Air can go from dry to about 4% to 5% water vapor (depending on temperature, pressure). Air mixed with water vapor is less dense (mass per unit volume) than dry air (even if at the same pressure if I remember correctly). This means that foggy air is is less "viscous" than dry air. Lift and drag will remain about the same, but air speed will increase. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]