I have a 1997 Super Decathlon, and I generally see true airspeeds around 123 kts when I go places. I try to cruise between 5000 and 8000 since it quickly and it’s most efficient around those altitudes. I normally don’t push the engine so I use 2300 rpm and full throttle (~23 inches) on most flights. This gives an indicated airspeed of around 125 mph. I do lean the engine aggressively in cruise so the fuel burn is typically less than 9 gph, averaged over the whole flight.
I do not have the optional strut fairing or streamlined tail wires. The book says you get a 2% speed increase of you do. I also have the steel gear, so my break lines are hanging out in the wind as well (I don’t expect it makes much difference). You can go a few knots faster if you run a higher rpm, but the fuel burn, noise and engine ware also increase and I never felt it was worth it. I’ve also been told with the 2-blade MT propeller, you get a couple more knots as well. Since my Hartzell hub is subject to the AD, I’ll probably switch to one of those this winter so we’ll see if I gain any speed.
Paul
