CHAPTER IV - Right side fuselage construction
As I said at the beginning of this thread, I decide to make the JT-9T building look more interesting and show the model in a way that airframe should look like cutaway side opened and let cockpit detail be easily observed.
THIS artistic diagram gave me the idea and that would be a nice opportunity to present my way to do it. To do so, I decide that a solid rock one-piece "negative image" cast of the right side fuselage should be made of plaster first and then build a right side solid replica made of polyester, epoxy or resin. This replica - virtual fuselage, would be the basic line to create a thin right-to-scale fuselage surface.
My local newsagent, usually wraps my newspaper and magazines into a plastic bag, which sometimes I use to collect the trash. This time, I decide to use the plastic bag in a completely different way. I cut free-hand few pieces of plastic, keeping in mind to make them longer & wider than the autogyro scale model dimensions. Using duct tape, I stretched the plastic bag across the airframe, in a way to simulate the full right side and half bottom fuselage surface, trying not to leave any visual wrinkles or marks.
I add some grams of plaster powder and few drops of water with a syringe into a soft rubber cup to make the right mixture. Materials like plaster, start as a dry powder that is mixed with water to form a paste which liberates heat and then hardens. Unlike mortar and cement, plaster remains quite soft after drying and this characteristic make plaster suitable for the job. Keep in mind that adding salt into wet plaster mixture, reduce the plaster's hardening time and adding vinegar into wet plaster mixture, extend the plaster's hardening time. When the first layer of thinned plaster applied on the plastic bag was dry and hard enough, a second thin layer of plaster was applied to form a basic strong cast. The basic idea, is to let the plaster follow the airframe details, accurate on scale and as thin as possible trying not to apply extra stuff where is no needed.
Found at my local supermarket and got for only 0.5€, the following modeling clay for kids. Some scale modelers, use this material to border camouflage patterns while airbrushing. I pick a piece, mold it into snake alike formation and placed it across the airframe to border the wet plaster flow - yellow color for up and purple color for bottom airframe side.
When I finally enclosed the right half JT-9T scale model into plaster, I left it few hours to get harden in order to be sure that the cast wouldn't break when I would try to remove the scale model from inside. Meanwhile, I took the soft rubber cup which I used to make the plaster mixture, squized it to break the last hardened plaster left inside, so it would be easier for me to clean it afterwards and prepare it for any future mix. That's the reason this soft rubber cup were used for.
As soon as the plaster cast was dry and hardened, I removed the the modeling clay I used for bordering the plaster flow and pull the enclosed JT-9T scale model airframe away, gently. Brushing the area with an old tooth brush, I removed unwanted dust or small broken plaster pieces.
Johnson's baby oil or similar is well know to anybody who have children in house. If you don't have children yet, ask your girlfriend - all girlfriends have a tiny bottle in their cosmetics drawer. If you don't have a girlfriend, close this web page, shut down your PC/laptop and get your feet out of house to meet one! Scale modeling is nice, but feeling a nice female next to you is much better. Continuing with the project, thin layers of vaseline based mixtures can be also used instead of baby oil to apply with a soft brush as a segregative material between the plaster cast and generous quantities of polyester filler applied on the plaster cast.
The specific polyester filler I used, comes with the proper catalyst which provides a solid rock build and approximately 3 to 5 minutes time window to form it into shape. I prefer to use epoxy putty or polyester filler with fiberglass grains for special purposes, because:
- It becomes solid rock within only few minutes or seconds,
- it does not shrink and does not crack after months or years,
- you can pour to any shape that you want but you need to work fast because as soon as you mix it with catalyst cream approx 5%, you have limited time before becoming solid rock,
- you can also put additional layers of epoxy or polyester filler to build up,
- you can sand it, you can drill it, you can use any type of scale modeling glue, any type of primer or enamel / acrylic paint on it with no problem,
- can be purchased at any good crafts store into 250ml, 500ml, 1lt (comes with a tube of catalyst hardener) or bigger canisters and if you can't find it, fear not and try your local decent hardware store and finally...
- it is cheaper than dirt - estimated prices are £3 to £10 depending the canister size, the quality, if contains fiberglass grains for maximum strength etc.
Keep in mind that the chemical reaction after mixing the polyester filler with the catalyst hardener, produces some heat that possibly effect on thin plastic parts, so test it first before try it on your scale model. I don’t think that the produced heat is more than Fahrenheit 110, but better watchout. Remember that epoxy materials are dangerous when breath or shallow and could result skin, eyes or lungs problems or even cancer when used for long period with no precaution measures. Always keep in mind, that a powerful vacuum system to suck away the epoxy dust should be used all time to keep the workbench area clean while sanding or milling epoxy or resin materials. Using an issued breathing mask and a pair of surgery latex gloves to prevent dust contact with lungs and fingers while sanding or milling epoxy, is also an important matter that you should seriously take care of! My recommendation is to also wear an overall working suit (as I do) to keep your clothes dust free while sanding epoxy. Some people might find it too much, but I wouldn't like to bring epoxy dust & grains from my work bench into living room and my beloved.
When the plaster cast used as a "negative image" of the right side fuselage, was filled with a thick layer of polyester filler and had enough time to polymerize and get solid rock, it was sunk into water and stayed wet for few minutes, in order to get moistened, become soft and let the right side fuselage replica made of polyester be removed easily.
…if you still read this, you are a father already or have a girlfriend.