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Old Jan 15, 2012, 06:44 PM
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Originally Posted by will in the 98 View Post
Subscribed for a cool plane. Will plans be available or are you just working off the three view?
Mostly, I'm working off the 3 view. I did trace the 3 view in CorelDraw to layout the fuselage formers and wing ribs. That way I can print out drawings of just the parts I need. The scale airfoils (NACA 23018 root and 23012 tip) were generated in Profili and imported into CorelDraw to draw the actual hotwire templates. So other than that, I'm working off the 3 view or cut and fitting parts as I go along.
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Old Jan 16, 2012, 11:55 AM
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Here's how I doing the mold for the windshield plug. I've had mixed results using foam for vacuuform plugs and prefer to cast them from plaster or shape them from solid wood. To cast the plaster plug I'll need a female mold of the fuselage.

First, I covered the windshield area with shrinkable window insulation film. It's a pretty common item at home centers in cold climates. It comes in large sheets that you tape around the inside of your windows and shrink it tight with a hair dryer. I use it to create a barrier between the foam and fiberglass. Cut piece to size, tape down the edges, and shrink it with hair dryer.

Then apply several layers of glass cloth and epoxy. I used a full sized piece of 4 oz cloth and scraps of 6 oz. to build up 3 or 4 layers.

As is, the fiberglass would not be stiff enough to pour the plaster plug so I added chunks of foam to make a frame. I hot glued a couple sticks to the foam frame and used them to hot wire a nice flat bottom to keep the mold level during the pour. I've learned the hard way to make the supporting frame from something with a little flex to make it easier to remove the mold from the fuselage and the plaster from the mold later.

The mold was then removed from the fuselage. The shrink film leaves a very smooth surface inside the mold. (the white line in the lower right corner is a reflection of the fluorescent light overhead!) I'll add dams at the ends and make foam plug to take up some space inside the mold. As is, it would take a couple pounds of plaster to fill the mold!
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Old Jan 17, 2012, 11:41 AM
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Here's the poured plaster plug for vacuforming the windscreen. Even with a foam plug in the center to take up all but 1" to 1 1/2", it took 3 pounds of plaster to fill the mold! Once it's fully dry I'll do a little shaping to get a more defined edge between the front of the windscreen and the fuselage, right now it's more of a radius.
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Old Jan 20, 2012, 10:35 AM
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I covered the fuselage with the same paper used on the wings. My "budget" for the fuselage at this stage was 200g and it came it at 192g. I marked out the cabin window locations and am getting ready to do those but I forgot to paint the inside of the cabin before I joined the halves! Looks like I'll have to paint the inside with a brush through the window cut outs...PITA!
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Old Jan 20, 2012, 10:43 AM
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Or since it is a sealed container at the moment, you could fill it with paint and shake it up, then pour out the excess.
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Old Jan 20, 2012, 11:10 AM
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Or since it is a sealed container at the moment, you could fill it with paint and shake it up, then pour out the excess.
That thought had crossed my mind. Might be kind of messy! I really just need to do the parts that would be visible though the windows; the sills and the "floor". Though I do have "friends" that will check to see if the roof is painted.........

Pat
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Old Jan 20, 2012, 12:30 PM
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Pat,

Could you just spray the interior colour through the window cut-outs before you painted the exterior?

Steve
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Old Jan 20, 2012, 12:54 PM
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Pat,

Could you just spray the interior colour through the window cut-outs before you painted the exterior?

Steve
I'd have to spray with acrylic paint so it wouldn't eat the foam and it's probably quicker to use a brush than to setup, spray, and clean the air brush. Besides, I can brush acrylic in the house instead of my unheated shop (7 below last night!).
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Old Jan 22, 2012, 09:02 PM
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I cut out the cabin windows and painted the inside brown to hide the foam. I cut away a rectangular area and recessed a piece of clear PETG to sit flush with the rest of the fuselage and glued it in place with canopy glue. Then I covered it with another layer of paper and WBPU. After the fuselage is painted I'll cut away the paper to reveal the window. the paper is translucent enough to find the window cut outs if I shine a bright light through the windows.

I tried this on a test piece and it worked great. The poly coated paper makes and excellent mask and peeled away leaving a clean surface and nice sharp edges.
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Old Jan 23, 2012, 11:09 AM
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Got to work on the motor mounts. The main structure is a pair of 1/8" lite ply plates sandwiching a piece of 3/4" foam (which conveniently, is the width of the retract units). The plates slide into gaps between the wing ribs and around the dihedral brace and back to the main spar.

I made them by jigging the wing into place on the work bench and sliding cardboard into the slots. Then I marked the motor center line and LG pivot point. From there it was just drawing the outline of the plates so all the parts end up in the right places.

Being able to slide the mounts in and out to work on them was a big help. I still need to add the actual motor mounting plates, cowl mounting rings and figure out where to mount the ESC's to get some cooling air flow.
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Old Jan 30, 2012, 03:02 PM
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Long Build with Lots of Details

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Originally Posted by pmullen503 View Post
Got to work on the motor mounts. ... Being able to slide the mounts in and out to work on them was a big help. I still need to add the actual motor mounting plates, cowl mounting rings and figure out where to mount the ESC's to get some cooling air flow.
Love the details and how you are sharing why you decided to do something. Hope for a good flyer and video of your success.
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Old Jan 30, 2012, 10:53 PM
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Love the details and how you are sharing why you decided to do something. Hope for a good flyer and video of your success.
I appreciate that Tsavah.

Got to work on the nose cone. First I made the foam plug that I'll use for the mold. I glued 1/16" ply formers to the fuselage and a block of foam keyed with pins so I could remove and replace the nose cone while I worked on it. When I was happy with it, I covered the nose cone with a layer of 1/2 oz cloth and WBPU.

I decided to do a fiberglass nose using the lost foam technique. I could have probably done a vacuformed nose cone but I think this will fit better and I can make it thick enough to be really strong. (I'll need the weight probably anyway)

I sliced off the plywood former (I'll eventually glue it into the fiberglass nose cone) and added a FFF extension to the base to make the nose cone a little longer than needed. That way I'll have a little extra glass I can trim when it comes time to fit it. I glued the plug to a base of FFF, gave it three coats of wax, and slathered about a 1/2" of plaster over the plug. I'll let that dry for a day or two and then set about removing the plug by grinding away the foam. I hope the layer of cloth will allow me to pull out the last of the plug without having to resort to acetone to dissolve the foam.
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Old Feb 01, 2012, 08:38 AM
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Happily, the plug was easy to remove. In fact it's almost perfect and can be used again to make a spare nose cone.

I gave the plaster mold a couple coats of paste wax and laid up a layer of 3/4 oz cloth followed by 3 layers of 6 oz cloth in epoxy.

When the epoxy had cured I broke off the plaster by smacking the mold with a hammer. Most of the plaster came off easily but I'll have to sand off the rest. The surface will need sanding and filling to get it ready to paint.
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Old Feb 05, 2012, 08:14 PM
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Here's a shot of the nose cone mounted. After trimming the fiberglass to fit, I glued in a 1/16" plywood bulkhead with pins and magnets to secure the nose cone. The whole thing pops off to change the battery giving excellent access to the connectors.

I finished the wing cut out and tail mount so I could get a feel for where I was on the CG. Unfortunately, it's going to be tail heavy with my original battery choice. Which gives rise to a real quandary. The windshield is huge and is begging for a detailed cockpit. Going to a larger battery is easy enough but it would protrude into the cockpit limiting what I can do for detailing. A pair of smaller batteries would work and will fit into the nose cone but I'm not sure I can stuff all the wires and connectors into the nose cone. A 4 cell A123 pack might fit and would be heavy enough so that might be the way to go.

I made up a light weight tail from 6mm depron which gets me closer to balancing but it looks too thin and I'd either have to go with exposed rudder linkage or no rudder control at all. I could upgrade the motors from 2209's to 2217's which would add an another 1 1/2 oz in front of the CG.

Decisions, decisions! At least I can add cockpit details through the wing cutout at the end once I sort out the CG issues.
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Old Feb 05, 2012, 08:16 PM
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splendid job
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