Converting the Airfix B-17G to a B-17E, Part I

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Like many of my modelling projects this one began with a decal sheet, specifically the “Fortress of the Skies Part 3: E Models” from Starfighter Decals.  Mark has included eight different Fortresses on this sheet, all of them interesting for their camouflage schemes and / or service record.  There are four different B-17Es in the Hawaiian Air Depot multi-colored scheme, two OD / NG, one RAF Temperate Sea scheme, and one HAD experimental scheme of overall Duco blue.  Having already built an Academy B-17E in the HAD scheme, that left four to choose from.  Choices like that are not one of my strengths so I chose two.  Starfighter Decals here:  https://www.starfighter-decals.com/
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I have built both an Academy B-17E and the new Airfix B-17G.  The Academy B-17E is the right version but needs several improvements to bring it up to speed, the Airfix B-17G is a really nice build but the wrong version.  I decided to try backdating the Airfix kit to an E model.  The Airfix kit comes with a Cheyenne tail turret, here is the tail position from an Academy B-17F test fit.  Not perfect, but something which I could work with.
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The Airfix B-17G represents a later production version with the staggered waist windows (why that wasn’t done right from the first E model is a mystery to me).  This window will have to be filled and a new one cut further aft.
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The earlier Forts had narrow prop blades.  When the broad props were introduced with the F model forts the cowlings were shortened 3” to allow the wider blades to feather properly.  In 1/72 scale the 3” cowling change works out to roughly 1 mm.  Comparing the Airfix cowling to drawings it was unclear if the kit had it right or not.  In the end I decided not to adjust the cowl depth.  However, replacing the props is a requirement.  Fortunately many of the Academy kits have both wide and narrow versions so I had enough.
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The nose glazing is almost completely changed, and the B-17E didn’t have the Bendix chin turret.  There will be some filling and cutting needed here.
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Construction began with the tail position.  I cut off the transparent upper portion, it was a bit too tall anyway and there is a nasty seam right through the middle of the aft-facing glazing.  After gluing the halves together I braced the piece with plastic card to increase the diameter slightly to match the Airfix fuselage.
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I then made an RTV mold and cast copies of the piece in resin.  I needed two new tails for this project, and having the mold will allow me to make any of the earlier Forts right up through the first runs of the B-17G series.
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I then set about moving the starboard waist gun position back.  Here I am working through the fuselage from the inside with my trusty UMM scriber / scraper.
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The forward opening was filled with sheet stock and superglue, then sanded smooth.  I built up rib detail on the inside and installed the slide rails for the new window panel.
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The bench in full modeling bliss.  Various sub-assemblies are in progress, most notably the cockpit / bomb bay modules.  Two rows of Quickboost resin engines are visible to the right.