Here is my thinking which may be a little or alot confused.
The wedge inside the tube forms a wing shape with the side of the tube, maybe causing a high and low pressure area that would cause lift.
Something like the inside of a carburator throat, except one sided.
Another idea might be like this toy: x-stream glider The air flow is accelerated by the internal ducting of the wing shape thus increasing lift. The foam glider can also be "flown" under water for added enjoyment at the pool.
Well, I'm not and expert by any stretch of the imagination, but I'd guess that the fact that the area above the low pressure zone in your model being enclosed in the tube will simply cause severe turbulence and not any sort of lift.
Additionally, I'm not sure that air-based designs are employable with water, as air is a compressible medium and water is incompressible.
I suppose if worse comes to worse, just mock up a model, throw it in a test tank and see what happens!
Just thought I'd chip in here, hope you don't mind.
It is just that I know that Dan Kachur's Disney Nautilus is built as plan and even though the dive planes are enclosed around with the side strakes they still function well. (I have a video of his model in a swimming pool - looks great) I only mention this because I too was worried that this design of enclosed planes would not be practically effective. In fact I thought the planes were also too near to the centre to be effective enough and so I altered my boat for those 'practical' reasons. Then I saw Dans boat functioning as is. I was quite surprised, (and wished that I'd just stuck to the original design!)
When I built my sub hull this way I used the green bricks from florist shops (used for flower arranging- they call it oasis). It is soft enough to just push in to the section formers then trim around with a junior hacksaw blade.
Oasis foam? I had not though of that. Thanks for the idea.
Another idea I have had is to plank it with cardboard strips using super glue to attach it. I have made a clinker style boat hull this way. The question in my mind is can I smooth over the cardboard with plaster or bondo if I seal the cardboard first.
As you can tell I want to do it as frugal (cheap) as possible.
Now I am in the grip of analysis paralysis, trying to decide how I want to inset the observation windows and trim the hull formers to give me the groove in the hull shape. The forms will need to be cut before the covering goes on.
When I built my hull for moulding I sculpted out the whole shape, including indented areas like the anchor recess. Then I put a thin skimm of polyfilla over it all. The polyfilla dried very fast so I could sand away quite soon. In places I sanded away right back to the oasis, so I had to reapply polyfilla and repeat the process. But it was a surprisingly quick and easy way to model the basic shapes.
Since my model was for R/C I then had to go through the mould making and casting stages to get a fibreglass version which I then put the superdetailing on. I sealed my oasis/polyfilla plug with a product from the fibre glass shop.
It sounds as if you are giving up on the foam filled idea. There is a product called 'sanding sealer' which aero modellers use to seal Balsa wood. It is thick but paints on with a stiff brush. (Also very smelly since it is cellulose based!) I think this might do the job of sealing your cardboard since it is a sealer for porous surfaces. I would think you could could then stick polyfillla onto it. Bondo would stick better and would be tougher of course, but Bondo is harder to sand.
I would quit penny-pinching. Think of how much time you have invested in this thing- add that up per hour, and you'll soon see that trying to save a couple of quid by using inferior materials is unwise.
I would recommend that you block out the formers with polyurethane foam, and then skin it in a layer or two of resin and glassfibre cloth (300gram). If you are using epoxy resin, you can use polystyrene foam instead- polyester resin melts polystyrene, so I use polyurethane foam or add a barrier coat of PVA.
This will give a very tough but lightweight master. This is how I produced my Yellow Submarine master, and it only cost a couple of quid in materials.
You can then either plate over this with litho plate or plasticard to get the very bold plating of this model.
In the case of the Yellow submarine, I built up the finish using polyester filler (Bondo), because I required a smooth finish.
With your boat you can work much faster, as you don't need to keep filling and sanding.
U812 wrote:You must not have looked at my link I gave you for my Type 17 build or you'd be on your way right now.
Hi Steve, just been to see your ..tutorial ? .. Boy that's a really well documented "how to" with great pictures too. They should make the thread a stickey. Impressive model too. Not seen any other type 17's before. I picked up lots of things from seeing how you went about building your model. Thanks for sharing.