Pro Resin 1/72 Convair XF-92A "Early" By Bill Powers

Introduction

Studying the plans and kit pieces before assembly began, the aft fuselage shape didn’t look correct. On the “early” version, the fuselage aft of the tail/wing curved to the exhaust nozzle. The kit fuselage resembled the later version: longer, almost straight/parallel, sharply tapered at the end. This might be a mistake in packaging. Oh well, it won’t take much effort to correct the aft section.

Construction

On to building the model! First task is to cut away parts from their pouring plug. For plugs this large, a saw is probably mandatory and a “coarse” blade will make the cutting easier. Dipping the plug in water several times during sawing results in a pile of “mush” not harmful resin dust! (see photo of mush) I strongly recommend ALL SANDING be done wet to reduce dust.

Sanding the mold “plugs” from the fuselage halves to obtain the circular cross section is tricky, like sanding a vacuum formed kit. Sand the sections on a flat surface with a piece of 220+ grit wet and dry. Cutting out circles in 20 thousand plastic to use as guides speeds the process and makes “getting it right” easier! (see photo of guide over aft section).

Installing the main wheel wells was easy but the nose wheel well required some cutting and fitting. The plans are not clear, but I assumed the bottom edge of the wheel well, part 6, was to be flush with the outside of the fuselage. After completing the model, I still don’t know if that was correct! Either way, the nose wheel would never retract into the kit wheel bay!

The cockpit tub, walls and ejection seat have beautiful detail (see photo of tub and sidewalls) but will disappear from sight when the canopy is affixed! Only the seat belts and control stick can be seen. The cockpit tub locating guide on the right side had to be removed so the tub would fit “square” to the fuselage.

The very long and delicate pitot tube probably would not survive long, certainly not with a butt glue joint! So, the splitter plate was carefully drilled out for a new pitot tube of metal. (see photo of drill bit through splitter) After the fuselage was assembled, I used a piece of 400 sand paper wrapped around an aluminum tube to sand the inside of the intake perfectly round (see photo) then installed the splitter...easier to achieve proper alignment. A new pitot tube was made from a hypodermic needle with 15 thousand music wire inserted. That won’t break!

Before gluing the fuselage halves together, add some weight in the nose or try to add some later before inserting the splitter plate (which I had to do!).

The fuselage in this kit was slightly warped which required careful gluing to “work out” the warp. (see photo of warp) Glue the halves together in stages beginning from the cockpit forward. Align the cockpit tub, panel lines and halves, then glue the top joint, Turn over and glue the bottom after checking alignment. Move aft about two inches, pull the halves into alignment, glue the top joint, turn over and do the same for the bottom, then repeat working aft and gluing only two inches at a time. At the final two inches insert the afterburner can, align and glue. Little notches in the fuselage halves about every two inches will keep the glue from running in the joint beyond the point you have aligned. When finished, the fuselage is beautiful! No hint of the warp, just a twist!

To assemble the wings, tail and the landing gear a jig was built to hold everything in alignment. (see photo of model in jig) This may be a personal thing, but it sure makes the process easy...for me! For those who haven’t heard my “jig talk”, the purpose of a jig is to hold the model and the pieces to be fitted, in the proper alignment, thus freeing your hands to make the necessary adjustments. On this jig, the fuselage rests in a half circle cradle and the trailing edge of the delta wing rests on a strip of plastic which is “square” with the fuselage and at the same level side to side as the top of the half circle. While the jig holds the components steady, I can study what action to take for correct alignment.

There were some fit problems where the wing fit the fuselage on the left side, probably caused by the warped fuselage, but they were easily corrected by cutting away part of the molded wing filet. Brass rod about 32 thousand was used to hold the vertical stab and wings while in the jig and for strength after gluing. Tamiya’s Epoxy Putty was used to fill the gaps at the wing joints. This epoxy is very sticky stuff that works like Milliput but dries quicker and sands easier.

To correct the aft section requires extending the fuselage and making new smaller exhaust orifice. I used “sleeved tubes” of plastic and aluminum. First, a short piece of 11/32” Evergreen plastic tube slid perfectly inside the kit’s afterburner can. Then a longer piece of 5/16” slid inside that and a ring of ¼” aluminum tubing cut from a K&S tube slid inside at the very end. (see photo of sleeved tubes) All the tubes were glued to each other and to the model with crazy glue. The “correct” distance from trailing edge of the wing to the end of the exhaust orifice is 24mm by my calculations. Sounds complicated, but the whole process takes about two minutes! Then slop on your favorite two part filler and sand away...which took longer than two minutes, but not that long! (see photo of tapered aft section). Don’t glue on the vertical tail until all sanding is done. Fill in those small holes in the rear of the fuselage; they were not present on the early version Very few pinholes appeared after all this sanding...a real tribute to the quality of the casting!

Now for the landing gear, which are 35 of the 55 parts in the kit! This plane has wacky main gear struts. While the assembly drawings are beautiful, questions are not answered such as which way to turn part 24? On the real plane, the strut holding the main wheel (part 25) seems to be perpendicular to the ground and there is a gap between the top of this strut and the bottom of the wing. If the top arm of part 24 is perpendicular to part 25, these criteria are met. A needle file “adjusted” part 24, until these criteria were met. Part 24 should be “handed, right and left”, but they are not. Part 24 fits between the two protrusions in the wheel well. One side fit beautifully, but the other didn’t if the struts were parallel to each other! In the end it worked, “I don’t know how, it’s a mystery!” I hope my photos will help explain how it should look, since a picture is worth a thousand words. (see two photos).

I drilled the nose wheel strut and wheel for a reinforcing brass rod. (see photo)

The wheel well covers required lots of thinning and the retract hinges had to be reduced in size. All the nose wheels covers are too wide for the opening, maybe a hint of how the how the wheel well part 6 should be fitted! The landing gear fussiness would make me suggest a model posed in flight with gear retracted!

So that’s it...short of painting. After spraying a primer coat, the panel lines on the wings and tail were too prominent, so they were filled with putty. I opted for the MIG 23 scheme. I would suggest a silver undercoat to cover all the discolorations and make it easier for the more translucent white paint to cover. I used Model Master Chrysler Engine Red; Insignia Gloss White and Gloss Black with Testor’s Airbrush Thinner...which I HIGHLY recommend! I would suggest toning down the black with a drop of white. The one picture I have shows another “color” at the leading edge and tips of the wing. I assume this is aluminum either not painted or worn off, so I painted this area aluminum before the black. Also, the demarcation between the black and red/white HAS A LOT OF OVER SPRAY. I also assume this plane only flew once with this scheme, so it would be in pristine condition. The interior of the intake should be red and maybe the wheels wells. The struts are definitely steel color and the wheel covers inside are aluminum, not zinc chromate.

The decal for “MiG 23” went on smoothly using Micro Set as a wetting agent. It didn’t react well to Micro Sol, not all the wrinkles went away. I covered the decal with Future and sanded it smooth with 4000 but next time no setting solution! The white is very opaque, no red shows through and the “yellow” in the clear film disappeared. I trimmed away some of the clear film but not too much, this is a large decal to move around. Smooth out the groove that represents the gap between rudder and stab or the roughness will really show after decaling.

Done! Thanx to Matt for the model and to Pro Resin for another kit of an obscure plane.

Website with picture of “MiG 23” version:
https://www.thenorthspin.com/photos_official_usaf_pastjet/245.jpg.