3D Robotics Comment by Chris Anderson on March 8, 2008 at 4:20pm

Awesome blimp! But $330 is by no means inexpensive--we're doing the same thing (modding a RC blimp), but starting with a 52" blimp that costs $15:
http://www.raidentech.com/skaiexairshs.html.

It doesn't look quite as cool as yours but at 4% of the cost we can live with the shark ;-)

That said, what you're doing looks very impressive, and I envy you your budget!

Comment by Howard Gordon on March 8, 2008 at 6:08pm

Actual cost of the blimp was $230 because I got it without the motor controller. If I were to start over, it would be even cheaper, because the only parts I ended up using from the kit were the blimp envelope, carbon rod, 3" props, and servo gears - the plastic gondola could be replaced by a cream cheese tub.

The bag that comes in the shark kit unfortunately does not produce nearly enough lift for my purposes (I already tried). In terms of budget, expenses are a relative thing - this is beyond the range of your $100 goal, but a LOT less than what I spent on the coaxial or quad flyers.

3D Robotics Comment by Chris Anderson on March 8, 2008 at 6:30pm

If you're just looking for an envelope with more lift, you might use this $23 one, which is the one we used for the Minimum Blimp UAV:

http://www.rctoys.com/rc-toys-and-parts/MACH-HLENV/RC-PARTS-BLIMP-HELIUM-BALLOON-ENVELOPE.html

Comment by Howard Gordon on March 8, 2008 at 6:52pm

I need about 200gm lift for the electronics, motors, and battery. So that requires about 7 cu ft of helium. Beyond that, I need enough helium to offset the weight of the envelope. The envelope I'm using isn't light - maybe 250gm, so it takes another 9 cu ft of helium just to lift itself. A mylar bag would probably be lighter. In any case, it is worth doing more research on this topic - we're probably employing less than $2.00 worth of raw material.

3D Robotics Comment by Chris Anderson on March 8, 2008 at 7:19pm

Ah. The envelope we use (the one linked above at RCToys.com) can lift about 130 grams. Our electronics are optimized for weight and power (our entire payload, including NiMh batteries, was just 80 grams) so we were able to use smaller and cheaper envelopes.

The next version, with a custom PCB and LiPoly batteries, will probably be just 60 grams, which will allow us to add all sorts of cool extras, such as wireless communications and cameras, without having to move to a larger envelope. One of the lessons we've learned about blimps is that weight is everything, and the lower the weight, the lower the cost, from the initial parts to the helium you use each time (to say nothing about the size of the room you need!)

Comment by Howard Gordon on March 8, 2008 at 7:42pm

My electronics, including the radio, processor and camera, only weigh about 65 gm total, so it looks like I need to put the rest of the components on a diet.

3D Robotics Comment by Chris Anderson on March 8, 2008 at 7:51pm

That's not bad at all. Our weight distribution for the version 1 blimp that we showed last week is as follows:

--Processor board, sensors, motor drivers and associated battery holders and supporting framework: 45 grams.
--Battery: 20 grams
--Motors, props and other wiring: 15 grams.

We can save at least 10 grams in the first category, and maybe another 10 in the battery by switching to a LiPoly.

Comment by Howard Gordon on March 8, 2008 at 8:02pm

It sounds like I could work with your envelope. For the moment, I'm set, but further down the road, I will look more closely at my weight budget.

Again, the purpose of this exercise was to create a stable platform that could be used for computer vision and autonomous robotic navigation algorithm development. I've gone through a lot just to get my computer eyeballs off the ground, but it seems like I might have finally reached a useful starting point for the work I had planned.

Comment by Gareth Farrington on March 9, 2008 at 1:16am

You can get some very light flight packs these days. We use 2S 300mah lipoly batteries for F3P indoor aerobatics. These are 20g. The small spektrum rx is only 3g. Each servo is 4.7g. An esc and brushless motor is about 18g-25g. So you can get a full house 4 channel foamy for 60g in flight gear. Runs for about 5 mins and is fully aerobatic. Like So:

http://www.youtube.com/watch?v=Ux497FTW_5M

I think you could get lighter than 60g on a blimp payload.

Comment by Howard Gordon on March 9, 2008 at 6:44am

Gareth -

What brushless motors do you recommend that weigh under 20gm ? For the blimp, we need reversible ESC's, though I just found this one - http://www.horizonhobby.com/Products/Default.aspx?ProdID=LOSB9530 - that weighs only 7gm.

For YARB Version 2.0, I will try the envelope that Chris recommended, as everything should be able to easily fit within its 130gm weight limit.

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