Eezebilt RAF Fire Boat

[Tim CooperParticipant @timcooper90034]

I have been slowly building an Eezebilt Fire Boat.

It started with some part sheets of lite ply I needed to use up, but I am now using Balsa sheet .

I redrew the plans to give a slightly larger model at 23″. The cabin still wants fixing in place once motor and prop shaft installed
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[Dave ReedParticipant @davereed72029]

That’s interesting, it would make it the same scale as the Vic Smeed RTTL plans I have. Maybe I should do the same….

…. oh wait a minute, I already am!

Great minds think alike!

 

Dave

[Dave ReedParticipant @davereed72029]

By the way, if you scale up the propshaft length to match and use a huco style coupling you could end up with the motor in an awkward position under the wheelhouse window frame.

[Tim CooperParticipant @timcooper90034]

Dave

Not using a Huco coupling. I have splined brass ends from a Huco joined by thick pliable plastic tubing. This was suggested to me by Dave Milbourn when I first used a brushless motor in a model.

It does seem to run quieter than a Huco.

Tim

[Richard SimpsonModerator @richardsimpson88330]

Tim that actually makes for an excellent coupling as long as the power being transmitted is low.  Looking at the size motor Dave has used and bearing in mind a 23″ model I’m sure you will be OK.  I once did a conversion of the Revel U-Boat plastic kit to RC and originally fitted dog bone type couplings.  The thing sounded awful.  I replaced the couplings with silicone tube and it now runs beautifully smooth and quiet.

[Tim CooperParticipant @timcooper90034]

Richard

I have used the aluminium couplings with a fixed “rubber” insert on a couple of models . They have worked well. Dave suggested the Huco / tube combination as a cheaper alternative.  For set up he told me to use a rigid tube around the coupling to get the best alignment.

Tim

[Richard SimpsonModerator @richardsimpson88330]

Tim,  I think that highlights an interesting aspect of couplings that some modelers don’t always seem to appreciate.  While a coupling does allow a degree of misalignment in a drive train the more that misalignment is the more power will be lost in the coupling.  If you imagine the coupling to be perfectly aligned then it isn’t actually doing anything.  There would be no movement in the separate parts and therefore no frictional losses.  The more that misalignment is the more relative movement is and the greater the frictional losses.

Ideally, if we all built our models perfectly and built a perfectly aligned shaft arrangement we should be able to have a solid connection.  I have seen steam engines in the past with quite steeply angled UV type couplings transmitting the power and failed to convince the builder why he was loosing power in the coupling.  This is particularly the case with the plastic centred huco type couplings that are sometimes quite stiff to flex.

Dave was spot on with the huco brass insert and silicone rubber pushed over the splines, it is an excellent coupling  but, even then, there is less losses the better the alignment.  In that case you are actually stretching and then compressing the silicone as it rotates, which requires power to do.

[Tim CooperParticipant @timcooper90034]

Richard
<p style=”text-align: left;”>My Model Slipway Tamar Lifeboat uses a double Huco coupling. I remember the what seemed like hours of adjustment to get it right. This was before Dave told me to use a rigid tube.</p>
Tim

[Colin BishopModerator @colinbishop34627]

I have used the aluminium couplings with a fixed “rubber” insert on a couple of models . They have worked well.

I have these in my Faireys. Basically they are semi rigid couplings and one of those I bought initially had a slightly off centre rubber section and vibrated horribly. A replacement cured the problem.

For models with lower RPM and power, silicone tube does work very well. However, with most of my models I have literally sidestepped the issue by using pulley drive with ‘O’ rings. Works perfectly and the only alignment you need to make is to get the tension right by being able to adjust the motor mounting slightly. There is a ‘sweet spot’ which you can easily find by putting a very low voltage through the motor and moving it to get max revs without slipping. The setup is very quiet.

The big bonus is that you can put a small pulley on the motor and a larger one on the shaft. This improves the efficiency of the drive by bringing the RPM difference between motor and shaft closer together and does wonders for current consumption. 2:1 or 2.5:1 is a good reduction. (it also allows a small motor to drive a larger prop more efficiently).

Colin

 

 

[ashley needhamParticipant @ashleyneedham69188]

You can buy all sorts of sizes of silicone tube on ebay. I got some thick wall stuff and replaced almost all the huco u/j with bits of tube. The fit is nice and tight and I have not had an issue with slip.

Ashley

[Tim CooperParticipant @timcooper90034]

Some progress on model.

Front of cabin took several tries

Trying to find a way to make the mast removable.

 

[Colin BishopModerator @colinbishop34627]

Very nice! How about gluing a length of stiff thin wire along the inside of the uprights and bend it vertical at the bottom. Then drill small holes for for them to plug into? You might need to add some extra balsa to the underside of the cabin roof to ensure it remains vertical.

Colin

[Tim CooperParticipant @timcooper90034]

Thanks Colin I will have a look at that.

I have just made a length of polystyrene with slots that it will fit into. But still thinking.

Yes the roofs, three of them are very light. I have usually used magnets to hold them down. But might need something more than that.

I was going to cut windows to fit each opening but after trying to fit the first two, I decided life was to short and have cut clear sheet to fit behind the window aperture!

Tim

[John W EParticipant @johnwe]

hi there,

as they used to say on Blue Peter – here is one I made earlier from the same set of plans.

Here is a sketch of my idea; I used brass tube and brass pins and glued to the cabin as per scribble.

To secure the cabin roofs on mine, I used 2 strips of balsa wood glued to the underside of the roof, making it a push fit on the inside of the cabin walls.

I also used plastic from Ferraro Roche box (chocolates) to glaze inside of the windows.   Obviously, I ate the chocs first.

 

[Colin BishopModerator @colinbishop34627]

A more sophisticated version of my suggestion John – and effective.

Colin

[ashley needhamParticipant @ashleyneedham69188]

A couple of screw hooks and a rubber band (obv underneath the cabin!) will hold the top on if you could arrange that. Used on a couple of craft I have.

Magnets are good but it’s a fine balance of holding power and rip-outness with the strong ones…esp if gluing to balsa.

• Ashley

[Richard SimpsonModerator @richardsimpson88330]

I’ve used magnets a few times, they work extremely well but, as Ashley says, you need to be careful that they are not too strong.  It doesn’t take much to simply hold something in place against the wind.

[Tim CooperParticipant @timcooper90034]

The magnets I have are Neodymium ones . I have some quite small ones. Not had a problem so far on other balsa models, but I will check when I get that far. Not all the roofs need to be removed for every sail.

Tim

[Richard SimpsonModerator @richardsimpson88330]

They are easy enough to set into a snug hole with some resin or epoxy.  Just make sure you get the polarities right!

[Tim CooperParticipant @timcooper90034]

Not as much progress as I hoped for recently.

I have made some ‘bits ‘ to add to the model.

I am struggling with the Fire Monitors at the moment.  A few attempts went into the bin. The red pipework is made from plastic tubing and plasticard.

Tim

[Colin BishopModerator @colinbishop34627]

That all looks really good Tim.

Colin

[Tim CooperParticipant @timcooper90034]

I’ll try to post updates a bit more often but progress seems very slow. Think I am getting there with the monitors but need to finish the mast and start a Search light.

Would like to find some figures in a Charity shop that I can customise.

Tim

[Richard SimpsonModerator @richardsimpson88330]

What sort of scale is this one Tim?

[Tim CooperParticipant @timcooper90034]

Richard

I have used the Eezebilt plans from the Website.

This is my 4th model from the website.

PT boat enlarged to 1/35 scale, Triton enlarged to give space for RC and bigger motor.

OSA Missile Boat built as plan at 32 ” but extra detail added from articles in MB magazine

I redrew the Fire Boat plans, on a drawing board, to give a a 23 inch hull. This gives a scale of 1/24 -1/25. I hoped this would give scope for picking up some cheap figures and give a little more space for batteries.

Trying to make the fittings from all that stuff I saved just in case it might be useful.

Well that was the plan anyway!

Tim

[Tim CooperParticipant @timcooper90034]

I have finished painting the monitors and the pipe work, and stayed painting the cabin roofs.

Started a searchlight from bits out scrap box. Hopefully it will work via a servo / micro switch.

Tim

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