Converting a Silo into a Wind Tunnel

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So I've got this crazy idea that is probably WAY too expensive and not at all feasible, but I thought I'd put it up here anyway and get some thoughts...

I just bought a house w/ 15 and a half acres of land on it, some barns and this wonderfully tall silo... it's very wide inside and it's not going to be used by us. Wouldn't it be nice if we could convert it to a tunnel?

How could I do such a thing? From what little knowledge I have, I'd need...

1. some source of wind, so an engine, probably on top, to suck, so I'd have to take the cap off, it's also have to have a power source, controls and all of that...

2. I'd have to dig out under and provide some sort of intake so there was a source of air

3. the interior is just cement so there would have to be some sort of lining for safety, right?

4. I suppose some sort of netting or wire mish up top and below to prevent going into the fan or into the intake.

What else? What do you think such a conversion would cost, if it was even possible?

Oh, the dreams of a madman... pic of silo attached.
edit to add second pic, taken atop a 30 foot grain bin

I miss Lee.
And JP.
And Chris. And...

[PhreeZone 15]

The cost to retrofit a structre to a new purpose is almost always higher then the cost to build new. Current costs on a Skyventure setup is 3-5 million if I have heard rumors correctly. Something like a FlyAway pusher setup is less, but its also less attractive from a skydivers point of view.

Honestly, some of the best uses I've seen for old silos is outdoor ice climbiung structures in the winter. In the summer they turn them into climbing walls.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

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The cost to retrofit a structre to a new purpose is almost always higher then the cost to build new. Current costs on a Skyventure setup is 3-5 million if I have heard rumors correctly. Something like a FlyAway pusher setup is less, but its also less attractive from a skydivers point of view.

Honestly, some of the best uses I've seen for old silos is outdoor ice climbiung structures in the winter. In the summer they turn them into climbing walls.

Climbing wall! that's a great! idea, and it wouldn't cost much at all!

the flyaway push-up would cost less, but more excavation work I think. plus, dropping in the motor form on top and all... oh well, just a pipe dream really...

but the climbing wall, THAT my friend is a rad idea!!!

thanks dude!

I miss Lee.
And JP.
And Chris. And...

[JohnRich 4]

Paint it flesh-colored to look like a giant penis.

Then let women climbers climb all over it.

Charge admission to men to watch.

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Paint it flesh-colored to look like a giant penis.

Then let women climbers climb all over it.

Charge admission to men to watch.

and people accuse me of having penis envy now!

I miss Lee.
And JP.
And Chris. And...

[PhreeZone 15]

Off topic for this fourm, but contact a local climbing club or two and talk to them if you are not a climber. There is a lot of things that need to be considered for a safe climbing environment. Lots of clubs are willing to donate time/material to a place they can come to for free or club dues also.

The Ice walls are something I'd love to try once.

Yesterday is history
And tomorrow is a mystery

Parachutemanuals.com

[daniel_owen_uk 0]

Isn't this forum partnered with www.rockclimbing.com? Surely that would be the place to go for a start?

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[Eule 0]

I think that it probably wouldn't be economically feasible, but it's fun to think about. It's sort of in the same league as sitting around the DZ in the evening, drinking beer, and trying to figure out how big of a big-way you could launch from a Super Guppy or how many loads per hour you could get with an SR-71.

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1. some source of wind, so an engine, probably on top, to suck, so I'd have to take the cap off, it's also have to have a power source, controls and all of that...

Your options here are probably one or more piston engine(s) or electric motor(s). The exhaust from a turbine would be too hot to use directly; if it would be _really_ expensive to string new electric lines to your silo, it _might_ be feasible to use a turbine and a generator to make electricity. Most commercial tunnels seem to choose electric motors, probably because they can be run efficiently at a wide range of speeds and are fairly reliable (many fewer moving parts than an engine). If you wanted to run a piston engine, you'd probably want a big diesel, as they are slightly more efficient than a gasoline engine. I think the portable wind tunnels often have diesel engines.

As to how much power you need, I seem to recall a figure of 1200 hp (900 kW) for one of the tunnels. To put a rough number on it, Grainger (not the cheapest place to buy motors, I know) sells a 250 hp (188 kW) motor, no. 5N354, for $11,754; five of these would get you 1250 hp for just under $59,000. Then you get to buy the variable frequency drives for them - Grainger 5HV34 will run a 125 hp motor for $13,412, so ten of those would cost just over $134,000. You also probably get to buy 1000 kVA or so of power transformer, plus wire, conduit, etc. For a diesel, a price I found here on a _rebuilt_ 250 hp Caterpillar diesel engine is $9695, or $48,475 for five of them. You will also get to buy an air filter, radiator, fuel tank, etc.

Putting the power source on top is not something to take lightly. This means that your structure has to support the weight of the power source and the fan(s). The electric motors above weigh about 2,000 pounds (910 kg) apiece, so your structure has to support at least 10,000 pounds (4550 kg) fairly high up in the air. I don't know what the diesel engines weigh but I suspect they might be slightly lighter. Putting the power source on the ground is probably a lot cheaper in terms of construction costs.

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2. I'd have to dig out under and provide some sort of intake so there was a source of air

This is probably the biggest problem you have. If you dig out too much, the silo will fall down, and adding reinforcement to keep that from happening is not easy. One alternative would be to make lots of little holes in the silo wall down low, but this would also weaken the walls and create a lot of air restriction besides.

You might be able to use a "tube inside a tube" design - go to Bodyflight Bedford's site and click on the "our facilities" tab (no direct link possible as it's all in Flash, ugh) to see one example. That tunnel is completely recirculating; it might be slightly easier to have a total-loss design. One advantage to doing this is that the diameter of the test section is smaller, which means that you don't need as much power to move the air. The 180-degree turn that the air has to do at the bottom might be interesting, though. See the attached cross-section sketch. It's not in the sketch, but to get into the test section, you'd climb some stairs outside the silo, go through a door in the outer wall, across a walkway, and through a door into the test section.

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3. the interior is just cement so there would have to be some sort of lining for safety, right?

If it's rough concrete you might want to smooth it. IIRC, the walls are just smooth concrete once you get above the glassed-in area in SVAZ.

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4. I suppose some sort of netting or wire mish up top and below to prevent going into the fan or into the intake.

You'd probably have to have at least the mesh below. You probably need the mesh up top if you have a sucker, but you may or may not need it if you have a blower.

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What do you think such a conversion would cost, if it was even possible?

See above for some of the costs. Another idea would be to spend much less than the above on some pumps, pipes, water tanks, electric lights, and a generator with a really good muffler. That way you could grow plants inside the silo. I hear that if you choose the right crop, you can make enough money to afford quite a bit of tunnel time.

Eule

PLF does not stand for Please Land on Face.

[AggieDave 6]

Firstly, you drew the beer fridge MUCH too small.

Secondly, the silo into an indoor rock climbing gym thing has been done around the country. Its been done VERY succesfully too. Maybe you can turn it into a money making venture, put up the capital for conversion and let someone start a business with managing it.

The obvious downside is liability.

Side note: Who says you have to have a skyventure. You could basically build an old school push tunnel and still have fun. It would be loud as hell and expensive to run a huge diesel engine like that, but it would definately be interesting.

--"When I die, may I be surrounded by scattered chrome and burning gasoline."

[micro 0]

That post was fantastic!!! A thousand thanks for the time and energy you took, not only for the post, but for the cool drawing too! That was really great of you!

I miss Lee.
And JP.
And Chris. And...

[Eule 0]

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That post was fantastic!!!

Thanks! At SiloTunnel, we always enjoy hearing from our customers. AggieDave's suggestion has resulted in a revision to the original design - see attached.

Eule

PLF does not stand for Please Land on Face.

[mdrejhon 8]

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Thanks! At SiloTunnel, we always enjoy hearing from our customers. AggieDave's suggestion has resulted in a revision to the original design - see attached.

Priceless! Now, that's a windtunnel I'd go to, even if it was just a cheap push-tunnel.