With a crew of two or three, the Po-2 first flew in January 1928, and over 13,000 had been built by June 1941. Though it was used primarily for training and liaison, it pioneered night raids. It was powered by one 100hp M-11 that gave a maximum speed at sea level of 150km/h (93mph) and a maximum range of 530km (239 miles). It weighed 635kg (1400lb) empty and 890kg (1962Ib) loaded. The upper wing span was 11.4m (37ft 5in) and the lower 10.65m (34ft 11 in). It was 8.15m (26ft 9in) long. Production continued into the mid-1950s in Eastern Europe. Its armament consisted of one 7.62mm (0.3in) ShKAS machine gun in the rear cockpit and it had a maximum under wing load of 250kg (550Ib) of bombs or rockets. The pilots employed a simple night attack tactic of flying to within range of their target and then cutting their engines and gliding in to drop their bombs. For the German soldiers in the front line the silence that presaged the explosion of the modest bomb load was always disconcerting. A number of captured aircraft were flown by ex-Soviet Air Force volunteer personnel for the Luftwaffe in night attacks on the Eastern Front. The first Soviet all-female formation to be activated was the 588th Air A Polikarpov U-2VS in service with a Polish squadron of the Red Air Force. This slow biplane operated largely at night as it was vulnerable to AA fire and fighters. In the ground attack mode the pilot would glide over the target after cutting the engine and release the bombs. Regiment that went into action in the summer of 1942. The women often flew the fragile Po-2 biplane. It was terribly vulnerable and so attacks were conducted at night from altitudes of between 1200 and 600m (4000 to 2000ft). By October 1943 its performance had earned it the title 46th Taman Guards Bomber Regiment. The 46th was the only all women regiment in the Red Army with a total strength of over 200. It was commanded by Major Yevdokiya Bershanskaya throughout the war. The 46th was composed of three squadrons with a training squadron. Thirty air crew were killed during the war and the regiment flew over 24,000 combat missions in 1100 nights. It was the most decorated of the women's formations with 23 members receiving the Gold Star of the Hero of the Soviet Union, the nation's highest award, five posthumously. The Regiment adopted the slogan 'You are a woman, and you should be proud of that'. To the Germans the Po-2's 100hp radial engine sounded like a malign sewing machine and when they discovered that some of these front-line intruders were piloted by women the pilots of the 46th Guards Regiment earned a new title from the Germans, they were 'The Night Witches'.