A friend has made and documented what may be the highest flight in an RV12! Here is a summary, and there are more details and pictures at the link.
A private pilot with medical can fly the RV12 to 17999 ft. (I guess if you are instrument rated and the RV12 is equipped for IFR, you could legally go higher.) If you are exercising Sport Pilot privileges (such as being a PP with lapsed "driver's license" medical) then you are limited to 10000 feet or (the KEY) 2000 ft AGL, whichever is higher. So for maximum altitude in that case, fly over a mountain - like Mt. Rainier, at 14410 MSL, 14800 on the chart! So that would allow for a 16,800 ft attempt.
He waited for good weather, took oxygen and a saturation meter, and made the flight with ATC flight following.
He achieved 16214 feet (density altitude) and was still climbing. He was at less than gross weight, about 1070 pounds.
He has flight logs form the Skyview and all the Density altitude/true altitude calculations.
Climb rates were:
Sea Level to 10,000 ft was 14 minutes. = 714 fpm
10 - 12 thousand was 5 min. = 400 fpm
12-16 thousand was 24 minutes. = 167 fpm
15 to 16 thousand was 8 minutes. = 125 fpm
The RV12 POH lists the service ceiling as "Estimated 12,000 feet." Service Ceiling is defined as the maximum altitude using max continuous or climb power when the ROC (Rate of Climb) falls to 100 fpm while flying at Vy (Best Rate of Climb Speed ) (75 kts for the RV-12) at an ISA Standard Day, which defines a "normal" temperature for different altitudes.
Bob Bogash says "I could have held on for 17,500, but that would have probably taken another 10- 20 minutes - and at less than Vy.
That would likely be the Absolute Ceiling - the Maximum Altitude the airplane can achieve at any speed when the Rate of Climb goes to Zero.
I didn't want to get into that part of the flight envelope - my goal was the Service Ceiling."
"I figure I determined the Service Ceiling with some degree of accuracy - it's about 16,500 feet at ISA at a "typical" solo operational weight of 1050 lbs.
The Service Ceiling is no longer "estimated."
Much more detail and pictures of the flight are here:
Has anyone gone higher?