By the 1930’s it was well understood that military aircraft would play a crucial role in future conflicts. But there was an issue that had challenged aircraft designers since the dawn of flight. Large, heavy aircraft, like bombers, could carry plenty of fuel, allowing them to fly great distances, but smaller planes like fighters needed to be light and agile could carry only a small amount, limiting their range. This mismatch in flight range meant that on long range missions, bombers couldnt rely on the protection of escorting fighters. The Zveno Project was a Soviet experiment in the 1930s that involved attaching fighters to a bomber mothership and using them as long-range bombers or escorts.