The top picture, the M17A1 white star, contained a
parachute-mounted candle case on its upper end, with a 5.5 second
time-delay fuze and 15 grain smokeless powder propelling charge in the
tube above the stabilizing fins. The signal could rise above 600 feet
before igniting, producing a 20,000 candlepower signal for 20 to 30
seconds. This was also useful for battlefield illumination.
The bottom picture, the M18A1 5-star signal, essentially produced 5
star signals, but in free fall. The parachute kept the fall rate to
about 7 fps, so the flare would extinguish several hundred feet above
ground. The 5-star signal lasted for 4 to 10 seconds, extinguishing
finally at about ground level.