Engel ballast systems - opinios...pictures...?

[eckloss]

Later this year I might be able to get around to my OTW Vanguard.

In an effort to simulate a scale hovering at launch depth, I was considering an Engel piston ballast system. I have heard from others that very tight depth control can be achieved.

I have never used the Engel system. I'm eager to hear how others have adapted their ballast system in a wet-hull boat. Anything you can offer would be appriciated.

Pictures of the Engel piston tank in wet-hull boats are encouraged =)

e.

[Guest]

The piston ballast tank system

The piston ballast tank system is the only one I know of that enables proportional ballast control. It's the precise method of control and repeatable ballast quantity that makes it straightforward to 'hover' the boat underwater.

I have just ordered a couple of electronic boards from a chap called Markus Rieger. These use hall effect sensors and permanent magnets to precisely monitor the position of the piston at any point, the electronics also control the piston tank motor.

There are disadvantages to the piston tank system. If you use a single tank, you have a shifting CG, this can be compensated by have a moving weight i.e. battery to compensate, or you can trim the boat stern heavy (I don't like that idea).

A lot of modellers get round this problem by using twin tanks, but this is more costly and slightly less efficient, I think.

Also the tanks can take up a lot of room in the boat, and you need to make allowances for the retracting thread.

Ron Perrot got round the problem of a retracting thread by making the piston run up and down the threaded shaft.
Unfortunately, this solution produces a lot of friction, so the motors draw a lot of current.

According to Norbert Bruggen, unless a high efficiency thread i.e. recircualting ball, rack and pinion etc. is used, then the piston tank motor is running at about 20% mechanical efficiency. This means you need a powerful motor to evacuate the ballast tank- which means high current draw.

If a high efficiency thread is used, then the efficiency climbs to 80% or greater. Thus a much smaller motor can be used to achieve the same result.

Norbert detailed a method of producing a simple efficient thread for piston ballast tanks in his book Model Submarine Technology (No longer in print, unfortunately).

The Engel tanks are the only commercial piston tanks on the market. They are proven and reliable, but not particularly cheap (especially if you require a pair) and they use a standard threaded shaft, so they're rather inefficient.

It is possible to use the piston tank with another ballast system- a hybrid.

In this instance, the piston tank is usually used as a trim tank for accurate underwater positioning. The main ballast system could be gas, compressed air or a water pump.

Andy

[wingtip]

for sale, make a resonable

for sale, make a resonable offer... included is the control unit (servo operated which could be upgraded to electronic), pressure sensor, some fittings and tubing, and i'll even throw in a 6v motor and gearbox (actually for dual motor dual shaft) @3]http://home.insightbb.com/~davet/junk/engel1.jpg[/url]

[Guest]

That tanks a bit small

That tanks a bit small for the Vanguard.

I have the Vanguard, and roughly calculated you'll need at least a 750ml tank or very likely the 825ml tank to lift it to the correct waterline.

You could double up two 500ml tanks.

The Vanguard has a high freeboard for a modern vessel.

Andy

[jsl]

The Engel Piston tank system

[color=#000000]The Engel Piston tank system only needs some kind of regulator to meet their true potential.

Two Engel Piston Tanks is the only way, if you're thinking of doing things the scientific way. Two tanks act as both ballast and trim tanks.

Two 500 ml Engel Piston tanks is the solution we've adopted for our university midterm project. Simulations predict that the sub will be fully capable of any manover (except sideways motion) with those two tanks and a suitable regulator.

Any desired angle and/or depth is within reach with this advanced system. Only two servo signals ,specifying depth and angle, is needed. The regulator will do the rest.

Actually, the system should be able to do any manover in two dimensions (up/down, down angle/up angle) without any diveplanes with or without forward motion. Shift of the centre of gravity combined with adjustable desplacement will make any manover within reasonable limits possible.

Our project is aiming at producing a fully commecial regulator taking either servo-signals or advanced serial communication , as well as it comes with a datasheet included. (yes, It's intended to benefit all of us).

These systems, able to stay at a desired depth with or without forward motion, seem to have been developed already, but we have decided to develop our own solution to push the potential of the Engel Pistontanks to their limit. Engel specifications state that the tanks stall at 3 bar (about 30 meters). This mean that our project is intended, as in the official project specifications, to have a maximum depth of 25 meters. This will take our project slightly beyond the "toy"-designation. Simulations also predict a maximum change of angle at 20 degrees per second, as well as a maximum level diving speed of 23 cm/sec and a maximum ascend speed of 32 cm/sec when zero buble is selected at two thirds flooded tanks.

The project is aimed at producing a commercial regulator for R/C subs, but it is also designed to be extremely versitile, as to be expanded to take place in a semi-scientific submersible. Two-way communication is intended to take place by ultra-sound communication where RF-communications is futile.

Point to all of this babble]

[eckloss]

Andy

Do you have any photos

Andy

Do you have any photos of your boat you could email to me? I'd be interested in seeing them.

erich

eckloss@yahoo.com

[Guest]

Not much to look at,

Not much to look at, at the moment.

Been spending my time on other things.

Up to now, the Vanguard has been research and planning.

Here's some inspiration though-

[steve nuttall]

(quote)Ron Perrot got round the

(quote)Ron Perrot got round the problem of a retracting thread by making the piston run up and down the threaded shaft.
Unfortunately, this solution produces a lot of friction, so the motors draw a lot of current.

According to Norbert Bruggen, unless a high efficiency thread i.e. recircualting ball, rack and pinion etc. is used, then the piston tank motor is running at about 20% mechanical efficiency. This means you need a powerful motor to evacuate the ballast tank- which means high current draw.

If a high efficiency thread is used, then the efficiency climbs to 80% or greater. Thus a much smaller motor can be used to achieve the same result.

Norbert detailed a method of producing a simple efficient thread for piston ballast tanks in his book Model Submarine Technology (No longer in print, unfortunately). (end quote)

I could make high lead threads on brass rod


my 4 axis mill/drill

[Guest]

You could make near enough

[color=#000000]You could make near enough anything with that! ]

[dietzer]

Steve,

As usual, I'm impressed by

Steve,

As usual, I'm impressed by your craftmanship! I've been following your Yamato build on the j-aircraft site, and the work you showed there is equally stunning.

I just got a sherline 4500 lathe (and a vertical milling column so I can use it for milling) to make my own WTCs. But I'm just a neophyte to machining (and I can't afford to make it CNC just yet), so I have no doubt it will take me years to be able to produce a thread as nice as yours!

I do need to build my own piston tanks. I want to do 1/96 scale WWII subs, but none of Engel's piston tanks would fit in subs that small, so I have to roll my own. ;-(

If you're interested in making the high-efficiency threaded rods and matching hardware for me, please contact me (editor@subcommittee.com).

Carl

[steve nuttall]

Hi Carl

I'll have to look

Hi Carl

I'll have to look at how to match the outside thread with some form of cheap brass nut; or maybe a pure teflon nut
I can cut a faster thread than the test piece here

[scott t]

I have the motor drive

I have the motor drive assemble from a car radio antenna.
It has worm gears and start stop contact that might be canablized to build a piston tank setup.
You could get one from a salvage yard or borrow the one from your car.

Scott

[steve nuttall]

I have the motor drive

I have the motor drive assemble from a car radio antenna.
It has worm gears and start stop contact that might be canablized to build a piston tank setup.
You could get one from a salvage yard or borrow the one from your car.

Scott

I have one in my Snowberry RC conversion
look here