You could put these under and on the sides of the
and sync them so the viewer sees a propeller that's
apparently spinning quickly so it's obvious that it's
but not so fast that it's just a blur.
The strobes would be aimed at the sides and bottom of
out of the pilots line of site but at the
areas most likely to have people walk into them. The
strobes would also somewhat illuminate the surrounding
area so people facing away from the
airplane might get some warning.
It would be easier to do than putting lights on the blades
and might do a better job.