Little Willie MkII (oz7840)

About this Plan

Little Willie MkII. Rubber indoor model.

Quote: "The 'Easy B' type of model makes an ideal beginners introduction to indoor modelling as well as being a great 'fun' model for the mode reperienced. As it is capabale of flights in excess of ten minutes, it is certainly not a toy.

To keep the competition class within reach of the tyro, we have stuck to the spirit of the original rules, that is:

1. Maximum wing span 18 in flat, not projected.
2. Maximum wing chord 3 in.
3. No curved surfaces or spar bending rectangles only.
4. Tissue covering only - no microfilm.
5. No bracing.
6. Solid motor stick, tail boom and prop blades.

Stewart and I got together on the design while looking for a suitable project for young nephews, and have been pleasantly surprised at the perform-ance of the models built. Over the past three months my model has been used to give flying exhibitions in schools and youth clubs and is still going strong. The only difference being that the rudder has been mounted upright in front of the stab to save it from damage in cluttered rooms.

The Propeller: This is the most important part of any rubber model, so we will start here. If this is a first model, the easiest way to make a propeller is to cut out two blades and a spar. Bend the prop shaft and cement to the spar. Line the shaft up vertically and glue on a blade at 45° in such a way that the front of the blade on the left hand side of the spar slopes upwards towards you, then glue on the other blade to the right hand side so that the back slopes downwards. When the propeller turns anti-clockwise you should feel a draught on the same side as the shaft.

For the more experienced or ambitious builder a jig is carved from block, as shown on the plan, the blades soaked for a few minutes in hot water, then individually strapped to the jig with strips of tissue and baked in a cool oven (Regulo 1/4) for 10-15 minutes. When both blades are dry and shaped, one is laid on the jig with the datum lines corresponding and the prop spar glued in place, so that the shaft is vertical and parallel to the corner of the jig. Use white PVA glue for this job, using as little as possible. When dry, remove and repeat for the other blade.

Wing and Tailplane: To cut ribs to shape you need a template. Either trace the rib curve from the plan on to a piece of 1/32 ply or find an old 12 inch record or dish which you can cut round. Make the compression rib as shown on the plan. If you use the arc section the upright must be in the middle. Templates can be used for building round. These are best made by tracing the inside lines on to card or balsa sheet and cutting out. It is best to cut a 'V' in the template where the ribs go, so that the ribs can be glued in over the former. Cut ribs from a rectangle of 1/32 sheet 3 inch wide. The same section is used for both wing and stab. Ribs are trimmed to length from the trailing edge.

It will be noted that the port wing panel is longer than the starboard. This is because indoor models turn with the motor torque to the left, and this provides more lift to the inside wing, enabling the model to turn tighter..."

Direct submission to Outerzone.

Update 04/07/2016: article pages, text & pics added, thanks to RFJ.

Supplementary file notes

Article pages, text & pics.

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