Based on our experiments so far the blimp envelope supplied with the blimpduino project has a payload capacity of about 120 grams when fully inflated. The blimpduino board weighs just about 80grams by the time we add in some velcro to hold it to the envelope. The wireless camera we are using has an internal lipo battery but even when pulling it out of its case it still weighs about 70 grams. We are about 30 grams over weight. We need to shave some weight off somewhere or get a larger envelope.Envelopes that are 52 x 37 inches are commercially available. I believe the blimp envelope supplied with the blimpduino kit is 52 x 27 inches. (Will have to measure it to be sure.)Another possibility is that the helium we got from the Party City Helium balloon kit is not very pure.We could also pull the lipo off the camera and run it from the one of the cells on the blimpduino board. The camera only pulls about 30mA so load balancing issues shouldn't be that bad.What sort of payloads are folks getting out of their envelopes? It seems like the 52 x 27 is the most common size. There are also 66 inch envelopes available commercially, has anyone tried one and can give an idea of the payload?I have an extra 52x27 envelope and I suppose we could just velcro the two envelopes together to give increase payload, but that would really increase the inertia of the system.Alternately, maybe I should find a lighter camera?Ideas folks?Thanks!mmasonmtsacflight.blogspot.com
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Ok, so after making some measurements, the envelope plus blimpduino board plus the balloon envelope weigh 94 grams. This leaves us with just about 26 grams of payload. (Our RC receiver weighs just about that so the blimp is barely neutral with the RC reciever attached. What ever camera system we use should weigh less then about 26 grams total.
I have ordered the 36" envelope. This should give us an additional 160 grams or so of payload (assuming rho air is 1.2 kg/m3 and rho He is 0.18 kg/m3. Since 27^2 is ~730 and 36^3 is 1300 we should get about 1300/730 = 1.7x the payload. Of course as a practical engineering approximation we should hope for 1.5x since the balloons aren't perfect cylinders.
According to the website, the 27inch holds 5 cubic feet and the 36 inch holds 7 cubic feet. This does not fit with my calculations at all!
Before you get a bigger envelope, with the cost (both of the envelope and the helium) and the larger room, you might want to look for a lighter camera. 70 grams is very heavy. Have you considered cameras like this, which weighs about 8 grams?
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Bigger and high end one is way better but they cost two or more times than of ordinary or unbranded one, at least but it is safer.
Regards.
Tomm of http://www.digitekprinting.com/.
I have ordered the 36" envelope. This should give us an additional 160 grams or so of payload (assuming rho air is 1.2 kg/m3 and rho He is 0.18 kg/m3. Since 27^2 is ~730 and 36^3 is 1300 we should get about 1300/730 = 1.7x the payload. Of course as a practical engineering approximation we should hope for 1.5x since the balloons aren't perfect cylinders.
According to the website, the 27inch holds 5 cubic feet and the 36 inch holds 7 cubic feet. This does not fit with my calculations at all!
We also had better fill the 110 liter helium tank.
Ordered:
http://www.rctoys.com/rc-toys-and-parts/MACH-HLENV-SILVER/RC-PARTS-...
Will report on the new payload when it arrives in a week or so.