About this Plan
Wildcat. Control line profile stunt model.
Quote: "A 33in. span multi-role profile control line model, suitable for 1.5 - 2.5 cc motors. Can be built with foam or conventional wing structure. Wildcat, by Dick Cowburn.
WILDCAT WAS designed a couple of years ago as a general purpose sport model taking advantage of foam-wing construction for quick building and low cost, while having a reasonable appearance for display work. The design exceeded expectations being fully aerobatic, easy to fly, and tougher than expected. it has therefore become our MRCA (Multi-Role-Club-Aircraft) in Humberside MFC being used for anything from training to slow-combat.
The ply-skinned fuselage was chosen to survive most normal flying accidents, the raked fin slides off in inverted landings while the forward cockpit protects the needle valve. The semi-disposable foam wings are easily replaced or repaired and have proved much more durable than expected. In a hard crash they tend to tear off at the root and this action protects the rest of the model from damage by absorbing the inertia. If the spars don't crack, the wings can be stuck back with epoxy, but if the damage is more serious the foam cores can often be salvaged by trimming a few millimetres from the root and replacing along with new spars.
A balsa winged version is also shown on the plan. This is more durable, but is not quite so aerobatic as the the thick winged foam model and takes much longer to build! (I will be keeping mine as a balloon-bursting model in the next display season).
Construction: Start with the fuselage, cutting the core from soft 12mm balsa (you can get four out of one 100mm wide sheet) and fitting the 12mm sq ramin bearers spaced to suit the intended engine, any excess being planed off when cleaning up the assembled fuselage. The 0.8mmply sides are now laminated to the balsa core with PVA glue, the nose and cockpit areas being filled with scrap balsa and the whole assembly left overnight under weights to dry thoroughly. While the fuselage is drying, the tail group can be cut from medium 3mm balsa and the elevator hinged to the tailplane. (It is possible to cut two complete sets of tail parts from one 100mm wide sheet). Note the 0.8mm ply reinforcement for the elevator horn mounting.
Wing foam or built-up? Now decide which version is required and make the appropriate airfoil templates from 'Formica' or similar (I have found this to be ideal for use with a hot wire cutter but it has to be sawn and filed very carefully with fine-tooth tools).
Foam wing: I use 900mm x 600mm x 50mm foam polystyrene sheet from an insulation supplier which is marked out to give three pairs of blanks. Port are 450mm long, starboard 435mm long. Identify L/E, T/E, port or starboard on each to avoid errors when cutting. Pin profile templates to each end of a blank and weight down to the bench. Draw hot wire through from L/E to T/E. Turn over and repeat. Change templates and cut spar slots, using the top and bottom offcuts for support. Now cut out the lead-out space in the port panel only. This is the most difficult part of cutting the foam blanks and you must take care to make sure that the wire enters and leaves the foam simultaneously at both ends..."
Scan from DBHL, cleanup by theshadow.
Direct submission to Outerzone.
Update 12/07/2019: Added article, thanks to NeilAlleyn.
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User commentsBuilt a number of these models years ago and taught my sons to fly. I believe a better model than the Peacemaker (oz1633) plus more suited to a glow motor. Have article and picture and will post at later date.
Neil Alleyn - 10/07/2019
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