22 March 2024
A simplified method for building a lightweight model for beginners or for models that prioritize weight savings.
The Wing
Consideration: Need a slightly strong leading edge to withstand knocks but a very thin trailing edge to affix the covering.
- Most wings have straight leading edge so you can use a 1/8" balsa strip that can be sanded to shape later.
- Most wings are double covered spaced by ribs, and you need ribs also to maintain the planform of the wings. Instead of drawing up all the ribs and cutting them meticulously, you can substitute with right angle triangular profiles that can be sanded to rib shape later.
- All wings have a sharp trailing edge and it is too much work to sand sharp balsa trailing edge only to have them buckle at the last moment or when knocked. Substitute them with a single fold paper strip so it will cover the sharp ends of the previously mentioned right angle triangular profiles.
- Over a drawing of the wing planform, lay down the creased paper strip so that the crease or fold is to the trailing edge.
- On the drawing of the wing planform, draw a parallel line from the leading edge to show where the rear of the balsa leading edge shall be. Use this to mark the length of each triangular rib profile by first placing the sharp end on the line of crease. Cut and number each rib.
- Pin the 1/8" square balsa strip over the drawing and glue the ribs in place.
- Glue the other flap of the paper strip to the top of the ribs.
- Remove and sand the curvature of the ribs.
- Lay it back on the drawing and use a straight sanding tool to sand 1/16" square slots onto each shaped rib.
- Glue the 1/16" top spars onto the wing.
- Reinforce those areas that will be stressed with some balsa.
- Remove wing and sand thoroughly before covering with tissue.
The Empennage
Consideration: Need this to be very light because it is at the tail where there isn't much chance of it being knocked. Deformation can be easy to set right by just running the edge between thumb and forefinger.
- Cut an outline of each empennage from paper. 5mm wide should be sufficient.
- Glue a 1/16" spar to the outline.
- If some area is too far from the spar, put in some balsa strengthener.
- Sand the empennage before covering both sides.
The Fuselage
Consideration: It is there to separate the wing from the empennage. It could be built with balsa, then you have to consider if it is to be rubber powered. If so, some strengthening is necessary, 4 pieces of 1/16" square longerons is enough. Start with building a basic balsa frame of 1/16" square sticks to house the rubber. Add formers, strengtheners, stringers. Sand and cover. Foam construction is to cut to shape, sand, and cover, if rubber powered, hollow the foam, sand in slots to receive 1/16" square longerons, recess for balsa strengtheners at places that will be stressed.
19 January 2024
All righty! Let's make a mini class of free flying models for living rooms. Hand tossed, catapult, rubber powered propeller. There's pistachio scale, but that's too difficult. So let's just make small things that can fly, adopting the 8" wingspan rule.
Material and tools shall be commonly available, for beginners, carbon fibre, balsa and nichrome cutter are permissible.
Models may be tossed, catapulted or uses rubber band to power the propeller. Rubber powered propeller models are to use the rubber bands used by hawkers/office, beginner can use 'speciality' indoor rubber.
Material MUST be cheap, so the first rule is:
Rule 1: Material cost for each model shall be less than 1 SGD, 5 SGD for beginner.
Adopting the 8" or 200mm format, which can be drawn on a single A4 sheet of paper, comes the second rule.
- 4x8"x3" + 1x4"x3"
- 3x8"x3" + 1x12"x3"
- 3x12"x3", etc...
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