Millie (oz15013)

About this Plan

Millie. Radio control (or free flight) sport biplane model. Wingspan 31 in, for 0.75 to 1 cc engines. All-sheet design using a Jedelsky-style wing.

Quote: "This little biplane is a quick build and won't take up much of your precious flying/ gardening/TV watching, or drinking, time. Inspired by wanting a sports RC model to be powered by my newly acquired Mills .75 replica, and as a sister-ship to the Twinkle (oz11643) free flight design, 'Millie' is a biplane suitable for small field flying. It is small enough to fit in the boot of your car assembled.

Before you commence building, take a couple of sets of photocopies of the plans, one reversed to give you the opposite wing panels and you will then be able to spray mount the parts direct onto the wood. If you don't have facilities for copying the drawings, you will have to be careful with the order of construction - the wings and tailplane should be built before the front section of the fuselage can be joined to the rear.

Which Wing? I actually built two sets of wings, one has a simple curved plate construction, built over the ribs, with the lower part of the ribs being planed and sanded away after construction, allowing the covering material to lie flat on the underside of the wing. However, for general flying with rougher grass areas, I would recommend the Jedelsky wing, which features 3/16 leading edge and 3/32 rear wing sheeting.

Pin the ribs in position over the plan - angling the root rib - and then glue the sheeting in position. The leading edged can be pre-profiled, with only a final sanding of the joint between the front and rear sheeting being necessary. Join the wing panels popping up the outer ribs to give the correct dihedral and, when the glue has dried, the centre joint should be reinforced with a 2 inch wide gauze bandage and epoxy. All that remains is to trim the leading and trailing edges of the ribs.

With both methods of wing construction I suggest that the sheets are given coats of lightweight filler on both sides and sanded smooth, followed by sanding sealer dope. It is much easier to carry out the sanding at this stage, rather than waiting until the ribs are fitted.

Tail time: All that is required for the tail surfaces is to round the leading edges, taper the trailing edges (a square edge to control surface trailing edges gives better control than a rounded edge) filler, sealer and dope as before. I used my favourite closed loop method of linkage for the rudder and a lightweight control snake for the elevator. Position the horns accordingly, no plan view of the fuselage is shown, so work out the elevator linkage route. Hinging is according to taste, I still prefer the 'old-fashioned' thread hinging method as it is lightweight and gives free movement.

Body Beautiful: Cut out two fuselage sides from 1/16 sheet - you will need to join a 4 in sheet for the full depth - and locate and glue the doublers and reinforcing strips in position on each side - don't forget they're handed! Note that the doublers automatically locate the formers, although the nose requires a further tripler to position the 3/8 sq beech engine bearers. Glue the bearers to the sides, the spacing are correct for the Mills .75, so you may need to make adjustments for other engines, drill the mounting holes to provide about 2-1/2 degrees of right thrust..."

Direct submission to Outerzone.

Millie from R/C Model Flyer, January 2009.

Supplementary file notes

Article pages, thanks to RFJ.

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