Koster Aero/Revell PB4Y-2 Vac Conversion

Started by Bryan W. Bernart · 41 · 8 years ago · B-24D, Koster Aero, PB4Y-2, Revell, vacu-form
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    Bryan W. Bernart said 9 years, 1 month ago:

    Jaime, this will have the Erco turrets fore and aft. They're supplied with the kit, resin and metal parts, and the vac nose and tail are formed to accommodate them.

    To answer Bernard's question, the vac parts are pretty thin and very flexible, but when joined at the seams you get a form of panel stiffness and strength. It has been recommended that I pour a river of epoxy down the centerlines, top and bottom, to stiffen them up. Before doing so I'm going to roughen up the surfaces to afford a mechanical bond as one does not get the weld one gets with styrene cement.

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    Bernard E. Hackett, Jr. said 9 years, 1 month ago:

    Thanks, Bryan. I was guessing some kind of wooden or plastic scrap "longerons". Also heard of this spray foam that hardens, though I've never seen that done. Chemical reaction would be a concern.

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    Bryan W. Bernart said 9 years, 1 month ago:

    The real fun started last night. I sanded down the fuselage halves and horizontal stabilizer and added alignment tabs. Moved on to glue in the engine nacelle halves and tabbed (after dry fitting) them as well. Looks like I'll be able to glue together the wings halves shortly.

    Sanding wasn't as big a pain as others had expressed, and really improves the progress outlook as well. 100 grit wet and dry taped to a piece of glass, with a sheet of 320 grit alongside worked well, although I could have gotten away with 220 if I had some.

    4 attached images. Click to enlarge.

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    Bryan W. Bernart said 9 years, 1 month ago:

    I considered the foam trick, but decided against it. "Good Stuff", found in most home improvement stores would be a likely candidate, but the mess it would create in both applying and removing/sanding put me off. My intent is to do a more built-out interior than necessary, so by the time all of the extra stringers and ring frames are flying in formation, the entire structure should be stiffer.

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    Bryan W. Bernart said 9 years, 1 month ago:

    At this point I have managed to get the fuselage put together, at least in halves, and wings put together with most of the necessary fairing of the vac nacelles complete. The flight deck is fairly rudimentary at this stage. Locating it in the fuselage is going to be an exercise to be sure, starting with the Mk. ! eyeball, as no dimensions are given for the scratch-built parts that are necessary.

    No big surprises so far and has been really enjoyable-a great kit to work on accompanied by a couple of great baseball and football games.

    3 attached images. Click to enlarge.

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    Bryan W. Bernart said 9 years, 1 month ago:

    The last week of the build has consisted of sanding, filling, sanding and more sanding. Followed by filling...A coat of Mr. Surfacer 500, which did not aggravate the vac plastic, worked nicely and was the final finish before paint.

    Part of the flight deck is assembled after minor surgery that I can only attribute to misreading the somewhat vague instructional drawings.

    Cowl rings have been added to the cowlings, engines mostly painted. I need to take back my prior boast of "really nice resin engines", as the first and only one that I looked at WAS really nice, but later noticed that two other were short-poured, one looking like Swiss cheese. They're also of four different colors of resin. Hmmm. I also carefully looked at the nacelle fronts where the engines are to go, as they need to be on the same plane and axis. Squadron green putty filed to shape did the job.

    I managed to get some of the interior green laid down before my Paasche "V" died. Steel parts wearing on a chromed brass body take their toll, and a replacement has been ordered from Chicago Airbrush as nothing could be had locally. It will arrive Monday-I will (in)conveniently be in New York doing a project all week...

    As an aside, I've laid the nose of the Revell B-24D donor fuselage next to the PB4Y-2 for comparison. Quite a difference.

    6 attached images. Click to enlarge.

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    Bryan W. Bernart said 8 years, 11 months ago:

    I haven't posted an update for a while, as it's been slow going. I finally got all of the sub-assemblies completed, not without some difficulty. As one can imagine, copious amounts of test fitting, sanding filling and the like are required to make it all come together without issues.

    The high point of this build was a two part affair. Most importantly, I was invited by a friend to meet Bill Koster himself at his home and "factory". A spry 87 years old, he's still active in IPMS (Flight 19, based in Pompano Beach, FL), and attributes his youthfulness to his young friends in the modelling world. I intend to do a full scale write-up on that experience in the near future.

    Having been re-energized by the visit, I managed to get the turrets fitted and finally closed up the fuselage. The top turrets drop in, but the tail turret needs to be placed inside before gluing the halves together. The nose turret goes in next, as I left the lip beneath it unglued. It's a flexible section, so will be gently pried apart for access. I "did my own thing" with the two Erco waist turrets as I felt they needed more structural support behind them, lest a glue bond let go, allowing them to fall inside the fuselage Although there is a lot of filling and fairing to be done, it represents getting over the hump, at least in my mind. This really has been a project!

    6 attached images. Click to enlarge.

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    Bernard E. Hackett, Jr. said 8 years, 11 months ago:

    Bryan, good progress, and looks like the business! You'll be pleased with the result, I'm sure. It's all coming together, and really looks good. Drive on!

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    Bryan W. Bernart said 8 years, 11 months ago:

    Somehow I have managed to maintain the momentum on this build. In the last few days I have gotten the wings and tail feathers in place, and discovered a problem. Somehow I managed to induce a tilt into the vertical stabilizer, and the horizontal surfaces were askew as well. It took a while to figure out a remedy, but I decided that splitting the tail and re-gluing (despite creating an offset in the halves) was the best way to approach it. I scrounged around and found an old pair of wooden shelf brackets and some other scraps of wood to create a jig and supported the fuselage with taped-down paint bottles lest I make worse the issues. I shimmed one of the horizontal stabs at it's root to try to make up the difference. Once strapped down, I inserted a piece of plastic sheet vertically to stiffen her up. After leaving the whole assembly in place for twenty four hours it appears to have gotten her close to symmetrical. I filled and faired the offset created in the vertical stab and modified the rudder slightly and called it done.

    Affixing the resin engines inside the cowls took some fiddlng-every bit of this build requires thinking somewhat outside of the norm if you are used to having the kit fall together perfectly right out of the box-and they all ended up in the right place. Further "tuning" of the firewalls was required to assure they all lined up in reasonable fashion once the engine/cowling assembly was ready to be CA'ed down. I managed to get them pretty close.

    5 attached images. Click to enlarge.

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    Rob Anderson said 8 years, 11 months ago:

    Woah, I mean really woah 🙂

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    David Hansen said 8 years, 11 months ago:

    Way to go, Man! Mee Likee!

    david

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    Bryan W. Bernart said 8 years, 11 months ago:

    I have managed to get the radomes attached to the lower forward part of the fuselage, the canopy glued down (Formula 560), and the chin glass. Also remembered, just in time, to check the center of gravity. Thankfully, with the nose turret out I could load in a bunch of crushed .177 caliber lead pellets. No room for the bombsight, but at least it won't be a tail dragger.

    I spent a few hours filling what I thought would be the last of the minor blemishes and decided to prime the entire structure. Looks like I'll be filling and rubbing for a few more hours! I'll be glad to complete the fairing of this beast and get on with the final finish.

    3 attached images. Click to enlarge.

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    Greg Kittinger said 8 years, 10 months ago:

    Man - this thing is huge! You guys who build big multi-engine 1/48 aircraft must own oil wells to afford the real estate needed to display such beasts! (oh wait - oil is still dropping...)

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    Bernard E. Hackett, Jr. said 8 years, 10 months ago:

    Bryan, really looks good! Getting close, looks like, really great work.

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    Bryan W. Bernart said 8 years, 10 months ago:

    Since last posting, I've found that the dark primer is nice, but the details (or lack thereof) became obvious after shooting a thin coat of flat white on the undersides. Several spots that I had missed had to be addressed, which is becoming routine. Two steps forward, one step back, or something to that effect.

    After the white coat and repairs I decided that a heavy pre-shading, at least on the undersides and sides of the fuselage might be a good idea. We'll see. I'm headed in to shoot the undersides now.

    3 attached images. Click to enlarge.