Pressure/inflation Problem [pics]

[5point0]

Hello- i would greatly appreciate any advice from some fish tank experts. I realize this is completely not related to aquariums but am here to seek some info.

Im an industrial design student trying to figure out how to inflate a blimp with 7 ballons. The goal of the project is to articulate a 6" cube into an object (my blimp)-- limited to everything fitting within the 6" cube.

So far, I have a frame that telescopes out to 30" with 7 ballons attached to it.

Frame + 7 balloons + tubing:

I've attached fish tank T-way connectors to a network of tubes (0.25") so that ideally, all the ballons would inflate at the same time when i connect one tube from that network to a helium tank (2000 psi).

balloon configuration:

larger image HERE

The goal would be this:
Frame + Inflated balloons study model

(the 7 balloons will lift an under carriage inside the base)


My questions:
(1) only 2 out of the 7 balloons inflated. is there a concept of pressure/inflation that i am not understanding?
(2) how can i regulate the pressure so that all 7 would inflate at the same time? I bought an aquarium gang valve (2 1/2 way valve)... would that help this problem?
(3) does anyone have a recommendation for a simpler system?


I hope ive explained this well enough (lack of sleep...etc.) Thank you in advance to anyone willing to help.


jon.

 

[hoarp001]

You do know this is a forum for aquariums... you know, glass tanks with water and fish...

How does this have anything to do with fishforums, surely you would be better off on some engineering forum

ask yahoo answers...

I might be able to help anyway...

Balloons are made by dipping a metal form into liquid rubber. Some balloons may have a thicker skin than others, and if this is the case they will not inflate. The best/only way to fix that would be to run high pressure aire along the air lines (about 50psi or so) then have a regulator at the base of each balloon. This would ensure that each balloon received the same ammount of gas at the same pressure, rather than allowing the stronger balloons to s imply push the gas back into the others...

You could also have one single pipe branching off into 7 llines, each with a non return valve. The pressure behind the valves would be the same, so any that went through the valves i nto the balloons would not be allowed to es cape back.

 

[anodized]

i looked up balloons on wikipedia, this is what i found.

the pressure required to inflate a balloon is inversely proportional to its diameter. that means those little animal balloons are harder to inflate than big ones. but i think it would also mean then that to initially inflate a balloon is difficult (requiring the most pressure) and once inflated, becomes easier.

the gang valve will modify how quickly gas can enter the balloon(s), but not the final pressure they will sit at.

do you have a fixed number of balloons to work with? part of the challenge may be to find 7 balloons that inflate at the same pressure, assuming they all have to be inflated at the same time on a single line as designed.


sure this post is off topic but its related to the hobby in a way that we all like to tinker with gadgets and such.

 

[Tolak]

I've been looking into air systems for fishrooms for a while now, a centeralized pump is being planned for. Your group A/group B design could be the problem. With longer runs of pvc hooked to a large air pump, you have to have a line returning, creating a loop. If not, there is a pressure drop at the end of the line. Air will follow the path of least resistance, if one of the balloons is easier to inflate, it will inflate that one first. I have too much experience blowing up kids balloons for parties, getting them started is tough, once they start to inflate it's easy.

So, try a loop for all the inflation points, and find some way to contain the maximum size the balloons can reach. Plastic fish bags with some holes punched in them come to mind for size containment, light, cheap, and will fold down to fit in your cube.

 

[5point0]

Thank you for all the informative responses.

Balloons #3 & #6 were the only ones that inflated.

I will try out some of the suggestions; i will, however, have to keep the system light so that the cube will rise once the balloons are inflated.

Expect pictures of the completed project. Now to continue the streak of not sleeping!

 

[mr.dark-saint]

Hot pink toe nails and man hands aside. What you need to do is to have a "gang valve" with adjustable air flow since the ones close to the source will fill up faster so you'll need to restrict this so everything else gets equal pressure. You can buy the plastic ones but it's not the best and the brass or chromed out ones are harder to find but made better.

Also, the last one doesn't need to be recirculated back just plugged (as in, straight line set up). Or a full circle since all the inlet will have an adjustable flow you'll have to tweek it out. Remember to restrict the close ones and loosen as you go outwards .