The Last Savoia-Marchetti Airliner

Italian aeronautical engineer Alessandro Marchetti

The Italian aircraft manufacturer Savoia had a history dating back to its founding in 1915 by Umberto Savoia and after the end of World War I, it merged with SIAI (Società Idrovolanti Alta Italia), another firm known for its seaplanes. The company became Savoia-Marchetti (sometimes also referred to as SIAI-Marchetti) when the designer Alessandro Marchetti became its chief engineer in 1922 and quickly became famous for his work on the S.55 twin-hull flying boat. Many of Marchetti's designs during the interwar period would set speed and endurance records in flight. Most of what Alessandro Marchetti is best known for, though, was his line of three-engined aircraft that began with the SM.79 Sparviero that first flew in 1934 as a fast eight-passenger transport capable of air racing. With the storm clouds of war fast coming to Europe, the Sparviero became Italy's primary bomber aircraft and one of the few Italian designs produced in significant quantities during the Second World War. The trimotor layout of the Sparviero set the pattern for a whole seriesof aircraft from Savoia-Marchetti, In 1934 the Italian airline Ala Litorria asked Marchetti for a modern long range airliner to which the SM.75 Marsupiale transport resulted. The Marsupiale had its inaugural revenue flights with Ala Littoria in 1938 with the Italian air arm, the Regia Aeronautica, taking interest in the aircraft as a transport. 

With war embroiling Europe in 1941, Marchetti began work on a four-engined derivative of the SM.75 that accommodated 18 passengers on long-range flights. It was a departure from Marchetti's land plane designs which were nearly all trimotors save the obscure SM.74 of which only three were built of this pre-war shoulder-wing airliner. The new aircraft was designated the SM.95 and a prototype and two pre-production examples were built in 1942. In addition, work began on a long-range bomber version designated SM.95B. The original design called for either 14- or 18-cylinder Piaggio radial engines, but wartime availability meant that Marchetti had to settle for a 9-cylinder Alfa Romeo engine producing 780 horsepower. Typical for Marchetti's designs of the period, the SM.95 was of mixed construction with a welded steel tube fuselage with metal alloy skin for the nsoe section and underside and fabric covering for the rest of the fuselage. The wings were plywood-skinned with three wood wing spars. The mixed-material construction likely also made the aircraft much lighter given the fact that lower-powered engines were used instead of what was originally planned. 

The prototype first flew on 8 May 1943 and was immediately impressed into transport service by the Luftwaffe. The fate of the first pre-production aircraft is unknown but is believed to have also been impressed into Luftwaffe service. The second pre-production aircraft was stretched and designed SM.95GA for "Grande Autonomia", featuring increased fuel capacity and revised cockpit instrumentation. Work on the SM.95 was soon hampered by the Italian Armistice in September 1943, but work was completed on the SM.95B bomber prototype with had the wings, engines, and empennage of the transport variant married to a new fuselage that was deepened to allow a bomb bay below the wing spar carry-through structure. A glazed nose accommodated the bombardier with the flight deck moved forward with defensive armament consisting of 12.7mm Breda guns in a turret aft of the flight deck and lateral positions in the aft fuselage and a ventral position forward of the bomb bay. No known photographs of the SM.95B are known to exist though the bomber prototype did fly at least once in 1945. 

Alitalia's SM.95 I-DALL "Marco Polo"

The third SM.95, the SM.95GA, finally made its first flight on 28 July 1945. It and the next aircraft built were put into military service with the Aeronautica Militare. The stretched fuselage of the SM.95GA became the production standard, the nine-foot fuselage stretch allowing for the carriage of 30 passengers in three-abreast seating. The military transports entered operational service starting in May 1946. The new Italian flag airline Alitalia had just been established in September 1946 and orders for six SM.95s were placed. The first two were I-DALJ "Cristoforo Colombo" and I-DALK "Amerigo Vespucci", delivered at the end of 1947 to Alitalia and promptly put into airline service. The production SM.95s had upgraded 9-cylinder Alfa Romeo radials that had increased power output from 780 horsepower on the wartime prototypes to 930 horsepower to accommodate the increased weights of the increased fuel and stretched fuselage. The balance of Alitalia's order, though, was completed with British Bristol Pegasus engines that delivered 1,000 horsepower- these aircraft were I-DALL "Marco Polo", I-DALM, I-DALN "Sebastiano Caboto" and I-DALO "Ugolino Vivaldi". The first two Alitalia SM.95s were subsequently re-engined with the more powerful Bristol Pegasus. It was I-DALN "Sebastiano Caboto" that inaugurated Alitalia's first postwar services to Great Britain on 3 April 1948. 

One of LATI's three SM.95s, I-LATI "San Francesco"

Another Italian airline also ordered the SM.95- Linee Aeree Transcontinentali Italiane (LATI), which had operated air services between Italy and South America prior to the Second World War. LATI had ordered three SM.95s which were all delivered by 1949- I-LAIT "San Antonio", I-LATI "San Francesco" and I-LITA "San Cristoforo". When LATI ceased operations in 1950, their three SM.95s were assumed by Alitalia. Interestingly the only other airline operator of the SM.95 was SAIDE of Egypt, which operated three aircraft to connect Cairo with European capitals. While Alitalia configured its aircraft for 20 passengers, LATI flew shorter routes than Alitalia and configured its aircraft for 26 passengers but SAIDE operated even shorter routes and packed in 38 passengers on their aircraft. Both LATI and SAIDE's aircraft were powered not by the Pegasus radial engine but Pratt & Whitney R-1830 Twin Wasp 14-cylinder engines producing 1,200 horsepower. 

Only a total of 12 production SM.95s operated commercial services out of a total of 20 airframes built including the prototypes. The mixed material construction wasn't terribly robust with the rigors of scheduled passenger services and lacking pressurization also limited their usefulness. Compared to the Douglas DC-4 and the Lockheed L-749 Constellation of the time, the SM.95 was an outdated design. The last passenger flights took place in 1950 less than a year after the last production aircraft was completed. 

Interestingly, there was a plan by the Regia Aeronautica called "Operation S" prior to the 1943 armistice that would have used a modified SM.95GA to fly at very long ranges to bomb New York City. Benito Mussolini, however, would only allow the mission to drop propaganda leaflets as he didn't want to alienate the large population of Italian-Americans in the city. The mission was under preparation when the 1943 armistice occurred. 

Source: Air International "Plane Facts" Volume 10 Number 2, February 1976. Photos: Wikipedia, Alitalia, Air International

The Reverse Lend-Lease of the Bristol Beaufighter

When the attack on Pearl Harbor brought about the entry of the United States in the Second World War, not one single aircraft was in operational use that was capable of night fighting let alone equipped with an airborne intercept radar. The US military, however, had long been cognizant of the need for a night capability and ten months prior to the attack on Pearl Harbor had already awarded a contract to Northrop for the prototype XP-61A Black Widow night fighters. In the interim, the Douglas A-20 Havoc light twin bomber was modified with British AI (air intercept) Mk. IV radar sets that were built by MIT and an underfuselage pannier that housed four 20-millimeter cannons. This Havoc variant was designated P-70 and the prototype made its first flight in September 1941 before the US entry into the war. It's little known that this interim night fighter conversion did have the name "Nighthawk" but it was rarely used in practice. While most Douglas P-70 Nighthawks remained in the United States to train crews bound for night fighter operations, a small number did serve in the Southwest Pacific where the aircraft was found to be slow and lacking in high altitude performance. 

On 26 January 1943, the USAAF activated its first dedicated night fighter squadron, the 414th Night Fighter Squadron, in Florida at Kissimmee Army Air Field with sixteen officers and enlisted personnel transferred in from other units. Three other squadrons (415th, 416th, and 417th NFS) were also established in Florida where the USAAF had its School of Applied Tactics in Orlando. Given the highly technical nature of night fighting by radar, pilots were specially selected for their technical skills and above average flying skills. The radar operators were selected were the first AI (airborne intercept) radar observers to come from a special training program started by the Army Air Forces. At Kissimmee AAF the pilots and radar observers trained together as a team on the Douglas P-70s. After a month of training, the crews of the 414th NFS were sent to the UK for further training with RAF night-fighter crews on Airspeed Oxfords, Bristol Blenheims, and Bristol Beaufighters. With the P-61 Black Widow not expected to be operational in Europe until the end of 1944 to early 1945, a "reverse" Lend-Lease was arranged in which over 100 radar-equipped Bristol Beaufighters were transferred to the USAAF as they were more capable than the underpowered P-70s used in training. The 414th NFS's radar observers found the transition from the American copy of the AI Mk.IV radar set to the British version. Although identical, wartime experience introduced a set of improvements to the British sets on the Beaufighter that the American versions on the stateside P-70s lacked. To give you an idea of the limitations of the airborne radar sets of the day, the British AI Mk.IV was only usable over 15,000 feet due to ground clutter at lower altitudes and had a detection range between 400 feet to only as far out as 3 miles! 

Following their respective conversion training, the pilots and radar observers of the 414th NFS reunited at RAF Valley in Wales where they took delivery of twelve Beaufighter Mk.VIFs. With additional training through the early summer of 1943, they were joined by the 415th NFS and the two squadrons of American Beaufighters shipped out to North Africa. The second group of squadrons, the 416th and 417th NFS, followed them in August 1943 to North Africa as well. Leaving the UK in groups of five aircraft and led by a Coastal Command Beaufighter for long-distance navigation. After stopping over in Gibraltar, the Beaufighter squadrons then proceeded to their operational bases in Tunisia and Algeria. Operational necessity, however, had the American crews flying daytime interdiction missions against German and Italian aircraft making supply runs to North Africa across the Mediterranean Sea. On the first combat mission for the American Beaufighters, a Heinkel He 115 floatplane was shot down by aircraft from both the 414th and 415th NFS. By the end of the month, however, wiser heads prevailed that didn't wish to waste the specially-trained night fighter crews on daytime air and shipping interdiction missions. Night time enemy air activity would be quiet for the remainder of 1943 until the Allied landings at Anzio, Italy, on 22 January 1944. With the beach heads only thirty miles from Rome, for the next four months some of the most savage fighting until the Battle of the Bulge took place as the Germans tried to overrun the Allied pocket at Anzio. Luftwaffe bomber units based in southern France increased their night time raids on the landing zones and the American Beaufighter squadrons were moved to an improvised base on the island of Corsica to be better positioned to intercept the nocturnal Luftwaffe raiders. 

On 23 January 1944, the day after Allied forces hit the beach at Anzio, 1Lt. James Anderson would of the 414th NFS would score the first night kill for the American Beaufighters against a Dornier Do 217. That first night many of the pilots of the 414th NFS would fly two, even three missions from their improvised base. Of the twelve Beaufighters in the squadron, nine of them flew nearly nonstop that first night. By the time Allied gains at Anzio had been consolidated, the 414th NFS had converted to the vastly improved AI Mk. VIII centimetric radar set. The squadron was then moved to the mainland in October 1944 and two months later converted to the Northrop P-61 Black Widow. The 415th NFS operated from bases in Sicily after moving across the Mediterranean, as did the 416th NFS where they covered the Allied supply line from North Africa to Italy. The 416th eventually got moved forward to Italy itself as well while the 417th stayed behind in North Africa to cover the rear logistics areas of the Allied invasion of Italy before moving to Corsica in 1944. By that time, those three squadrons had also converted to the AI Mk. VIII centimetric radar set for their Beaufighters. In addition to the night fighter patrols, the three squadrons' Beaufighters also flew night intruder missions against ground targets as well throughout Italy during the drive northward from Anzio. 

With the Beaufighter squadrons now based on Corsica, they were well-placed to protect the Allied invasion assembly areas for the August 1944 landings in southern France, Operation Anvil-Dragoon. In addition to night fighter patrols of the rear logistics areas on Corsica and the assembly points for the invasion fleet nearby, the squadrons were also tasked with night intruder missions on various Vichy and German targets in southern France in the run up to the 15 August landings between Cannes and Toulon. Once the Allies had captured the port city of Marseilles, the 417th NFS was moved forward to Le Vallon in the Rhone River valley to intercept German reconnaissance flights and raids on Marseilles where incoming Allied forces were being disembarked. Other missions included the continued nocturnal raids and patrols for increasing numbers of midget submarines seeking to disrupt the Allied shipping in Marseilles harbor. By this point the Beaufighters were over three years old and much overhaul work had been delayed due to the combat situation. In less than three months, the 417th NFS alone would lose nine Beaufighters to technical problems. By the end of 1944, the USAAF decided to begin the drawdown of Beaufighter operations- the 414th NFS, still operating in Italy, was the first to convert to the P-61 Black Widow in December. The 415th NFS, operating near Nancy, France, converted to the P-61 Black Widow as well. The 416th NFS traded in its weary Beaufighters for the De Havilland Mosquito NF Mk. XIII and the 417th NFS, the last of the four night fighter squadrons, was moved northward to Belgium and traded in its Beaufighters for the P-61 Black Widow in March 1945, marking the end of the unique "reverse" Lend-Lease operation for the USAAF. 

Source: Air Fan International, July 1996, Volume 1, Number 5. "Southern Beaus- USAAF night fighter operations in the Mediterranean during World War II" by Rene J. Francillon, p54-63. 

Although progressively improved and more powerful versions of the Bristol Olympus jet engine powered the Avro Vulcan bomber, there were also other versions of the Olympus destined for other aircraft that made their initial flights on specially-converted Vulcan testbed aircraft. In addition, other similarly-equipped Vulcans served to flight test other engines during their development cycles as well.

The first engine to be flight tested on the Vulcan wasn't an Olympus variant, though. That honor goes to the Rolls-Royce Conway low-bypass turbofan. The first prototype Vulcan, tail number VX770, was retrofitted with four Conway engines in 1956 and delivered to Rolls-Royce for the start of the Conway flight test program in August 1957. Unfortunately, VX770 was lost during a Battle of Britain flying display at RAF Syterston in September 1958 when the maneuvers it was performing overstressed the airframe, resulting in the loss of the crew. A second Vulcan bomber, XA902, was then selected to undergo conversion with the Conway engines to replace VX770. The conversion work began at Avro's facilities in December 1958 and was completed in July 1959. The Conway engines used were the Conway 11 engines (RAF designation Conway Mk.102 and 103) which were destined for use on the Handley Page Victor B.2, an upgraded version of the original Victor B.1 model.

The Conway test program called for the engines to be run at cruise power at 40,000 feet- however, at that power setting, the Conway 11s were more powerful than the Olympus engines of the Vulcan and the testbed would have easily exceeded the Vulcan's maximum speed and overstressed the airframe! As a result, the Conway 11 engines had to be operated at lower thrust settings similar to what was used on BOAC's Boeing 707-430 jetliners. It was found that two Conways could be operated at cruise settings as long as the other two engines were run at lower settings. Given that the prototype Vulcan VX770 that was lost wasn't as structurally strong as XA902, it became possible to complete the Conway flight test program.

With the Conway test program complete in 1961, XA902 was then converted to take Rolls-Royce Spey engines on the inboard positions while retaining the Conway 11 engines on the outboard positions. It made its first flight in this configuration in October 1961 to support the Spey development for its use on De Havilland DH.121 Trident, the BAC One-Eleven, the Blackburn Buccaneer S.2 and the Hawker Siddley Nimrod. XA902 would be retired from service in 1963.

In 1962, another early-mark Vulcan B.1 was taken from service to test the Olympus 22R engine that was destined for the BAC TSR.2. Vulcan XA894 was modified with a large ventral nacelle with bifurcated intake on each side of the nose landing gear. Conversion work on XA894 began at Filton in 1960 and it made its first flight with the much more powerful Olympus 22R in February 1962 in support of the TSR.2 development program. In December of that year during a ground run test, an uncontained turbine blade failure resulted in a fire that destroyed XA894. No replacement was needed, though, as the Olympus 22R had completed enough of the needed test points for the TSR.2 program.

In 1964, another Vulcan was pulled from service to serve as an engine testbed, this time it was tail number XA903 which arrived at Filton in January of that year for conversion work to flight test the Olympus 593 in support of the development of the BAC/Aerospatiale Concorde. Using a similar ventral nacelle as had been used on XA894 in the Olympus 22R flight test program, this time instead of a bifurcated intake a straight-through intake was used that resembled a single-engine Concorde engine nacelle. A retractable spray bar was also fitted ahead of the intake and water from a bomb bay water tank was used to test water ingestion and icing conditions on the Olympus 593 engine. The first flight was made with the Concorde engine in September 1966 and the test program finally ended in 1971 with over 400 hours of flight time. With the Olympus 593 at full power, the Vulcan testbed could still fly and maneuver with its own four engines at idle!

Testbed work would continue for XA903, though. In August of 1971 XA903 was flown to Marshalls of Cambridge for conversion work to support the development of the Rolls-Royce/Turbo Union RB.199 engine for the Panavia Tornado program. The ventral nacelle used for the Olympus 593 program was modified by Marshalls to not only accommodate the RB.199 engine, but to replicate the starboard side of the Tornado's fuselage. The first flight with the RB.199 was made in April 1973 and one of the most unusual aspects of the RB.199 flight test program was that the ventral nacelle was even equipped with a Mauser 27mm cannon that would be used on the Tornado. The cannon's location in relation to the intake replicated its location on the Tornado so that gun gas ingestion trials could be carried out. The firing trials were carried out at Boscombe Down but weren't done while airborne- XA903 remained on the ground and firing butts were used while Rolls-Royce and Turbo Union engineers analyzed the engine's performance as gun gas was drawn into the intake. A total of 285 flight hours were accumulated with the RB.199 on XA903 when the Vulcan was finally retired in February 1979, the last early-mark Vulcan B.1 to have flown.

Source: Avro Vulcan- Britain's Famous Delta-Wing V-Bomber by Phil Butler and Tony Buttler. Midland Publishing/Aerofax, 2007, p70-73.

Although the Bristol Type 167 Brabazon is often labeled as a "white elephant", the aircraft had many milestones for commercial aviation and set the foundation for bigger successes by the British aviation industry than is widely known. The Brabazon design first originated as a bomber design to meet the Air Staff specification B.8/41 which laid down the features and performance of a very large bomber similar in class to the Convair B-36 Peacemaker. B.8/41 asked for a range of 5,000 miles with a speed of 300mph capable of reaching Russia or Japan. Bristol's design had an all-up weight of 225,000 lbs and a 225-foot wingspan. The project never got pursued, though, as the RAF preferred increased production of the Avro Lancaster.

When Lord Brabazon convened his famous committee to determine the course of British commercial aviation post-war to compete with the Americans, the Bristol bomber design was adopted for the Type I role, that of a large trans-Atlantic airliner with an anticipated service date of 1948. It was christened Brabazon in honor of the committee chairman himself.

When work began at Bristol's Filton works, the runway was 2,000 feet too short and had to be extended for the anticipated flight test program of the Brabazon. Despite local protests and the need for Cabinet approval to start work on the runway, when completed along with a massive assembly hall, it became the longest runway in Europe.

There were four features in particular that were commercial aviation milestones in the design of the Brabazon. It was the first aircraft to be designed from the outset to have 100% fully-powered flying controls, the first commercial aircraft designed to have a high pressure hydraulic system (the higher the pressure, the lighter the hydraulic system), and the first aircraft to have electric engine controls (electric control of engine power and mixture would lay down the foundation for modern FADEC systems). But most significantly yet little known, the Brabazon was the first airliner to be designed with cabin pressurization and air conditioning, and that pressurization was set at 8'000 above sea level, the current standard for modern airliners.

By 1949 the Brabazon was still in flight test and the De Havilland Comet prototype had just flown and BOAC was already using the Boeing 377 Stratocruiser on the trans-Atlantic routes intended for the Brabazon. In 1953 the project was canceled (despite the design of the Brabazon Mk.2 which used Proteus turboprops instead of the Centaurus radials of the prototype), but the expertise gained by Bristol formed the foundation for the more successful Bristol Britannia and when Bristol became part of the British Aircraft Corporation in 1960, the Filton works and its long runway and large assembly hall would be used for the Concorde program.

Source: Airliner Classics, November 2009. "The Bristol Brabazon: White Elephant or Technological Marvel?" by Gerry Sweet, p53-58