The performance figures will vary considerably depending on whether you're looking at a 180 hp, 250 hp, 260 hp or 400 hp Comanche. The 260 hp was also made as a turbocharged variant.
I have a share in a normally aspirated 260 B model Comanche. I get the following performance out of it.
55% at FL100: 135-140 kt TAS @ 34 L/h (20-40F LOP)
75% at FL70: 158 kt TAS @ 58 L/h (70F ROP)
Service ceiling is 20000 feet, but it takes about 50 minutes to get there. I typically see an average climb rate of 700-800 ft/min up to FL100 when heavy, and as much as 1100 ft/min average up to FL100 when lightly loaded in the winter.
My Comanche has tip tanks giving it a total fuel capacity of 120 gallons (454 L). At 55%, even allowing for climb and reserves, that's more than 11 hours endurance and a range of 1500+ nm. I have yet to make a trip that long, but it's nice to be able to make a round trip to a destination 500 miles away without needing to refuel.
Empty weight is 874 kg, gross weight 1429 kg. With full fuel (454L) that only leaves 229 kg payload, but with a more typical 340 L of fuel (full mains and full auxes) the payload increases to 310 kg.
/Thomas