Sorry, the only reason that you are gaining/loosing airspeed at low level is the influence of the ground being close, and your are sub consiously adjusting for groundspeed.
Climb away from the ground, say to 2000', in strong wind, say 30kts, and assuming that you can, set the trim to a constant speed, say 70-80 kts. Trim in 5 or 10 degrees of bank. Adjust the power to maintain height. Let go of the controls. The aircraft will fly around in circles at your set speed, plus or minus a knot or two for gusts.