The Plan Page
[ Home ] [ Previous Plan Pages ] [ Special Things ] [ Earl Stahl Plans ]
In the August, 1939, issue just eleven months ago - we presented the "Hi-Climber." Well, since that time letters have been coming in by the sack-full asking for another Earl Stahl model. And now, balsa fans, we've got one for you that matches the "Hi-Climber's" performance in every respect-the "Hurricane!"
By Earl Stahl
Author of "A Top-Notch 'Hi-Climber' "
HERE'S A MODEL that's the result of two years experience with low wing - designs. And in it are crystallized - the desired characteristics for stable, consistent flights. The craft has been flown hundreds of times, in all kinds of weather, without crashes of any sort. When winder - wound, the climb is interceptor - like, being nearly vertical. This job, like most low-wingers, goes from the power flight to the glide without any tendency to dip or stall. Flights in calm evening air average 1 min., 38 sec., but when aided by "risers" the length of flight is considerably longer.
Most parts are shown full size on the drawings, so little difficulty should be experienced in duplicating this plane. Trace the plans so work can be done directly atop them. Don't cut or deface the magazine pages, and, where necessary, enlarge the plans to full size.
Why is Earl Stahl pointing? Well, he's indicating the path the "Hurricane" always takes -- up!
It's easy to see from this photo that the "Hurricane" is designed both for speed and strength. And. as in all ships Earl turns out. simplicity is the byword. What's more his easy - to - follow instructions will make it a cinch for even, beginners to construct top - notch models from the graphic plans given here.
FUSELAGE AND LANDING GEAR
THE BODY consists of a rectangular under-frame to which the formers and stringers are added. The shaded areas of the side view indicate the part to be constructed first. Incidentally, it is advisable to make the tail-piece integral with the fuselage, and then it can be cut off after the entire unit is completed.
Work directly over the plan and make two sides, one atop the other, from medium grade 1/8" sq. balsa. The glue will probably cause them to stick together, but they may be separated by a razor blade. Set the sides erect over the top view and join them with 1/8" sq. spacers as indicated. Work carefully and line everything up correctly.
Bulkheads - halves of which are shown on the plans-are cut from 1/16" sheet balsa and are glued to their respective stations. You will notice that most of the bulkheads have no stringer notches, so glue the 3/32" sq. stringers directly on the formers.
Bend the landing gear from a single piece of 1/16" diameter wire. Bind the gear neatly into position with thread. Wheels, made from laminated balsa, are fitted with brass washers which serve as bearings. Washers soldered to the axles will hold the wheels in position.
Shaded areas in the front and rear are filled with 1/16" sheet balsa to provide a suitable place to hold the model while winding. Thin aluminum plates are cemented securely to the sheet balsa in the rear. These plates serve to cradle the hardwood dowel pin which is fitted through the fuselage to hold the rubber motor. Scrap balsa is used to form the cockpit. Once the tail piece is cut off, the fuselage construction is complete.
WING AND TAIL
EIGHTEEN ribs are cut from 1/16" sheet to the exact shape shown on the plans. Fit the various sized spars carefully into the notches, and cement the - hard leading and trailing edges into place. Wing tips, cut from 1/8" sheet balsa, are now cemented into position. When dry, the leading and -trailing edges, as well as the tips, should be trimmed and sanded to the indicated shape. The tail surface construction is very simple. A typical stabilizer rib is shown, and the smaller ribs are formed from it. The top spar is located after the ribs are pinned into position. Select medium-grade wood for the tip outlines and the trailing edge.
The rudder is formed from 1/8" thick outlines and 1/8" by 1/8" spars and ribs. When dry, it is lifted from the plan and the 1/16" by 1/8" pieces are glued to both sides to form the streamlined shape. This manner of construction, which is used for all tail surfaces, is very strong and light.
COVERING AND PROP
BEFORE starting to cover the various parts, it is advisable they should be carefully sandpapered to remove any roughness, and flaws.
Banana oil is used as the adhesive to fasten the colored paper to the frames. The grain of the paper should run lengthwise on all surfaces. Stick the paper to every rib and spar of the wing's undersurface -- only on all other sections adhere the covering to the extremities of he part being covered. Curved parts, such as the fuselage top and nose, as well as the wing tips are covered with several small pieces.
Spray a fine mist -of water on all the covered parts to tighten the paper. If the wings and tail planes are pinned to a flat surface they won't warp. When dry, two coats of light dope are applied to the whole plane.
Probably the most important single part of any flying model is the propeller. Be especially careful to make this one correct. Select a hard block for the prop, and cut out the blank as shown. Drill the hole for the prop shaft before going any further.
The back-face of the blades is cut first. Cut and sand about 1/8" undercamber into each blade and remove bumps and roughness with sandpaper before starting the front.
The hardness of the block will determine the thickness of the blades, but remember that a thin cross section is most efficient. Three or four coats of dope, if sanded between each application will make a smooth, hard finish.
The spinner is made in two pieces and glued to the sides of the prop. A simple "dogtooth" freewheeler is used. The gear is made from 1/64" sheet brass. Glue the freewheeler securely in place, and do likewise with the brass washer which protects the back of the propeller.
Make the nose block from hard balsa. Looking from the top, the hole through it should be slightly to the right. With a knife, cut the block to shape and then finish with sandpaper. A notch is cut into the front to permit a rubber-band to hold it in place. The projection on the back which fits into the fuselage is made from a separate piece of 3/16" balsa. Fix the thrust line by cementing washers in position.
The prop shaft is bent from .040 music wire, and it should have a hook as shown to keep it from straightening when the motor is wound tightly. A piece of rubber tubing slipped over the shaft will keep the wire from cutting the rubber. Several washers between the prop and nose block will reduce friction, and a loop at the end of the shaft will accommodate the winding hook.
ASSEMBLY AND FLYING
THE THREE wing panels are now cemented firmly together, forming 3-3/4" dihedral at the tips. When the wing is thoroughly dry, slip it into position through the fuselage.
The tail piece is held in place by wrapping a rubber band around the ends of the dowel and the bamboo pieces which are glued to the tail. Cement the stabilizer in place and line it up with the wing. Offset the front of the rudder about 1/16" to make for a right bank
A windshield and head-rest, and other decorations, will make the "Hurricane" more attractive. Naturally, the wheels and other exposed wood parts should be color-doped. A piece of 1/8" rubber wrapped over the wings and under, the fuselage will make the wings' position secure. The motor is 20" long, and 12 to 14 strands are needed for best flights.
In order to deliver maximum flight performance, a model must be well adjusted. First tests should be hand glides. Shifting the wing forward or backward will probably correct any tendency to dive or stall.
If for any reason the wing can't be moved far enough, a bit of weight may be added to the nose or tail. None of the test models needed such treatment, however.
While under power and in the glide the circle should be to the right. Confine all adjustment at first to the glide and be sure it is smooth and flat. Once the glide is good, correct any improper flight attitudes by offsetting the thrust line. Right or left thrust will control the size of circles.
Being a low wing plane, it is doubtful if down thrust will be needed. If a tendency to mush is apparent however, don't hesitate to try a small amount.
A mechanical, winder should used for beat flights, and at all times stretch the rubber about 2-1/2 times normal length before storing in the 850-900 turns.
Earl wasted many exposures before getting this swell shot. But it was well worth the time spent - for here we seethe "Hurricane" coming in for -a "eat, long - glide landing.
Sleek-- and how ! What's more, that color scheme makes the ship's lines even more flashing. When putting the finishing touches on your craft, refer back to this photo so you can get your tapering fuselage-stripe just the same as shown here. And those diagonal wing - markings go well in making the job stand out better at high altitude.
BILL OF MATERIALS
(Plans on following four- pages)
Nine strips 1/8" sq. by 36" medium balsa for fuselage stringers and cross-braces;
Eight strips 3/32" sq. by 36" medium balsa, for fuselage and cross-braces;
Two strips 1/16" sq. by 36" medium balsa for wing stiffeners;
Two strips 1/8" by 3/16" by 36" medium balsa for wing leading edge;
One strip 1/16" by 1/8" by 36" medium balsa, for wing trailing edge;
One sheet 1/16" by 2" by 36" soft balsa for ribs, formers, and covering;
One sheet 1/8" by 2" by 18" soft balsa for rudder trailing edge and covering;
One block 1" by 1-1/2" by 12" very hard balsa for prop;
One pair wheels, washers, 20' brown rubber, 1/16" and .040 music wire, glue,
dope, tissue, rubber tubing, hardwood dowel, pins, sandpaper, etc.
Scanned from July 1940
[ Home ] [ Previous Plan Pages ] [ Special
Things ] [ Earl Stahl Plans ]