Fun Scale X-20 Dyna-Soar

Introduction Motivated by curiosity about historic aircraft, I went to the nearest library and checked out Jay Miller's The X Planes. Around the same time I was building an Estes 1:73 scale Titan IIIE. Things clicked, and I realized that building an X-20 to fit atop my finished Titan might not be too hard, given its simple lines. And it really was easy! The model described here is a boost-glider that flies back independently while its booster drops away on parachute. It can can also be built as a non-gliding nose cone. Either way it's a fun fly.

Scale Accuracy The X-20 never flew, never made it past mock-up stage. Some contracts were signed by the Air force and that pinned down the serial numbers of the first series of Dyna-Soars (61-2374 thru 61-2383). These numbers are almost invariably displayed on the vertical tail surfaces in a contrasting color. However, beyond these numbers on the tail, black heat-radiating coating, a stars & bars on one upper wing surface, and something designating USAF ownership on the fuselage, the markings on this plane weren't finalized. Yellow NASA markings, shown in the inset graphic, might have been added to the vertical tails on some flights as was done in the X-15 research program. All of this confusion over markings, and even the final configuration, consigns any X-20 model to haunt the region between pseudo and true scale. Consequently almost any plausible marking scheme will be fairly authentic. The scheme I used is similar to the inset graphic, but without the Yellow NASA markings. Miller's book shows several other proposed schemes; pick a paint job that suits you. Also, nearly every large booster then available was proposed as a launch vehicle for the X-20, if only for suborbital hops. Given this selection, using a model of a mid-70's vintage Titan IIIE (produced as a kit until recently by Estes) to lift this model is reasonable at the fun-scale level of accuracy. If you don't have a copy of this kit, a large-finned BT-60 rocket, such as a Big Bertha, will almost certainly work (swing test it first, though; I haven't tried other boosters). A useable booster can always be bashed together from about 18" of body tube and some oversize fins.

Fun-Scale Approximations In the interest of simplicity and flight characteristics, I've taken some liberties with the X-20 design. The vertical flair at the rear of the fuselage is missing. The tails have not been 'toed in,' in order to reduce drag near the nose and make the model more stable under boost. There is some glide-related hardware hanging around the tail, unless you opt for the non-gliding version. The shape of the window cover plate over the nose isn't exactly matched by the simple paper wrap given. Finally and worst of all, the balsa adapter between the booster and the orbiter isn't contoured into a smoothly flowing surface. None of these is an insurmountable obstacle if you want to improve your model's accuracy, but I've elected to emphasize "fun" over "scale" in these plans.

Construction Figures: fig. 2, wing layout | fig. 3, adapter diagram | fig. 4, harness sketch

Pictures of the Finished Model: orbiter | exploded view | top | underside

References

Mark Wade's X-20 Page Source of the above inset .jpeg. Part of his Encyclopedia Astronautica. Amazing stuff, including more "what if" images of X-20s in flight.
The X-Planes Jay Miller, 1988 Aerofax, Arlington TX. It's all there!
PAT (Preservation of Aerospace Technology) Projects X-20 Appendix to lifting body publication. A good history of the program.