hi  do take the time when building a new plane to glue the balsa under the control horns-i make holes with pins below the horns-soak with thin  CA and install the horn(-we are talking having our planes hold up for many flights with the tips here )-if this is not done the horns will damage the balsa below them and get loose or danage the balsa at some time in the future - the CA will also prevent damage from any possible  fuel soaking in this area -another major source of airframe balsa damage-assuming the plane will be flying a long time that will happen    fuel soaking does apply to glo powered airplanes  i will be adding many more tips to this form as i do aprox 75-100 special proceedures to evey plane i build after 24 years of constant build and flyingi still fly my 40 size midwest sweet stick that was my third plane built 20 years ago -with about 450 flight on her and just freshened up by me last month-i just built anheadral into that planes wing (after reading an artical on the subject ) -and it fly better than it ever has in the past with its straight wing-but thats a whole other story and post