 Wing should had trasport over Malta an assault division, but finallythey were used to trasport Folgore division at El Alamein. After that battle, S.81 were used to reinforce with men and supplies the north-African troops, but also to ecacuate Tunisia, with 18 Wing alone that trasported 28,000 men. The S.81s were vulnerable, but in fact the most usually preys were S.82s and Ju-52. In Pantelleria and Lampedusa the S.81s were the only Italian air cargo that were capables to operate in that short airfields. The S.81s, after the first year of war were used only for second line tasks like troops and materials trasport, with very few modiphics. Many had the white and the red cross to evacuate wounded by some war teatry, without any armament and military equipment.

As second line tasks, almost all the first-line Groups had S.81s or other aircrafts in their squadrons, used as support aircraft (for trasport), with 1 S.81 often present in every squadron.S 81 with their fixed and robust undercarriage was able to operate from every terrain, despite the lack of slats, differently from S.79s.

In Russia were used other aircrafts, from 12 August there were 245squadriglia (Squadron) on 2, lather 10 S.81s, then 246 on other 18, and finally 247 on S.73 militarized. With the terrible Russian winter there was an heavy employ, with ice and cold all around. These aircrafts tried to help the trapped troops when soviets started the Stalingrad offensive, and so all these machines were lost in the tragic retreat.

On September 1943 there were still many S.81s in Italy. With many of them was costitued in the South the bomber and trasport group, with S.81 used for aviolaunches and even landing in balkan territories. But after 14 months the lack of spare parts forced to stop the S.81 operations. In the North Italy there were more aircraft: at least 60, 36 of wich were serviceable, They were used in Terraciano Group, Italian manned but operating with Luftwafe in eastern front. After 6 months of heavy employment in Finland, Russia, Poland, and other countries, the survivors aircraft were so badly reduced, with their wood and fabric structures, that were phased-out. No S.81 survived to the war, since the last four were soon demolished when the hostilities were ended.

Conclusions

As overall characteristics, this aircraft was pleasant and reliable to fly, with a big wing and a robust undercarriage. It was surprisingly fast for its time and the fitted power (especially compared to Ju-52). It can operated from every terrain, but the mixed structure was not the optimal for difficult climates. It was better armed than S.79s but with less range, because the drag induced, that reduced the maximum and cruise speed with the same engine power.

Apart this, the defensive weaponry, with several defensive turrets was better than S.79s and even S.84s, but this did not gave enough chances of survive wehn faced with enemy fighter opposition, for wich the Pipistrello was only a big and vulnerable target. It was too slow and too stable to survive to modern fighters, and in fact also in Spain it had many troubles, even if being faster and better armed but with a very vulnerable structure compared to the Ju-52, it was roughly in the same level of vulnerability. No armour was fitted, except self sealing tanks, to this machines. The visibility for the crew was overall very good. After serving in wars that did not have a real air threat, when it became old it was trasferred to less dangerous missions, possibly away from fighters. Its main role began the trasport aircraft and in this task it was still a valid machine, robust and with the capability to operate from almost any kind of surface,so in 1943 there were still S.81s in production, to make an honest duty as transports.

As colours and markings, the Etiopian machines had the 'white avorium' to discriminate them better in SAR missions. Normal painting was yellow, green and brown mimetic. The olive dark green was introduced lather, when the machine was used onlt in trasport missions.

Operators

China

• Chinese Nationalist Air Force received 3 aircraft, all were lost in training accidents in February 1938 at Yichang.

Italy

• Regia Aeronautica
• Italian Co-Belligerent Air Force
• Aeronautica Militare Italiana operated this type postwar.

Italian Social Republic

• Aeronautica Nazionale Repubblicana

Spanish State

• Spanish Air Force

Specifications (Savoia-Marchetti SM.81)

General characteristics

• Crew: 6

Performancewith Alfa 125:340 km/4,000m, cruise 260 km/h, min.speed,110 km/h. Climb to 1,000m/4'15,3,000m/11'48, 5,000m/20'36 Armament

• 6x 7.7 mm Breda SAFAT machine guns
• Up to 2,000 kg (4,415 lb) of bombs

References

• Mondey, David. The Hamlyn Concise Guide to Axis Aircraft of World War II. Chancellor Press, 2002.
• Lembo, Daniele, SIAI 81 Pipistrello, Aerei nella Storia, n.33.

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