Finally, a model hovercraft that can run for hours! I recently took this
craft on a 1/2 mile tour of Northwestern University's pathways and
sidewalks. I would have never bothered bringing a battery-powered craft
over to the campus - the run time is just too short when you're
using batteries. The model isn't very fast or powerful, but
it is a whole lot of fun and the nearly unlimited run time makes it a joy
to use.
The craft's performance is much better when the sun is high in the sky,
and needless to say, it only works on clear days. And watch out for shadows!
Solar cell specs: .5 volt, 2500 mA, 4.5 inch square. I used twelve connected in series to supply 6 volts,
purchased from Plastecs.
Motor specs: the 99 cent Radio Shack variety, labeled "1.5 - 3.0 volt, .98 amp max" but they work better at 6 v and draw as much as 2 amps.
Craft specs: 23 inches by 14 inches, two 4.5 inch props, 1 1/3 inch hover height.
The lift and thrust motors are powered in parallel by the solar cells. The radio receiver and servos can be powered off the solar cells or four optional AAA or AA batteries.
I'm considering a manual battery powered override so that the craft can still hover after it goes into shadow. Ideally, any batteries carried by the craft would be recharged by the solar cells, but in reality, I suspect the recharge time will be too long to be very helpful.
Alligator clips (visible in the photos) and velcro strips are currently being used so that the solar cell "roof" is removable to lighten the load for optional battery powered
operation.
Update:
I just tested a scaled-up version of the craft
described above which uses 12 additional solar cells, bringing the total to 24. The performance is much better! In
full sun, both motors got up to their top rpm, and the craft really zipped
along. When the sun went behind clouds, or when the craft was in partial
shadow under trees, the craft continued to hover at reduced capacity. That's what I
was looking for! Dimensions: 35 inches by 19 inches. Everything else is the same as the smaller craft (same motors, same hull design, same props, etc).
