We used 1-inch streamer. Do not know where they were purchased. In a bind, you can use the ones sold for parties, but those are 3-inch streamers, and will increase drag. We kicked around the idea of cutting party streamers in half with a band saw, but never did it.

Tie kite string around the tail of the aircraft, leaving a tail of string behind the aircraft. Tie the streamer to the string tail. We used 5ft separation between the tail of the plane and the streamer, and a 30ft long streamer. You could adjust that if the drag is too great.

I should add that this was using 25 size nitro combat birds.

Rafael