Discussion WTC Piston Tanks/Motors

[jaguar75]

I will go with the type III with PTFE for my aluminum parts.
I am designing my wtc with two aluminum 1,000ml piston tanks sized the same diameter as the 4"O.D. ploycarbonate pipe.The aluminum piston tank end-plugs will be machined with bajonet rings to attach the polycarb pipe on each end so the wtc will have clear polycarb in between the tanks and on each end of the wtc.You are probably asking how the motors will fit inside the piston tank diameter.I have sourced out a hollow shaft brushless motors that can drive any sort of threaded rod and has position,speed,reverse and forward sensing built into the motor.The motor is only 2-1/4" in diameter x 2-1/2" length and weighs 7oz. The voltage input is 5vdc-24vdc.The hollow shaft can be up to 3/4" in diameter and it has allen set screws for mounting your size of threaded coupling for rotating the threaded piston rod.

[expfcwintergreen]

Interesting, that may come in handy. Where did you get the motors?

[jaguar75]

You can source them out at a computer parts surplus store.They are used for scanning/printing machines and motion encoding machines.

[Sub culture]

Unless you're growing your own, you will not find a proportional brushless piston tank controller on the market.

The chief virtue of a piston tank is that it can be controlled like a servo. Remove that and you might as well fit a water pump ballast system.

High quality geared DC motors (Pittman, Maxon, Buhler etc.) are very efficient, last thousands of hours (several lifetimes for a model submarine) are small and can picked up cheaply surplus. You also have the choice of three or four commercially available proportional control boards to give you very precise control of your ballast.

This becomes all the more important when you use a pair of tanks placed wither side of the C.G.

[Aeroengineer1]

If they are standard types of motors (ie two wire input) the a standard esc will work.

Adam

[Sub culture]

Can't see how that will work. If they have position sensing etc. built in, it suggests to me that the motors have some sort of interface (serial?), which means you will need something to take the 1-2ms pulse from the receiver and convert it into something meaningful to send to the motors. Not a problem for a microcontroller, but you will need to be comfortable with coding your own software I would think.

[jaguar75]

The motor has Hall sensors for connectivity to the controller for the position,speed,reverse and forward and is position memory capable.The hollow shaft makes all of these features work for the best and eliminates gear-reduction,micro switches,etc.Yes.These motors can be built with various torqe ratings as well for larger pistons.I will need a porportional controller but I live in Northern Ca. and there are dozens of custom chipboard builders that will make my controller.

[jaguar75]

Originally Posted by Sub culture

Unless you're growing your own, you will not find a proportional brushless piston tank controller on the market.

The chief virtue of a piston tank is that it can be controlled like a servo. Remove that and you might as well fit a water pump ballast system.

High quality geared DC motors (Pittman, Maxon, Buhler etc.) are very efficient, last thousands of hours (several lifetimes for a model submarine) are small and can picked up cheaply surplus. You also have the choice of three or four commercially available proportional control boards to give you very precise control of your ballast.

This becomes all the more important when you use a pair of tanks placed wither side of the C.G.

I have used proportional speed controls in my business for over 30 years and familiar with the what I need to grow!
Why are you so skeptical about someone designing components that are improving the rc submarine ? I am building a wtc my way and not marketing any product so I have no hidden agenda.I prototype products for my business and enjoy designing things.
I know it is about expense with you and what you build is "old-school" but I am old-school being 60 years of age and using electronics and hydronics for over 30 years.

[Sub culture]

I'm merely pointing out that with a brushed DC system you can get excellent results, cheaply and simply. The range of products available is much more extensive too.

I appreciate the advantages of brushless designs, but I like to weigh that up against cost, complexity and how many hours I will need to spend developing a system that will only provide a marginal improvement.

[Skip Asay]

Personally, I think that directly driving that threaded rod will not give sufficient power to move the piston against water pressure when trying to surface (especially from any depth) as well as air pressure when trying to submerge. And this is compounded by the 3 1/2" diameter of the piston. That would probably work for, say, a 1" diameter trim tank using a fine thread but even there it would be much more efficient geared down.

That's just my opinion but I too, am up there in years (65) and have been building these things for 35 + years. As I said, it's just an opinion.

Skip Asay

[jaguar75]

Originally Posted by Skip Asay

Personally, I think that directly driving that threaded rod will not give sufficient power to move the piston against water pressure when trying to surface (especially from any depth) as well as air pressure when trying to submerge. And this is compounded by the 3 1/2" diameter of the piston. That would probably work for, say, a 1" diameter trim tank using a fine thread but even there it would be much more efficient geared down.

That's just my opinion but I too, am up there in years (65) and have been building these things for 35 + years. As I said, it's just an opinion.

Skip Asay

Skip,
So what driving torqe in lbs.-inch do you need to drive a 3.5" piston?
What is the rod's thread count per inch,which has something to do with the torqe and speed ?
It is strange how you and others are saying that a brushed motor,belt-drive gear-reduction system,RF motor resisters,BEC,ESC are so much less expensive than a brushless motor/ESC combo that has those options but does not require any gear-reduction.The brushless motor/ESC combo is only $150.00,uses less battery current,has low scale speed control,instant forward/reverse,makes much less noise,is easily disassembled for serving and upgrading.I take it that you also sell brushed motors and parts?

[jaguar75]

Forgot to mention that pressure inside the wtc increases with the piston pumping the water into the piston tank.This will decrease the amount of torqe lbs. per inch needed to pump the water out of the tank.

Skip and Subculture,
Have you guys used the Norbert Bruggen/Engel piston tanks in your subs ?
Just trying to get some insight into your experience with piston tanks.
I am not using the Engel tanks for another reason that the motor takes up too much space in the wtc and the piston tank that I am building is the same diameter as the diameter of the outside of the wtc.

[HelloMoto]

With Engel piston tanks, you can choose to have a different motor that sits inside the outer diameter of the cylinder, or a standard one that protudes a little.

[jaguar75]

I have everything from Engel showing their diving piston tanks,blueprints,images, and have never seen what you are talking about.

[Albion]

Originally Posted by jaguar75

I have everything from Engel showing their diving piston tanks,blueprints,images, and have never seen what you are talking about.

Clearly you dont have everything, cos it does exist, Hello Moto speaks the truth. Think they only appeared this year.

Check out the ones which end "380 custom"

ok higher current drain, but it s not like it is running all the time


Also you could consider these guys
http://www.piranha-modellbau.de/Tauc...tubeKolben.htm