Whisper (oz14896)

About this Plan

Whisper. Simple catapult glider model. Wingpsan 9 in. All-sheet balsa construction.

Quote: "If you're the outdoor type model flyer, then this zipsy-doodle dandy is the thing for you. You'll have lots of fun with this little fellow, thrills that'll make you want to shout. Whisper, by Ernest Copeland. Author of the Mosquito Sportster (oz5143), etc.

Although not listed as a type in the AMA rules, catapult-launched glider s are nevertheless widely used at local contests. For sport, sling-shot soaring offers a thrilling diversion from the old heave and hope method. An extra something is required in the design of this type of glider, since the speeds of the heavier jobs vary from more than fifty miles an hour to the regular gliding speed of less than fifteen miles an hour.

The heavy catapult gliders used for contest work are very sensitive to adjustments and a beginner, flying one of these jobs for the first time, would have a pretty fair chance of washing it out. It was to give the novice necessary experience to prevent such occurrences that Whisper was designed. With a span of only nine inches, the Whisper embodies - on a miniature scale - all the soaring qualities which the big gliders possess.

Construction and Assembly: The small size of the pieces used in this glider make it possible to utilize scrap balsa. All wood is selected quarter grained stock and of the size indicated on the plan. Wings and tail surfaces should be shaped from fairly soft balsa, while the fuselage is shaped from heavier stock in order to take the knocks.

Make tracings of all the parts and cut them to outline shape. The tail surfaces are sanded to a streamline pattern and the wings to a conventional rib section. Sanding the surfaces should begin with No. 3-0 sandpaper; use No. 10-0 later. This will give you a beautiful satin-like finish which will help a lot in stretching the glides.

The fuselage should also be sanded smooth, and a headless pin thrust into the wood and faired with a piece of 1/20 sheet balsa will make the launching hook and complete the body.

In order to rig up the sweepback angle of the wing, first cut the panel in half and carve a quarter inch wedge from the trailing edge as shown on the plan. Cement generously when setting the dihedral angle in the wing.

In assembling the glider, the tail surfaces and the wing must be sanded to perfection before they're cemented to the fuselage at 0-degrees incidence. Check for perfect alignment and be sure all parts are clean and secure at the joints.

As soon as the glue has hardened and the weather is suitable, take Whisper out for some test flying and real enjoyment.

Adjusting and Launching: As a preliminary step, release Whisper from shoulder level, gradually adding clay to the nose until the glide is smooth and free from "mushing" tendencies. It should be noted that in glider work careful and patient adjustment is equally important as accurate construction.

Using a one-foot loop of 1/8 rubber, try the first catapult launch - but gently. The hand holding the rubber should be held still until the ship has been released. Try various angles of bank until you get the one most satisfactory for a smooth launch.

It is not necessary to point this glider straight up, since it climbs of its own accord due to the excessive speed. Watch very carefully the pull-out at the top of the climb, for this is where most of the trouble of adjustment comes. If the ship rolls out too soon and does a stall before starting to glide, remove some clay from the nose and warp the elevators down. If it does not pull out soon enough, add clay and warp elevators up. The wing will probably also need warping to prevent twisting during the climb. Gradually increase the speed of the launch and iron out the bugs.

Another catapult method suggested is to drive a stake into the ground with a rubber strand tied to the top. The other end is attached to the launching hook of the glider, and after stretched to its maximum point the driving force of the rubber will be powerful.

If you learn all the tricks of adjusting Whisper, there are lots of thrills in store for you."

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