Geoffrey de Havilland’s Gipsy Moth was created in 1928 by replacing the 1925 Moth biplane’s Airdisco engine with the Halford 100hp Gipsy engine. An instant success, 1,162 were manufactured.
Frank B. Baker first saw one when it was housed in a hangar near his own. The thought of the biplane stuck in the back of his mind, and he realized the Gipsy Moth was an obvious model airplane design after purchasing an O.S. 20 four-stroke engine. By enlarging Aeromodeller three-views, the model ideally matched the powerplant and a 9 x 6 propeller.
Frank stressed that the model was not lightweight, and the builder should keep the weight down by using epoxy sparingly, because it “adds weight in a very insidious manner.”
Construction began with the wings, because they were the easiest part of the model and would be needed to build the fuselage. Wing spars consisted of top and bottom 1/8 x 1/4 spruce with balsa sandwiched between. The wing ribs were stacked 1/16 balsa blanks cut with a band saw. The rest of the wing construction was standard.
The two fuselage sides were built directly over the plans with the hardest 3/16 square balsa possible for the top and bottom longerons. Frank made his own fuel tank from K&S #254 easy solder tin sheet. He doubled the half-scale pattern on the plans and cut the tin accordingly.
After the fuselage was removed from the building board, Frank built two 1/16 plywood rear cabane strut fuselage doublers. He used a Robart incidence meter to set the top wing to 30° incidence, stating that it was also important to measure from the wingtips to the workbench surface to make sure that the wing was level.
The cockpit hatch was a 1/32 plywood floor with formers and 3/32 sheet bent over the formers. The 1/8 square spruce stringers provided strength. A 1/16 plywood servo hatch cover housed three servos on a side-by-side servo mount or on two 1/2-inch strips of 3/16 plywood.
Tail feathers were of standard construction, with a 1/4 x 1/2 rear post in the vertical fin going all the way to the bottom of the fuselage. Elevator hinges, the lower rudder hinge, tail wheel assembly, and the upper rudder ridge were all installed before the engine was added.
The top wing could be covered and painted before or after it was mounted. Burnt umber stain was used to color the struts before adding a coat of clear dope. Lightweight silk brought back from a trip to Japan was applied wet to the fuselage and tail feathers and several coats of clear coat were brushed on when they were dry. The wings were covered with regular model silk.
An engine cowl was made, although Frank only used it for photography purposes, and a two-inch Williams Brothers pilot was added to the rear cockpit.
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.”
The Gipsy Moth was featured in the September 1994 MA as AMA Plans Service number 768 for $14 plus shipping and handling. AMA members can access the MA Digital Library on the magazine’s website to read more about this airplane and its construction. See page ___ or go to www.modelaircraft.org/plans.aspx for ordering information.
Edition: Model Aviation - 2015/06
Page Numbers: 99
