I bought a completed RV-10 last November with a Lycoming IO-540 (260 HP) engine. I typically have been flying in the 5,000 to 10,000 foot range but wondered if I would be better off flying higher and taking advantage of the winds and better fuel economy. On the Van's website they "estimate" that the service ceiling for the RV-10 (with 260hp) is FL240. I am sure that most of you know that service ceiling is defined as where the airplane is climbing at a max rate of 100 fpm. To fly up at anything above 14,000 you of course need supplemental oxygen. This was a catch 22 for me. I needed the oxygen to see how high I could climb but I didn?t want to purchase a oxygen system if the performance did not warrant it. I fortunately was able to borrow a bottle for my test flight. I guess I could have done it when it was cooler and had better results but I wanted to get on with it and that happened to be at 12 noon one day last week when the OAT was 81 degrees at take-off. I figured that I would run out of manifold pressure before anything else so I kept track of it from 6,000 feet up (results below this note). I started using the oxygen at 10,000 feet and continued a VFR climb to 17,500. I called Oakland Center and requested a IFR clearance and a climb to FL200. I explained that I was doing a test flight in an experimental aircraft to determine the service ceiling. I did have to change frequencies to get the high sector controller but they accommodated me immediately and I was cleared to FL200. They were giving me vectors to say out of everyone else?s way so I did have increased ?G? loads every time I made a turn in the racetrack pattern. Out of FL180 I had to click off the TruTrak auto-pilot because it was having a hard time at that altitude. When I got to 18,800 feet I was still climbing at a rate of about 300 fpm but the engine was misfiring every once in awhile and I was in a very nose up attitude indicating 90 MPH. I decided that I had gone as high as I wanted under those conditions and asked for a descent out of the class A airspace. I kept a very close eye on all of the engine instruments during this trial and the engine RPM was always pegged on 2700 RPM. Although I was still climbing at 300 fpm and was indicating 90 MPH I don?t think I could have gotten above FL195. I have to wonder how Van?s came up with their estimate of FL240 for the 260 HP engine. Has anyone else tried to find out what the service ceiling is on their 10 by actual flight testing like this?
Alt MP
6,000 23.5
7,000 22.5
8,000 21.5
9,000 20.9
10,000 19.9
11,000 19.2
12,000 18.5
13,000 17.8
14,000 17.0
15,000 16.3
16,000 15.6
17,000 14.9
17,500 14.6
18,000 14.3
Alt MP
6,000 23.5
7,000 22.5
8,000 21.5
9,000 20.9
10,000 19.9
11,000 19.2
12,000 18.5
13,000 17.8
14,000 17.0
15,000 16.3
16,000 15.6
17,000 14.9
17,500 14.6
18,000 14.3