With my guidance, you will create paper model jet engines for use on the mono and biplane.

Step 1: Cutout

Cut the paper at the 2 inch mark. Save the scraps for the prop and bearing.
Wrap the paper over the bottom of the marker, and tape. Mark the wide and narrow ends.
Measure the diameter of the wide end, and cut a square out of the scraps so that the length of side S = diameter of tube W

Step 2: The Paper Clip--Part A

Bend the top of the paper clip, and bend the point back out. Attach the bearing(See my monoplane and biplane instructable for detailed instructions on the bearing).

Step 3: The Prop

Puncture the center of the square with the paper clip.
Cut out tabs. Bend tabs down. Insert the point of the paper clip through the prop.

Step 4: The Paperclip--Part B

Tape the end of the paper clip so the prop doesn't fall off.
Clip the clip to the narrow end of the tube so the point is inside, and pointed towards the wide end. Look down the tube, and notice any edges of the prop touching the tube. Remove the clip and snip away slowly at the prop until it can spin freely in the tube.