Interesting subject bandied around for years. The turning downwind accidents at low level still happen. To prove something to myself, I flew a Cessna 152 into a steady 40 knot headwind. IAS 80 knots. 2000ft. Then ripped into a 180 degree limit turn downwind at full throttle (to minimize speed bleed off) Took about 5 seconds. The IAS remained unchanged at 80 knots.