Hi,

It seems that you want to MOTIVATE your student to think and USE physics, not just solve textbook problems.

#1 What is your budget?
#2 Are land vehicles an option?

You have several viable options:

#1 build one gws slow stick as a class and have groups of students design modifications for the airplane
#2 get a $30 air hogs havoc heli and have your students measure lift, speed, runtime, design modifications and test them

You could save yourself a lot of trouble and assign your class a land based vehicle design project.

Purchase two 4-channel radios and a bunch of used servos off of ebay. Have your students design circuits and build rc robots/vehicles that will shoot each other with electric airsoft guns. Have your students take a trip to the local printer/scanner recycling center. There they can find belts and gears for your projects as well as motors and belts from cd rom drives. They can also learn about how electronics are recycled. Better yet, assign your students a project: design and make SOMETHING from using as much parts from old printers, scanners, stereos, etc.

The cost to each student would be as low as $50 if it is well planned and further reduced if the kids work in groups.