Shoehorn (oz5397)

About this Plan

Shoehorn. Amphibious free flight sport model, for .049 power.

Quote: "Evidence of the growing popularity of hydro flying was established this year with the inception of several all ROW contests, that included Payload, radio control and flying scale events, all run on the briny deep. Speedy runabouts replaced the old familiar 'chase cars.'

One of the contributing factors in the sudden interest in ROW models is, undoubtedly, the almost depleted source of suitable land flying sites, particularly along the East Coast. Another factor, perhaps, may be the desire on the part of many modelers to get away from the 'cut and dried' classes and try some new and relatively unexplored fields. Admittedly, there has always been a fair amount of interest in the free flight ROW events, particularly at the Nationals. Unfortunately, these models have seldom, if ever, in recent years, reflected any especially noteworthy hydro design. In the main, they were, and are, tried and proven pylon type ROG models quickly converted to this new medium by the addition of several small floats. This is not to say that the ROW contestants don't know what the score is: they certainly do! The models are designed to give maximum performance under the existing AMA rules and those guys who have the courage to fly a red-hot pylon job off the wet handkerchief that passes as a tank get my nomination for the Croix de Guerre!

Flying a free flight model off the water for sport is the particular phase we are interested in, since it alone offers the opportunity to try something new and unusual without being hampered by a stopwatch.

An amphibian such as the Shoehorn is an example of a model of this type. It will never win an ROW free flight contest, It probably couldn't get off the water in the tanks usually provided at contests. This ship was designed to give semi-realistic flight and hydro characteristics and is built ruggedly enough to withstand more than a normal amount of abuse.

If you're in the marker for something a little different, this may be just the job for you. Even if you don't live within miles of a sizable body of water, or can't swim, the Shoehorn is a nice performer flown as a conventional sport iob with the gear down and locked. Several features of this little ship are perhaps interesting enough to mention before we get into the construction details.

The fuselage or hull design is the conventional and very popular sheet balsa type with 1/8 in. square balsa stringers at the inter-section of the sides, top and bottom. In addi-tion to an appreciable increase in structural strength, it also reduces the hazard of a cemented joint popping open and thereby al-lowing water to enter the hull with possibly serious consequences.

When we just 'doodled' the design on a piece of scrap paper, it was decided that a trike gear would be the thing to have, never giving a thought at the moment to the feasibility of making it work. After one heck of a lot of head scratching and lost slumber we hit upon the arrangement shown on the plans. The nose gear (the real fly in the design ointment) is formed like a bobbypin and pressed into an aluminum tubing socket that is sewn to the first former. The main gear is held on the face of the step by three small clamps and No.2 wood screws. In this position the ship is rigged out for and flying. To convert to ROW operation, the nose gear is slipped out of the aforementioned socket and inserted in the socket shown in the nose block. The screws in the side clamps of the main gear are removed and the gear is rotated into the retracted position shown on the plans. The two small holes in the step can be plugged by replacing the screws and the main gear is held in the retracted position with a rubber band, This arrangement overcomes the problem of severe center of gravity changes when converting from ROG to ROW and vice versa.

The hull is somewhat wider and more spoon-billed than is normal for a model. This was done in a conscious effort to eliminate troublesome tip floats or sponsons. So far, the idea seems practical, if care is exercised in ROW take-offs. To increase further the hydro stability, the engine nacelle height was kept to an absolute minimum, providing only sufficient clearance for a 6 in prop and thereby lowering the CG.

Whether or not the hull design is hydro-dynamically efficient is debatable. A yacht designer friend says it could be improved and without doubt this is correct. The fact remains, however, that it works and provides loads of flying fun.

The Shoehorn is designed for .049 to .065 engines. Total weight, ready to fly, should be approximately 8 oz. Wing span is 32 in; wing area 165 sq in.

The original model is covered with light green tissue, with yellow trim and black pin striping. So much for the preliminaries. Lees get on with the main event - building your version of the Shoehorn.

Cut out the sides from medium hard 1/16 in sheet balsa. Notice where the sheets are joined together to get the proper width. Trace the outline of each of the formers on the proper type of material as indicated on the plans. Cut the formers carefully and accurately to size. Mark the location of bulkheads No.'s 3 and 5 on each of sides and begin assembly by cementing them in place, paying careful attention to proper alinement of the sides..."

Direct submission to Outerzone.

Supplementary file notes

Article pages, text and pics, thanks to theshadow.

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