HOW-TO: TAMIYA 61060 THUNDERJET EJECTOR BACKDATE

By Bruce Craig

Ejector (tailpipe) Backdate to D- and E-model Thunderjets

The Tamiya F-84G, being the current definitive 1/48th scale kit of the subject, is a worthy subject for after-market detail sets. Cutting Edge has produced a resin super detail set for the Tamiya kit, which includes most parts needed for either an E or a G version to be modeled. However, some blocks of the E-model, and judging by photographs, all of the D-model Thunderjets had an oval ejector with lateral taillights rather than the round ejector with stacked taillights. This "backdate" part is neither documented nor included with the Cutting Edge set. This is how I made the oval ejector to backdate the Tamiya G to the D or E with oval ejector.

THE MOLD

The D, E and G Thunderjets had additional panels internal to the ejector which were not present on the C and earlier models. The Tamiya kit has these panels molded into the ejector parts. The problem is, how to make an oval ejector that has these panels. I solved the problem by making an RTV silicon mold of the tail of an assembled Tamiya fuselage. I did this by cutting a paintbrush handle (I had already cut the handle off the brush) to about 1/2" longer the "depth" of the tailpipe, used a round cutter to cut a concave into one end of the handle, and lightly super-glued the concave to the aft end of the engine. When that was cured, I super-glued the other end of the handle to the bottom of a plastic storage drawer. This put the fuselage vertical with the ejector toward the bottom of the drawer. I poured the RTV molding mix into the drawer to a level above the joint between the stainless steel ejector fairing and the fuselage, and let it cure for the recommended 24 hours. When I removed the mold from the drawer, and removed the fuselage and handle, I had a round hole up through the mold in the center of the ejector. See photos.

THE CASTING

The next step was to distort the round hole to a slightly oval shape. I made wedge from a popsickle stick, pushed it into the round hole to make it oval shaped, and used 15 minute 1:1 resin to cast a part. After the part was cured, I inspected it for correct shape; it was too much oval, but about right for height and width, so I made the wedge wider by adding a piece of .020 sheet styrene to each side and tried again. That part looked correct to me, so I used it for the new ejector.

I cut the new part from the gross casting at the ejector/fuselage joint and filed it flat. I removed the stacked taillights from the top, filed a "square" grove into the top, and super-glued a piece of sheet styrene into the grove. When the glue cured, I used a hobby knife and triangular jewlers file to bring the fairing into shape for the lateral taillights; I used a close-up photo of the ejector on an E-model for reference to get the shape correct. I cut the old round ejector from the fuselage about 1/16" behind the ejector/fuselage joint, and, with frequent test fitting, filed the fuselage down until the new part protruded about 2 scale inches. I super-glued the new oval ejector to the fuselage, and when cured, filed the contours of the new ejector to blend with the fuselage.

This is a reasonably easy "scratch-build" backdate, and if you have never made your own parts, this is a good project to use as your first attempt.


Mold ready to pour RTV

This photo shows the mold completed. The fuselage is vertical with the paintbrush handle (dark red) running up the center of the tailpipe, and superglued to the bottom of the plastic tray. The clay is "filler" to reduce the amount of RTV mold material needed.


Mold after pouring RTV

This photo shows mold after the RTV has been poured.


Top of mold with raw casting and wedge

This photo shows the top of the mold, a "raw" casting, and the wedge used to slightly distort the round hole in the mold into an oval to create the oval ejector casting.



Mold bottom with wedge Round and oval ejectors

Bottom of mold with wedge inserted.

Tamiya round ejector (left) with stacked taillights, and cast oval ejector (right) with sheet styrene fairing added for the lateral taillights.


Tamiya fuselages with round and oval ejectors

Before (left) Tamiya fuselage with round ejector which is flush with aft edge of rudder, and after (right) with oval ejector which extends past aft edge of rudder.


Contents Copyright 1997-1999 Bruce Craig -- All Rights Reserved


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