For some reason I never did much with catapult gliders. The ones you used to be able to buy in the convenience store for a quarter or so were pretty good, but after a few hard landings you had to glue the balsa wing halves into the plastic holders. The ones we bought had the wing halves on a pivot that allowed the wings to fold up during the high speed launch and then a small rubber band pulled them back down at the apogee. None of them lasted more than a few flying sessions. This Viggen model has fixed wings and probably performs a lot better than those dime store models.
Airplanes and Rockets Forum poster Jaegee63 asked me to post this article. See the article "Thor's New Hammer - the Saab A37 Viggen" for information on the full-scale aircraft.
Viggen: All-balsa profile scale glider is catapult launched. Has a flashing climb and gentle glide.
Viggen: The three-forked thunder-bolt from the hammer of Thor. Viggen is also the amazing new fighter for the defense of Sweden.
Built by Svenska Aeroplan AB, better known to us as SAAB, the Viggen possesses Mach 2 performance yet will not rely on vulnerable airfields. It is as versatile as our own Phantom and will undertake attack, reconnaissance, and all weather intercept roles. All of this, yet it only needs a 1500-ft. runway, or highway, for its operations.
Our model has the flashing climb of the original, yet is quite easily built with little expense.
Begin by covering your work table with a piece of Saran Wrap so the glue won't stick where it shouldn't; glue the 1/16" sheet balsa wing pieces together flat as there is no dihedral or curved airfoil. While the wing dries, cut out the fuselage from a firm piece of 1/8" balsa. Round the edges with sandpaper and glue the 1/16" sheet balsa fin and sub fin in place.
The wing should be dry now; sand it smooth and round the edges with fine sandpaper.
The canard stabilizer, or foreplane if you will, is cut from 1/16" sheet balsa and sanded. Cut it apart at the center and glue back together propping up each stabilizer tip 3/4" for the necessary dihedral.
You will find that it is much easier to decorate the model at this point than after it is assembled; therefore mark out all desired control surface outlines and panel lines with fine pointed felt tipped marking pens or ballpoint pen. Well-stocked hobby shops may have Swedish decals, but if not, make your own insignia on plain white paper with colored ink or pen, then cut out and glue in place.
To assemble the model it is only necessary to slide the stabilizer and wing into their proper slots and glue very securely. Make sure the parts are carefully aligned before the glue dries.
Bend the launching hook from a paper clip, shove the end into the wood of the fuselage, and glue very securely to complete the model. It is important to locate the hook as shown on the plan.
Now that you're ready to fly the Viggen, check to see that your model balances at the location shown on the plan. No ballast has been necessary on our Viggens, but if yours does not balance correctly, add bits of clay to nose or tail as required.
Hand glide your model to check for proper flight, correct turning with bits of clay on the high wing and do not warp the surfaces for adjustments, as the higher speeds during launch can cause over control and subsequent surprises.
Prepare the hi-start launcher with a ten-ft. length of 1/8" flat rubber tied at one end to a stick driven into the ground and with a 30- or 40-ft. length of string at the other end. A paper clip may be tied at the remaining end of the string to complete the catapult.
Now it's launch time. Slip the paper clip over the hook in the model and draw the rubber taut. Face the Viggen into the wind and if you grasp the model by the upper rear corner of the fin it will automatically come to the proper angle for a smooth, high launch.
If the model tries to loop as it comes off the towing line, simply add more string to the towline until the model comes off in a flat glide. If the model stalls in the glide and flutters down without recovering, add a bit of weight to the nose and possibly bend the trailing edge of the stabilizer down to prevent diving. Note that the action of the elevators on a canard model is opposite that of the conventional airplane.
Have fun with your Viggen, and with a bit of turn in the glide you should have no trouble flying in a field the size of the average school yard.
One 1/16 x 3 x 36" sheet balsa (flying surfaces); one 1/8 x 2 x 18" sheet balsa (fuselage); two paper clips; model cement; felt marking pens and decals as required; ten ft. 1/8" flat rubber and string for catapult.
<click for larger version>
Full-size wingspan is 10" exactly.
The plans originally were printed on the center two pages and were removed and flattened for the scan.
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.
Try my Scale Calculator for Model Airplane Plans.
Posted March 22, 2012