Antenna wires that are too flexible to stand up on their own are threaded through a plastic antenna tube which keeps the antenna wire from falling over onto the ground. The tube is then poked up through a hole in the body of the RC.
To make it easier to thread the antenna wire through tubing, you could lubricate it with a touch of oil -- but oil can become sticky and does attract dust and dirt. An alternative lubricant is talcum powder. Put a little in your hand, hold the antenna and draw it through your hand to coat it. You could try sucking the antenna through the tube. Or, suck a piece of thread or dental floss through the tube, tie it to the antenna, then pull on the thread or floss pulling the antenna through the tubing.