Involvement in the Spanish Civil War gave the fledgling "Luftwaffe" an early experience of combat conditions, but the "Condor Legion" quickly found its main fighter aircraft, the He 51, was outclassed by the Soviet I-16 in service with the Republicans. The new Bf 109B was effective but in short supply. For some time, only six were available, making the 3-plane "Kette" impractical. Flying in pairs ("Rotte") or a two-pair "Schwarm" and using a more open formation (made possible by radio communication between aircraft) was found to confer other benefits.