Fan Piper (oz6628)

About this Plan

Fan Piper. Radio control ducted fan model delta for .60 power.

Quote: "This design was inspired by an article in RCM (April, 1968) entitled Banshee (oz9155) by Capt CW Peale. The photos and plans started up old fires which, after almost 30 years of inactive modeling, broke out in quite a blaze, cooling and flaring occasionally, as I progressed from plans through construction and taxi tests. Public reaction varied from 'poor fellow' to 'let me know (evil grin) when you try to fly it.' I naturally thought positive, it had to fly; eg. Bumble Bee Theory, and as miracles go, it flew right off the drawing board. It is very stable and trims hands off with no dutch roll or oscilla-tions.

The guidance system is Heathkit with ailerons, elevator, and throttle control. Elevons were not used and proved unnecessary. The fins are fixed, no moveable rudder. The nosewheel is steerable from the ailerons and a nosewheel brake operating from the forward elevator. These two features were used to great advantage on the trial ground runs prior to first lift off. If your flying field is limited in length, a brake is extremely handy. This bird can really move on the ground after a long landing. Just to be on the safe side, an arresting gear has always been set up and ready. It saved the plane twice when the engine quit at an inopportune time.

The dimensions are 66 in span, 81 in length, 10 lbs weight, and a wing area of 10 sq ft. Power at present is an Enya 60-II TV. The construction should be kept as light as possible consistent with good building practice since the thrust output is slightly limited (about 4 lbs), compared with the average prop driven model. Even with the present thrust, the climb out angle can be somewhat spectacular to say the least!

The plane is built around a crutch using the old fashioned spar, rib, balsa sheet covered wing and planked monocoque fuselage. Styrofoam might be a good way to go, but I haven't tried it yet. The original duct was made with 1/8 balsa planked on a form, but the duct shrunk when the weather warmed up and the prop had to be trimmed down several times to maintain tip clearance. I suggest the duct be made from 1/32 ply rolled with the grain lengthwise. The guide vanes, made from 1/8 balsa sheet, are rounded on the leading edge and tapered to a streamlined trailing edge. The guide vane center support is made with 1/16 sheet balsa strips planked on round 1/8 balsa bulkheads. Pin 1/2 bulkheads on plan, plank and when dry remove, add other 1/2 bulkheads and plank remaining 1/2. Make nose piece from a block or scrap balsa.

Glue the guide vanes to the center support, 6 on the front and 6 on the rear, spaced 60 degrees apart and in line with each other fore and aft. Dope on the silkspan plus two coats of clear and two coats of a dark color. Dope the inside of the duct with three coats of clear and two of color. Use fuel proof dope as the inside of the duct gets quite saturated with exhaust oil. When dry, fit and glue the guide vane assembly in the duct with a pair of guide vanes, vertical in front and rear. To keep a perfect circle in the prop area, when fitting the guide vane assembly, I cut a circle of 1/8 ply just large enough to fit around the duct and slightly forward of the prop line. The disc that comes out of the circle can be used later on the engine, when installing the duct in the airframe.

The general construction layout is similar to Capt Peake's Banshee. The crutch is cut from 1/8 Mahogany plywood. To keep weight down to a minimum I cut lightening holes in the crutch, all ribs, except R5, and in all fuselage bulkheads. The rib templates are layed out on light cardboard using the table of ordinates... "

Supplementary file notes

Article pages, text and pics, thanks to JHatton, AugustaWest.

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