Build a balloon powered vehicle

[NeedsHelp1212]

Im not sure where to post this thread, so its ok if you move it. But anyways, for extra credit in physics ( and i need these points really bad) we have to create a balloon powered vehicle. In other words as air is released from the balloon, it propels the vehicle forward. I need mine to go the farthest to get the most possible points. I have got some good ideas but I am fine if anyone has done this before and has some good ideas as well. So I would appreciate any insight or advice, Thanks !

 

[Danger]

Run a forum search right here on PF. This subject has been addressed in the past, quite extensively.

 

[NeedsHelp1212]

I did a search and went through like 5 pages with no luck. Could you please give me a link? thanks

 

[Danger]

I'll try to find one in a bit. Right now, I'm kind of busy. I will start with "air powered vehicles" and see what turns up.

 

[Frannas]

Idea: attach the balloon to a CD so that the outlet of the balloon blows through the hole of the CD. Blow up the balloon, place the CD flat on a smooth surface (with the balloon facing upwards) and let loose. It's like a mini hovercraft.

 

[NeedsHelp1212]

Idea: attach the balloon to a CD so that the outlet of the balloon blows through the hole of the CD. Blow up the balloon, place the CD flat on a smooth surface (with the balloon facing upwards) and let loose. It's like a mini hovercraft.

i don't see that working. The CD would just be flat on the ground? I think for our design to be "legal" it has to be made completely from household materials put together. For example what my group is doing is as follows; we are using an 8 by 10 inch piece of card board as the base and connecting two straws across it at both sides (taped down). Through both straws I will place a skewer with large bottle caps at the end of each that will be the wheels. I will then take a balloon and place a rubber band around it and stick a bendy straw out of it ( this is where the air will come out of). Tape the balloon down with the straw facing the opposite direction you want the vehicle to go. I got this idea from a youtube vehicle, we tried by putting it together yesterday but did not have the skewer so it didnt go. Hopefully it works after we get that material

 

[Frannas]

the CD will not blow away from the ground because the moving air underneath the CD forms a sort of vacuum which "clings"the CD to the ground, but lifts it off the ground enough so to minimalize the froction between the CD and the gound. with this in mind you can attach a nozzle that splits the air from the balloon, with one airflow going to the opening of the CD and the other will the be used for propelling the CD across the floor. I tested it myself and it worked very well. a CD can be considered as a household product because I don't know of any hose that hasn't got a CD of some sort in it.

 

[Frannas]

go to youtube and type in "CD hovercraft".

 

[Danger]

You guys seem to be missing the point. Hovercraft have nothing to do with the question in the original post. Needshelp is asking about linear acceleration of a toy vehicle which is powered by a balloon. Any hovercraft suggestions are irrelevant.
Needshelp, I apologize in that I was sidetracked from investigating further as to searches. In lieu thereof, I can say that there are essentially two approaches to the matter. You can try to develop a most efficient nozzle and use the balloon as a pressure source for a rocket engine. Secondly, you could blow the air through some sort of turbine or pinwheel or whatever in order to gear it into a driveshaft. The last thing that comes to mind, which would probably be terribly inefficient and not thought of by anyone else on the face of the planet would be that the physical contraction of a balloon as it deflates could influence something like an elastic harness and somehow impart that relaxation of tension into an axle mechanism.
The foregoing is a pretty good example of why I don't post often.

 

[sophiecentaur]

You could modify a CD hovercar by cutting a slot and directing some of the air out along the slot. That will give you a directed drive and a low friction vehicle. Best of both worlds.
With such a small amount of energy as you have in a balloon, you have to be very inventive in using the energy efficiently. Turbines and gears all waste energy and you have to 'match' the source to the machine well, to get efficiency. If you don't like the hovercraft idea, or think it's outside your remit, you could still consider 'jet propulsion' by using the air directly from the balloon as your propellant.

@Danger - I like your idea of using the 'elastic' of the balloon directly. It sounds quite well matched to the needs of a driven wheel system. Finding the right basic shape of balloon would be crucial.
Your "I don't post often", along with your total of 7417 posts indicates that you may have as much time to waste as I do, along with my bursts of addiction to this website! :)

 

[Danger]

Your "I don't post often", along with your total of 7417 posts indicates that you may have as much time to waste as I do, along with my bursts of addiction to this website! :)

Well, if you count GD I'm probably closer to 10,000 posts, but my point was that I don't have any formal education so I generally respond to only things that I'm fairly confident about. (And I've been here for something like 6 or 7 years, so it's a low average.)
As for wasted time... I'm unable to work, am on Social Assistance, and still have not gotten around to applying for AISH. All that I do all day, every day, is watch TV and either visit PF or smack orcs around on "Adventure Quest". That's a bit irritating and disheartening, in that I used to read sometimes 2 books in a day. Out of my 2,000 or so books, almost 1/3 of them are still in my house, as opposed to the C-can in my yard that holds everything else. Now that I have cable, though, I just can't get around to reading. That shames me, in a way, but makes it easier to relinquish my grip when I have to move into an assisted-living facility in a few months.
There's more to be said, along that line, but I don't care to say it now.

I like the idea of slitting the disk to make a forward impelled hover platform. Directional controllability will be very problematic, though.

 

[sophiecentaur]

Sorry to read of your circs. What can I say? I'm sure you would benefit from taking up reading again. I always have one or two books on the go but, luckily for me, I am fairly busy although retired and I can't get through them very fast. Just bought a book of poetry by Philip Larkin. Brilliant and he's such a grumpy old sod that I feel very positive compared with him. - he shows a dislike for nearly everything in the world but is a very entertaining writer.
PF is a pretty useful activity so more power to your elbow, in that respect. See / read you around.

 

[Danger]

PF is a pretty useful activity so more power to your elbow, in that respect. See / read you around.

Cheers, mate. PF is my home away from (actually, within) home.

 

[mrspeedybob]

Does "balloon powered" necessarily mean air pressure powered? If not you could use the balloon like a rubber band. Attach one end to a fixed point and the other to a drive shaft. Then you have a wind up vehicle.

 

[NeedsHelp1212]

Well we had the competition and i got 2nd place within my class. Not sure how many extra credit points i got. But hopefully enough to take me from that B to an A. I am pretty mad though because people told me I should of blown up the balloon more. At home when I did it went another 5 feet then what happened at school. Oh yeah at school it went 13.5 feet, while right now i can get it to go 18-20 feet. Whatever mostly everyones else went to the right or left after a couple feet and hit the wall

 

[Danger]

Congratulations for your fine finish. What design did you end up using?
It's always easy to criticize from the outside and after the fact. Unless replacements were allowed, over-inflating the balloon could have resulted in bursting which would have left you with no power source. In that case, being conservative with your breath was a prudent move.

 

[NeedsHelp1212]

Congratulations for your fine finish. What design did you end up using?
It's always easy to criticize from the outside and after the fact. Unless replacements were allowed, over-inflating the balloon could have resulted in bursting which would have left you with no power source. In that case, being conservative with your breath was a prudent move.

I ended up using a piece of cardboard with two straws on both ends with skewers going through the straws to acts an axle for the wheels ( we used bottle caps as wheels). Then we taped the balloon down so the air came out the opposite end we wanted the balloon to go.

 

[Danger]

I ended up using a piece of cardboard with two straws on both ends with skewers going through the straws to acts an axle for the wheels ( we used bottle caps as wheels). Then we taped the balloon down so the air came out the opposite end we wanted the balloon to go.

That's pretty much the design that you originally suggested yourself, so you essentially achieved success without help. Good job!