How slow can you go?

On May 14th we once again took to the skies. I wanted to get the hang of slow flight this time. I wanted to do my best and nail it. I got my opportunity this lesson. In addition to working on turns, climbs and descents, emergency and engine out procedures, we worked on more slow flight.
We wanted to work specifically on MCA (Minimum Controllable Airspeed). This is the airspeed at which the airplane is right on the verge of a stall. My job was to get us as slow as possible while maintaining control. You have to fly slow to approach your landings.
Most aircraft, including the Cessna 172SP, are equipped with a stall warning indicator. It's a rather strident sounding "horn" that whines at you when your wings are about to stop being able to support you in the air. Mind you, if you need the stall horn to tell you you are about to stall them you've got some troubles. The airplane tells you all be itself. You just have to look for the signs. Slow airspeed, high angle of attack, mushy controls, and physical sensations are all present before the stall. You just need to pay attention. Having the stick way back is usually your biggest clue.
Slow flight can be fun. You're just sort of bobbing along and pitched way up. It's sort of quiet and peaceful. With full flaps we stall at about 38knots. I got us down to 40 knots. I was rewarded by flying around with the stall horn continuously sounding. I was also able to conduct gentle turns and even a 100 foot per minute climb at about 40 knots.
Lastly, I was starting to get the hang of the traffic pattern for the landing approach. It was a great flight.