During the war their products included pursuit planes, single motor two-place fighters (Plate 23), two and three motored bombing planes and four and multi-engined giant planes—all for over land flying. Seaplane types included single engine two-place fighters, two and three motored flying boats and four and multi-engine giant flying boats. More than one hundred domestic patents were held and more than 250 filed in foreign patent offices. Twenty-one different designs for experimental types had been produced, seventeen of them worked out in as many machines which were flown, and four Plates 24-25-26-27 made into models Plates 24-25-26-27. The following is a list of the experimental personnel year by year: 1915 1916 1917 1918 1919 1920 Engineers 15 25 25 69 52 23 Workmen 30 250 300 547 207 80 [PLATE 40: The “DELAG” Passenger Zeppelin “Bodensee.” Landing at Friedrichshafen September 1919. The “DELAG” Passenger Zeppelin “Bodensee.” Floating in the large shed at Friedrichshafen.] Zeppelin Builds Giant Airplanes But there was another angle to the Zeppelin airplane activities. Count Zeppelin held the rank of General in the German Army. He had long been in a position which kept him informed of the needs of the fighting forces. For several months after the declaration of war he observed the heavy tasks to which his airships were put and then undertook the development of larger airplanes, far larger than any existing in the world at the time. He consulted the noted aviator Hellmuth Hirth, and together they conferred with Professor Baumann of the technical university at Stuttgart. Baumann was already noted for his work as an aeronautical engineer. Within a few months they produced a multi-engined giant bomber. It proved successful. To produce these machines in quantity the Zeppelin works at Staaken were erected at the same time as the airship building plant. The airplane factory at Staaken soon employed more than a thousand men in turning out the giant night bombers, numbers of which were flown in the raids over London and Paris in 1917 and 1918. The Airplane Works at Staaken The plant at Staaken was complete, including two great airplane assembling sheds, workshops, offices, etc. It is now closed. Other German firms have built similar bombing planes under the Zeppelin patents. Twenty-six of them were built at Staaken, however. They had a 137.76 foot (42 meters) wing span, carried 4.5 tons useful load, could climb to a height of 14,760 feet (4,500 meters) with their motors which aggregated 1,250 horsepower. Their average speed was 90 miles per hour (Plate 23). [PLATE 41: The “DELAG” Passenger Zeppelin “Nordstern.” Leaving Friedrichshafen for France. Note the progressive increase in the size of the sheds. The “DELAG” Passenger Zeppelin “Bodensee.” Passengers enjoying an excursion over Berlin.]