1/48 Special Hobby X-15

Speed record breaking version X-15A-2 

by Michal Sekula

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History

The X-15 rocket-powered aircraft was developed to provide high-speed, high-altitude flight research information. The X-15 was air launched from a B-52. Depending on the mission, the rocket engine provided thrust for the first 80 to 120 sec of flight. The remainder of the normal 10 to 11 min. flight was powerless and ended with a 200-mph glide landing.

The No. 2 X-15, crashed and damaged in Nov. 1962, was redesigned to the X-15A-2 and modified for testing hypersonic ramjet engines.

Among the most visible modifications were:

· the fuselage was extended to carry liquid hydrogen for a supersonic combustion ramjet that was flown (as a dummy) but never tested. The basic X-15 was a rocket-powered aircraft 50 ft long with a wingspan of 22 ft, the X-15A-2 had been elongated to 52 ft 5 in.

· external fuel tanks were added to increase engine burn time by about 70% (roughly additional 60 seconds). They were used on the aircraft's Mach 6.7 flight.

In June 1967 the X-15A-2 received a full-scale ablative coating to protect the craft from the high temperatures associated with hypersonic flight (above Mach 5). This pink eraser-like substance applied to the X-15A-2 aircraft was then covered with a white semi-translucent sealant coat before flight. Two flights were made with this white ablative coating.

In 21 August 1967 was the first test flight with full ablative coating and ramjet mock-up. Maximum Speed 5419 km/h and the maximum altitude 27740 m were achieved. As a result the another modifications were performed and included:

·  mechanical “eye-lid” cover over the left canopy windscreen was added to protect it from the deposition on the windshield by the ablative sealant,

· new ventral fin was used after the original one was damaged.

In 03 October 1967 Pete Knight during the second flight with full ablative coating set up an unofficial world speed record. Maximum Speed 7273 km/h and maximum altitude 31120 m was achieved. The dummy ramjet and external fuel tanks were used again.

On this cropped photo from NASA web page is X-15A-2 during the speed record breaking flight just after releasing from B-52 carrier.

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There was major damage to the X-15A-2 structure from aerodynamic heating due to shock wave impingement from the nose of the dummy ramjet. The aircraft was transported to North American Aviation for reparation but it was to never fly again.

X-15A-2 in his original “black look” with ablative coating removed is displayed at the USAF Museum, Wright-Patterson AFB, Dayton Ohio now. 

Here is my X-15A-2 together with another record-breaking aircraft, Bell X-1 “Glamorous Glennis”.

The kit

The X-15 is one of the „must-to-have“ aircraft kit for me. But for a long time there was no way to obtain one in 1:48 scale. Fortunately, the Czech company Special Hobby released X-15 in the 1:48 scale approximately one or two years ago. The package contains gray plastic and resin parts. Windshields have to be cut from the included transparent plastic sheet.

I very appreciated a box design. There are helpful color pictures of the various X-15A-2 details on the back side of the box.

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Regarding the kit itself the best general comment that almost 100% fits also this kit I found on the Modeling Madness, written by Lee Kolosna: http://modelingmadness.com/musings.htm

 

I hope I do not violate copyright when I quote a bit from Lee’s article:

„...What does one get in a limited-production kit?  Well, the ones that I have purchased and worked on have been quite challenging, to say the least. Despite the initial seductive inspections of the finely engraved detail and all the cool resin cockpit parts, the modeler soon realizes that there are a few things missing. First, there are no locating pins on any of the fuselage or wing half parts. No big deal, you say, as the pins aren't really needed anyway. Then you notice that there are no tabs for attaching the wings or stabilizers. This means a butt-join -- not the strongest way to attach major assemblies together. A closer look at the smaller plastic parts reveals some amount of flash to deal with, and the detail is sometimes quite soft. Some kits have landing gear doors that are molded all as one piece, which the modeler has to scribe and cut into individual components. More often than not, the larger pieces like wing and fuselage halves have large plugs where the injection ports squirted in the molten styrene. These need to be cut off before they can be glued together. Recessed panel lines tend to be very finely rendered, sometimes too petitely. I'll often have to scribe the lines a bit deeper to avoid having them disappear under a layer or two of paint

In the end, I get a model of a really cool and unique aircraft that stands out from the legions of Mustangs and 109s, but I end up killing myself to do it....“

 

A conversion sets NW015 1/48 X-15A-2 World Speed Record Flight Configuration and NWD005 1/48 X-15A-2 tank decals from Czech company New Ware were used. Link to this company producing mainly a broad range of space rockets, modules etc. is: http://mek.kosmo.cz/newware/index.htm#Prodlist Very recommended to visit.

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Assembling

I browsed a lot of web pages searching some info and detail pictures of this record-breaking aircraft. After I decided that I have enough information I had started to build the kit, approximately a year ago. Regarding the kit quality almost all was written before. Fitting the plastic and resin parts was at least challenging. It required endless probing, sanding, putting, probing, sanding, putting... Sometimes I wondered whether all that parts are from one producer. 

Some parts did not have correct shape (right wing leading edge, landing gear leg, etc.). I had not time, experience and skills to correct them so I had problems to fit geometry.

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In the meantime, I found perfect books on www.amazon.com – see references.

I bought them both. A lot of questions were answered, but a lot of new questions and ideas arose. Unfortunately the fuselage with cockpit and both fins were already completed and glued together. As I worked on the kit only a couple of hours per week, sometime per month, I decided not take apart already completed parts and started again but live with it.

Based on the referenced photos from mentioned books other details like exhaust pipes, all cockpit canopy interior details and fuel tank details were made from wiring, paperclips, pins, baby milk can cover and plastic from my spare box.

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Canopy “eye-lid” cover supplied in the conversion set is in the closed position. I wanted it open. So I cut it apart and then only a frame glued together. The “eye-lids” itself in open position were cut from old used PE parts frame.

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Trolley was completely rebuilt to look more realistic and to keep engine part of the aircraft higher as it is more usual according to the photos. Again paper clips, wiring and plastic parts from my spare box were used.

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Painting, Marking & Weathering

Original X-15 is well known with its standard black surface with a lot of colorful marking and stencils. However, I have decided to build the plane in its speed record-breaking configuration and appearance – covered by white ablator.

In reality, before ablator was applied aircraft had been washed to remove any oil, marking etc. from surface. All removable panels were taped. The pre-molded details like leading edges were applied and then entire aircraft was sprayed with pink ablator that was sanded then to the required thickness. The taped panel edges were masked off to allow panels to be opened, now visible as the black lines. Finally white wear layer was brushed over the entire aircraft. This white layer was translucent, so it did not cover pink areas and black lines totally. Therefore additional coats of this white layer were applied generally to the upper surfaces.

After the first ablator test flight some damaged pre-molded parts were replaced and charred areas were refurbished. The surface of the canopy pre-molded leading edge was sanded to remove the white layer to minimize deposition on the windshield during the next flight.

I partially repeated the described process on my kit. I used Humbrol and Revell enamels.

The complete kit was airbrushed with matt white (only cockpit was brushed before and masked). After drying I used a shred and Sidolux (acrylate liquid to polish stones, concrete, rubber, etc.) to polish kit. Then I draw black lines by a permanent black marker and airbrushed the kit with thinned white again to emulate translucent coat.

Basically no rivets and lines of permanently closed panels were visible as ablator coat covered them safely.

 

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The fuel tanks were airbrushed by matt aluminum. After drying I masked aluminum areas and airbrushed white. The white color was airbrushed also on the front part of the both tanks after small rectangular areas for stencils were masked. Then my own mixture of the orange was applied. The white basement made it much more bright.

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All small parts like front landing leg & gears, trolley, engine area etc. were brushed. The kit plus fuel tanks were polished with Sidolux again and decals and stencils were applied. Despite the decals of the orange warnings, rescue arrow etc. located on sides of the cockpit seem to be bigger then they should be when compared with referenced photos I decided to use them.

In fact, I used instructions supplied with the kit only for stencils. For the main, more visible decals and painting, especially on the fuel tanks I rather used reference photos.

Some panel lines were highlighted by strongly thinned oil black&brown color mixture. Then another matt coat was airbrushed over the entire kit. 

As the white plane flew only once before it’s second, record-breaking flight, I would rather use an expression „thermal degradation“ then weathering.

So all thermal degradation of the ablative coat on the fuselage, fins, wings etc. as well as of the rocket engine exhaust nozzle was simulated by orange, brown, gray and black chalk using brush and shred.

After all final matt coat was applied again.

 

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Finally, after more then one-year effort I was happy that it was finished. However, problems are already gone and there is only a big, white, quite dominant kit in the gray-green-brown mass on my shelf I am happy with.

Taking Photos

The shots were taken in the indirect sunlight using digital Sony camera and then modified in the PC. You can see the damaged dummy ramjet (broken tip) on one photo. Bu sure it is not my attempt to simulate high-speed damage. After I put it on the table during photo session with X-15 in the second hand it started to roll and roll... The table edge was too close and ground too hard

 

References

· Hypersonic: The Story of the North American X-15 by Dennis R. Jenkins, Tony Landis, Scott Crossfield (Foreword), William H. Dana (Foreword),

 

· X-15 Photo Scrapbook by Tony R. Landis, Dennis R. Jenkins,

· Dozens of the Internet web pages.

 

 

I hope you enjoy it.

Misos

 

Photos and text © by Michal Sekula