Realistic-looking, fun flight from this 50-inch biplane
Background
Geoffrey de Havilland’s Gipsy Moth was created in 1928 by replacing the 1925 Moth biplane’s Airdisco engine with a Halford 100 hp Gipsy engine. An instant success, 1,162 were manufactured.
Frank B. Baker first saw one housed in a hangar near his own. The biplane stuck in the back of his mind, and it became an obvious model after he purchased an O.S. .20 four-stroke engine. By enlarging Aeromodeller magazine three-view drawings, the model ideally matched the powerplant and a 9 x 6 propeller.
Frank stressed that the model was not lightweight and advised builders to keep weight down by using epoxy sparingly because it “adds weight in a very insidious manner.”
Construction
#### Wings
- Construction began with the wings because they were the easiest part of the model and were needed to build the fuselage.
- Wing spars consisted of top and bottom 1/8 x 1/4-inch spruce with balsa sandwiched between.
- Wing ribs were stacked 1/16-inch balsa blanks cut with a bandsaw.
- The remainder of the wing construction was standard for the period.
#### Fuselage
- The two fuselage sides were built directly over the plans using the hardest 3/16-inch square balsa possible for the top and bottom longerons.
- After removing the fuselage from the building board, Frank built two 1/16-inch plywood rear cabane-strut fuselage doublers.
- He used a Robart incidence meter to set the top wing to 3° incidence and emphasized measuring from the wingtips to the workbench surface to make sure the wing was level.
#### Fuel tank
- Frank made his own fuel tank from K&S #254 easy-to-solder tin sheet, doubling the 1/2-scale pattern from the plans and cutting the tin accordingly.
#### Cockpit and servos
- The cockpit hatch comprised a 1/32-inch plywood floor with formers and 3/32-inch sheet bent over the formers.
- 1/8-inch square spruce stringers provided strength.
- A 1/16-inch plywood servo hatch cover housed three servos, either mounted side-by-side on a servo mount or on two 1/2-inch strips of 3/16-inch plywood.
#### Tail
- Tail surfaces were of standard construction, with a 1/4 x 1/2-inch rear post in the vertical fin running all the way to the bottom of the fuselage.
- Elevator hinges, the lower rudder hinge, the tailwheel assembly, and the upper rudder hinge were all installed before the engine was added.
Covering and finish
- Burnt umber stain was used to color the struts, followed by a coat of clear dope.
- Lightweight silk (brought back from a trip to Japan) was applied wet to the fuselage and tail surfaces; several coats of clear coat were brushed on when dry.
- The wings were covered with regular model silk.
- An engine cowl was made for photography purposes, and a 2-inch Williams Brothers pilot figure was added to the rear cockpit.
Flying impressions
Frank noted that the Gipsy Moth required coordinated rudder, elevator, and aileron to make proper turns, but landings were a joy. The airplane was predictable and operated in a slow, stately manner.
“My Gipsy Moth has hundreds of flights,” he said, “and each one was just plain fun.”
Plans and resources
The Gipsy Moth was featured in the September 1994 Model Aviation as AMA Plans Service number 768 for $14 plus shipping and handling. AMA members can access the Model Aviation Digital Library on the magazine’s website to read more about this airplane and its construction. See page 145 or go to www.modelaircraft.org/plans.aspx for ordering information.
Transcribed from original scans by AI. Minor OCR errors may remain.
