All this talk about descent angles got me curious about what my Pitts can do. Tried it yesterday. I got on google earth and measured an area on the ground with features that I could reference from the air. First I climbed to 1000' AGL and tried a power-off, full deflection slip, stabilized at my normal approach speed. Based on the point on the ground that remained stationary during my descent, I later measured that to be about 1600' horizontally from the point where I started the slip. Busting out the high school trig, this gave me a 32 degree descent angle. Descent rate was 3200 fpm.
I was also curious what the descent angle would be if I flew in a full stall, coordinated with the wings level. I climbed up to 2000' pulled power to idle, stalled the airplane over a point on the ground and held the stick on the aft stop and kept the wings level with rudder. Once I had lost 1000' I noted the point on the ground next to me. This was 2300' horizontally from where I started the descent. This works out to a 24 degree descent angle. I thought it would have been higher in this configuration.
Wind was negligible at the time I did this. I've also got a fixed pitch prop. CS prop would descend steeper. Even so, my Pitts slips much steeper than anything else I've flown. But I've never tried to extract max descent angle out some of the other types, so don't know what kind of numbers others will do. Pretty sure I can't beat the Pitts in the Cub, though.
A near 60 degree descent angle would be very impressive to see.