Bipe Buggy (oz949)

About this Plan

British Bipe Buggy. From the July-August 1967 Sig Air Modeler. For Cox .020 power.

Quote: "Sport biplanes are great fun. This one is exceptionally stable according to our British designer, and easy to build. Realistic takeoffs and 'Copybook' landings make it an ideal sport flier's aircraft..."

Update 31/05/2013: Replaced this plan with a clearer copy, thanks to theshadow.

Update 23/10/2022: Added article, thanks to theshadow.

Quote: "Bipe Buggy, by Cyril Shaw.

Sport biplanes are great fun. This one is exceptionally stable according to our British designer, and easy to build. Realistic takeoffs and copy-book landings make it an ideal sport flier's aircraft.

The Bipe Buggy is for sport flyers and beginners. Construction is straight-forward and so is flying. When I first started thinking about a simple realistic biplane, my thoughts were - How quickly can I build it? This is truly a quick-build model, and strangely enough, the sheet wings take a good percentage of the building time. A true airfoil section with careful accurate block sanding will pay very big dividends in flight performance.

The glide on Bipe Buggy is slow and flat with perfect landings every time. Double size versions with built up wings should be fine for sport or stunt RC. The Cox .020 provided ample, reliable power, and the original model flies in large lazy right-hand circles and glides to the right. Bipe Buggy is unaffected by torque, so no right thrust is necessary.

Weight, with motor should be about 6-7 oz. I haven't tried a heavier version, but would imagine a deterioration in glide performance.

For extra realism 'I' struts, pegged in, can be added. The model was treated with Sig-Superfill and then covered in tissue using banana oil as an adhesive. This method gives a smooth, lightweight finish. I went a step further and sprayed color on, finishing with a brush coat of fuel proofer.

Make sure the front sections of the fuselage are well proofed, particularly inside around the engine bulkhead. This saves the engine (complete with bulkhead) flying off on its own, due to fuel seepage.

Construction: Cut out 1/16 balsa fuselage sides and all the formers including ply former No.2. Bolt on the 1/16 music wire undercart using an old cocoa tin for metal straps. Cement the two fuselage sides at rear and lay upside down. Cement in all formers starting from rear including No.1, making sure it is drilled ready to receive motor. Make sure No.1 is at the correct downthrust angle. Any small mistakes can be corrected with thin washers on the flying field. Very carefully slot in 1/8 sheet pylon and double cement. Make sure the pylon is vertical viewed from the front and sits correctly in side view. Use a card template to check if necessary. The pylon fit determines the angle of incidence of the wing, so take care.

Cement rudder and tailplane onto fuselage, checking the rudder against the vertical pylon.

The bottom of the fuselage is covered in soft 1/16 sheet except for the space where the lower wing attaches by rubber bands over dowels. Fuselage is sheet covered over the curved sections of the formers with soft 1/16 sheet. The section rear of the cockpit is easy and I found I could do this with two well fitted pieces. Front of the cockpit requires more care, and very soft block forward of the pylon could be used if sheet covering does not agree with you.

Both wings are identical, so cut four halves from 3/16 sheet. Start sanding using a flat block and 80 grade open coat production paper, finishing off with a finer grade. Cut slots in wing halves to take the hard 1/8 or 1/16 ply dihedral braces. After the wings are assembled cover the joins with silk. It takes a little more time but pays off in strength.

After deciding which wing you intend to use on the pylon, turn it upside-down and pin a small piece of greaseproof paper over the wing join. Assemble the hard 1/16 wing platform over this, using pins to lightly hold it in complete union. This will make sure of a perfect fit between wing and platform. Remove platform from wing and cement onto pylon. Before cement sets completely rest wing on platform and make a final check. 1/8 fairing strips can be added to the joint between platform and pylon, plus a strip of silk to fair everything in.

Flying: I found Bipe Buggy flew well towards the right with very slight right built in. Being a basically stable design, quite a few trim combinations can be tried. For the extra cautious, put the prop on back-to-front for less efficiency to carry out your favorite trim combination.

The original model was sprayed lightly in lemon yellow with dark green trim."

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