SIG 'Mister Mulligan'

Written for 'Aero Modeller' November 1977.

Mister Mulligan

Open the box, and the first reaction is - what wonderful wood! Unfortunately, the next reaction is - what diabolical die-cutting! However, some careful work with a balsa knife and a tube of cement soon produced an acceptable set of sheet parts, and construction commenced. A noteworthy point on the plan is that both fuselage sides are shown separately to cater for the side window layouts being slightly different. The fact that the resulting sides are not quite identical in outline is probably due to printing problems! This is easily corrected, of course, but the moral is - never take anything for granted.

The fuselage does go together very nicely and results in a surprisingly rigid structure. It is necessary to cut out notches in the bottom formers at each stringer location, a rather tedious operation which was avoided by making the former 1/16in. smaller all round, and gluing the stringers on to the edge. This also ensures that the formers do not cause 'bumps' in the covering.

One minor criticism of the fuselage structure is that there is no provision for making the sheeting around the front formers flush with the stringers. The instructions state that the rear edge of the sheeting should be bevelled to blend in, but in the writer's opinion this was far from satisfactory, so each stringer was cut away from F3 and raised to the level of the sheeting. Incidentally, there was insufficient 1/32in. sheet in the kit to sheet the various parts in the manner instructed. However, this can be overcome by sheeting the cowl in three pieces instead of four as instructed. There were no problems with the remainder of the kit, the undercarriage and strut assemblies being fiddly but by no means difficult.

Covering of the model required some careful thought. The bottom of the wing was covered first, and the wing then attached to the fuselage using epoxy to avoid warping. The top stringers were then added and the remainder of the wing and fuselage covered. After covering the tailplane and fin, these too were epoxied in place. The tissue was then watershrunk and the undercarriage and struts added, again using epoxy to avoid deforming the covering. One advantage of an aeroplane with struts is that they can be used to remove any warps that might appear during construction!

Finally, the entire model was given one coat of thinned clear dope, and the transfers, etc., added. Panel lines were put on with a 0.4mm Rapidograph pen. Rubber motors were then made up from Keil Kraft 'white' strip - nothing exotic was used.

Flying was carried out with the plastic prop supplied, and 4 strands of 1/8in flat rubber. In this form, a small piece of lead was required in the nose to obtain the specified CG position. The trim was just about perfect with no other modifications being necessary to give gentle left turns under power and slightly wider turns on the glide. The model was, however, somewhat underpowered and did not gain much height. Flight times were around 15-20 seconds.

The next stage was to make a 'contest prop' as detailed on the plan but for which parts were not supplied in the kit. This has curved 1/16in. ply blades formed by the traditional means of soaking in water, binding to a 3in. diameter former (small coffee bottle) and baking in the oven. The resulting rather cumbersome device is fitted with a motor tensioner to allow the use of much longer motors. In fact, this propellor makes the model so nose heavy that a much longer motor is needed to bring the C.G. back to a reasonable position!

The specified motor for this propeller is four strands of 3/16in. flat. All of this meant that the model now weighed roughly twice what it did before! The performance was spectacular to say the least, but hardly scale-like. Flight times now around 40~50 seconds and the trim was very touchy. In search of a compromise, the plastic prop was returned to with a loop of 1/4in. flat rubber. This gives fairly realistic flights of around 25 seconds. To anyone contemplating building this kit, I would very much recommend them to try C02 power as I feel that this would be just about perfect for this model. If you should decide to bulld the rubber version, however, I'm sure that you will not regret it. Altogether a most excellent kit which is only slightly marred by one or two very small details.

Mister Mulligan

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