ORIGINAL: Carl.E
Equations are great, but they don't take full-power dives into account.
200mph from a power dive I could see.
You're right, equations do mostly not display the real in-flight situation. Each plane/engine/pipe/prop combo gives different results, sometimes much differing from the performance expected.
However, I personally do prefer the trial end error method and lots of practice. But in that particular case i found the theoretical approach being a good argument
Here's an example to achieve good maximum speeds.
http://www.rcuniverse.com/forum/220_...2001757/tm.htm
Post No. 13 of that thread also explains why an airframe like Diamond Dust or Whip is not well suited for ‘high speed’.