First R/C Scratch Build

[Green nomadParticipant @greennomad]

[Green nomadParticipant @greennomad]

Need help and suggestions for my first R/C scratch build. I intend to build a 1:30 scale Lochin 40′ sport fisherman , about 1 1/2” in length . The proposed material for the hull is plywood skin not planking, and i want to put twin screws in it with an electronic speed controller. The area for the electronics should be about 14” square. If the space is not enough I will settle for single prop through the centre of keel.

 

Is this enough area?, are there any hints or links for a gallery for this type of construction?.

 

Appreciate expert advice.

 

[Armando LoniParticipant @armandoloni78860]

You might have trouble with the curved bow, using the skinning technique – perhaps consider block balsa or planked in that area?

 

1/30 is quite big –  you mean 1’1/2″ (1.5′).

 

14″ square should be more than sufficient to accommodate a mini receiver (I use Cirrus units) and mini servo; Mtroniks do a small 10A ESC (I run a couple of these), which may be a bit on the low side for this boat – a 15A-20A would be better – even the ‘standard’ Mtroniks units are small. The motor(s) can be placed forward in the hull to create more space. The problem is likely to be down to the type of battery pack you’ll be using. Small gel-cels are available, as are custom-built NiMH packs.A.Edited By Armando Loni on 04/12/2009 11:29:36

 

Edited By Armando Loni on 04/12/2009 11:32:13

[Green nomadParticipant @greennomad]

 

Thanks for the good info Armando.   Did consider using block balsa for the complete hull, but as i am based in Oman it is not easy to get a lot of balsa. Will possibly use for the bow section as you suggested, what sort of thickness of ply would be best for the skin of the hull? and does it require water soak before bending, if that is how its done?

 

The electronics should be no problem we have a small r/c club here with tonnes of spare radio gear. The motors may be a problem,however, but  what size would i need to look for, and what dimensions would they be with the gearboxes included?

 

 

[Armando LoniParticipant @armandoloni78860]

The thinner the ply, the easier it’ll be to conform to the required shape – 3mm should be okay. Steaming the ply surface will facilitate bending. The grain of the ply should run fore-aft, if possible. You could use marine quality, if available, although I use whatever I have to hand!  The ply skin should be sealed before painting, of course. 

 

I’m not sure that you’d require a motor-gearbox combination, to be honest. Especially if you’re limited for space. A 500 or 600 size can motor with direct drive is likely to suffice for this size/scale of boat – these can usually be run up to, say, 12V, with a 35mm-40mm prop (at least 3-blade).

 

A. 

[Peter FitnessParticipant @peterfitness34857]

You may have trouble bending 3mm ply in a small hull, I use 1.5mm ply, even for hulls around a metre long. This builds a very strong hull, particularly if sealed with fibreglass resin inside and out. I sometimes reinforce around the chine and keel internally with fibreglass cloth as well.

Peter.

[Dave MilbournParticipant @davemilbourn48782]

Nomad

I calculate a hull length of 16″ at that scale, in which case 3mm ply is totally OTT. If the hull is hard-chine (“flat” sides and bottom) and not round-bilge then you would be best with nothing thicker than 1/32″ (0.8mm) WBP ply. I’ve used this as skinning for models twice as big e.g. Model Boats Plan “Shamrock”. It can be bent easily in the steam from a kettle – or probably just dampened and left outside your window over there!!

I have to disagree with the use of a 600-size motor, which will be too heavy with its attendant battery pack, as well as too large and way too powerful. A 280 would be nearer the mark, although they are a bit fast-revving and should be kept down to around 4.5v supply. A Speed 400 7.2v would also be OK, again if you keep the supply voltage down to avoid your fishing boat planing like a FPB!

As far as twin props are concerned, I doubt if the space available (which I read as 14 square inches and not 14 inches square) would permit the use of two motors or a drive-splitter gearbox – even if you can obtain one to suit. If it’s your first scratch-build then stick to a single-screw until you get the ‘feel’ of matching motors to props to batteries to model size and type.

There are a couple of pictures of my little Fairey Swordman on my Album – this is 20″ long, built mainly of balsa sheet and uses a Speed 400 on six AA NiMH cells. Pretty darn quick!

Dave M

[Green nomadParticipant @greennomad]

Thanks for all your replies, some things for me to think about.

Dave, I did mean a 16-17 inch length hull, (used the Toycollector.com scale calculator)  I am not actually used to working in imperial, Ive grown up in metric, and I live in spain.

Anway, yes using a single motor and drive etc is probably best for my first build, and using thinest ply  I can get my hands on. I will have to ask my aero- modeller mates here what is lying around the club.  

 

How do i link through to any galleries on the website with in progress build photos?

 

 

[Dave MilbournParticipant @davemilbourn48782]

How do i link through to any galleries on the website with in progress build photos?

 

I’ve no idea, mate! Over to the other members here……………

 

[Colin BishopModerator @colinbishop34627]

Dave, if you get the album you are intereted in onscreen and then click on one of the pictures tou should have the option to start a forum discussion in the usual way. You can then add photos to that.

 

No, I’m not quite sure why it works that way either!

 

Colin

[Bob Abell 2Participant @bobabell2]

What about just copying the title at the top of the page….then paste it?

 

EG………….    http://www.modelboats.co.uk/forums/postings.asp?th=34698&p=1

 

Just an idea……………….Bob

[Green nomadParticipant @greennomad]

Further to Daves suggestions for the electronics/motors how many battery packs do I need, presume one for receiver / ESC, and one for motor?.

 

Steve

[Dave MilbournParticipant @davemilbourn48782]

Steve

You have two options. The first is to buy a speed controller which is fitted with a Battery Eliminator Circuit (BEC for short). MTroniks are a popular type. This is connected to the main motor battery and has a small regulator built into it which “taps” that battery, reduces the voltage down to a suitable level and feeds it to the receiver. This eliminates the need for a separate battery for the receiver.

The other is to use a non-BEC speed controller. Even then, you don’t need a second battery if you don’t have the room – you can fit a remote BEC/regulator. Here’s a link showing this: http://www.action-electronics.co.uk/pdfs/Single%20motor%20with%20P19%20BEC.pdf 

It’s down to you, mate!

Dave M

 

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