Jeff Speed in any plane is a function of excess thrust overcoming whatever drag is present in a given plane. I am over simplifying but basically the less drag the plane makes for a given horsepower the faster it flies. And drag reduction has MORE effect than more hp. Several companies have done test after test and proven that it requires much more increases in hp to overcome a dirty airplane, than it does to get big improvements by reducing drag and get the same speed increases, using already available hp in the plane's setup. Why is this? Because it is very easy to increase cruising speeds and top speeds when going from say 80 knots to 120 knots in the same plane by just adding hp and maybe a prop change. This is because the parasitic drag, or drag produced by anything in the slipstream is much less at lower speeds, and the hp increase is taking the plane from having marginal thrust above minimum to climb and cruise, and adding more than enough to cruise with hp to spare. Also, altitude has an effect based on the density altitude, and the friend may be reporting true airspeed, not indicated based on adjusted numbers. Now take that same plane and try to push it up to say 200 knots. Horse thinking would have you say, well if I double the hp I will fly twice as fast, right? NOT! Parasitic drag begins growing rapidly above certain speeds in different planes, and in fact if the airspeed is doubled the parasitic drag is 4 TIMES what it was at half speed ( FAA Pilots Handbook Aeronautical Knowledge ). This is why double the hp increases the climb rate so much, because climbing is a function of excess hp over what level flight requires, and does NOT necessarily translate to alot higher cruise speeds.
Take 2 KRs: look closely at the attention to detail. The one that has the cleanest airframe, the slipperiest paint, the lightest weight, smallest wetted area, least drag producing anything, and he will be the fastest for a given hp of others. Troy Pettyway has one of the fastest KR2's, and also has one of the cleanest KRs. Brain Kraut referenced a book written on this very subject called speed with economy, and is well worth reading to provide even more information. Look at a Varieze, 100hp and 200 mph cruise. Colin Rainey Sanford, FL.
