Loughead Sport S1 (oz15290)

About this Plan

Loughead Sport S1. Radio control scale model biplane.

Quote: "Plane on the cover. A replica-in-miniature of the most technically advanced biplane of all time. Model includes all the real plane's unique features, too. Loughead Sport Biplane Model S-1, by Monty Groves.

One can become addicted to early aviation research. After researching and building a model of Wiley Post's beautiful Winnie Mae (oz8173), we became interested in the aircraft immediately preceding the Lockheed Vega. Precursor to the Vega was the Loughead Sport-1 biplane, and research into this little-known one-of-a-kind aircraft has been an engrossing and fascinating project.

Though built and flown 52 years ago, with the exception of Allan and Malcolm Lockheed, most of the original participants are still with us. And without their cooperation, the S-1 project would never have gotten off the ground.

During the Vega research we came across six photos of the slender little bipe. With these and five or so others we located in the Lockheed-Burbank files, we began the project. After two years of constant correspondence and probing into various personal and public archives, some 55 construction and flying photos have been amassed. The original 1920 Loughead sales brochure, as modified, provided all the dimensions. Interviews and correspondence with Jack Northrop the principal engineer, Tony Stadlman the shop superintendent who built it, Gil Budwig the original test pilot, and several others provided an almost complete story.

One of the more exciting side effects of historical aviation research came the day my wife and I drove home with the original, one-and-only, two-cylinder engine, its propeller and spinner ring. The S-1 engine, which had dropped out of sight for over 30 years, is slated to go to the Smithsonian as soon as it's overhauled and test run, providing I can locate a Master Carburetor.

Since no original drawings have been found, the drawings with this article were generated over a long period of time, and are based on the photos, published dimensions and review by the men who created and flew the S-1. Data and photos are still being located, so the search will continue.

The Loughead S-1 had several unique design features - an elliptical molded, monocoque fuselage, and for lateral control the entire lower wing pivoted at the root. After landing and during the landing roll, the pilot could disengage the lower wing and pivot the entire lower wing 90° to assist it in braking to a stop. The wings folded up so that the plane could be towed down the highway and stored at home.

The configuration of the model of the Loughead S-1 is scale, and based on the S-1's appearance at the 1920 San Francisco Aero Show. Like the original, the model is complete with folding wings. Since most of the flying of the real aircraft was done without the cheek cowls, these can be eliminated and you'll still be scale.

While the model has folding wings, they can be eliminated too, if you're concerned about the structural integrity of what appears to be (but isn't) a Mickey Mouse arrangement. The folding wings were built into the model to confirm the functional operation that the original designers intended and to further confirm that the dimensions and proportions were correct.

Except for the lateral control surfaces, which may seem strange but really are practical, the aircraft is conventional in configuration.

Construction: Wings: Wing construction is conventional with the exception of the trailing edges. To obtain the scalloped effect, use 1/32 wire, much the same technique as on the original. Small brass tabs are spaced 2 in apart and soldered to the wire edge prior to attaching it to the ribs. This, coupled with the use of one-piece Super Coverite covering for each panel, provides the proper amount of shrinkage for the scale, scalloped effect.

The lower wing is built up using a spruce box spar which will carry the required loads when it's used for lateral control. The number of ribs and their spacing is scale with respect to the original. However, the airfoil still isn't exactly known, so the model airfoil is approximated from the photos we've collected.

The 'V' struts, the cabane strut construction, and their installation are shown on the plans, and are easy to follow. The small fittings on top of the cabanes for wing and wire attachment are made from tubing and soldered to the cabane wire mounts before the wood fairings are attached.

The plans depict a different leading edge than that shown in the construction photos. The more solid leading edge shown on the plans will tend to keep the wings from warping.

To cover the wings, cut one piece of Super Coverite to cover both top and bottom of the wing. Start at the leading edge and cover the bottom to the trailing edge; follow Coverite's instructions. With the bottom section now covered, continue up and over the top so that you end up back at the leading edge. Super Coverite provides additional strength to the wing, and the shrinkage can be controlled without getting out of hand.

Fuselage and Empennage: As with the Lockheed Vega model, we chickened out in making a scale concrete mold for the molded fuselage halves. The model is planked over a preformed skeleton frame.

Unlike the Vega, which was made up of two identical symmetrical shells, the Loughead S-1 required two asymmetrical shells. (On the S-1, there's greater depth below the centerline.)

Construct a crutch, and attach the top and the bottom formers and stringers. This helps reduce the likelihood that you'll run into a fuselage warping problem, which is, as we all know, a giant pain in the neck. All formers, except for F-1, the firewall, F-3, and the end former F-1D, were made from 1/8 ply. F-4 and F-5 are to be doubled later as shown, and provide suitable landing gear and cabane mounting..."

Direct submission to Outerzone.

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