Flip (oz12508)

About this Plan

Flip. Control line 1/2A model.

Quote: "The Flip, by Dick Sarpolus. A fine project for any young modeler. Helps to get the feel of cutting, sanding, and finishing balsa wood. All parts easily cut from sheet stock no fancy shaping required. And oh yes, it flies great, too!

This very simple 1/2A model is a practical, capable stunter. It will per-form all the pattern maneuvers - not quite like a 'real' stunt model, but well enough for fun flying, and it offers some advantages as a stunt trainer. Our Flip was designed to see if it was possible to work within the limitations of using all sheet balsa, simple construction techniques, and still get a ship that would perform the pattern maneuvers well enough for a skilled flier to enjoy, or for a beginner to learn the maneuvers.

The May 1975 MODEL BUILDER issue had a 'real' 1/2A pattern ship, the Gremlin (oz4699). That was built just like the big ones; flaps, thick airfoil, built-up wing, full fuselage, etc, and it is the way to go for competitive performance in a small package. We wanted to get most of that performance with a model that could be built quickly . say, one hour or so. Experience with .049 engines made it obvious that Cox engines, in particular the Tee Dee or Medallion .049's, had ample power for good performance. Experience with the typical plastic ready-to-flies, and many of the all balsa kits on the market, showed us that they will fly but sure won't do for stunt capabilities. We believed the big problem was size most 1/2A designs just don't have the wing area necessary for good aerobatic performance.

Aside from the model, those dacron flying lines have got to go! Just too much drag and stretch. Going to 35 foot, .008 or .012 stranded cable lines make a tremendous performance difference. One other design consideration was the landing gear - or lack of one. We fly almost exclusively over grass, where a landing gear is useless, as take-offs and landings can't be made with small wheels. Grass field flying also permits hard landings; the straight-in full bore type, usually with little or no damage. So we left the landing gear off and gained more performance.

The model ended up with a 27 inch span, 130 square inch wing area, and 20 inch length. And for us at least, the performance is pure fun. Speed is high, too high for really smooth flying, but fun. Perhaps a reed valve engine like the Cox Black Widow or Golden Bee would give a more restrained performance; we show a mounting on the plans but have not tried that version. Speed does make it harder to learn the maneuvers, and there is a case for learning on a larger, .19 to .35 size, built-up ship. But a mistake with the larger craft gives you a broken plane; the .049 all-balsa model will usually bounce back for more, or can be 'Hot Stuffed' back together right away. Performance in a reasonable wind is not a problem with this small ship; line ten-sion is good. The Flip has no difficulty with vertical and overhead eights.

Material selection was interesting - with an all wood wing we know we couldn't get much of an airfoil, so instead of trying to sand and carve an airfoil from 1/4 inch or thicker wood, we went to an absolute flat plate, 1/8 inch thick wing. It can flex while flying, is amply strong, and yes, it works. Tail surfaces are also 1/8 inch; more rugged than 1/16..."

Direct submission to Outerzone.

Update 05/10/2020: Added vectorPDF and CAD (dxf and dwg) versions of this plan, thanks to Valeria367.

Quote: "Hi, Steve and Mary. Good afternoon. Some days ago, I started the redraw by CAD of the plan "Flip" by Dick Sarpolus (oz12508) and, surprisingly, you published that plan two days ago!... What a coincidence! Right, as usual, I send you the plan in PDF vector format, as well as in both CAD vector formats; DWG and DXF.
Greetings, from your friend. Valeria367"

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