ORIGINAL: DAVID WILDE
I have built and flown the smaller 46 bobcat with wren 44 gold and i have 5 degrees of down thrust which i will be doing the same to the falcon 120. I believe the bobcat has about 7 degrees of down thrust.The reason for this amount of down thrust is two fold ,one so you don't burn your lovely covering but i suggest you ali tape it and secondly the increased thrust velocity under the flat bottom tailplane if was dead straight increases pressure under the taiplane giving a tail up tendency hence the reason for the down thrust to decrease this pressure and reduce pitching down tendencies.
David Wilde COLCHESTER A1 MODELS UK SELLER OF THESE MODELS
Nope, sorry. Plz no offense but you've got it exactly backwards.
Increased velocity across a surface decreases the pressure, pruducing "lift" on that side of the surface. That's Bernoulli's principle. It's how carburetors work. And sprayguns. And wings.
[link]http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html[/link]
So the high velocity airflow under the stab DECREASES pressure, causing a nose-up pitching moment. The Reaction 54 jet has same issues, fixwd same way.