Plan Download Page
Saab J-29B "Tunnan"
This model is my own design for Rapier L1 power.
Span is 12.5" and all-up weight 18.5 grams, including a loaded motor and some nose weight
and all outlines are accurate. I have always had a soft spot for this tubby little Swedish
fighter, and the layout is good for a flying model. It has proved stable, and a good performer.
As at August 2002 it has made over 40 successful flights over the last two years
and has suffered no significant damage in that time.
I kept the structure light, using 1/20" square balsa for
the fuselage and tail surfaces. The wings are all 1/16", the two
spars being webbed with 1/32" sheet for extra strength.
The motor tube is mounted well forwards, behind the former where the
cockpit instrument panel would be - you can just see it in the photo below
Finish is silver enamel over white Japanese tissue. Swedish roundels are
home made decals. The pilot is carved from balsa, a task made easier by the fact that much
of his face is obscured by an oxygen mask and visor! The motor trough is lined with self-adhesive aluminium
tape. In the photo below you can just see the green end of the motor sticking out of the
paper mounting tube. A small wire spring clip stops the motor falling out of the back.
here to download zip file (44 KB)
Construction is conventional using half formers and keels. Lay down the top
and bottom keels, a set of half formers, one side of the cockpit
surround, plus wing mount and side keel. Then remove from the building board,
add the other half formers, side keel etc before adding the stringers
one at a time, alternating sides to avoid introducing distortion.
The dihedral shown on the plan is 3 mm per side (1/8") - I think mine ended up with a touch more, so
consider 3 mm a minimum value. The wash out in the tips helps as well, giving the trailing
edge effectively more dihedral than the leading edge.
The built-up fin and tailplane could be replaced by items cut from light balsa sheet, for simplicity, at the
expense of a little extra weight. I think the separate elevator could also be dispensed with, as I never had to
adjust mine at all during the trimming process. Having a movable rudder did prove useful though, but a
small acetate trim tab would have done the same job.
The original plans fit onto two sheets of A4 paper - you may find that if you print them out to fit the page,
they will come out slightly too small, depending on the printable area that printer can handle. For this reason
I have put a 10 cm scale on each sheet so you can adjust afterwards using a photocopier with a % scaling function.
The plan could be enlarged to suit a Rapier L2 (maybe 14" span), in which case use 1/16" balsa wherever 1/20"
is noted on the plan. Aim to have the nozzle of the L2 motor in the same place as that
shown for the L1. The model could also be flown with a
Jetex 50 motor, in which case a span of around 15" would seem appropriate. You will have to work
out for yourselves how to incorporate the mounting clip though.
Click here to find out more about Jetex and Rapier powered models, and how to trim them.