Water Tunnels useful?

[HELModels]

I'm wondering if a Water Tunnel might be an easy and useful tool for a modeler to visually extrapolate how a wing will behave in air. You could build a smaller model and use slower denser water and some pixie dust or something to see the lift and drag.

1) Is this easier to implement than a wind tunnel?

2) What are the reynolds effects?

3) I dont know, you tell me.

4) could water tunnel be useful to aeromodelers?

[raptor22]

I would think that a windtunnel would be MUCH easier (fans vs pumps), but most (all?) modelers don't have the time, money, and experience to build a good wind tunnel. Or water tunnel. Its very difficult.

That said, since we are at such low speeds, I think you could probably mess with velocities and so forth to get the same RN, and acceptable results.

--Alex

[Ollie]

All you need is a water proof model and a swimming pool. To swim (fly) the model in the pool, you trim the model with weight and buoyancy. The density of water is about 790 times the air density. Look up the two viscositys. Measure the time and distances swim of the gliding model from the bottom to the surface of the pool. You can calculate velocities (V and H) and the L/D. You swim the model upright or inverted, depending on negative or positive buoyancy. It can be fun.

[Sparky Paul]

"Mythbusters" used a water tunnel to determine why a tail-gate up pickup had less drag than a tail-gate down pickup.
They tried dyed water first, but the results weren't useful.
With styrofoam beads, the entrained bubble behind the cab, tail-gate up, became obvious. Also it's non-appearance tail-gate down was obvious.
The practicalities for model use would be slim though.

[HELModels]

That Was where I saw it! I saw an episode once where they used a scale model of San Francisco Bay to model possible escape route from Alcatraz.

I like the flying underwater idea, as does mother nature. Got an old fish tank, but that wouldnt work too well. Oh well, dream on.

[Ollie]

The water model size is about 1/10 the size of the air model.
The water model velocity is about 1/10 to 1/100 the velocity of the air model.

[HELModels]

1/10, that is way smaller. Maybe I could do something with that fishtank. If what I'm trying to look at is small at full scale, then 1/10 at 1/100 the speed might work in a fishtank. Hmmm. I knew I didnt toss that tank for a reason.

[Guille]

Shall you know that water behaves as air in supersonic speeds even taking into account taht does not change density.
You can build a not calibrated wind tunnel for general testing; mean: just to get an idea of "how the stuff works"... add a little smoke also!!!!
Remember that the fan must be placed "sucking" air instead of blowing it; also the model's chambe must be closed.
regards
Guille

[ElectroLawndart]

All you need is a water proof model and a swimming pool. To swim (fly) the model in the pool, you trim the model with weight and buoyancy. The density of water is about 790 times the air density. Look up the two viscositys. Measure the time and distances swim of the gliding model from the bottom to the surface of the pool. You can calculate velocities (V and H) and the L/D. You swim the model upright or inverted, depending on negative or positive buoyancy. It can be fun.

When I was a kid, I used to take my 1/32 scale Revel plastic models, put some lead in the nose and take it into the swimming pool. Shake out all the air and let them glide to the bottom. Swimming in formation with a model P-51 was just like the real thing to an 8 year-old. :D

Dart

[HELModels]

Flying a kite attached to a raft, or using a piece of drift wood to tell time was more my style.
My only time spent under water was when a wave would crest and pull me under. Rip currents would really get the adrenaline going.

Anyway, I think the junk tank would serve a more useful purpose as a way to cure epoxy.

[ElectroLawndart]

Anyway, I think the junk tank would serve a more useful purpose as a way to cure epoxy.

Huh? How do you use a fish tank to cure epoxy? I'm always looking for cool ways to build. Hopefully it involves getting more equipment. :rolleyes:
<sigh> I'm such a geek. :D

Dart