[PSUBS-MAILIST] Non developable surfaces

[Alan]

Hi Joe,
that sounds a lot easier.
I cooked some cast acrylic that was just over an inch thick & was surprised
how tough it was to bend. A bit like the bendiness of an eraser. When a local
firm blew a dome for me, they had to get another clamping ring made because
the original one looked like it would break under pressure. This mightn't be the
case with acrylics other than cast. I don't know. What I'm getting to is that you will need to
clamp it in place some how. I don't know how you intend to mount it, but if you 
are bolting it on this is how I would do it...... I would put glad wrap over the area
of the ballast tank where the acrylic was going, & coat it with an inch of plaster
of paris, then when dry build it up with more plaster of paris so you have a strong
p.o.p. shape the same as the ballast tank contour. Maybe cut the p.o.p. to size
or mark around the p.o.p. with a felt pen on the ballast tank for positioning.
Heat & drape the acrylic over the area & position the p.o.p. over it, with a sheet of
felt between. Weight the p.o.p. with a sand bag to disperse weight & add more weight 
on top of that.
If that doesn't quite do it, after that process you could drill holes through the acrylic
& ballast tank & reheat the acrylic & clamp it with bolts & a retaining ring.
Not quite in Tahiti yet. Most people did there big OE in there 20s. I 've had to wait
till my 50s.
Alan



Sent from my iPad

> On 16/02/2014, at 6:00 am, Joe Perkel <josephperkel at yahoo.com> wrote:
> 
> Hi Alan,
> 
> I figured you to be distracted by Polynesian dancers by now! :)
> 
> Small window ala Nekton, but located in a spot where the shape curves in two directions. A flat slab like the Nektons would detract from the lines unless made too small to be practical.
> 
> The whole thought process here, is to expound on James Frankland's forward MBT by fully enclosing for the purpose of reducing tow drag.
> 
> Joe
> 
> 
> 
>> On Feb 15, 2014, at 10:39 PM, Alan <alanlindsayjames at yahoo.com> wrote:
>> 
>> Hi Joe,
>> I'm not quite following you, but here are some suggestions.
>> you can cut out an oval section from a sheet of ply wood or similar & use it as 
>> the template to blow the acrylic. Or blow it in to a female form. However
>> contouring it to the sub shape & having it bubble out from there seems difficult.
>>  The only way I could imagine you doing it would be to tip your sub on it's side,
>> heat the acrylic sheet & drape it over the sub. Then trim it to shape & weld brackets 
>> to the sub to clamp it & a female mold on. Then heat the acrylic & quickly bolt it & 
>> the mold to the submarine. You could blow compressed air in to it through a through hull.
>> Experimenting with a scale model would help.
>> Hope that makes sense. Of course Greg is our resident expert.
>> Alan
>> Sent from my iPad
>> 
>>> On 15/02/2014, at 6:18 pm, Joe Perkel <josephperkel at yahoo.com> wrote:ex
>>> 
>>> 
>>> How much trouble is it to form acrylic in two directions? As in following a complex hull form to make an integral window.
>>> 
>>> In other words a transparent section of MBT with a bidirectional curve.
>>> 
>>> Joe
>>> 
>>> 
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