How to design a new model.

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How to design a new model.

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22 March 2014 at 18:43 #47764
Andy C
Participant
@andyc56856
Hi all.

If you saw Paul's Thor thread, I asked how he came to create a build plan from nothing but an idea or a photo. We thought it might be a good idea to have a thread exploring this further. Please feel free to chip inwith any and all advice, it's all welcome.

Andy
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22 March 2014 at 18:43 #2378
Andy C
Participant
@andyc56856
I thought it might be a nice idea to create a thread to help beginners, like me, understand how to create a model from a blank peice of paper, leading to a design plan and thenn a build project.
22 March 2014 at 18:48 #47765
Andy C
Participant
@andyc56856
So, my idea was to take one of my sons favourite toys of the moment, i.e. the octonauts, and try to make a working model. The Gup in question was the Gup B as this is a nice shape. It does not necassarily have to be a diving model, but who knows where thhis mission will take us.

There are lots of photos on the web and I have saved some to my pc. I can pretty much draw it free hand now, but that is where I get stuck. How do I take my drawing and turn it into a build plan?

I would imagine the model being roughly 35-40 cm in length.

Any ideas???

Andy

Edited By Wraith Leader on 22/03/2014 18:54:24
22 March 2014 at 20:08 #47768
Paul T
Participant
@pault84577
Andy
A set of clear images showing views of the top, sides, front and back is a good place to start.

The views need to be in a high resolution to show every detail so that they can be traced or copied.

A word of caution regarding copyright as an exact copy might upset the copyright owners it is advisable to make some significant changes or to ask permission to create a one off copy.

After getting a good set of images use a scanner, photocopier or computer drawing programme to expand the images to the required size, in this case 400mm.

Any tracings will then be the correct size to produce full size working drawings.

Its not as complicated as it sounds.
Sorry for the poor script I’m using a tablet and its useless

Paul

Edited By Paul T on 22/03/2014 20:25:16
22 March 2014 at 22:07 #47769
ashley needham
Participant
@ashleyneedham69188
Andy.

There are several things to think about here.

One is you are making, according to my research a sort of orange fish with wings, and with a big dome on top and a pirate pussy cat inside it (I think thats about right??)

a) you need a pilot pussy cat to suit the finished size of boat

B) you need a big clear dome

c) there is no prop on the Gup-b (it flies??) and so propulsion will have to be by ducted propellor..

Essentially you are building a semi-submersed boat, or at least, I cant see it being totally just a boat, and so water sealing will have to be taken into consideration. At the least, there will have to be interior access of some sort. The hull is basically round and will not have a steady freeboard..there will be water everywhere.

Think perhaps of a tube as the basis for a body. This tube, of a size to fit to scale with the pussy and dome, will need to hold batteries, motor, ducted prop and so on.

Without a doubt, the secret of this sort of thing is the pussy and dome to fit. They appear to be the defining feature of this build and have to be sourced first before you can say "imagine so-and-so length"

If you could imagine building a sealed bottle containing the gubbins and drive, then the body could be made to fit on top of this, freeing the upperworks of this sort of design constraint. It would get over the gear access and sealing arrangements.

Stability could be ensured by, for instance "optimising" the wings size and thickness wise to be used as stabilisers (make them out of Styrofoam for instance).

How about getting a 2ltr coke bottle, cutting up a smaller fizzy drink bottle, stuffing a pussy inside this, taping the items together and then adding card appendages and seeing what this looks like for size and proportion.

Another thing, the pussy sits INSIDE the craft, which will be difficult if not impossible to engineer, so half a cat will have to be the thing.

What is the largest toy Gup-B available..could you perhaps convert one with a cylindrical insert as described??

Shall I use the word imagine again? do you get my drift…

Ashley
22 March 2014 at 22:40 #47770
ashley needham
Participant
@ashleyneedham69188
You have of course chosen something a bit tricky as a first attempt, and I realise I have not particularly addressed your initial question.

The Paul method would be to get a good isometric (whatever that is) drawing and extrapolate the lines and get some framing going and so on, OR you can stare at the 2ltr coke bottle and a selection of toys and let the old imagination run wild.

Both methods are quite valid as far as I am concerned. Certainly if, like Paul, you wish other people to be able to make your design then of course it is the ONLY way to go. BUT a one off is a bit different.

A not-so-close study of my oddities will reveal that the majority of them are nothing more than a box..sometimes long, sometimes a bit short and fat, but a simple box nonetheless.On to this box I stick sufficient other bits to resemble the item I want to make.

The Ecranoplan (either) is a good example. A long thin box. The lid comes off for access. At the front there is a bit of foam stuck on and carved to shape, wings stuck on the side, a tail and tailplane added and thats that. I used a blown up 3-view line drawing, its almost all I use for any model. Cardboard prototypes are good, Paul has been using foamboard, easy to cut and glue..to try out his drawings. A card model, no need to be neat, will give you a 3-d space to lay batteries and gear inside to see what room you have and indeed what the room looks like for installation and maintenance..

Alterations for "operational reasons" are easy to effect..in your case, the wings could be used for addiitonal floatation and balance (rather than having to use a keel), and they will need to be a bit bigger than the toy…but how much bigger?? the card model will help..cut them around to get the largest size you feel comfortable with (for the look). This means they will not be to scale but……

Ashley
23 March 2014 at 08:09 #47771
Paul T
Participant
@pault84577
Andy
What Ashley has so eloquently made clear isthat the choice of mataerials can also influence the size of the build.
Another consideration regarding materials is to choose something that you are comfortable working with……..its no good opting for fibreglass if you have never used it before.
My favourite choice is plywood but to form the three dimensional curves of this project I would opt for a skin covering of 1mm birch aircraft ply however this material is expensive so balsa might be a better option.
Given the buoyancy effect of the clear bubble I doubt that the model will ever be able to dive below the surface but I am thinking about it.

Paul

Edited By Paul T on 23/03/2014 08:18:59
23 March 2014 at 12:07 #47774
Andy C
Participant
@andyc56856
Hi Paul

It just so happens that I have access to the to y Gup B, as well as all the others in the fleet for that matter, which is where the crazy idea came from. I should be able to produce some good pictures as you suggest and I will have a look at doing that over the next couple of days. I think that by the time the model is ready, it will not look exactly like the original but I am hoping to keep to the general appearance if possible. I will let you know once I have the photos ready to go. I have a program called Photoshop elements 7, not the whole Photoshop package but quite a powerful package, if one knows how to use it, which I am still learning about.

Ashley, I like your idea of a coke bottle and see where it leads and it may be that I use a combination of both. For now though I would like to try Paul's method as it should be able to be used in other applications.

Right, off to find that camera.

Cheers

Andy
23 March 2014 at 12:13 #47775
Andy C
Participant
@andyc56856
Posted by ashley needham on 22/03/2014 22:07:22:

a) you need a pilot pussy cat to suit the finished size of boat – Quawzi is available in various sizes, from quite small to very large, I will have to shop around for the right size character

B) you need a big clear dome – Might cause some difficulty, but I will investigate

c) there is no prop on the Gup-b (it flies??) and so propulsion will have to be by ducted propeller. – The Gup be is powered by something called a bubble engine, but I think a ducted prop or water jet might be worth investigating. I can picture the ducted prop being encased by the aft section with the whale tail at the back being used as a rudder. Well I can imagine it, building it might be something else entirely.

Cheers

Andy
23 March 2014 at 13:32 #47777
ashley needham
Participant
@ashleyneedham69188
Andy. Pauls method, as he has described it, is in essence exactly what I use.. the three view drawing blown up to the size of boat that you will be making.

You can get clear acrylic tube and domes to fit on them in a wide range of sizes. This would give you a line at the joint at the top, however if needs must. (EMA model supplies, check website)

I was using a coke bottle a "for instance", but its one of those things..it may be that you try it and look hard and see that it indeed does have potential.

Waterproofing the machinery space will be your issue. The hatch method works well, the gubbins and ducted prop can bee in one section and the rest of the craft could plonk on top,. If you are not fussed about diving then the body can be Styrofoam (EMA), easy to get a good shape. ballast will be needed, but only to keep it upright.

Picture, my sub, the top bit is underneath…this is the only bit you see when it is in the water. It would be very easy to adapt this for your vessel. Second picture, alternative top.. this could be the Gup-b ?

Ashley

Edited By ashley needham on 23/03/2014 13:34:21
24 March 2014 at 20:37 #47806
Paul T
Participant
@pault84577
Hi Andy

This is how I would start this project

Take square on pictures of the top, side, front and back (exactly as you have done)

Then crop them to remove the excess material

The images can now be manipulated (expanded) to make them the right size

Now the images are the correct size they can be traced to produce line drawings

These line drawings become the basis of the design drawing.

More to follow tomorrow.

Paul
25 March 2014 at 15:37 #47819
Paul T
Participant
@pault84577
The line drawings are tidied up and reduced to the bare essentials.

The next stage is to make sure that all of the equipment will fit within the hull, the problem with Gup B is that the hull is shaped like a squashed rugby ball and has very little internal space.

This is a good time to work out the projects centre of mass (sometimes incorrectly called the centre of gravity) so that the equipment can be positioned correctly.

The equipment should be drawn full size and positioned in its ideal position i.e. keeping the heavier objects lower down.

It is important to carry out this procedure before you start the detailed drawings as this will allow you to see if the equipment will actually fit within the internal void because if it doesn't you might have to increase the size of the hull.

This pretty picture is NOT drawn to scale and has been produced to show the internal equipment located in its possible best positions.

After this has been done and the equipment size / locations been confirmed the project can move on to producing the detailed drawings.

Paul

Edited By Paul T on 25/03/2014 15:41:27
26 March 2014 at 23:18 #47845
Andy C
Participant
@andyc56856
Hi Paul

that is amazing. I am getting to grips with PSE 7 and have produced this;
27 March 2014 at 14:12 #47855
Paul T
Participant
@pault84577
Hi Andy

So far so good, the next step is to manipulate the drawing to make it the correct size.

Paul
27 March 2014 at 17:37 #47857
Andy C
Participant
@andyc56856
Ok, as per PM, I have 2 versions, 400mm and 500mm. I think 500 would be better as looks like it gives more room inside. I guess it would also make it easier to cover with a skin. I will investigate the article about 3rd person whatyacallit and see if I can transfer my line diagram on to it. Will post a piccy of the results.

Cheers

Andy
27 March 2014 at 17:39 #47858
Andy C
Participant
@andyc56856
Oh, forgot to ask. How do you go about finding the centre of Mass? Is their some science or magic behind it?

Andy
27 March 2014 at 18:37 #47862
Paul T
Participant
@pault84577
Andy

Don't forget to make sure all of the RC equipment will fit in the 500mm model before you go any further with producing detailed drawings.

The problem with Gup B is the lack of internal space as it is has the profile of a squashed rugby ball, the saying 'square peg in a round hole' springs to mind when trying to fit all of the rectangular bits of kit into the curved space.

Then there is the allowances for the hull framework.

Lots to think about before starting the detailed drawings.

Paul
27 March 2014 at 20:24 #47865
Andy C
Participant
@andyc56856
The electronics bit got me rooting around in my spares box. The reason I thought small brushless was twofold, one it's small but I also have one (2826/12) that was going to go in my hovercraft. That is on hold while the builders knock walls out to fit a kitchen in the existing garage and then my workshop / small room at the front.

I also have a std size servo and also a small servo plus associated esc for the motor. I have layed them all out on the drawing below with a rather large Tamco 4200mAh 7.2 volt battery sitting in what would be the bottom of the craft and the other stuff arranged around it.

I know there will need to be bulkheads somewhere in there, but it all seems to fit height wise. The Gup is also wider than it is tall as it is squashed rugby ball shape.

What do people think….. Bonkers or might work sort of?

Cheers

Andy
28 March 2014 at 08:57 #47875
Amy jane September
Participant
@amyjaneseptember49770
Hi Andy.

No reason in the world why it shouldn't work, go for it!

Personally I would build a simple plywood space frame

fill it in with polystyrene… carve to shape… stretch a couple of layers of stocking over it…epoxy coat… and dig out the polystyrene where ever it wasn't needed.

Soft drink bottles can be moulded over a wooden mould with a hair drier, for a clear dome…

I shall be looking forward to your progress!

Amy jane
28 March 2014 at 09:44 #47877
Trevor Holloway
Participant
@trevorholloway99134
No such thing as a "bonkers" model boat as long as you enjoy the build.

If it works, there is the added bonus.
28 March 2014 at 14:01 #47878
Paul T
Participant
@pault84577
Andy

The last consideration before you plunge into drawing is the choice of materials.

Designing and building the hull is fairly straightforward but the choice of materials will have a bearing on how the hull is designed so before you start the detailed drawings it is best to have a fixed idea of which materials will be used.

The choice of materials is usually driven by ease of use, durability, availability and price.

For example balsa is easy to work with, is readily available and not to expensive but is it durable enough to survive the playful attention of an excited child. Alternatively plywood is stronger than balsa but more difficult to work with.

The biggest problem though will be sourcing the clear dome and, whilst we have already had a few inventive suggestions on this subject, I would be looking for some commercially available parts…for example a clear plastic wine glass with the stem removed or the protective dome from a frozen ice cream desert…..whatever the choice its size will have a bearing on the dimensions of the boat.

Paul
28 March 2014 at 16:10 #47883
Bob Abell 2
Participant
@bobabell2
Andy

What about using a good sized Marrow as a starting point and cover with small pieces of fibre glass, as a starting point?

Uniformity and super smoothness is essential on this model

Or a sausage balloon?

There are some large sized pop bottles in the shops with a lovely domed end, which have a base stuck on somehow

Just passing

Bob
28 March 2014 at 22:16 #47887
Andy C
Participant
@andyc56856
Well, I have done a bit of surfing, and after I dried off and put the board back in the shed, found that E.M.A do hemispherical domes of various sizes.

I might have to loss the nice curve of the cockpit area, and have a straight line instead, but might be able to get a dome that fits. for not too much outlay. The straight line might also help with internal space too.

I think it might be time to draw me a plan. Fingers crossed, and toes too.

Andy
29 March 2014 at 14:36 #47896
Paul T
Participant
@pault84577
Andy

Are you drawing on paper or computer?

Paul
30 March 2014 at 11:26 #47903
Andy C
Participant
@andyc56856
Hi Paul

I don't have access to CAD software so will be using pen and paper. I will refresh my memory of your article and have a go at laying down some lines.

Cheers

Andy
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