5/30/05 - I've been working on the model but not on the web site journal so I have some catching up to do. This month was the I.M.A.A. West Coast Festival and I wanted to bring the Liberator out for display so I have been working towards getting as much done as I could before May 27th.
Well now it's onto the plastic parts. I'm especially excited about getting the canopy on because I've been looking at the fuselage for what seems like ages without one and now it will look complete. The plastic parts I bought were OK but not great. The canopy is too small and the turrets are the very early Consolidated A6-A type. I also need to make the chin greenhouse and ball turret. Since I have never done this before, it will be a learning experience. I do have some expert help when I pull the parts but the plugs will be sort of an experiment. There are many ways to make them so I thought I would try a few different ways using stuff I have sitting around. My hope is to get some reasonably good looking parts made and the more parts the better but I would like at least two of each, good enough to use.
A while back I turned some wood on the lathe to form the basis for the front turret (and also the ball turret) but I thought it might be easier to use the plastic turret I have and modify it to make an Consolidated A6-B turret. I had some Plaster of Paris on hand so I used that for the first plug.
I poured plaster of paris into the plastic turret
While that was going on I made up the canopy blank. At first I thought I would use some florist foam but it was a mess to work with and dented easy so I removed some of the foam and filled it with clay which was messy but sort of fun. I think that with the canopy I could have built it up with ply and balsa since there is a lot of flat glass.
I let the clay harden up for a few days and then sanded it down and added spot putty. It's actually looking pretty good! The clay sands very easy. The problem with the clay is I shrank slightly when it dried so I had to add some putty. Now I really feel like an artist!
With new confidence I started on the chin windows. For it I'm using balsa blocks glued to plywood frame. I cut some 1/8" ply the shape of the window opening, tack glued them to the fuselage, cut a ply side view and glued that on then sanded it all to the fuselage contour. When that died I popped it off and glued some balsa blocks to it and shaped it up on the sander and by hand. So far the balsa blocks were the easiest to shape.
Glued the fairing bottom and side views to some balsa and shaped it into a fairing then glued it to some ply to make the attachment flanges. As on the canopy and chin window, I fiber-glassed, filled and sanded. Of course, it would have been less work to just make another fairing out of balsa and glue those on, but this is more fun and will be lighter too!
5/25/05 - 3
Today I finally got to try vacu-forming the plastic parts. A good friend, fellow modeler and master builder, Ken Safer, generously offered to help me vacu-form the parts in his kitchen. Since I have never done it before, some help is greatly appreciated and cuts down the waste and the learning curve. I bought 10 sq. ft. of .030 clear Butyrate from Balsa USA and 2 sq. ft. of .015 clear from the LHS. It all went well and I got two canopies, two chin windows, and two turrets. I wanted to make my own vacuum box and try it myself on the wheel fairing.
Well, the plaster of paris didn't hold up to the vacu-forming but it will work anyway. The plastic stuck to the plug so I will leave it on and fix a few places where the plastic didn't get pulled down very well before trying again. I don't like the plaster of paris as a plug. It's too soft and doesn't seem to like very hot plastic.
5/26/05 - 6
We pulled four canopies but only two are usable. The last one stuck to the first one we put on over the plug to smooth the plug out. I cut the canopy from out of one of the good canopies. That took awhile!, about 3 or so hours to tape up the frame, cut it out and sand it 'till it looks good. In the pictures, the other canopy is under the frame. It is sooo much better than the piece of crap I paid Nor-Ray products for.
Some other things I got done --
- Built the front turret and painted the front and rear turrets. I will go into more detail on the turrets later.
- Made a ring for the top turret mount from carbon fiber and balsa and glued it in.
- Added a .007" thick strip of carbon fiber to the top wing sheeting at the flap area (for a better trailing edge).
- Added .030 carbon fiber rod to the trailing edge of the flaps, ailerons and elevators for strength. I wanted the trailing edges fairly sharp and also want to avoid hanger rash. I've found that by making trailing edges and wing tips very stiff they look good longer.
- Adjusted the end gaps on the ailerons and flap
A major change.
I'm going electric on the propulsion system. The O.S. 25's, mufflers and mounts have been sold and in their place I will use 4 x AXI 2820-12 brushless motors (or equivalent), 4 x 4200Mah LiPo batteries and 4 x speed controllers. More about that later too. I haven't bought anything yet. I will make that purchase after the finishing is done.
Summer rest - Last year I worked through the summer thinking I will be finished soon. This year I wasn't so foolish. My new atitude is I'll get it finished someday but no deadlines anymore.
8/20/05 - Back on the project after taking the summer off.
I got back to it by getting the plastics done. I still needed to make another canopy to fit inside the frame for the glass, a ball turret, two wheel fairings, the superchargers and the A6-B nose turret front & back.
I wanted to try pulling some parts myself. It was still too hot to heat up the kitchen and besides that the large frame I made didn't fit in the oven so I used the bar-b-que grill to heat the plastic. It worked great although the first sheet of plastic melted onto the grill with my wife watching. After that I removed the grills and everything went much better.
I made two vacuum boxes and frames to go with them. The boxes are both 3" tall with 1/8" peg board tops and a piece in the center for support. Since I was planning to use the plastic sheeting that my LHS sells and that comes as 17" x 17", I made one large box & frame to use one whole sheet. The smaller box and frame fits a 1/4 sheet. Using the home vac they work well. The frames are 1/16" x 3/4" x 3/4 " aluminum angle. I used .015 & .030 Sig Manufacturing clear plastic.
During the first parts pull a few months ago I got a good enough canopy to make the frame and had one pull still on the mold. The A6-B turret plug also was left with a plastic cover when the last pull we did stuck firmly to the plug. I figured both of them would work in my favor because at least they have a good firm top layer now. On the canopy I only needed to do some finish sanding to get it ready. The turret needed more. I tore the plastic and broke some plaster trying to get it off the plug so I patched up the tear and glued down the plastic with epoxy and then sanded and filled until it looked good. I also re-heated some of the plastic where it didn't get pulled down all the way to make shaper inside edges.
I pulled a new canopy from .015 plastic and it works perfect with the frame. Here's the plug on the large box, with a layer of plastic, ready for more hot plastic. I think it took 4 tries before I got a good canopy I can use. I was letting the thin plastic get too soft and then slammed it onto the plug which created wrinkles or webs. I found that by not letting it sag too much on the grill and using a slower more careful placement on the plug and placing some 3/4" thick wood under the plug to raise it up, I can get a good canopy.
A-6B Nose Turret continued...
The refined Turret plug after a pull on the small box. Making good parts now. The back of the turrets are made separate. Unfortunately, my LHS & I ran out of .030 plastic so I had to use .015 on the turret. It's a little on the thin side but I'll see how it takes the aluminum. I will pull a new turret with .030 if needed.
I then set my sights on making the Turbo-supercharger plugs. I used some dowels, clay and a plastic bottle cap and got someting that looks pretty good I think. It just barely fit on the small box. I can get four from one .015 sheet this way. Later I'll add the little fin that goes on the turbine part.
The two ball turret plug halves were turned on a lathe and then the best looking one got modified to include the round flat window and the gun fairings. It doesn't need to be perfect because no one will ever see it!
Wheel Fairing continued...
All in all I have maybe 20 hours to make the all plugs and pull the parts. Probably 10 of those on the nose turret alone. It's nice to have that behind me!
The conclusions and things I learned;
- Plaster of paris is not a very good plug material. It flakes off under heat.
- Clay is not a very good plug material for large plugs. It tends to shrink. Small parts are fine.
- Balsa is the easiest to shape and work with and is stable when heated. Fiberglassed and filled with a sandable primer the plastic comes right off the plug.
- Pulling a thin sheet of plastic over the plug helps the following plastic parts look much better but is only necessary on canopies and clear stuff.
- Scuffing the first plastic will allow the second plastic to separate better when pulling one plastic sheet over another
- Having the plastic soft (hot) enough is crucial, but not too hot. I found that if the plastic is too soft it wiil "drape" over the part and cause wrinkles.
- Raising the plug helps keep any wrinkles below the plug. The wrinkles seem to form close to the vacuum box.
- The plastic does stiffen up pretty quick! You have to work fast! Although I had to be careful when placing the hot plastic on the mold to get the best parts.
- Buy extra plastic. It takes a few tries to get the hang of it and even then stuff happens.
- I was surprised by the lack of smell. I thought it would smell like burning plastic.