Hi,
As the title suggests, I am building a 1:28 scale Hamina Class Missile Boat.
Unfortunately, as I am an 80's child I am not satisfied with 2 channels of scale action. I required a little more from this most recent build, I also don't have massive amounts of time to spend on detail. I found that on most previous builds the detail dragged out and in some cases was never completed, I needed something with very little detail and a large gun relative to the size of the boat.
After several weeks I found the Hamina Class Missile Boat, there are only 4 all serving with the Finnish Navy and based out of Upinniemi (Finland of course). Most info about the boats can be found here
http://en.wikipedia.org/wiki/Hamina_class_missile_boat What I am doing may seem a little extreme, I don't know as I have not come across anyone else doing something like this. Maybe there are others on the forum doing similar work, if there are then I would very much like to meet up and share this interest.
Anyway, less of the speal and more about the build.
As all the real complicated unknown engineering as far as I could see was based around the Bofors Mk111 57mm I decided to approach that first.
It really was a case of starting from the ground up, I had a few ideas of how it was going to work but nothing really solid. Fortunately for me I am an engineer (Electronic and Mechanical) so I have access to several software packages which allow me to produce designs and physical hardware from those designs, this made getting a few concepts modelled and simulating relatively inexpensive.
it doesn't take too long of cost much to make parts in plastic so this was the medium of choice, I had to select a projectile which of course meant that the barrel was going to have to accommodate the round and could end up not being to scale but I figured it's only one barrel. As long as everything else is to scale then it doesn't matter.
The MK111 has both rotation and elevation which I needed to recreate reliably and proportionally, I decided to go for 2 x 1:150 Micropile motors from
www.cornwallmodelboats.co.uk to drive both azimuth and elevation coupled with potentiometers (just like a servo motor). This means I can get precise repeatable positioning and accuracy, they are also very small so plenty of space for all the other gubbins.
The MK111 also fires at 4 rounds per second, this also seemed like a difficult challenge. I know you can get electric BB guns firing at faster rates but to be honest plastic BB's aren't going to cut through ply and balsa!
I needed 4.5mm Steel BB's, 4 or more rounds per second at air pistol power in a super small space. After a few days of head scratching I came up with a design which I felt was a good starting point, here is a picture of the internal design of the first prototype and progress up to the current form which is pretty much ready for the electronics controller PCB which controls all motors, firing, CO2 temperature monitoring and coolent(warment) flow, rate of fire, power of shot, round store level and monitoring motor current.
I'll update as I go, I'm close now to moving on to the Hull which is Aluminium with composite everything else.