LeO 45

Lioire & Olivier Leo 45

Prior to the German invasion of France in 1939. The French metal works company, instructed by the minister Raoul Dautry were building fuselages for Liore et Olivier LeO45 medium bomber. These were then commissioned to the 6th Bomb group of the French Airforce, based at the time at Persan-Beaumont.The commnader of of the group being Mr. Ruth.

Brissoneau & Lotz's factory, in the town of Montataire was vulnerable to bombing. They looked for a safe place in which they could continue to build the fuselages and it was not surprising that they chose the caves at Saint Leu d'Esserent just down the road. Brissoneau & Lotz moved all the equipment needed to the Saint-Leu caves. At the time they employed three thousand workers and converted the caves to suit their needs. They installed heating, air-conditioning, laid concrete floors and managed to build about 45-50 fuselages before France was occupied by the Germans.


Report by a worker:

Mr. Jacobee was an aluminium worker. He carried out his work on the photo hatch of the craft. He worked in the caves on the Leo45 and most of the work was carried out on scaffolding. There was different work shops within the caves and it seems that the engines where mounted to the craft somewhere in Paris?


LeO 45-1 was conceived as a second-generation strategic bomber for the new French Air Force. In contrast to its predecessors which relied on machine guns for protection, the emphasis was placed on high-speed high-altitude cruise. The expectation was that high speed would force enemy fighters into tail-chase attacks and to that effect the aircraft was designed with a rear-firing cannon with an unobstructed rear arc of fire thanks to the twin rudders. Service Technique Aeronautique released the initial requirements on 1934-11-17, specifying a 5-seat bomber with a top speed of 400 km/h (215 knots, 250 mph) at 4000 m (13,125 m), and a payload of 1500 kg (3,300 lb) carried for 900 km (485 nm, 560 mi). In September 1936, the requirements were revised to account for development of 1,000 hp (746 kW)-class engines, with cruise speed raised to 470 km/h (255 knots, 290 mph) and crew reduced to four. The Air Force's Plan II called for 984 of the resulting B4-class bombers. The LeO 45-01 prototype powered by a pair of Hispano-Suiza 14Aa 6/7 radial engines producing 1,120 hp (835 kW) each flew for the first time on 19-01-1937. Despite problems with longitudinal instability, and engine reliability and overheating, the aircraft demonstrated excellent performance, reaching 480 km/h (260 knots, 300 mph) at 4000 m, and attaining 624 km/h (337 knots, 388 mph) in a dive. In July 1938, the prototype fitted with new Mercier-type engine cowlings reached 500 km/h (270 knots, 311 mph). Subsequently, the troublesome Hispano-Suiza engines were replaced with Gnome-Rhone 14N 20/21 producing 1,030 hp (768 kW) each, and the aircraft was redesignated LeO 451-01. The aircraft was of all-metal construction with a monocoque fuselage fitted with a retractable ventral machine gun turret. Wings were equipped with slotted flaps and small bomb bays in the wing roots in addition to the main fuselage bomb bay. On production aircraft, propellers rotated in the opposite directions to eliminate the undesirable effects of propeller torque.

Operational history

The first production LeO 45-1 was built in 1938. The decision to abandon Hispano-Suiza engines and a shortage of propellers resulted in production delays. The latter also caused most aircraft to be fitted with slower Ratier propellers which reduced the top speed from 500 to 480 km/h. As the result, although 749 LeO 45-1 had been ordered, only 22 were delivered by the start of World War II. Of these, only 10 were formally accepted by the Air Force. At the start of the Battle of France on 10-05-1940, only 54 of the 222 LeO 45-1 were considered ready for combat, the remainder being used for training, spares, or undergoing modifications and repairs. The first combat sortie was flown by 10 aircraft from GB I/12 and GB II/12 on 11-05-1940. Flying at low altitude, the bombers suffered from heavy ground fire with one aircraft shot down and 8 heavily damaged. Within the next 8 days many of them were shot down, like the one driven by sergent-chef Herve Bougault near Floyon during a bombing mission over german troops. By the 25-06-1940 Armistice, LeO 45-1 of the Groupement 6 flew approximately 400 combat missions, dropping 320 tons of bombs at the expense of 31 aircraft shot down by enemy fire, 40 written off due to damage, and 5 lost in accidents. A total of 452 aircraft had then been built, 373 accepted into service (including 13 for the Aeronautique navale), and around 130 lost in action in Europe. Following the Armistice, LeO 45-1 continued to fly, now under the Vichy government. The aircraft were fitted with larger rudders and two additional 7.5 mm machine guns in the rear turret, and an additional 109 aircraft were manufactured under the Vichy regime. The most notable of these was LeO 45-1-359 which was fitted with a large degaussing coil for remotely detonating naval mines (some British Vickers Wellingtons and German Junkers Ju 52s also carried a similar device). After Operation Torch which began on 08-11-1942, surviving French LeO 451 in North Africa were used primarily for freight duties, although they flew a few bombing missions against Axis forces during the Tunisia Campaign. They were ultimately replaced in active service by Handley-Page Halifax and B-26 Marauder bombers. Aircraft captured by Germans in occupied France were also primarily used as transports, although a small number saw action with the Italian Regia Aeronautica. Following the war, the 67 surviving aircraft were used primarily as trainers and transports. LeO 451 was finally retired in September 1957, making it the last pre-war French design to leave active duty