Building Hand Launched Gliders
If you are making your first Hand Launched Glider then don't place too much emphasis on the type of Balsa wood that you use. Just select a Medium / Straight grain sheet of balsa wood.
If you are not sure what Medium / Straight grain wood should look like when you are in your local model shop, ask the shop assistant (they ought to know). If the assistant is unsure then ask to examine their whole stock of 1/4" (6mm) sheet. Compare the sheets and reject the very soft wood (prone to breakages) and also reject the very hard wood (makes cutting and shaping difficult). Also reject any sheets that have obvious flaws in them. Look for nice 'clean' wood. Look along the edge of the sheet (lengthways) to see if it is straight - not bent or twisted.
If you have decided to venture into the world of HLG competition flying or just fancy having a sparkling performance from your glider then you should use Quarter Grain (quarter cut) balsa wood for the wings, fin and tail.
The major benefit of using Quarter Grain wood is its stiffness.
Quarter Grain has a mottled appearance and is easy to spot once you have seen it.
I have included my sketch of the grain pattern to give an idea of what to look for.
In my experience the local model shops generally cater for the radio fliers and radio fliers reject Quarter Grain because of the mottled appearance. I've had a field day at some shops I've visited !
Be aware that quarter grain balsa can also be too heavy - I use 100 mm x 1 metre sheets which weigh approximately 60-65 grams.
There are some specialist mail order suppliers that can supply Quarter Grain balsa to order.
Tail and Fin
Use medium weight quarter grain if you can get it, otherwise use medium straight grain.
Use a Hard grade of wood for the fuselage. If the fuselage is laminated (Mr Shifter) or covered in fibreglass cloth (Hybrid) medium grade will do. Fuselages very rarely break - wing / fuselage joints do.
One or two of the plans mention Spruce, if you cannot obtain Spruce locally use any lightweight hardwood.
Before you start building any model photocopy the plan and use the photocopy to build from.
Please note: plans Downloaded from this website will have shrunk 5% - while photocopying - re-size if you wish.
Cut out the main shapes from the plan and use these paper shapes as templates to mark out the parts on the wood. If you prefer to cut around the templates use spots of Copydex (Ammonia based glue) to stick the templates to the wood, then cut out the parts, remove the paper templates immediately.
Take the template for the wing, position it for the first wing half then flip it over and mark (with Biro) the other wing half. Before cutting out the wing (as one piece), mark the wing centre line and dihedral positions on both the top and bottom of the wing blank.
Cut out the wing, use a sanding block to smooth off the leading edge making sure that there are no dips or bumps. If a Spruce leading edge is indicated on the plan, now is the time to fit it.
Measure and cut two strips (one for each half). Lightly sand one side of the square Spuce strips (we'll glue this side). Use a razor plane to taper the opposite side of the strips towards one end. Using a smooth round metal object, rub the sanded side, this will encourage the strip to curve (important). Keep rubbing (it takes practice) until the curve of the Spruce almost matches the shape of the wing leading edge.
Use Cyano' to glue the strip to the leading edge - remember to allow for any up-sweep indicated on the plan.
A Spruce leading edge will strengthen the wing and help prevent LE damage.
After cutting out the wing shape from the balsa sheet, sand in any washout that is indicated on the plan
Washout gives stability to a model and helps prevent spiralling.
Shaping the wing
Use a razor plane to shape the wing to a rough section.
First thin the wing from the centre to the tips.
Mark the high point onto the thinned wing and then shape in the wing section.
The final shaping and finishing of the wing should be done using medium and fine Emery paper. Sand the trailing edge and tips down to at least 1/64"
Use a metal 90o square to re-mark the wing dihedral breaks onto the top surface.
Fit a new blade to your modelling knife and using your metal 90o square - carefully cut through the wing breaks.
Sand the dihedral breaks as shown in this diagram.
Hold the wing tip/centre section rock steady and with backwards and forwards strokes carefully sand the angle as shown. The table edge will ensure that the sanding block is kept 'square' to the balsa, thus achieving a straight edge.
The sanding block should be at least 5" long, make the sanding block from 1/2" sheet - Cyano a piece of emery paper to one side. Support blocks should be at least as wide as the wing it is supporting..
You should now have perfectly straight wing joints which you can glue with Cyano'. If you are not confident that you will be able to position and hold the wing in the few seconds that you have using Cyano' - then use Epoxy glue. Position a piece of thin plastic underneath the joint while gluing to stop the wing sticking to your work surface.
To prevent the wing from moving, place a weight on top of the wing section that is flat on the work surface.
Remove the plastic strips once the glue has set hard.
Use hardwood and follow the plan outline accurately to ensure that the wing / boom incidence is correct.
If building a model with a balsa fuselage always thin the rear end to reduce weight. A heavy tail means more weight on the nose to counter balance it and that means a heavier model - not good !
Use Cyano' glue to build and laminate fuselage parts (Mr Shifter) and to attach the boom pivot side plates.
Wing / Fuselage joint
When gluing the wing to fuselage, use Epoxy, ensure that you have a neat joint before gluing.
Apply any fibreglass re-enforcing after glue has set.
Tool for making the V joint .......
Make the tool from 1/4" balsa sheet. Glue (cyano) a strip of 1/8" x 4" sandpaper where indicated. Bring the balsa fuselage upto the tool and slide backwards and forwards to remove the required amount of balsa.
The angle required can be judged from the plan of the glider you are building.
Tail and Fin
Neatly cut out the parts, then feather (sand) the edges down to about 1/64" as shown (keep the edges smooth).
Glue the Fin and Tail to fibreglass booms with Epoxy, use Cyano' for wood to wood joints.
Give the wing / fin / tail surfaces one final sanding with 600 grade Emery paper.
Round off the nose section of the fuselage.
Fit the d/t tube if there is one. Use a rat-tailed file to start the hole and slowly enlarge it.
Now apply three coats of thinned (50/50) non-shrinking dope, allow to dry thoroughly between coats, sand smooth with very fine Emery (600/1000 grade) between coats.
Apply a further coat(s) of non-shrinking dope if required (if the wood still looks 'dry').
To fully waterproof the model, apply a thinned (50/50) coat of two-part fuel proofer such as Tufkote.
Lightly spray the wing tips and 'tail feathers' with Flourescent orange paint (essential for ground location / recovery)
It isn't necessary to paint the whole model, as this only adds weight.
Fit any wire parts and d/t lines.
Write your name and phone number on the wing ( use an indelible pen ).
Assemble the model (if using a glass' boom) and go flying !!
For initial trimming and launching advice refer to the Launching page.