Active Stabilisers

[David WilliamsParticipant @davidwilliams11464]

I am hoping to build a 1:48 scale of the OPV(H) HMS Clyde based on the hull produced by SIRMAR and thought it might be an idea to make the active stabiliser on the bilge keel line work for real.

 

Any advice (I have already considered don’t do it) would be most welcome.

[David WilliamsParticipant @davidwilliams11464]

How can you create active stabilisers on model boats

[Paul TParticipant @pault84577]

 

Hi David

 

Why not?

 

The principal of semi active stabilisation is relatively easy to achieve in any model providing that you have sufficient room in the hull for the tank and ancillary equipment.

The problem at 1:48 scale is the stabiliser and motor will probably clash in the narrow confines of the Clydes hull.

 

Paul

[ashley needhamParticipant @ashleyneedham69188]

Paul is I think referring to an active stabilizing TANK, ie a cylinder 2/3 full of water tht  acts as a roll damper WHEREAS David wants to make the little stabilising fins work ~?? is that right??? I think this might be dead tricky, but using perhaps some sort of pendulum arrangement to provide the control for fins may do the trick. The fins would have to be oversize to have any effect mind you. Ashley

A rate gyro from a helecopter and servos would be dead clever mind you…..

 

 

 

 

[Bob Abell 2Participant @bobabell2]

I don`t understand the reason for moving stabilizers……….What can they do compared  to rigid bilge keels?
 

Bob

[Paul TParticipant @pault84577]

Hi Ashley

 

The Clyde’s semi-active stabiliser tank is installed for roll damping at all speeds, including when stationary the ship also has active fin stabilisers which I understand work in unison with the tank, the fitting of fins is straight forward but the fitting of the tank is not so easy.

 

Bob

 

After crossing the Irish sea in a force 8 I fully appreciate the ability of fin stabilisers to steady the ship.

 

Paul

[Colin BishopModerator @colinbishop34627]

Bob, the fin stabilisers act in a similar way to aerofoils. As the ship rolls, the angle of attack of the stabiliser isaltered to exert a force in the opposite direction thus helping to keep the vessel level.  Bilge keels are passive in that they simply act as a damper to the rolling of the hull. But they also add significantly to hull resistance and thereby increase fuel consumption.

[Bob Abell 2Participant @bobabell2]

Thank you Colin for that information

 

I did suspect that they would move somehow…………I wrongly assumed they simply went in and out…………….but they must be similar to aircraft ailerons then?

 

Thanks……………Bob

[60wattParticipant @60watt]

It just requires the stabilisers hooked up to the rudder servo.

 

If routing the linkages are a problem you could  use what the model submariners use.

This one has the advantage that the  craft will not keel over when you go astern.

[ashley needhamParticipant @ashleyneedham69188]

The whatever it is (sentinal??)customs cutter kit has “active “stabilisers hooked up to the rudders, but all this does is attempt to keep the boat upright when it is turning. Stabilisers to keep the boat on an even keel when it is moving in a straight line need to have an input to them that IS vertical, or some sort of gyro. I believe the  Helicopter boys have a device for this, but how you woud connect it to a pair of fins????? I have an oversize pair of stabiliser fins on my “HMS Jersey” offshore patrol boat  (fixed) and these work a treat in damping down the motions (ooooh matron) but the boat is relativley heavy for the length/beam and this must help. I think a tank is the best bet, possibly built in as part of the ballast??? Ashley

[60wattParticipant @60watt]

Nah! The helicopter boys can’t help because a gyro senses acceleration.

 

The model submariners pitch controller that I just provided a link to senses force of gravity (90 degree tilt = 1 g) and operates a servo to reduce tilt.

That one was actually fitted to an 18″ Academy XXI uboat in the article that a previous poster asked about.

It works by operating a servo.

 

[Peter FitnessParticipant @peterfitness34857]

Ashley, the stabilisers in the Model Slipway “Sentinel” are very effective in helping to keep the boat upright in a turn. The model is relatively top heavy, and has a shallow draught, so it’s quite “tender” when turning. I have the stabilisers in my model connected as per the instructions in the kit, and they work very well.

Peter. 

[ashley needhamParticipant @ashleyneedham69188]

Peter, I have no doubt that they work very well, its quite ingenious really. I have a pair of fin stabilizers on my HMS Jersey OPV, and despite being fixed, and relatively small (although I recall the Sentinel ones being very small) they make an amazing difference to the stability of the ship. Most warships are under bilge-keeled, for a variety of reasons….cost , speed reduction, mooring problems etc etc, but models could definitely do with oversize stabilizing features. Its such a shame the Sentinel isnt made with two hull options, one for static display and one for sailing, with a slightly deeper hull. I have sailed with a chap with a Sentinel and they appear to be very weight sensitive.  Ashley 

[Peter FitnessParticipant @peterfitness34857]

Ashley, the instructions with the kit point out the necessity of keeping weight down low for stability, and suggest using 2 NiCd (or similar) battery packs. I weighed one pack, then weighed a 6v 4ah SLA battery, and found that the wight of the NiCd pack was exactly half the weight of the SLA. Accordingly, I use the SLA mounted on the floor of the hull, and with the active stabilisers Sentinel behaves very well.

 

Peter.

 

[Colin MillerParticipant @colinmiller68338]

Was reading this thread there is some info about differant ways

for working stabilizers on modelwarshipsuk.co.uk.

some using rudders others with gyro’s

 

Paul,

the Clyde is about 11″ wide so there is plenty of space for working bits.

I have one sitting here ready to  make a start once I finnish my type22

 

David,

Did you get a clyde?

[Mark Scott 1Participant @markscott1]

On the same web site “modelwarshipsuk.co.uk.” you will see in the frigate forum that a few people are using servos with linkage conected to the stabilizers on there Type 22 batch 3s.

 

Mark

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