The Lohner B.II (originally designated Type C) was a military reconnaissance aircraft produced in Austria-Hungary during World War I. It was a development of the pre-war B.I design, incorporating changes requested by the Austro-Hungarian army, but inheriting its predecessor's basic design, including its characteristic swept-back wings.
Intended to perform better in the mountainous terrain of the Austrian alps, the Type C featured a longer fuselage, greater wingspan, and strengthened undercarriage. The Type B's Austro-Daimler engine was exchanged for a Heiro with slightly less power but also much lighter. The extended wingspan soon led to problems, however, when the prototype's wings collapsed under stress testing. A second prototype, with strengthened wings, was accepted by the Army in August 1913, and placed an order for another 24 aircraft. Soon after deliveries began, the wings of a Type C failed in flight, and all examples were grounded. Work to strengthen the wing design was carried out under the direction of Professor Richard Knoller but this was not yet complete when war broke out. Six Type Cs were immediately put back into action, with the grounding of the others being lifted shortly afterwards. The design proved too slow and too fragile for operational service, and was quickly reassigned to secondary roles. In February 1915, the Luftschiffabteilung revised its designation system to match that in use by Germany, and the Type C was redesignated B.II. Later the same year, a new and strengthened wing was fitted to all remaining B.IIs, and the B.II (along with the B.I) was put back into production under licence at Flugzeugwerk Fischamend for use as trainers.
As the year drew on, the B.III, B.IV, B.V, and B.VI followed, featuring a variety of engines. None were produced in quantity, but the B.III and B.IV were also built by the new Ufag firm that had been established to produce these Lohner designs in Albertfalva in Budapest. Further development eventually resulted in the Lohner B.VII by the end of the year.