The independent variable I believe would be the amount or number of paper clips that would represent the mass added to the paper airplane.
The dependent variable or the variable we are measuring is the distance the paper airplane was capable of moving. (After the respective amounts of paper clips were used for each flight).
The control group I believe would be running this experiment without any paper clips added to the paper airplane, to use as a comparison of what the expected distance the paper airplane was capable of flying.