LMML: Sounds like it had a gas turbine then!
Ducted fans powered by two cycle engines don't sound anything like a jet - more like an overreving motorcycle!
Models don't have trim tabs. The radio transmitter, however, has a small trim wheel for each channel(throttle, rudder, elevator, and aileron). Trimming is accomplished by moving the entire control surface the necessary amount by using the trim wheel for the appropriate channel.
Say your plane is slightly nose heavy, and you find yourself having to hold back stick pressure in order to mantain level flight. If you move the elevator trim a bit, the servo will apply a bit of up elevator and leave it there while the stick is still in the neutral position. It works exactly the same way as the trim control in computer joysticks.
Btw, do you know if that F-18 had brakes? They probably need an arresting gear to stop that thing!