Hello + R/C sharks

[darencogdon]

Hi all

Newbie here, whose previous modelling experience comprised building things with wings for a good few years!

For a long while now, I've been wanting to build a radio-controlled model shark. There are relatively few available online - mostly unrealistic toy ones that I've found, and very few of those have been available in the UK - but the best ones I have found are these:

http://bateaux.trucs.free.fr/jojo.html

http://home.wanadoo.nl/m.m.avos/rc-models.htm

Sadly no plans are available for either, so that means doing my own!

I did try to construct something before, but sadly the project stalled and was lost in the destruction of my grandfather's garage a couple of years ago!

So.... does anyone have any tips I could use? I had wondered if building one in a similar fashion to a model aeroplane would work. A previous contact had offered a lot of help, but unfortunately I don't have his details any more, and this was some years ago now!

[giovanni]

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[Guest]

Re: Hello + R/C sharks

Hello,

Do you want to make a shark with a swimming tail, or one that is more like a novelty submarine with a propeller?

The ones you linked to fall into the latter category. If you want speed it's the only way to go really. If you want a flapping tail then it's a bit more work, but I do have an article I can forward onto you about a swimming shark made by Nick Burge about 15 years ago. The Shark was 3 feet in length, and featured a hard GRP body for about 50% of it's length, and a flexible silicone rubber tail for the remaining 50%.
You can see it working amongst other models in this video-

http://vimeo.com/20679846

[darencogdon]

Re: Hello + R/C sharks

Hi there

Yes, I was thinking more along the lines of the models in the links. This was always my intention as I didn't think my design/building skills were good enough for a model with a swimming tail.

I have read the article on "Dennis the Menace" some years ago. Great looking model. I had a copy of that video, too.

[Guest]

Re: Hello + R/C sharks

No you won't find any plans out there for this type of model. Norbert bruggen does a nice Dolphin kit, which looks a lot of fun. his kits aren't cheap, but are good quality and very well designed. You can also pick up some tips from the construction manual which is free to download-

http://modelluboot.de/menu_delfin.html

http://modelluboot.de/Anleitungen/Anlei ... n_4_10.pdf

With a Shark you wouldn't be able to use the rear fin to control depth, but you could use the pectoral fins instead.

You could make a shark master from many materials- wood, foam, even clay, then take a mould from that in fibreglass. You could purchase a bayonet ring from Norbert or make something yourself to make a watertight seal for access.

A Belgian modeller who visited the Uk for one of the Dive-ins a couple of years ago had a R/C killer whale and also a small shark, you can see the Killer whale in action in this film and some shots of the shark at the poolside, which unfortunately I didn't manage to capture in action.

http://www.youtube.com/watch?v=um7Gpp99cGM

[darencogdon]

Re: Hello + R/C sharks

I had a look at the link that comes up in the video - there's a couple of photos of what I presume is the same shark (a small blacktip job) - looks pretty good.

I did wonder whether or not it would be feasible to make a master from, say, plastic bottles? Some of the smaller Coke bottles taper towards the cap, so by gluing a couple together, I'd have a reasonable shape to begin with?

Failing that, I did find a French site which detailed the building of quite a large shark using foam and fibreglass.

[giovanni]

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[Guest]

Re: Hello + R/C sharks

Well if you read his earlier response, you can see he says he doesn't want to build a shark with flapping tail, so we can dispense with any discussion about servo actuated mechanisms and rubber moulds.

Using coke bottles for a mould will not give you a very satisfactory result IMO. If you feel your skills are not adequate to carve out a master, I would suggest taking the time to learn by building a model boat or a simpler shape of submarine where drawings are available.

[darencogdon]

Re: Hello + R/C sharks

I reckon I probably could carve a shark-shaped mould of some description (I did once build a model over 3ft long, out of balsa), but thought the coke bottle idea would save quite a bit on materials. I suppose the bottles could be used as a basis, with the rest of the body built around the shape to create the mould?

[Guest]

Re: Hello + R/C sharks

You won't save very much at all. Plastic sheet is very cheap to buy.

For something of this shape and construction I would use a glassfibre lay-up, much stronger. If you use plastic sheet, you're going to need to heat it to get it to conform to the double curvatures in the sharks shape. Not easy to do.

[darencogdon]

Re: Hello + R/C sharks

I reckon then that I could make a wooden mould, built up with a framework rather then using lots of planks of balsa, then lay up the fibreglass on that? Presumably all the fins etc would be built separately and then attached during final assembly?

I'm not planning on building a monster shark, though! Two feet, maximum. (Although the big model I once built was almost double that!)

[salmon]

Re: Hello + R/C sharks

You could use a Taxidermy form here are black tip shark forms (which you can get in 24" size)

http://www.mckenziesp.com/Black-Tip-C204.aspx

[Guest]

Re: Hello + R/C sharks

A plank on frame style method of construction can work very well. You will have to draw out frames and a keel of course.

Fins are best moulded separately.

[Guest]

Re: Hello + R/C sharks

What you can do is make a smaller master, say a quarter of the size, maybe a bit bigger-8-10". You can make this with cardboard and foam, and carve it to the right shape. These materials work quickly and easily.

Once you are happy with the shape, you can slice it up and use the pieces to make profiles for the bigger version.

[darencogdon]

Re: Hello + R/C sharks

That's not a bad idea. I'll work on some drawings at some point this week.

The taxidermy model idea would be a good shortcut - and funnily enough, I was looking at a blacktip shark this afternoon!