Betterfly (oz846)


Betterfly (oz846) by Norm Ingersoll from Flying Models 1952 - plan thumbnail

About this Plan

Betterfly. FF all-sheet powered glider, for K&B .020 Infant power. By NP Ingersoll.

Quote: "A powered all-balsa glider so easy to build that a novice can make it in a few nights. Takes a K&B .020 Infant. Betterfly, by NP Ingersoll.

Betterfly was designed to provide the utmost in flying satisfaction with a minimum of effort on the part of the builder. Actually, it, is an over-size hand-launch glider with a power plant to provide climbing power supplied by the K&B .020 Infant. With an easy starting .020 and a consistent air-plane, sport-flying is tops in free-flight pleasure.

As a pure sport model, Betterfly fills the bill admirably. It is of all-wood construction which lends itself to easy building, easy repair and durability. The flying surfaces are fixed - with a plane this light removable wings and tail are unnecessary. Lastly, its simplicity is such that even the slowest of builders can complete the plane in one or two evenings. Plans are half-size, but you can obtain the full-size plans free by using coupon on Page 44.

WING: Let's begin construction with the wing. Select clear, straight-grained balsa and cut to outline shape. The next task is that of carving in the airfoil, which is simple if the right tools are used. A long-bladed X-Acto knife is recommended, though a modeler's plane should do the job. Be sure to check the airfoil from time to time as work progresses - this can be done by means of the template supplied on the plans.

Now cut the required dihedral. Make certain that all joints are strong, coating them with cement at least four times. Cutting the wing ailerons from 3/32 sheet and joining them to the outboard panels by means of soft-wire hinges completes this component.

FUSELAGE: Using a hard strip of 1/4 x 3/4 in balsa as the base, butt-join a sheet of medium 1/4 in balsa to one edge. This assembly, when cut to the proper shape, forms the fuselage. Make sure that the balsa strip is the hardest available, as this is to form the backbone and must absorb the shock of hard landings, crashes, etc.

Next, attach the firewall, using the nacelle keels to insure a perpendicular arrangement. Solder the engine nuts to a thin brass plate and cement to the back of the firewall. Finish the engine nacelle by filling in with soft sheet and sanding the entire assembly - taking care to flow the lines of the nacelle into the fuselage. This can be done by effective use of a sanding block. For added strength and appearance, cover the nacelle with silk or nylon, using sanding sealer not only as the adhesive but also to fill the pores of the fabric.

STAB & RUDDER: The tail surfaces, are so simple, the plans are self-explanatory. Care should be taken, however, to prevent warps.

ASSEMBLY: Final assembly of the model should be done with extreme
care, as any mistake here will be magnified during the adjustment period. Place the wing at 3° positive incidence while keeping the stabilizer at 0°.

Models of this type are not difficult to finish, and there are many methods from which to choose. The original had an especially attractive finish, as follows: The entire model was carefully sanded with fine paper and given three very thin coats of sanding sealer which should be used in lieu of dope as it is less susceptible to warps and simple to apply. Each successive coat was given a light sanding. Next, the trim area was marked off and given two coats of International orange, while the cabin was painted black. This was followed by an overall application of high-gloss fuel-proofer.

ADJUSTING: Although Betterfly is a good all-weather performer, it is advisable to wait for a relatively calm day for initial testing. Since the
model is not equipped, with a landing gear (though you may add one if you desire) test-gliding is best conducted over tall grass.

Adjust for tight left turns, but do not attempt to get a nose high gliding attitude so popular with contest flyers. The glide should be flat and fairly swift. To obtain this left turn, make all adjustments with the wing flaps. Raising the left aileron (viewing the model from the rear) and lowering the right will force the model to glide left - but change the aileron settings only a small amount each time until the correct balance is achieved.

The climb is next (a right turn is preferable) and this is attained by varying the thrust line only. Do not change the glide settings! This set-up will give an 'S'-shaped flight pattern which is not only graceful but also an asset on a windy day, when it tends to keep the model over the field.

Realistic performance will be achieved by the use of an over-sized propeller and low-power glow fuel. The original used a 6 x 3 Tornado, cut down to 5-1/2 in diameter with the tips left square - in conjunction with O&R Economy fuel.

With the .020 engine, no trouble should be encountered. If you wish to have more power, an OK .039 or K&B .035 can be installed though they may tend to affect the sport performance of this model.

As a final thought, this job can double as a towline or hand-launch glider just as well. In other words, we have a triple-threat machine. Properly adjusted, and sporting a consistent engine, Betterfly will give unparalleled pleasure and enjoyment. "

Supplementary file notes

Planfile includes article.


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