Self inflatable sculpture question: What amount of horsepower is needed ( how big does the wind powered pump need to be) ? The pump would most likely be made of a small converted gasoline motor.

Non - stretchy material. Tenara (made by Gore (gore-tex) http://www.tenarafabric.com/air-inflated.html ) if it's affordable enough and heat weldable (it is, UV proof, 25 yr lifespan). Almost air tight. No big holes like those jumping goof balls on the side of the highway.

A volume of 14 cubic meters and a surface area of 29 sq meters.

A wind speed of 10 knots.

Hopefully inflate from flat on the ground to full in less than 3 hours and stay inflated.

What if the wind increases to 30 knots?

50 knots? (assuming the anemometer style pump doesn't fall apart)

Horsepower requirement: anything above zero. Power is function of work done per unit of time.

Thanks for your brevity JS but can't say I feel any kind of satisfaction or clarity from your response. Not that that's what you had in mind.

I have pretty much already concluded it is completely possible and not because I have a wall of physics diplomas. Just "experience".

I think the trick will be to find a high volume, low pressure, somewhat efficient pump that spins in low rpms. If you know of anything like that I'd love to hear about it.

Thanks for your reply.

Not sure how you'd know what I had in mind. I was just trying to clearly answer your very specific theoretical question.

However, suspecting from your subsequent post that you're actually looking for details on the mechanics and/or source for such a pump...

Any size or power of turbine and pump could be set up to work, as long as it can sustain adequate pressure while pumping. It's just a matter of how long it'll take to inflate your balloon. I doubt you'll find a contraption already set up for your task, at least on a small scale, so you'll probably have to improvise:

1. Find any 'cup' or alternate type of turbine that you can attach a pully or gear to. Almost any size will do.
2. Find any functional piston or diaphragm type air pump. Impeller type pumps may not work because of stalling flow at slow speeds and (even slightly) elevated pressure.
3. Connect the turbine and pump with pulleys or gears, and experient with ratios to make the pump run as fast as possible without stalling against the expected inflation pressure, in the ambient wind speed.

A bigger, more powerful turbine will allow you to run a bigger pump and/or at higher speed, inflating your balloon faster, but it's not necessary. Even a miniature 'cup' turbine, connected with the correct precision gears to a tiny pump, will get the job done, albeit slowly. You'll only have a problem if your turbine is so small it can't even overcome gear friction at a ratio adequate to turn the pump, or if your balloon is porous, in which case 'slowly' might not overcome leakage.

There are way too many variables you haven't provided for anyone to specify all of the parts and ratios required, so you'll have to experiment. I suspected you realized that, so I originally replied with the intention of simplifying what could otherwise appear a complex question, like those trick school test questions which throw a lot of irrelevant parameters at you.

Once inflated, if your balloon is (practically) nonporous you won't need the pump to keep it inflated. Just clamp the nozzle and forget about the pump.

Cheers,
James

Now yer talking. I do have some cups around. Below are two machines I've made with cups. One has 100 leds that light up via home made generators. The other is a ball lifting machine.
Thanks for the very considered reply.

Looks very cool, familiar (BM, perhaps?) and effective for driving a useful air pump.

Btw, note edit/addition to my previous post.

JS, I started a mini version of BM in 1989 on a rooftop in Chelsea on 25th st between 10th and 11th aves. Huge parties, fires, beautiful women, moving sculpture, and many other extremes. A lot of fun. It moved to an island in the pac norwest in 1995 where it continues to run from June until August although in a more "august" kind of existence. So when the real BM comes around I'm a tad bit "burned out" although many insist I'm missing out. Maybe you were in NYC and made it to my rooftop?

Thanks again for the helpful info. And apologies for schlepping off of Spork's amazing achievements.

No apology necessary. I'm just using this thread to post occasional updates since this forum is where this project sort of started for us. I'm liking your kinetic sculptures and am happy for the thread to go wherever the wind takes it. If and when the new records are ratified, I'll post them here anyway.

I just got word that our upwind record of 2.1X wind speed has been ratified. It feels good to close that chapter.

Congrats Spork!