siphon ballast idea

[Scott T]

For very small subs with no room for pumps would something like the diagram work to
empty the ballast? Just need to be able to open or close vent valve and move forward.

1. vent closed / tank empty / check valve closed - surface running
2. vent open continuously submerged running
3. vent closed / check valve open - by vacuum / forward motion - siphon empties ballast

[He Who Shall Not Be Named]

Your siphon dumps into a venturi? You want this thing to work like an eductor it looks like.

M

[Scott T]

Yes a eductor is what I was thinking of.

[trout]

Hmmm, Scott again you are a thinking man. I am just rambling off what is going through my mind, not saying it will or will not work. For a Venturi effect you would need speed because it would need to pull the water down enough to let the air in. Right? If the wtc is in the hull it would be protected from the motion of water going past the check valve so it would need to be mounted in a way for ducting to draw water in and guide it past the valve while increasing the power (bring water in from open torpedo doors and then narrowing the path over the valve) to pull water out and draw air in. The air intake would need a one way valve to allow air in and not out although the way you have drawn it maybe not. I don't know. How much flow through the venturi is needed to draw air in?
Your description does say too small for a pump, but there are some pretty small pumps. Generally speaking, tiny subs would usually just be a dynamic diver which saves all the additional hardware. If the sub is too small for a pump, would it be too small to have a ballast tank?
Thanks Scott you got my mind thinking! Do you smell smoke?

[Von Hilde]

Hmmmm? "theres always some alchemist trying to turn lead into gold, Leonardo. Just keep painting on the cealing and you'll be famous"

[Scott T]

I am creating un-obtain-ium here!

[trout]

You ARE creating and testing! Excellent, is that your work Scott?

[Scott T]

I guess you could call it work or playing in the tub. The eductor did not work or pull air into the tank as the forward motion was suppose to cause a vacuum as the water was pulled out. So I made a larger hole thinking it would act as a self bailer. It appeared to get some air in the tank. More play is required to see if it might work. The shape of the eductor did not have the venturi shape. Did find out the air venting tube would need to be near the top of the tank so air would not need to be pulled past a extra column of water.

[trout]

So, the column of water is in the tube, but if you cut the tube, how do you prevent air leaving the vent?

[Scott T]

Another vent valve idea.
With ballast tank full of air and vent tubes 1, 2, 3 blocked the sub is at surface trim
With valve moved back to open tube 1, 2 the tank floods to half full.
Move valve to open tube 1, 2, 3 and the ballast tank floods completely.
Cruise around with all tubes closed to maintain water level in ballast tank.
Maybe could leave tube one open all the time?

If self bailing works open tubes 1, 2, 3 and drive sub around to bail water and draw air into ballast tank.
Still a big maybe.