Along with a couple of Tri-Turbofan toy blimps, one of the purchases for my early blimp experiments was a Plantraco MicroBlimp, which is the company's current offering. After ordering, I found out that it was too small to carry any useful payload, so I left it in the box until deciding to take a closer look yesterday.Plantraco seems to specialize in really small radio controlled aircraft. They tend to be somewhat expensive, but there are some cool designs. Their current blimp design bears no resemblance to the original Tri-turbofan except that it still uses 3 motors. However, these motors are really small - approx 6mm diameter. The motors may have been designed for pagers or cellphones - I haven't worked with motors this size, but they seem to have a lot of power. These seem to be similar in size to the pager motors sold by Solarbotics. Props are 45mm diameter (1.75"), and everything is attached to a very thin flexible circuit board (0.63mm or 0.025") that's been trimmed to shape. The entire circuit assembly with motors weight 8gm, and total weight with the lipoly 90mAh battery is 10gm. I really like the small motors - I'll have to get some samples from Solarbotics just to see how they compare with the larger N20's.
Two other interesting features - the battery pack uses magnets for the battery terminals, so installing the battery pack is quite simple. I read somewhere that they have a patent pending on this, so someone should do a patent search before taking the idea into production. Also, they use magnets for ballast - also a slick idea (more elegant than kids' eating utensils). Only problem with the magnets is that they will probably screw up the local magnetic field for compass readings, but still something to consider.
The blimp itself is 20" diameter, so it holds approx 2 cu ft of helium. I didn't bother to weigh the envelope, but would guess 20gm, so with electronics, the total package weighs 30gm. I had to add more than 20gm ballast to get neutrally buoyant, so there's a lot to be said for minimizing the weight of the motors and electronics.One additional observation - I don't really care for the 3 motor propulsion system for blimps, as compared with two motors plus a servo for thrust vectoring. However, the 3 motor approach is simple, light and cheap.
Plantraco does indeed do many things really well with their electronics integration, and that blimp PCB is a brilliant piece of work. But the magnetic attachment of the batteries is a disaster. They tend to pick up dirt and dust (especially ferrous grains) and then establishing electrical contact becomes a very hit or miss affair. I took some of the microplanes to the beach (as encouraged by their own videos) and although they flew brilliantly, they may never fly again because the contacts are now all gummed up with tiny bits of ferrous sand welded to those rare earth magnets.
A much better solution would have been to have magnetic physical attachment of the batteries, but traditional plugs for the electrical attachment. They can keep their patent!
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A much better solution would have been to have magnetic physical attachment of the batteries, but traditional plugs for the electrical attachment. They can keep their patent!