More interesting use of clear payload bays....
1) If you are into "forrest mims" types electrical projects... how about connecting a solar cell to a small rechargable battery (or maybe a capacitor) and then launching it (at noon with sun directly overhead and with some spin on the rocket to keep the cell from always pointing the same direction). measure the voltage in the battery before and after the launch (and recording the number of seconds between these two measurements). Now discharge the battery, and repeat the test but with the rocket just sitting vertically on the ground for the same number of seconds. See if you can get more charge from getting higher in the atmosphere ?
2) build a circuit to count pulses or a timer to time the pulse interval and launch in the morning or evening with a CdS light sensitive cell in the payload to count spin rotations during flight as the cell "sees" the sun as it rotates on way up or down
3) build a mechanical accelerometer in the payload section: put a vertical metal pin/wire in the center of the payload running top to bottom of payload. Thread a spring from a "clicker" ballpoint pen on the pin and then thread a cork disk onto the pin so that it "rests" just touching the top end of the spring. Make sure the cork disk does not slide freely on the pin, but "sticks" in place slightly. Use 2 chutes on the rocket, one for payload and one for the body tube (no shock cord to connect the parts) With the thing assembled on the pad, look thru the clear tube and draw a line on the tube at the top of the cork disk. When you launch, there is a big upward G force - the mass of the cork will push "down" onto the spring as a result. This will compress the spring slightly and the stickyness of the cork (might?) keep the spring compressed until you recover the payload. Re look at the payload section and see of the top of the cork is now lower than before the launch. Launching the same rocket a couple times to see the compression on a B6-4 and then on a C6-5 you (might?) see that there is a higher G force measured on the C6-5.....
-Kerry