X-15A-2 by "Bondo" Phil Brandt (Special Hobby 1/32)

Special Hobby's 1/32 X-15A-2
White Lightnin'

by "Bondo" Phil Brandt

X-15A-2

Special Hobby's 1/32 scale X-15A-2 is available online from Squadron.com

Introduction

Background

The X-15 is unarguably the most successful high speed aircraft research program ever conducted in the U.S. These rocket-powered designs by North American Aircraft Corporation flew an aggregate 199 sorties between 1959 and 1968. Of the three X-15s built, the definitive X-15A-2 version (tail number 66671) in 1967 set an unofficial world speed record of Mach 6.70, a record that still stands today. Piloted by Pete Knight, the white ablative-coated airframe sustained burn-through heat damage to the ventral fin and dummy scramjet. 66671 never flew again, but is on display in its original black Inconel finish at the USAF Museum in Dayton, Ohio.

Bondo Industries always favors the definitive version of any airplane and has already completed both black and white schemes on resin1/48 Collect-Aire X-15A-2 kits. Special Hobby’s release of a big X-15 offered the opportunity to do even more detailing.

The Kit

At the Anaheim Nationals this past summer the Acquisitions Department of Bondo Industries was most fortunate to score the first two 1/32 Special Hobby X-15 kits sold in the U.S.A. That said, this curmudgeon was more than a little disappointed to discover that the kit, although meant to represent the elongated X-15A-2, didn’t include the distinctive external tanks used only on this version, or the dummy scramjet mounted on the ventral fin. Further, no decals for the white ablative-coated airframe were included (although said extra decals were in the 1/48 release.)

When I queried George, the genial Czech MPM honcho, as to whether a follow-on version was in the works, he just smiled enigmatically. I’m guessing that Special Hobby will do a 1/32 follow-on with added detail, just as they did with the1/48 kit. Not wanting to wait that long, I took the bus to Scratchbuild City, determined to do an accurate portrayal of the white record setter.

Construction

Because I am sure a “tanked” version will be released after the first run is sold out, and assuming most of our HS brethren would prefer to skip the practice-bleeding scratchbuild drill and wait for said follow-on kit, I’m going to skip construction pix.

Tanks

The big externals are the most distinctive feature of the longer fuselage bird, the lengthening of which coincided with a factory rebuild following serious structural failure–the spine broke--during a heavyweight emergency landing by famed test pilot Scott Crossfield in 1959.

The basis for the scratchbuilt tanks was 3/4" I.D. PVC pipe from Home Depot. The outside diameter fell somewhat short of what was deemed accurate, so multiple layers of plastic sheet were laminated around the pipe. While this procedure worked, it required many iterations of Blue Acryl, wet sanding and lacquer priming.

The hemispherical aft end caps were fashioned from PVC pipe caps. Asymmetrical tank front sections–they contain recovery parachutes in the real deal--were cast in resin from a carved basswood master. I have taken many closeup pix of the restored-to-black X-15A-2 at Dayton, and they’ve been invaluable for detailing the tanks, especially the lengthwise tubing and other plumbing apparatus. Very thin stainless tubing (from Kalmbach, the model R.R. folks) was bent and CA’ed to the tanks after painting.

Scramjet

The last flights of the A-2 bird carried dummy scramjet shapes, mounted to a modified ventral fin, to investigate airflow and heating characteristics that would be encountered if and when envisioned scramjet-powered X-15s became a reality. Various components from the Bondo Industries Reclamation Archives were kitbashed to achieve the requisite shapes. The Special Hobby ventral fin was shortened in length and multiple sensor tubes added per pix.

Cockpit

Although Special Hobby provides nice instrument panel representation through PE and film backing, the rest of the cockpit is too plain if the canopy is displayed in open configuration. Two types of canopy are included, one of clear cast resin and a vacuformed one. An apologetic note accompanied the kit, saying that in the future an injected clear canopy would be furnished. Even though the windows of the resin version are cloudy, I chose it because it’s more substantial (read thicker) and therefore could better withstand the many modifications that would soon occur.

Pix of the 1:1 bird’s opened canopy reveal that it’s a fairly thick assembly, so I laminated an extra layer of plastic sheet to the inside. This inside layer also provides a proper base to which I added scratchbuilt details and piping. Because of the cloudy resin windows, I kept the “eyelids” on the left side window closed, as provided in the kit’s resin components; that cut the cloudy problem by 50%!

The seat is also somewhat plain, and the provided PE belts and harnesses are much too narrow, IMO more like “spaghetti straps”. I substituted the wider color-etch belts and leg restraints–in the RF-4C, we called ‘em “garters”-- from the Eduard 1/32 F-105 set. Seat stencils were done on a computer and laser-printed on decal paper.

Sidewall detailing, T-handles added to the main instrument panel and a scratchbuilt equipment container between the seat back and bulkhead completed this portion of the project.

Skid Struts / Nose Gear

The X-15A-2 was never fitted with the dummy scramjet while the airframe was on its yellow transport dolly; ground clearance was simply too insufficient. Although the scramjet was mounted after the airframe had been hung on the B-52 launch pylon, I really didn’t feel like building a 1/32 B-52 wing section-cum-launch-pylon, so artistic liberty was taken to pose the X-15 airframe and attached scramjet in a landing configuration, that is, with deployed skids/struts. The struts had to be lengthened 1/2 inch to achieve the proper ground clearance. The extra skids furnished for the inflight configuration provided the additional lengths of strut.

The Special Hobby mounting scheme of the struts to the fuselage is seriously inadequate (a tiny plastic pit inserted into a tiny depression in the fuselage), especially with the added weight of the external tanks, so brass wire was routed through the fuselage and into pre-drilled 1/4"-deep holes in the strut mounts. After gluing with 5-minute epoxy the whole assembly became much stronger. Retraction and shock absorbing cylinders in the struts/skids were made from brass tubing because the resin items in the kit were too delicate IMO.

The kit’s nosegear strut has essentially no detailing; not even the oleo scissors are included, which is hard to believe. I scratchbuilt the scissors assembly and lengthened the strut 1/4" to partially alleviate the severe nosedown fuselage attitude.

Per inflight pix of the bird under the launch pylon just prior to the release for the record attempt, the model’s skids were finished in the pink ablative color sans the white outer layer.

Miscellaneous Details

For the record flight some types of equipment /sensors were mounted on the corrugated aft face of the vertical fin. I was unable to find head-on, closeup pix of the equipment, so I simulated them with a general outline of the ones pictured in sideviews. Per previous OOB kit reviews, the stabilator tips were lengthened. A small pressure measurement “rake” was fashioned and added to the top front of the vertical fin.

Painting and Markings

Painting

A considerable advantage in doing the ablative-coated record holder is that only one main color is involved. And, wonder of wonders, Tamiya makes its outstanding spraycan lacquer primer in white. This stuff is so fine-grained that it dries not flat, but semi-gloss. Perfect for appearance and decaling! Plus, it’s completely compatible with later detail additions of Alclad and Testors Metallizer. After appropriate applications of Blue Acryl gray primer and wet sanding, the airframe received three white coats overall. The black Inconel airframe areas that are not coated with ablative because they’re out of the punishing airflow and heat received airbrushed Testor's Gunmetal. Testors Metallizers are fine if not masked over and if used as the topcoat.

The external tanks were done in Tamiya black and white lacquer primer and overlaid with Alclad as necessary. Fluorescent red is also from ze ol’ Tamiya spraycan.

Panel Emphasis

At a distance, the blinding white ablative coating appears pristine, but closeup pix reveal that it’s covered all over with dark panel lines, many of which are not sharply executed. In the real thing this is because many black Inconel panel seams were masked prior to application of the pink underlayer of ablative. When the seams were unmasked and a thinner white overcoat applied to the pink, the black panel lines showed through distinctly, but not necessarily sharply. After the record-setting flight, the panel lines became fairly “messy.” The model’s panel seams were drawn in with light gray colored pencil.

Decals

Practical considerations of the heat and vaporization of the ablative that would be generated at Mach 6+ dictated minimal stencils as opposed to the Inconel black versions. Only rescue stencils, ejection symbols and safety markings on the aft jettison/vent plumbing were used. I scratchbuilt the stencil backgrounds by spraying fluorescent red on white decal paper. Stenciling was done by reading the fine print on the kit decals (through a magnifying glass) and retyping them on the computer in very small font. Clear decal paper through a B&W laser printer, and voila!

Conclusion

The X-15 is one of this senior modeler’s favorite aircraft, made more so on that Fall day in 1969 when it was loaded into our great silver C-133A at Edwards, and carried by us to Dayton.

References

“North American X-15/X-15A2", Ben Guenther, Jay Miller and Terry Panopalis, Aerofax, ISBN 0-942548-34-5. This is the original authoritative book on the X-15.
“Hypersonic,” Dennis Jenkins and Tony Landis, Specialty Press. This is the book I really need to buy!
“X-15 Photo Scrapbook”, Dennis Jenkins and Tony Landis, Specialty Press, ISBN 1-58007-074-4. A great pictorial sequel to “Hypersonic”.
“X-15, NASA Mission Reports” edited by Robert Godwin, Apogee Books, ISBN 1-896522-65-3. This thick book contains, among other items, the
Dash 1 (flight manual) from the X-15, as well as many other rarely seen pix and line drawings of X-15 assemblies, systems and procedures. To top it all off, a CD is included with pix, interviews etc.

Additional Images

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