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Scratch built 1/48 scale resin

by "Bondo" Phil Brandt



 AML's 1/72 scale Avia S-199 is available online from Squadron.com




The X-24C, begun as a NASA/USAF design study in 1974, was slated to be a Mach 8 “lifting body” follow-on to the wildly-successful-but-closed-out (1969) X-15 program. Here was to be a lifting body using not relatively low-output Bell X-1 engines as in the existing lifting body programs (XC-24A/B; HL-10; M2F2/3); this one would be driven by the X-15's XLR-99, with the even more powerful Atlas ICBM engine as a backup.

A second, airbreathing, version was to be produced concurrently. Design and wind tunnel work continued, and even the Lockheed Skunk Works got into the act with a larger, even more radical (Mach 12) modification proposal.

The X-24C was not to be, however. In 1978, NASA, using the reasons of project overruns, cancelled the program, although some have suspected that it went “Black.”




In the Beginning...

This curmudgeon’s had the expensive-but-decent ($55!) 1/72 French Sharkit resin release of the X-24C on the shelf for years, but since its scale clashed with the four 1/48 lifting body offerings by Collect-Aire, which were already residing at the Weirdness Works Division of Bondo Industries, it was going to have to be Scratchbuild City. The Sharkit included decent three-views which were enlarged to 1/48.

A basswood master of the wedge-shaped fuselage lent itself to straightforward shaping via bandsaw and large table sander; same, same for the flying surfaces. The most difficult part of this operation was getting the join surface angle between the fuselage and wings just right. The vertical fin and canted minor fins were fairly easy to sand to overall shape (but more difficult to form a snug join line on the fuselage).

Dividing the fuselage master into segments for pouring RTV molds was the same arrangement as with the Sharkit release. Hollowing the fuselage pieces was easier than I had envisioned, since the Dremel with coarse sanding drum mounted went through the stuff like a hot knife through butter.


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Since the NASA /USAF plan was to reduce costs by maximum use of X-15 and other off-the-shelf components, the Weirdness Works Division employees went the same route, utilizing the Special Hobbies X-15 cockpit tub (suitably modified to fit the slimmer driver’s area of the X-24C) and seat, nosegear well and the XLR-99 engine exhaust.


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Scratch building continues...

The X-24C was to use a larger, extended exhaust cone, and that of the model’s came from resources in the Bondo Industries Airframe Reclamation Area. The aft bulkhead and detailing (through which the exhaust flows) was handmade, as were the jettison/dump tubes ala X-15 (formed from aluminum and brass tubing) protruding from said bulkhead.


Your correspondent had considered using the resin Special Hobby X-15 dump tubes, but they were much too delicate and, IMO, too small. The subject’s instrument panel and shroud were built to fit within the X-24C’s narrower (than the X-15) forward fuselage.



Maingear wells were created from plastic sheet with some corrugated sheet in the ceiling.


A basswood master was carved and cast in resin, to use as a vacuform mold. I try as much as possible to do open canopy configurations which, IMO, add materially to any model’s busy-ness and presentation. And, an open canopy, especially one made of thin, vacuformed plastic, needs framing of some type to give the appearance of structure, especially in a subject such as the X-24C which undoubtedly had to withstand even more forces than that of the hefty X-15 one. Accordingly, I poured an additional canopy shape and cut away much of the resin to leave only a frame, which, of course, nests perfectly within the vac outer shell. The finished canopy mounts to the fuselage spine via a brass pin.


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Gear Struts / Wheels

Cannibalized–we used to say “cannonballed” in USAF flightline parlance–from the ol’ Monogram F-5.



The modified nose strut and wheels are from an Evil Empire fighter item; I can’t remember which.

Detailing the Cockpit

After searching many, many Eduard color-etched cockpit sets at our own King’s Hobbies, the Mirage III item was selected because it had a relatively narrow instrument panel and narrow consoles. Seat belts came from a True Details generic jet belt PE fret. Unfortunately, the canopy obscures much of the interior cockpit view.

Before the large trapezoidal opening in the fuselage (beneath the cockpit) was filled with plastic sheet, quite a bit of balancing lead had to be added, and I feared for the plastic gear struts; so far they’re hangin’ in.


Finishing and Markings


Because so many decals would be used, I elected to go gloss black lacquer in the spraycan (Testors) over a suitably prepared (read many iterations of Acryl Blue, wetsanding and automotive lacquer-based primer) surface.

Five color coats did it, and after overnight drying–even lacquer, when applied in multiple “wet” coats (this wetness is especially needed for dark colors so that the lacquer will level with zero orangepeel) needs additional time to harden–the decal drill started.

The hardest decal to find was an appropriately-sized yellow/black “NASA” stripe for the vertical fin. The ancient Revell 1/65 X-15 tail logo fit the bill almost perfectly, albeit with a bit of additional--I had two of the sheets--yellow background. All stencils came from the Special Hobbies sheet, and the tiny NASA logo on the nose from the Cutting Edge NASA sheet.



To seal the decals and knock down some of the gloss, the bird was given a “dusting”–and I really mean dusting: the airbrush pressure is set to almost 30 psi, the gun held more than six inches away, and yours truly’s hand make swift strokes above the airframe–with greatly thinned (at least 50%) Testors semi-gloss clear water-based acrylic. The light dust coat practically dries as it contacts the surface, and the sheen is quite uniform: no bluish-white puddles which will not dry uniformly.

It works. Try it!



Don’t know why this curmudgeon suddenly put aside straightforward kits–yeah, Collect-Aire is real “straightforward”--to do something like this, but hey, somebody in HS Land’s gotta demonstrate that there’s been a whole lotta aerospace development since 1945. Can I have an Amen on that?



Additional Images


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Model, Images and Text Copyright © 2007 by "Bondo" Phil Brandt
Page Created 31 May, 2007
Last Updated 24 December, 2007

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