That's a good point. Let me give you a few reasons, or maybe just rationalizations:
1. Ease of starting. Many of the old
Cox RTF (plastic nastys) had inverted engines, per your thinking, and later retrofitted to upright (
for my reason). One prime example was the
Little Stinker, of which I had an original with the inverted PeeWee. It taught me a lesson that has lasted a lifetime. Later
Little Stinkers had upside right engines.
2. Engine experts on this forum and others have testified that these engines put out the most HP with the cylinder up. Sounds illogical, but I accept their word.
3. I have a strong suspicion that I might fly the
"model with the gear retracted" as we say. Hardly cricket on a Great War bipe, but appropriate for an aircraft that could, in reality, pull up it's feet.
-------------------------------------Bellcrank Mount ------------------
I always try to put the bellcrank and leadouts on or near the vertical CL of the model, and also square with the control horn. If that requires an extra pice of 1/16" plywood, so be it.
Also, I religiously support both ends of the BC axle, even on tiny models.
-------cowling --------------
ps:
It's symetrical and round. With a little paint work I could easily rotate it 180 degrees for the next contest, if the jury bombs me for the upright engine.