BRUTUS MK 11

[Bob Abell 2Participant @bobabell2]

Hi Paul

Have you still got Brutus 1?

You could try tank steering yourself?

Bob

[Paul TParticipant @pault84577]

Hello Bob

Yes I still have Brutus 1 but I prefer the rudder steering system for tighter turning on the smaller local ponds.

Paul

[Tim RoweParticipant @timrowe83142]

Hi Bob

Bow thrusters don't work unless you are stopped or moving very slowly. Not a practical idea for steering I'm afraid.

Tim R

[Bob Abell 2Participant @bobabell2]

OK, thanks Tim

Bob

[Bob Abell 2Participant @bobabell2]

Work in progress

Cobbled up the stand, which will be reduced in height shortly

On the last stretch of the ply covering now

Certain areas of the sheeting have a few lumps and bumps, which will be sorted one way or another

Bob

[Paul TParticipant @pault84577]

The notion of using bow thrusters instead of rudders to turn a model isn't such a far fetched idea.

Obviously traditional prop driven units wouldn't have the power but they can be replaced with high pressure water jets.

Water jets in the bow and stern that were linked with tank steering could make for a very manoeuvrable boat,

Whilst I can't see any advantage employing this system on a long slim hull I can certainly see a definite bonus when used in a tug.

Paul

[Tim RoweParticipant @timrowe83142]

Paul

You can have as much power as you like in a conventional bow thruster and as effectively they are ducted propellers, they are very efficient. If you were going to use jets they would have to exit above the water which would make some very interesting viewing if tugboats were to use them. The jet works on the principle of mass x velocity. If the jet is submerged you have no velocity so not much use. To use another analogy a jet can have very high power but not much torque so great when you want to achieve speed. A propeller can be configured to absorb much torque, large and slow.

As much as I admire experimentation I stand by my point that bow / stern thrusters are principally manoeuvring devices and the rudder is hear to stay Voigt Schneider and Azimut type propulsion units excepted but these are only ever used in displacement mode.

Tim R

[Ray Wood 3Participant @raywood3]

Hi All,

I'm slightly worried that Bob won't be using his trademark chain & sprocket rudder linkage !!I

Also mentioned positioning a rudder amidships but I think that would be a brake ??

Regards Ray

Edited By Ray Wood 2 on 27/06/2020 19:46:20

[Paul TParticipant @pault84577]

Hello Tim

Thank you for your comment

I agree that this system would be fairly ineffective on full sized ships but we are talking about a four foot model where the effects of high powered water jets are totally different.

I have to disagree with one of your points as a submerged jet of water still has the same velocity as it would have above the surface.

A simple experiment to demonstrate this is to put a hose pipe into a paddling pool, the incoming water will make the water in the pool move and eventually the pool water will rotate in the direction of the incoming jet of water, increasing the force of incoming flow will make the pool water rotate faster.

Some years ago I built a model tug to demonstrate how directional water jets could be used with traditional propeller drive to increase both towing power and manoeuvrability.

Four bilge pumps sending water through four fully rotating chain driven outlets.

The model was agile enough to turn on a sixpence and powerful enough to tow a 60ft narrow boat

[Ray Wood 3Participant @raywood3]

Hi Paul,

Very impressive plumbing, I suppose if the copper bends!outlets could be deepened and the pumps reversed the tug would be able to hover ?? 😀

Regards Ray😉

[Bob Abell 2Participant @bobabell2]

The rear end under construction, for Paul`s interest really……And all the Kevin`s out there, who like a challenge

The hull is a parallel shape at the waterline, but the top of the hull tapers inwards

Bob

[Paul TParticipant @pault84577]

Hi Ray

Yes it would hover and if the jets were turned to face each other it would disappear up its own a–e.

Hello Captain Bob

Lots of memories are coming back about the first build, like why I designed the stern with an extended keel rather than keeping the bottom of the hull flat.

A few posts ago you mentioned sponsons which started a train of thought as it struck another memory.

Buried in amongst the original designs was a theoretical drawing for sponsons.

The sponsons were intended to be lowered under the hull for high speed travel, the sponsons contained motors and worked in the same way as torpedos, the idea being that less surface area contact would result in higher speeds.

Paul

[Bob Abell 2Participant @bobabell2]

Still working on the hull carcass, chaps

The Bows section are almost done now

Bob

[ashley needhamParticipant @ashleyneedham69188]

Excellent work Bob. You make it look easy.

There is a craft which sits on sponsons, at the bottom of which look like torpedoes, props forward, and high pressure air is fed into a ring at the front thus smothering the torpedo bits in bubbles and reducing drag. Apparently it is very fast.

no doubt a quick google will reveal the thing.

Ashley

[Bob Abell 2Participant @bobabell2]

Thanks Ashley

I can see the bubbles, working sort of

In fact, like a Hovercraft?

Bob

[ashley needhamParticipant @ashleyneedham69188]

Ghost stealth ship.

[Bob Abell 2Participant @bobabell2]

Hi Ashley. I remember this project with Paul

We got really involved with this type of ship.

The wings could pivot and spread, to float on the surface

It became too complicated in the end and the project fizzled out……..Luckily

Bob

[Paul TParticipant @pault84577]

Hi Ashley

Yes that's the one, I spent some time playing around with this design and even produced a prototype model

[ashley needhamParticipant @ashleyneedham69188]

Yes I can see where you went wrong Paul…unsuitable materials for the torpedo bits…

I think that there is just too much tech involved in making a model, unless it was a bit big and ruinously expensive.

On the real thing I think the propellers super cavitated and then there’s the issue of supplying high pressure air.

A project fraught with difficulty (as someone who likes making odd things work). I seem to remember some discussion at the time?

Ashley

[Paul TParticipant @pault84577]

The biggest design problem was keeping the weight down on the main hull so the batteries had to go in the torpedos along with the motors and air compressors, all the kit would be on a slide out tray extracted via the stern of the tube.

The construction of the torpedos was quite simple as I used 75mm dia rigid plastic pipe with threaded dome shaped ends.

The main mechanical problem was the stress load on the wing root hinge and keeping the torpedos parallel so I was experimenting with using copper tube as the chassis.

[Bob Abell 2Participant @bobabell2]

Progress picture

Glued the decking on, using 3 mm ply

Using a full sheet across the side walls to ensure a flat surface for the super structure

Progress at last

Bob

[Paul TParticipant @pault84577]

Good Afternoon Captain Bob

That 3mm ply will certainly stiffen the hull

Paul

[Bob Abell 2Participant @bobabell2]

Hi Paul, the hull feels quite rigid, but I only had 3 mill and 1.5 mill felt a bit feeble

Looking back at the first Brutus, I notice that you were thinking about a Mark 2 thenI

Do you reckon the Brushless Motors on MK 1 are OK for MK 2

I'm not intending to build a high speed ship, as they are frowned on at Etherow these days, it's just a model boat as something to build and sail about etc

Bob

[Paul TParticipant @pault84577]

Hello Bob

The brushless motors that were fitted to MK1 should be fine in MK2 for slow to moderate speed but to get the best response from MK2 I would encourage you to upgrade the motors to a more powerful pair.

You don't have to use the extra power at Etherow but you might visit a more enlightened lake where you can open the taps and let MK2 fly.

Paul

[Bob Abell 2Participant @bobabell2]

Hi Paul, I'll give it some thought

Have you got a suitable motor in mind?

Bob

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