Updated june 2004


This description is quite brief and focuses on points unique to this model. Also try to get articles on Goodyear, wing pressing and so on in old issues of Aeromodeller and other magazines. The plan is originally made as a PostScript program for printing on laser printers that have a PostScript interpreter. Now there is also a PDF file. The full size version of the plan is printed on eight pages to be pasted together.

Wing Balsa 7 mm quarter grain, density 80-100 grams per (26-33 oz per sq.ft.) Note that the joints allow the lead out channels to be cut and bellcrank with leadouts inserted before joining. Leading edge abachi. Trailing edge very hard balsa. Outer tip .5 mm steel cut into center of wing with hard balsa strips on top and bottom. Lead weight added for a total of 15 grams. Try to render the wing section accurately. Thickness tapers from 7 mm at centre to 4.5 mm at tips. Section symmetrical.
Make tip skids from PET soda bottle material, cyanoed in place after finishing is complete, replace as they wear out.

Tailplane Balsa 5 mm medium, quarter grain, leading edge abachi. Elevator cut out after glassing.

Fuselage Balsa 10 mm, 100 grams per Side doublers .4 mm plywood, shape shown. Engine bearers 10x10 mm beech. Note the taper. Adjust spacing to engine used. Save weight by drilling 6 mm holes vertically into the bearers (not through) from the tank lug position and rearwards, spaced 9-12 mm. An engine heavier than USE (135 grams) will require a shorter nose. (10 mm allowance by the 1/8-10% rule) Top & bottom reinforcements abachi. These are important as they prevent cracks from starting here. Fin 5 mm light balsa. Nose cheek light balsa. Insert pushrod slot and cutoff wire tube before joining the side doublers. Bearer plates 3 mm dural, held by six countersunk wood screws. Nose & tail skids 1.25 mm piano wire stitched to 1 mm plywood pieces. Note wing and tailplane incidence angles when cutting their slots. A temporary plywood cutout is needed to be able to connect the pushrod. Use polyurethane wood glue (expanding) to set wing and tailplane in fuselage.

Bearer, Tank and Valve detail

Tank The tank works by the uniflow principle. By having the filler tube inside the tank end at the outboard wall and the overflow closed, the fuel supply becomes independent of fuel level.
Materials: Epoxy-fibreglass (works for diesel fuel only). Capacity 20-25 cc. Bulb built on balsa form with a thick layer of wax as release agent. (Normal release agents are not enough.) Lay patches of thin glass cloth to a thickness of 4-6 layers. After curing use heat for removal and clean off the wax very carefully. Make bottom and walls at wing cutout from .4 mm printed circuit board material. Reinforce all wall joints with an extra layer of glass. Mounting lugs reinforced with .3 mm brass brackets, covered with glass. Right wall should be outboard of carburetor jet, 15% of forward distance. (Example: if the Carburetor jet is 60 mm forward of the tank feed point, the tank outer wall, where the feed point is located, should be 7.5 mm outboard of the carburetor jet.) Tube connecting ends are recessed into front of tank facing the valve for maximum forward location of the tank. Recesses made from 5 mm Al tube. Feed tube 2 mm, ends in lower rightmost point. Filler tube 3 mm ends in vertical symmetry line rightmost point. Overflow tube ends in highest point when in refueling position (upper leftmost).

The tank can also be made by balsa, hollowed out and carefully sealed with epoxy and covered with fibreglass.

Where rules don't allow tank valves (such as in Denmark), the overflow tube has to be open in flight. In this case the potential problem of fuel siphoning out of the tube that gets the least pressure is overcome by having both filler and overflow tubes going through the fuselage, facing leftwards (inboard). The overflow in this case should have its tank end in the upper rightmost point. Fix the overflow and filler tubes to the fuselage and connect to the tank by neoprene hose. In any case the filler must not be placed on the tank, since the construction won't support the forces of refueling. Finished weight 7 grams. Attach by small sheet metal screws. Rear screw needs a dowel plug inserted into the fuselage. (Front screws go into the bearers.)


This is just a tube pincher valve. It operates by filling the tank, so no extra handling is needed to reset the cut-off. The feed line is closed when filling, which eliminates the risk of flooding the engine.
Two tubes go though it: The feed tube and the overflow tube. The latter is pinched closed except when filling. The filler is always open and used for venting the tank. There are a number of pieces that move inside the outer square tube. Three springs that load the moving parts are not shown in the figure, just their attachment hooks.

The Moving Parts

  1. The Filler Plunger. The fuel just goes down through it, and then passes to the tank by a flexible tubing. It is spring loaded upwards and pushed down during filling to operate the valve. The overflow tubing is pinched between two 1.6 mm brass tubes. The lower one is attached to the filler plunger and the upper tube is fixed. Pushing the plunger down opens the tubing.
  2. The Cutoff Valve. Shown in open position. Spring loaded upwards and pushed down by the filler plunger. It is held latched in the open position by the cutoff lever. Feed tube is pinched between the brass tubes of 1. and 2 when closed.
  3. The Cutoff Lever. Holds the cutoff valve in the open position until pulled rearwards by a wire from the bellcrank. It is spring loaded forwards.
Materials: Brass square tubes 6.35, 5.55, 4.75 mm (T&S). Brass round tubes, 1.6, 3, 4 mm. Piano wire .75 mm. The 4.75 mm tube is just used for a short piece inserted between the 4 mm filler tube and the 5.55 mm plunger. It can be replaced by a piece of .4 mm brass sheet that is wound around the 4 mm tube. Filler mouthpiece machined from 7 mm brass rod, to mate with bevel shaped finger valve or bottle nozzle. Opening must face forward if a front induction engine is used, otherwise upward. Springs, (not shown) filler & cutoff piano wire .4 mm wound on 1.8 mm drill shaft. Lever spring .2 mm, arrangement not shown. Filler hose 4 mm o.d. neoprene, overflow and feed 3 mm o.d. Note that the arced mating ends of the filler and cut-off sliders are important since flat ends will gnaw on the tubing.
Don't try this valve design without tools and experience in precision soldering. The job is ruined if tin overflows inbetween the moving parts. A fine tip soldering iron such as those used for electronics is recommended. With the open overflow tank design a simple mouse trap type cut-off can be used instead.

Landing gear Box middle piece: 3mm plywood saturated with cyano after jigsawing to shape. Sides: epoxy pc board .8 mm. After glueing in place drill around 25 small holes along the cavity contour, stitch together with kevlar thread and soak with cyano. Also stitch the whole box to the beech bearer. The cavity is to hold a cushion of 3 mm soft polyurethane, cut and drilled to adjust spring action. Leg: 3 mm dural, is ground to streamlined section. Leg pivot: 4 mm brass tube, length 3.05 mm squeezed between the box walls and held by M 3 screw and nut. Wheel: Hub is from steel, threaded M6x.75, drilled 4 mm, length 5 mm. Flanges: Dural sheet 1.5 mm, threaded on hub. Tyre: 2 mm hard polyurethane. Secure with cyano. Pivot: Steel 3.95 mm with flange, M3 threaded hole, held to leg by M3 countersunk screw. Secure with epoxy.

Covering After sectioning of wing, tailplane and fin the balsa is saturated with cyano right behind the wing right leading edge abachi strip, the tips and trailing edges. Apply a thin dope coating (50% thinner added) before covering with epoxy & glass cloth, 23 g per sq.meter. Wing right leading edge double layers. Fuselage front & fuselage to wing and tailplane joints triple layers. "Wing pressing" technique is preferred for wing and tailplane.

Control mechanism Bellcrank .8 mm steel with 4 mm brass tube pivot & 2 mm brass tube pushrod sleeve, soldered. Shaft 3 mm steel, attached to two .4 mm pc board reinforcements into wing. Pushrod 1.25 mm piano wire, adjustment piece 2 mm brass tube. Elevator horn .8 mm pc board with 2 mm brass tube pushrod bearing. The horn low end follows the contour of the elevator section to cover the end and is secured by glass cloth wrap. Lead outs .6 mm 7 strand wires, bellcrank connection loops .75 mm piano wire, copper wire wound over the joints before soldering. Cut-off wire, .4 mm, connects between pushrod and valve lever hook through 1.6 mm Al tube cut into the fuselage under the plywood. Lead out guides 2 mm brass tube. Guides shown for 15.92 m .3 mm lines. British 'Open Goodyear' with .35 mm lines require the guides to be moved rearwards by 4 mm. Use handle with 47 mm line spacing. Remember that a hidden control mechanism can't be inspected for wear and weaknesses. Build it to never have to worry, using double safety wherever possible.

Finishing Polyurethane enamel preferred, but car enamel in spray can is convenient. Allow ample drying time before flying. Racing number "71" on fuselage twice and left wing tip. Canopy, ailerons & rudder markings and "Lil Quickie", "EXPERIMENTAL" & licence number text add to authenticity.

Added notes on finishing.


The plan dimensions are at the absolute rule minimum. Make actual model a little oversize!! Swedish rules require a .5mm safety wire between bellcrank pivot and engine. Danish rules allow only non-schneurle diesel engines and some older design schneurles, like KMD and Kosmic. Weight ready to fly 280-330 grams excluding engine.

Remember that 40 grams can be saved not by saving 40 grams someplace but 1 gram in 40 places!

The Achilles heel of Goodyear models is the fuselage between the wing and the tailplane. Often the fuselage gets snapped off here in a hard catch. There may be lighter constructions than the sandwich design used here with plywood - balsa - plywood, but I doubt anything can match the strength vs. lightness. It could be a good idea to add an extra strip of carbon or glass cloth on both sides.

Göran Olsson, 1996 - - - SWE-1362

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