Notes:Attached is a photo of my RV-7 panel taken on December 23rd, 2008. The winds at altitude were howling over Kansas City, Missouri - common over the US plains during the winter months. So, a friend and I jumped in the plane to see what kind of ground speed we could get in level flight at 17,500 feet.
The result was 283 knots ground speed (about 170 knots TAS). I didn't think this was a big deal, but after several days on Doug Reeves VAF site, no higher claims were made.
The aircraft has a normally aspirated Lycoming IO-390-X (210 hp), built by Barrett Precision Engines in Tulsa. Just a week earlier, I had 262 knots at 5,000 feet, (185 knots TAS). I look forward to beating 283 knots this winter. Next time, I'll leave my friend on the ground and go higher.