BuiltWithNOF

MIKE ROACH’S SOPWITH AVIATION COMPANY

THE SCORPIO SE5A

THE AIM OF THE REVIEW

I was so impressed by the scale appearance, light weight and flying qualities of the Scorpio Hurricane (reviewed in AMI June 2004) that I asked Mantua Models if they would be prepared to let me have one of their SE5A kits for conversion to a real indoor model. I say this because although the brochure describes it as suitable for outdoor and indoor flight, those who read my Hurricane article will know that I was sceptical of its suitability for indoor flying and as kitted the SE5A is also on the heavy side. With a weight of 11.75 oz and a wing loading of 4.5 oz/sq ft it will fly far too fast and furiously to be compatible with any models at Calshot or Fleming Park, the biggest venues I have access to. I’m sure that it would be a great success as a small field outdoor flyer with the kit motor (a geared 280 and 7 or 8 cells) and could be built in a day and flown that evening without any changes to the kit, but I wanted to try something different.

The weight of the foam parts is only 2.5 oz: add to that a set of GWS hardware and a 2-cell Li-Poly battery and you get to 5.5 oz, with an ounce to spare for formers, struts, wheels and so on.  At this weight the wing loading would be just under 3 oz/sq ft and within the “indoor zone” for realistic performance, so a simple and very successful conversion seemed on the cards.

WHAT’S THE KIT LIKE?

The brochure firmly says “semi scale”. As long as you accept this limitation, the mouldings look pretty good, the transfers are very good and at a glance the finished model does look just like McCudden’s SE5A, details and drawings of which are in FSM for November 2002. The 1/10th scale fuselage profile is rather deep-chinned (photo 1) and the real thing had a flat-bottomed cross-section not an oval one.  (This is one of life’s abiding mysteries: why spend all that time and trouble making a semi-scale mould for the fuselage, when it would have cost no more to make a scale one and would have made other aspects of the model easier to manufacture and assemble?). The wings are curved plate section (excellent for indoor slow-flying) and are in one piece with built-in dihedral (and here’s another mystery – scale dihedral is 28mm at each wingtip and perfect for rudder/elevator flying, but the model only has 20mm!). The wings have moulded half-round “rib tapes” on the top surface, which must add some strength, but I had grave doubts as to whether the transfers would be flexible enough to fit over them, or merely sit untidily on top. The tail surfaces are not as well prepared as the wings or fuselage and are plain sheet foam. 

The wings and tail are coloured PC10 on top and “natural fabric” underneath. The colour match of the PC10 is good but should overlap the leading and trailing edges and despite some misgivings, I found this quite easy to do. The fuselage is PC10 all over, which is apparently correct for McCudden’s aircraft, but some sources say that the lower part of the rear fuselage was natural fabric. This would be easy to duplicate with a can of Holt’s Duplicolour “Ford Ivory” acrylic spray, which is a very good match for creamy yellow varnished linen, but you would have to be very careful with the masking, as tape will rip off the PC10 in a trice, leaving you with double the problem! A straight edge and a brush would be the best answer.

The rest of the kit consists of ply, liteply and balsa, beautifully die-cut and, where necessary, painted in the base colour (photos 2 and 3). A rather heavy set of wheels, a gearbox for the 280 motor (not supplied with my kit, but may be in the one you buy) and all the rest of the hardware you need.  The A4 instruction book is not as comprehensive or so well laid out as the Hurricane but was easy enough to follow.

MAKING A FEW CHANGES

Bulkhead 2 is the motor mount for the 280 and can be thrown into the spares box. B3 and B4 have an important role to play in supporting the cabane and UC struts, so they ought to stay, but the battery box can be discarded, saving a few more grams.  If you want to keep the kit “wire in tube” control system, the servo tray should be fitted – a tricky operation which I failed to complete correctly due to the size of my fingers! Everything else was built with kit components, give or take a few cosmetic alterations here and there.

MOTOR AND BATTERY PLATE

The only major change I made to the fuselage contours was to cut off the whole of the curved lower front part. A simple motor mount and battery tray was glued to B3 and the fuselage sides  (photo 4) and a beam mount made for the GWS A series IPS motor (photo 5). A flat section was made from a laminate of 3mm Depron in order to make the nose of the aircraft look much more scale-like and provide a hatch for battery access (photo 6). I used a 2-cell Li-Poly battery, GWS Naro servos and receiver and an “Enjoy Models” speed controller made to suit their Li-Ion batteries. With the battery right forward the model balance was spot on for buoyant and responsive flight.

TAIL GROUP

The instructions suggest using tape to hinge the elevator and rudder, but I found this to be too clumsy on the Hurricane, so I faced the hinge lines with 2mm balsa strip and sewed the pieces together with fig-8 thread. This is my favourite method for small indoor models and has the great advantage of looking vaguely scale-like. A few dabs of Tamiya Khaki Drab (XF51) disguised the changes.  This paint is perhaps too green for PC10, but the matt finish can be used to suggest rib tapes over the rather glossy kit finish.  Part 16 has slots cut for the wire-in-tubes to run up to the servos, but again, as in the Hurricane, these are too wide apart to provide straight friction-free runs. A few seconds work with a 3mm drill soon fixed this.  The elevator control horn needs to be moved in about 5mm for the same reason (photo 7).

The good news is that the tailplane, fin and underfin all slot into the fuselage in perfect alignment and make what is usually a tricky job very easy. I do suggest that you apply the fin stripes before you do this: it’s so much easier!

OUTLINING THE WINGS

Outlining the undersurfaces with PC10 is easy to do and adds considerably to the “at a glance” scale appeal. Weight the wing down and block up a ruler about 20mm above a trailing edge.  The size of brush you use is not important - in fact a medium brush will hold more paint and make the job easier – what is important is that the hairs come to a point.  Load the brush and wipe off the excess, then using the ruler as a guide, carefully draw a straight line along the wing. If you make a mistake, just wipe it off with a damp cloth and try again until you get it right.  The curved tips are a little more difficult, but persevere!  If you do the tailplane as well, do so before you fit it to the fuselage…I know.

DECORATION AND DETAILS

The instructions advise that all transfers should be applied before assembly – I concur. The large wing roundels will fit over the “rib tapes” with a bit of persuasion using a damp kitchen towel to tease out the bubbles and wrinkles and the white fuselage band is slightly more tricky, but the transfers are excellent quality. I added a few small details to make the “at a glance” scale slightly more believable: a Vickers gun and sight on the fuselage from balsa dowel, and a Lewis gun on a rail mounting above the upper wing.  The radiators are a must (otherwise there is just a gaping hole at the front of the fuselage) and some rigging adds considerably to the strength of the model.

FINAL ASSEMBLY

The kit includes some accurately cut jigs, which are used to hold the upper wing in position while the struts are added. I changed the assembly order slightly, as the rear cabanes merely slot into the fuselage and not into a former, so they can be fitted more easily after the wing is epoxied to the front cabanes. I had to shorten the interplane struts by 6mm each to get parallel dihedral, helped greatly by the jigging system. (photo 8).

After the struts had dried, only the undercarriage remained. To save time I used all the kit components, even the heavy wheels, but you could save quite a few grams by making your own.  The UC springing is neatly designed and if you made the outdoor version with a 280 motor would be essential, as the UC parts are only medium balsa.  With my landing, I’d give them only a flight or two before replacement was necessary.

An essential “at a glance” detail are the exhaust collection chambers and the long pipes (although my reference shows that McCudden’s aircraft did not have these!).  These are supplied as a flat plastic half-moulding, intended to be fitted to the curved fuselage. Rather than curve them with a little heat, I blocked in the chambers with some pink foam. When filled and painted (black chambers and Tamiya X-34 metallic brown on the exhausts), this small modification significantly improved the look of the front end (photo 9). A couple of thin wire ”straps” secured the exhaust pipes to the fuselage, otherwise they would just flap around in the breeze.

RIGGING

Unless you add some rigging to the model, the wings gradually sag and lose the “at a glance” scale effect we are looking for.  A full set of thread rigging, including doubled lift wires, will take an afternoon of fiddly work, which is best done before any of the other details have been added.  If like me you leave it to the end, then it may take a bit longer!  There is no need to drill the strut ends: the balsa is soft enough for a needle to be pushed through.  Follow a logical sequence, use small drops of cyano to fix and you’ll find that rigging is not too difficult and makes for a much stronger model.  The only small reinforcement you need is where the rear lift wires pass though the wing (where the front spar joins the fuselage on the real thing) and a scrap of ply is needed under the wing to take the strain.

FLYING

I don’t know how, but the model weighed 8 oz exactly (I was expecting 7 and hoping for 6.5) but still has 3 oz/sq ft loading.  September began bright and windless in this part of the world and Stanpit Rec, with its old cricket pitch as a runway, is an excellent “silent flight” location. At full throttle, the SE swept off the ground and flew perfectly, with no corrections needed, for a scale-like climb out to about 50 ft. A click of down and half throttle had it pottering about the sky, looking very realistic in sweeping turns and low passes. There were a lot of bumps in the warm air, but despite the model’s light weight and limited power they gave no cause for concern. I did try to take some photos while flying HOCAS (Hands on Camera and Stick), but failed miserably. But it does fly very well indeed, even with full rigging, pilot and guns adding to the drag and weight.

CONCLUSIONS

I know, I didn’t stick to the instructions and I changed the whole concept of the model, but the flying qualities are excellent and I’m sure that another ounce/sq ft wing loading will not make a lot of difference, at least for outdoor flying. I wouldn’t like to try it indoors with the 280 motor and larger battery, but cleverer people than I do fly similar size and weight models indoors without any problems. The conversion to lower power and lighter weight works exceedingly well and with a little balsa-bashing you get a very satisfying almost-scale model for a very reasonable price.  Mantua also do an Albatros DV and a Neuport 28 in the same series, each with a lower wing loading than the SE5a and these may be an even better basis for indoor flight.  Their Mosquito for twin 280s (and another one for twin 400s) also look very nice indeed.  As usual, I’d love to hear from builders. I’m on 01202 477553 or roachfoxwood@aol.com

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