Sportsman owner Lou Nathanson recently moved to Alaska from Colorado. Read about his high altitude experiences in his Sportsman:
Friday was the day that all the stars aligned for aircraft, pilot, and weather. My bird was still on small tires with wheel pants, had the new IO-390 with 10:1 pistons, cooling air intake ramps, and an over-sized oil cooler. Ambient temperatures were still cool, but winter winds had abated, and the forecast at 24000′ was 15-18 K.
So, I launched from Anchorage at about 1:00 pm and started climbing. About an hour later, I flew over the top of Denali with a few thousand feet to spare. Interestingly, I was able to achieve that altitude with 2600 rpm. It was glass smooth, and while not perfectly CAVU, there were only some low clouds on the north side.
After topping the summit at right about 24k pressure altitude, I cranked it up to 2700 rpm, and kept climbing for a bit on the way back, managing to peddle my way to a density altitude of 24700 before running out of steam. I started with full fuel, plenty of survival gear, no passenger, and two bottles of oxygen. Cylinder head temperatures never got above the mid-300s, and at maximum altitude, were actually below 300.
From past experience at FL 220, I’m sure I could have kept my oxygen saturation in the mid-90s with a cannula, but that usually requires cranking up the rate pretty high, and I didn’t want to end up having to change bottles at that altitude (while talking to ATC and hand flying on the backside). So, I dug out the full mask that that came with my Aerox system. It definitely was more effective; I was able to stay at 98% saturation with rate to spare, and still landed with more than half a tank of oxygen.