The Greenwood circle consists of about 200 druids, with another 200 or so support staff (farmers, coopers, rope makers) and their families.
These devices are powered by small air elementals and can fly at 120'/round. They're extremely maneuverable: at full speed they can execute a 90 degree circular arc and maintain full speed, or do a 180 degree turn and slow to a stop. Similarly, they can accelerate to their max forward speed in one round.
The payload of up to 200kg is supported by a hydrogen gas bag.
These small cargo vessels are driven by larger elementals and can maintain a top speed of 275'/round, but ... they are much less maneuverable than the sky cycles. It takes a sloop ten rounds to accelerate to full speed