July 1962 American ModelerTable of Contents
Aeromodeling has seen significant changes over the decades both in technology and preferences. Magazines like American Aircraft Modeler, American Modeler, and Air Trails were the best venues for capturing snapshots of the status quo of the day. All copyrights are hereby acknowledged.
This rocket boost glider called the Dyna-Soar was powered by American Telasco's version of the Jetex 50 engine. Jetex rocket engines were quite popular with model airplane, boat, and car builders through the early 1970s, at which point the fuel supplies began to disappear. Most Internet sources posit that Imperial Chemicals Industries (ICI) ceased making the fuel pellets due to a combination of liability and regulation issues. ICI, based in Scotland, manufactured the Jetex fuel pellets* from a measured blend of guanidine nitrate, 2,4-dinitroresorcinol, potassium nitrate (aka saltpeter), iron oxide, kaolin, and asbestos. Today, obtaining the required chemicals, or even doing an Internet search for them (as I just did), will probably get you a big red flag in the Department of Homeland Security's database. There are probably a couple agents on the way to my house as I write this.
* See the Jetex Propulsion Lab for a incredible bit of information on the motors and the fuel.
Rocket (Jetex) Powered Dyna-Soar
Designed and tested by Paul Del Gatto
Dyna-Soar, the manned space glider, is an incredible flying machine. Compared with this Mach 25 terror, even the famous X-15 is a toy. Boosted aloft by a Martin Titan, it will combine the high speed of the ballistic missile with controlled, accurate flight of manned aircraft.
Dyna-Soar's pilot will shorten or lengthen its range by thousands of miles, changing course to reach a landing site. He can choose fields as far apart as Point Barrow, Alaska and San Diego. Able to operate subsonic, transonic, supersonic and hypersonic, Dyna-Soar will be capable of operating like a large, fast aircraft when approaching an airport.
Later developments of Dyna-Soar for weapons-system and escape missions and to circle the moon will take various combinations of Saturn boost stages.
Surprisingly, a model Dyna-Soar is easier to make than many a free-flight design. Deltas like Dyna-Soar long ago demonstrated their performance and stability capabilities. The Jetex Pay-Loader "150" rocket motor with its augmenter tube provides plenty of push and the craft presents no adjustments problems.
Your Dyna-Soar, built as a unit, is practically complete before lifting it from the workbench. Only the fins, part of the elevons and the landing skid remain to be added.
Since weight and balance are important, the craft should be covered with lightweight Silkspan tissue and colored dopes should. be used sparingly. Follow the hardnesses of balsa specified.
Wing: Pin down 1/8" x 5/8" hard-balsa tapered leading edges and wing trailing edge pieces, followed by medium 1/8" x 3/8" balsa center-section pieces. Fit and double-cement in position 1/8" x 3/8" medium ribs and diagonal pieces.
Assemble built-up portions of the "elevons" using hard 1/16" x 1/4" trailing edge pieces and medium 1/16" x 1/8" and 1/8" -sq cross pieces where required. Aft sheet-balsa pieces (elevens) are added later.
It is important that this procedure be followed in making the elevons ... for each elevon pin down and cement to wing trailing edge the four main cross pieces; attach the elevon trailing edges flush with the top of the cross pieces, then the diagonals. Elevon cross sections (on side view) are obtained later by sanding the bottoms of the elevons cross pieces and diagonals to match the 1/16" thick elevon trailing edges.
Fuselage: Cut formers from medium sheet balsa, noting thicknesses. Erect formers F-5, F-5B, F-6, F-7 and F-8 on center section pieces, then slip augmenter tube into position. Tube is rolled to shape from .005" aluminum 2-5/8" wide plus allowance for an overlapping seam.
After erecting formers F-1 and F-2, cement in motor mount. This is assembled from 3/32" medium balsa base (full body width) and 1/16" thick plywood overlay 3/4" wide (to which metal motor-mounting bracket is screwed).
Before sheet covering the fuselage make sure you understand the hatch construction. Fuselage sides are 1/16" medium balsa sheet, extending forward to 1/8" sheet fill-in cabin nose piece. Sides are feathered together where they meet at the nose. Fill in where necessary with balsa scraps.
Forward portion of removable hatch is carved from soft balsa block 5/8" thick. Hatch extends to F-4. To complete hatch, insert formers F-3 and F-4 and plank with soft 1/16" sheet. When thoroughly dry, model is removed from work surface.
Final assembly: Add 1/16" x 3/4" soft-balsa sheet elevon pieces, then sand smooth entire model, taking care that elevons taper from the bottom to a thin edge at their trailing edge, as per the side view. Cut fins and rudders, sand smooth, cement in place. Note they are offset slightly relative to centerline. Round off leading edge pieces.
Cut air-intake holes in forward fuselage. This air flow is required for augmenter tube to serve its purpose - stepping up thrust. Cover the holes with fine wire screening.
Shape 1/4" thick landing skid from two laminations of 1/8" sheet balsa, cement securely in position.
Painting and finishing: Give wing framework a coat of clear dope wherever covering will touch. For sheet-balsa fins, rudders and elevons plasticize dope with four drops of castor oil per ounce of dope. This minimizes warping due to dope shrinkage.
Cover wing top and bottom with lightweight Silkspan; use one piece for the bottom and two for the top. Run grain spanwise. The fuselage is not paper-covered. For overall doping of completed covering, use mixture of 1/3 thinner and 2/3 dope. Give covering three coats, allowing each to dry, and each time apply a coat of dope to the fuselage. After each of the first two fuselage coats, sand sheetwood skin with fine paper.
Color scheme is dark blue fuselage and silver wings. Mix colored dope with thinner 2/3 and 1/3 as before, apply two coats. Lettering and insignia trim are from hobby shop decals.
Flying: Test glide model, launching it by the landing skid. If tail heavy, add clay ballast to nose. If nose heavy bend up elevons slightly. For best performance model should be trimmed with elevons raised 5° to 10°. Make these initial tests over soft grass and avoid windy weather. Aim the model at a ground spot about 50' ahead in these hand glides.
When flying with power point nose up slightly, launch with the same force as for hand gliding.
Further adjustments are carried out by bending individual elevons and/or the trim tab (note bend line) of the left fin. For example, bending up the left elevon (looking down on the craft from the rear) will cause a right hand turn and vice versa. Never bend an elevon down.
If more turn control is desired, or if a smoother, coordinated turn-and-bank is needed, bend the fin trim-tab in conjunction with elevon adjustment. Thus, bending the tab toward the center line while bending up the left elevon, coordinates both controls for a right turn. If Dyna-Soar turns too tightly, use opposite adjustment.
Be sure to select plenty of flying space because your Dyna-Soar will live up to its name. It climbs like a homesick angel and probably will come down out of sight unless adjusted to circle.
(Balsa unless otherwise specified)
One 1/16" x 2" x 36" (medium) for fuselage sides and formers; (1) 1/16" x 3" x 18" (soft) for fuselage top and elevons; (1) 3/32" x 3" x 18" (medium) for fin, rudder arid engine platform; (1) 1/8" x 2" x 18" (medium) for fuselage formers, gussets and wing fill-ins; (1) 1/8" x 5/8" x 36" (hard) for tapered wing leading edge; (1) 1/8" x 1/2" x 18" (medium) for wing trailing edge; (2) 1/8" x 3/8" x 36" (medium) for wing ribs and diagonals; (1) 1/8" x 1/4" x 18" (hard) for elevon trailing edge; (1) 1/16" x 1/8" x 36" (medium) for elevon ribs and diagonals.
Also: 1/16" plywood engine mount; aluminum foil liner; fine wire mesh screen air inlet; 1/32" diameter wire; light weight Silkspan covering; Pay-Loader "150" engine; clear and colored dopes; cement; decal; .005 aluminum for augmenter tube; clay ballast.
Full size drawings for Jetex-powered model are on Hobby Helpers' Group Plan #762A (85¢).
The AMA Plans Service offers a full-size version of many of the plans show here at a very reasonable cost. They will scale the plans any size for you. It is always best to buy printed plans because my scanner versions often have distortions that can cause parts to fit poorly. Purchasing plans also help to support the operation of the Academy of Model Aeronautics - the #1 advocate for model aviation throughout the world. If the AMA no longer has this plan on file, I will be glad to send you my higher resolution version.
Posted June 21, 2014