S&L Speed & Vx, Vy

[racaldwell]

Yesterday I did another glide test from 7,000 ft down to 1,000 ft. As I restarted the engine and waiting for it to warm up before I could add power, I drifted down to 680 ft MSL. I then did another acceleration test that I use to extract Vx & Vy. I started the test at 40 kts and went to full power while keeping the 680 ft constant. With the cooler air and a now broken-in engine with plenum airflow more sorted out, I did not have to reduce power because of high CHT's like I did back in Oct. when I first did the accel. test.

At about 46 seconds, the airspeed tape when to red and I passed thru 135 kts, Vne. I pulled power off and saw 139 kts as I raised the nose to slow down. So with 127 hp from the CAMit 3300, I just exceeded Vne in level flight.

This test was done with the long wingtips as the 1st test was with short wingtips. My Vx was 60 kts and Vy 83 kts. from this run whereas with the short tips Vx was 55 kts and Vy was 65 kts.

The L/D was 18:1 at 55 kts with cowl flaps closed and long wingtips. This is only about 1.5 points better than with short wingtips. It is nowhere close to the 24:1 advertised by Sonex. Regardless of the numbers, it still climbs in a thermal, which is what it is all about.

Rick Caldwell
Xenos 0057 26 (engine) hrs