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PART 2
A High Powered Contest Model That Climbs Straight UP
Equipped With Pontoons If Won the First Official Seaplane Contest
By SAL TAIBI
LET US emphasize that the wing of the Powerhouse is designed not so much for sheer beauty as for ruggedness and high performance. The aspect ratio of six has been found admirably suited to all flying conditions and the entire wing is rugged to an extreme.
We can't define the wing section. It has not had the benefit of wind tunnel tests by experts; however we've found in actual practice it gives us the results we want . . . a fast climb and a slow, steady glide.
The rib sections are indicated on the drawings. Cut them from soft 1/8" sheet balsa, and after cutting them be sure and sand them. This is best done by pinning all the ribs together and sanding them even with a sand-block.
The wing spars, leading and trailing edges, should be of a hard grade balsa. In order to avoid warping of the wings, be sure the balsa used is straight in grain. Pin the quarter-square balsa spar to your work table and cement each rib in position according to the plan. Next cement the top spar in position. The leading and trailing edges are then placed according to the plans. Allow all joints to dry at least an hour before removing from the board.
The spars are cracked slightly, as indicated, to form the tip and the wing tip outline is then added to the structure. Form the other half of the wing in the same manner. After sanding and cementing all joints thoroughly, the wing is ready to be joined at the center section.
If you will study the construction details on the plans, you will observe that the center section is simple, yet very strong. Pieces of 1/8" hard sheet balsa are cemented in each side of the front and rear spars. Pins are used to hold the construction while the cement is drying.
Note that there are eight inches of dihedral in each wing tip. Check your construction very carefully to insure that the two sides of the wing do not vary, as this is detrimental to good flying.
The bottom of the center section should be cut flat. The ribs are then added to this section which is then sheet covered with 1/16" sheet balsa, top and bottom.
The Stabilizer
The stabilizer is elliptical in outline and may be easily constructed by referring to the plans. The method of tracing the outline is as follows:
Obtain a piece of cardboard, approximately 15 by 17 inches. Measure out the space needed to form half of the stabilizer. Box this space into two inch squares, then trace the stabilizer outline. Cut the outlined form from the cardboard and you will have a pattern for half of the stabilizer. On a piece of paper 15 by 33 inches, trace both halves and you will have the entire outline. Draw in the spar and ribs and follow the method of construction as shown on the plans. Wings and stabilizer are covered in the conventional manner. Silk or two layers of strong tissue may be used. Several coats of dope over the tissue make it very strong.
Adjusting And Flying
Incidences in this ship are "built in." Very little, if any, incidence will be needed in either the wing or the stab.
The ship should be hand glided to assure a steady, smooth glide before any power flying is done.
On the first flight the motor should be just "ticking over." In other words, run the motor as slowly as possible. Hand-launch the ship, letting the motor run about 20 seconds.
If the ship shows no spiral tendencies, due to warps, etc., more power may be used until finally you are using the maximum power available. It is advisable to decrease the motor run as you add power for the ship has decided' "out-of-sight" tendencies.
Slight thrust adjustments, right or left, and rudder adjustments are all that are needed to give the ship proper turn under power and glide.
Notes
Propeller - With a Forster motor best results have been obtained with an 18" propeller of approximately 12 - 14 pitch. If you make your own prop and follow the diagram you will have such a propeller and will find that the performances is much better than that which may be obtained from a majority of custom-made props on the market.
If yon wish to check your finished ship with the original model, here are the weights. Original job, Forster motor, medium batteries, 4-1/2 pounds. Same job, plus floats, 5-1/4 pounds.
Scanned From December 1939
Model Airplane News
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