Rick,you have been breathing too many Jet A fumes. "61 knots, 90 knots"? No real Cub ( that is built by Piper in the 30s or 40s) flys at any knots, anymore than a real Ford Model T goes 50 kilometers an hour.
Bill,
I know that! I tell people that J-3 Cubs will be flying the Fisk approach at 70 M.P.H. Then they tell me that most aircraft should have no problems staying behind an aircraft going 70 knots. NOT the same speed!