Gerrard Feeney reviews the fun flyer from Mainly Models - 13/12/10
Making R/C model aircraft airframes from hot-wire cut blue foam, that’s subsequently covered with PVA-adhered brown paper is a construction method that’s been around for years. Mainly Models of Hertfordshire have now embraced this cheap ‘n’ cheerful airframe production philosophy in their expanding range of 1/12 scale W.W.II fun-fighters. The designs in this series of ‘combat legal’ semi-scale warbirds are designed to live fast, possibly die young, but be easily repairable if the battle damage is relatively minor!
The 391/2” span Hawker Hurricane reviewed here is typical of the type. The compact airframe can be dragged around the sky by a .10 - .20cu. in. two-stroke glow engine, a Speed 480 electric motor or, if you wish, it can be converted to a slope soarer for a bit of fun in a brisk breeze. Three control functions are required, throttle (or speed controller), ailerons and elevator. The rudder is non-functional.
The kit exudes a pronounced ‘cottage industry’ vibe. The durable box is visually unexciting with just a printed label delivering the basic airframe information along with a typical Hawker Hurricane side view. Inside, bubble wrap keeps the blue foam and the odd balsa bit well protected, and I have to tell you, the part count is minimal: two wing panels, five fuselage sections, a clear moulded canopy, an ABS cowl, sheet balsa tail feathers, an underside fin strake plus a comprehensive (all items supplied) poly-bagged accessory pack. The rolled plan and instructions are best described as ‘basic’! Generally, the component quality was good. The checklist arrived pre-ticked, confirming that all items were packed as present and correct - even the (rolled up) brown paper airframe covering is supplied.
The optional self-adhesive decal sheet was also provided for this review, though to my mind this should really be included with the kit as standard. That said, the roundels and registration letters are nicely made and do, at least, save the builder having to rustle something up in Solartrim. Okay, preamble over - time to retire to the shed and put the thing together.
A long Perma-Grit sanding block is ideal for achieving the required dihedral angle on the wing panels. Sand the roots of both panels at the edge of the bench with the tip propped up by the prescribed amount, taking care to hold the wing panel steady during the task. I suggest leaving the sanding of the wing tip contours until after the panels are joined as the un-contoured tips allow more accurate dihedral angle packing. Once glued together the panels are trimmed very slightly at the centre-section leading and trailing edge to provide a snug wing seat fit.
Sand the wing smooth and fill / re-sand if necessary before covering with the supplied brown paper, which is applied using a brushed-on 50/50 PVA glue / water solution. For those of you who might be new to this particular covering technique, I’ve written an article, starting on page 47, that attempts to explain the process in a little more detail. Take a look if you’re interested in having a go.
Our next task is to mark the strip ailerons onto the now-covered wing trailing edges, carefully cutting them out using a very sharp No.11 scalpel or a single-edged razor blade. The aileron leading edges are best chamfered with a long Perma-Grit block after first centreline-scribing and slotting / drilling / grooving them for the Mylar hinges and torque rods. Do work carefully here as the separated ailerons are extremely thin and potentially fragile. When this is complete the aileron leading edges are sealed using the PVA / water solution.
The instructions suggest that you form span-wise slots in the rear centre-section of the wing to accommodate the torque rod assemblies, which can then be hidden and blended with lightweight filler. However, I chose to deviate here and employ my preferred torque rod mounting method, i.e. remove the centre-section trailing edge in its entirety, groove out said item, fit the torque rods to the newly exposed trailing edge and then re-attach the centre-section piece hiding the torque rods in the process. Simple.
Remember that the torque rod wires must be cut to the correct length and bent to the required angles only after slipping on the hard plastic mounting tubes!
A micro servo is required for controlling the ailerons and this sits in a builder-cut hole in the wing centre-section; bury it as deep as possible into the foam to avoid a clash with the components in the radio bay of the fuselage. To this end I chose to recess the hardwood mounting blocks flush with the wing skin to obtain a really deep-seated servo fit. With this done it’s a simple matter to connect the ailerons using the supplied kwik-link fittings.
A single l.e. dowel and a lone wing bolt at the t.e. holds the wing in place. It’s best to use a sharpened tranny aerial offcut to form the dowel / bolt holes as a drill bit will be deflected by the wing centre-section glue line. I used Evo-Stik impact adhesive to attach the load-spreading wing bolt plate, and gently scored the ply on the inner surface to allow the plate to flex and thus match the dihedral angle.
FUZZY FOAM FITS
The fuselage is fabricated from five pre-shaped foam segments: front nose block (pre-cut internally for fuel tank mounting), middle radio bay / cockpit block, rear coaming block, tail-seat block and a small upper cockpit ‘headrest’ block. Once these components are glued together they’re sanded to form one streamlined, homogenous fuselage unit - a lot of careful fettling is required here! An ABS plastic cowl covers the engine to complete the effect.
So then, the first task in building the fuselage is to relieve the lower gluing faces of nose block ‘A’ and rear coaming block ‘C’ with a razor saw, to accommodate two, inset, ply plates. The front plate supports the wing dowel whilst the rear ditto provides a bearing surface for the captive nut anchor plate. Speaking of which, our next task is to trim the captive nut plate to clear the aileron torque rods on either side. With this done, the plate can be glued in place. Incidentally, the radio bay was 1/4” narrower than that shown on the plan, so you’ll need to exercise care when fitting the torque rods to prevent them clashing with the fuselage sides.
With all the foam segments glued together, but before the final body-sanding process, the thick ply firewall must be attached up front. This oversize component is shaped to match the fuselage cross-section in-situ using a sharp Stanley knife followed by 80-grit glass paper on a hardwood block.
Achieving a precise engine mount centreline is tricky because neither the ply nor the foam carries any guidance marks. To overcome this I made a paper template by drawing around the (fitted / sanded) firewall, then folded the template centrally and transferred the lines back to the firewall. When allied to the plan’s side view datum line this gave reasonably accurate results.
An inverted O.S. 10FP, attached to a matching alloy mount, provided a neat powerplant layout. Allen-head bolts hold the engine to the mount whilst two self-tappers and two anchor bolts hold the mount to the firewall. The reason for using a combination of self-tappers and bolts was due to the difficulty of placing captive nuts behind the upper firewall mounting holes - access from the inside being hampered by the internal cross-section of the nose block. The ABS cowl is then carefully cut to clear the engine, and access holes added as necessary. It’s attached to the airframe using small self-tappers secured into hardwood blocks glued to the firewall. A 4oz SLEC tank is suppied, which I’m pleased to report fits snugly within the pre-cut nose block. As builders we’re required to clear a path in the foam to make way for the throttle snake which, incidentally, should not be glued in position until the tank / radio installations are complete. Even then, it can be held perfectly well with just a friction fit, minus any glue.
The small headrest block needs shaping before being glued in position, after which it can be sanded to match the main fuselage contours. I added rudimentary ‘office’ detail after the model was covered, just before the canopy was stuck in place.
The wing-to-fuselage fit was initially very poor - the two components just didn’t match up! As such, I had to cut away fuselage wing seat material on each side to get the wing fitting flush with the fuselage. A card template, taken from the original wing seat shape but moved 1/8” upwards, set the new seat location. One assumes that this disparity will be rectified in future kits...
Before fitting the thin-section balsa tail feathers, the fuselage must be covered in brown paper. The stabiliser and elevators are then prepared for hinging, with the supplied Mylar strip, before joining the elevators with a (builder fashioned) 16swg piano wire joiner.
The tail feathers are meant to be left uncovered, with just sanding sealer applied prior to painting. However, since I dislike a grainy wood finish, lightweight tissue was applied before gluing the tail parts in position. I also added non-standard balsa fin fairings to give a more attractive finish to the backside! Finally, a thin-section balsa strake is butt-glued to the underside of the fuselage along its centreline. This I tissue covered as before.
Although standard-size R/C gear is discouraged from a weight point of view, I find it hard to imagine a completely ‘non-micro’ installation actually fitting in the cramped radio bay. I compromised with micro servos and a standard NiCad / Rx / switch arrangement. It took considerable forward planning to get everything into the fuselage where it should be; the foam-clad NiCad and Rx were set just behind the tank, the wire-actuated switch was fastened with Velcro whilst the ply plate-mounted servos and NiCad had to be recessed into the top deck to avoid clashing with the aileron servo.
PAPERING AND PAINTING
After a light sanding, the brown paper was brush painted with Humbrol matt enamel. The underside colour was completed first then masked off while the upper surface camouflage was painted freehand. Strips of Flair masking tape were used to ‘frame’ the canopy, these being painted to match the fuselage.
The sticky-back decals were easy to apply and with this complete the whole airframe was sealed with a few coats of brushed polyurethane varnish. If you’re lucky enough to have a model shop that carries the entire range of Flair Spectrum aerosol paints and fuelproofers then my advice is to use them for the airframe decor. The sprayed matt finish is much lighter and looks far better.
Unfortunately some nose ballast was required for my model, though a larger capacity engine (and possibly the inclusion of dummy exhausts) might alleviate the need for this. Ready to roll, the model was set up as stated in the data panel.
Since the O.S. 10 hadn’t been run since 1994 (!) the start-up and mixture tweaking procedure took a while to sort. Anyway, eventually, after a plug change, it performed okay. So, with the little powerplant on song, my glamorous assistant Padraic Cryan flung the petite airframe into the murky sky.
After an initial dip, a slight dab of back-stick saw the Hurricane climbing vigorously. Its small size and gathering speed called for much concentration in the terribly downcast conditions. Before long I was guiding a small black silhouette through alternating right- and left-hand circuits in what now became a persistent thick drizzle and choppy breeze. The initial control response vibe and general flight ‘feel’ was good. Having added some up and right trim the model was behaving itself nicely, seemingly very responsive to aileron and elevator inputs.
Allowing her to travel a good distance upwind before turning back for a fast pass I was amazed at how quickly she shifted on the downwind leg, in fact, I had to throttle back a bit. Despite being hard to see, the airframe looked great slicing through smooth, low, groovy turns. I tried some low passes, coming in along the landing approach path, and then climbing steeply into a half-loop with half-roll out to a downwind trajectory to repeat the manoeuvre...
I mused that model looked more like a pylon racer than a W.W.II fighter as its speed at full throttle was considerable, despite my using the lowest recommended engine size. When throttled back to half power and below the model became twitchy in the wind; it bounced about a bit and some aileron / elevator prodding was required to keep it steady. It will stall when held in a steep nose-up attitude at low power, but the washout built into the wing eases the situation and it recovers quickly when the controls are neutralised and full engine revs are re-established. The control surfaces are certainly effective at inducing very spirited single or consecutive loops and rolls. I enjoyed combining various loop / roll patterns from quite low level - unusually daring stuff for me!
I was in the process of reducing the airspeed prior to landing when the engine suddenly cut, too high up to perform a dignified arrival. I knew I’d overshoot, so some extremely unscale-like tight turns were required to sort out the landing approach. I was pleasantly surprised by just how responsive the ailerons and elevator remained when dead-stick, indeed it was good that the model could perform tight turns in the glide without dropping from the sky! With the model straightened up the glide proved to be quite prolonged, the smooth belly-landing ending up ‘kissing the grass’ a considerable distance away. Whilst flying the Hurricane was enjoyable, I await seeing its true colours in better light and calmer conditions.
From a constructional / finishing viewpoint, the Mainly Models Hawker Hurricane is an experienced modeller’s project. It’s not hard to put together and the kit contents are very complete, but interpretation is sometimes needed to get the best build results, and the covering procedure is initially a bit tricky. In practical terms this is a tough little model that’s easy to transport in one piece and behaves well in the air. Frankly, I can see it becoming very popular on flying sites all over the place on sunny September evenings.
Name: Hawker Hurricane
Model type: Semi-scale fun-fighter
Available from: Mainly Models, Hitchin, Herts. Tel. 01462 422204 www.mainlymodels.com
Wing area: 280 sq. in.
All-up weight: 2 lb 11oz (fuelled)
Wing loading: 22oz / sq. ft.
Control functions: Ailerons, elevator, throttle
Control throws: Ailerons ±1⁄4'', elevator ±1⁄4''
Rec’d engine: .10 - .20cu. in. two-stroke or electric
Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!