1025 Duo mono mod. MINI

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in Series 1000 – Sheet Wing, Profile Fuselage Gliders

Span 42.5 cm / 16 ¾ in

Weight 22 g / ¾ oz

The original Duo Monoplane was a Jetex (rocket) powered model by Bill Dean published in 1952 January issue of Aeromodeller magazine. I liked its appearance and its concept as a tandem wing model. So I only altered a bit the distance between both wings, the planform of the main wing and draw the bottom line of the fuselage continuously — without the stepped cutout for the Jetex unit. All this led to my Duo Mono mod. 1021 which turned out to be a very successful model. I offer here my second rendition to Bill Dean’s remarkable design – a smaller lighter variant with profiled wings.

Bill Dean’s original Duo Monoplane:

https://outerzone.co.uk/plan_details.asp?ID=3901

Building the sheet balsa chuck glider Duo Mono mod. MINI

Materials:

Fuselage: B 1.5; both wings: B 1; wing supports for front and rear wing: B strips 3 x 3; fins: B 1; fin supports: B strips 3 x 3; fin-template: B 2.5; linen/cotton band width ½ in; ballast: piece of steel or lead.

Assembly:

Cut out balsa parts according to plan (photo). Sand meticulously. Transfer outlines of canopy with pen from plan to wood (photo). Make colouring now, if wished (photo).

Fuselage:

Make cutouts for both wings. Cement wing supports in their positions. Use clamps, clothespins or needles (photo).

Wings:

Wings can be built as flat sheets or profiled. If you opt for the profiled variant, wet wing undersides with water and let entirely dry before you continue. Balsa will keep its bent profile.

Cement front wing halves flat one to the other according to plan thereby using needles to hold in place. Pay attention to given dihedral! As you will see when you finished this step the outer section of each wing half remains convexly shaped. Visual check to obtain best possible symmetry. Repeat procedures for rear wing except that rear wing remains flat sheeted and is not profiled. Use linen/cotton band for reinforcing wing half joints on top and bottom. The same sort of reinforcing can be done on leading edges of front wing.

Fins:

Cement fin support strips on rear wing tip undersides leaving only one mm as seat for fins. Let dry. Make a template (B 2.5) to assure that fins stand at the same angle on rear wings. Template can be used for both sides.

Remember model only looks professional when absolute symmetry of all parts is maintained. Cement fins to rear wing and let dry.

Final assembly:

Put fuselage on a so called „third hand“. Glue wings into their given positions. Double check here once more symmetry.

Balance at given CG.

Have fun with your Duo Mono mod. MINI which is a very stable glider. For altering direction of flight warp left or right rear wing up or down a little.