2014 Hargol

—

Robert Schlickewitz

in Series 2000 – Sheet Wing, Profile Fuselage Rubber-Powered Models

Span 39.5 cm / 15.5 in

Weight 26 g / 0.9 oz

The concept:

small/intermediate
rubber powered
for 4 in / 10 cm or 6 in / 15 cm airscrews, brown and/or black rubber
good flight characteristics
low-wing monoplane
easy to build
few parts

Name: Hargol (חַרגוֹל) is the Hebrew equivalent to English grasshopper.

Building the rubber powered balsa profile-fuselage model Hargol.

Materials:

Fuselage: B 3; nose stiffeners: B 3; fuselage nose parts: B 5; rubber hook: piano wire 1.2 or 1.5 diameter; wings: B 1; wing reinforcement strips: B 1; wing supports: B strips 3 x 3; horizontal stabilizer: B 1; fin: B 1 or 1.5; linen band width 10 mm / ½ in; ballast: 5 g / 0.2 oz small piece of scrap metal or lead; one commercial airscrew 15 cm / 6 in diameter; brown rubber.

Assembly:

Cut out balsa parts in accordance to plan (photo). Sand well. Transfer outlines of cabin, rudders, elevators, etc. from paper to wood with pen or paint (photo).

Wing:

Wing consists of a right and a left wing half and each half has a balsa strip as reinforcement. Fix both wing halves upsides down on building board with needles. Cement the reinforcement strips onto the undersides of the leading edges and let dry.

Fix one wing half on your building board. Underlay the other wing half tip in accordance to required dihedral. Join both halves and cover wing center (joining) area with linen band (photo). Let dry. If wing has the tendency to rest only on one side then it is too heavy on this side. To compensate the imbalance disperse a small amount of white wood glue on the opposite wing tip area and let dry. Do it if necessary twice until balance is obtained.

Fuselage:

Bend as shown on plan piano wire into given hook shape. Carve out with knife and round file seat for rubber hook on left or right side of fuselage. Cement hook in place and cover hook area with linen band as seen on photos. Let dry. Cement fin on fuselage using needles to hold in place (photo). Always visual check twice that symmetry is obtained.

Cement wing support strips onto their given places (photos). Hold with clamps or clothespins or with needles.

Cement B 5 nose parts one on the other as shown on plan and let dry (photo). Sand well than treat this part with balsa putty. When dry sand again. May be this procedure has to be repeated. When the nose part is smooth you can start to carve out opening which holds prop-bearing. Start from behind and don’t do it in a hurry. A little electric drill machine can be useful.

Cement nose on fuselage according to photos. When dry add triangle nose stiffeners one on each side.

Empennage:

Cement horizontal stabilizer into its place using needles. Visual check symmetry from all sides. Let dry.

Final Assembly:

Put fuselage on a so called “third hand” upside down. Cement wing on wing supports using needles to hold in place (photos). Doublecheck visually symmetry. Let dry.

Use a piece of lead or scrap metal to balance model properly.

Remember a correct center of gravity (CG) is essential for successful flights.