Louise Hose
Well Known Member
I taxied Mikey (RV6) down the runway yesterday morning to start a dawn patrol. The air was nearly saturated with moisture but the sun was about to rise and there was no forecast of fog. As I did my run up, I noticed a misty spray of moisture coming back along the left side of the cowl and from the prop. Confused, I slowed the RPMs back down and tried to determine where the moisture was coming from. The spray stopped. There was no water on the plane (or ground) and no rain in the immediate area. I run it up again and the spray re-started. I ran through any possibility I could think of...fuel, engine oil, prop oil? Slowing the RPM down again, I reached out to see if there was any oily film on the canopy or fuse. Nope. It was apparently just moisture. I didn't understand the physics but decided that the higher RPM was forcing condensation of the air vapor into tiny droplets. So, we headed out for a nice flight.
After I returned, Paul suggested that is was the equivalent to a con trail but he hadn't seen it occuring behind a prop before. Anyone else had this sort of observation? (I might add that the muted sunlight was coming from directly behind the mist, which might explain why I only saw it on the left side.)
After I returned, Paul suggested that is was the equivalent to a con trail but he hadn't seen it occuring behind a prop before. Anyone else had this sort of observation? (I might add that the muted sunlight was coming from directly behind the mist, which might explain why I only saw it on the left side.)