The fastest aircraft….
Here is my latest, a 1/32nd-scale cardmodel build of X-15A-2, 66671, as it looked on Flight 2-53-97 on 3 October 1967. Pete Knight set a world speed record of 4,520 mph, Mach 6.7. To reach the record speed, the airframe was covered with a pink ablative, and then the ablative was covered with a white sealant. (The ablative had a habit of exploding if something hit it after being exposed to liquid oxygen, so the sealant was added to prevent that.)
The build was pretty much an experiment. There is no card model available of the white 66671. The only card 1/32nd scale X-15A-2 available depicts the early black 'A-2. Normally, advanced cardmodelers would do a digital "repaint" of the model to change the colors or markings, but I only have an iPad and I lack any computer repainting skills. So how to model a white X-15A-2?
Simple. Build the model inside-out.
I printed out the model and just reversed the pieces as I built them. The project involved some scratchbuilding and accurizing to depict 66671 as it appeared on the speed-record flight. I had to scratchbuild the "eyelid" used to cover the left pane of the canopy. The shortened ventral and the dummy scramjet were scratchbuilt. On the record flight, the 66671's canopy had a revised leading edge, so I added that. I also added detail and accurized the XLR-99 motor and jettison tubes. (A lot of modelers depict the jettison tubes as silver, but by 2-53-97, the tubes had weathered to a metallic black color.) There were numerous other bits of added detail throughout, and the markings are correct for the speed-record flight. (Plastic modelers building the Special Hobby kit should be warned that SH got the markings wrong for Flight 2-53-97.)
When the sealant was added, technicians didn't worry about complete coverage of the lower wings and tailplanes since they were less likely to suffer an impact. In in-flight photos, you can clearly see pinkish areas through the streaky white paint. I added the light pinkish tint on the underside of the wings and tailplanes with pink chalk.
I will probably add some light weathering at some point. The white 66671 came out of the paint shop pristine, but by 2-53-97 it had already flown once (reaching Mach 4.94) and had been carried aloft on a captive flight, so there was some light wear of the white sealant around some of the panel lines. I also will probably add the external tanks the 66671 carried on its record flight.