Mike Sharman Models 'Killer Queen 3'

Written for 'RCM&E' March 1982.

Picture of 'Killer Queen 3'

The kit - Construction - Radio installation - Flying - Conclusions

In an age when most high performance model gliders are built around a glassfibre fuselage, a glider with an all-wood fuselage is a rarity. Not only is the 'Killer Queen 3' just such, but it is difficult to tell from the shape of the finished model that GRP is not used in its construction.

Designed to fit the 100S Class rules, the model can be used for F3B with the optional canopy airbrake, and would also perform quite well in cross-country, or even slope pylon events. Airfoil section is the ubiquitous Eppler 193.

The Kit

Immediately impressive is the quality of the wood, with wingtips and tailplane blanks being cut from the kind of light, firm, stock that some of us spend hours searching for in vain. All balsa and ply parts are supplied ready shaped, the ribs being banded together in the correct order and packaged in a shaped polythene pack. Another plastic bag contains a complete set of ply and wire parts for the ingenious releasable tow-hook. Ballast tubes and wing dowel tubes are ready-made and are a superb fit in the ply ribs.

Wing attachment to the fuselage is a little unusual in that separate wire dowels are used for each wing half. These locate into stub tubes mounted in substantial ply fuselage formers. The holes in the formers are deliberately made oversize to allow for some adjustment to give correct alignment.

A full-size Plan of the fuselage is included, together with three pages of typewritten instructions. The wing plan is printed onto the inner face of the wing sheeting, as with other designs from this stable.

Construction

Fuselage assembly is very straightforward apart from one snag which could problems if not spotted in time. As previously stated all the parts are ready cut to shape. Comparison of the fuselage parts with the plan showed that they were all larger than the Plan (the fuselage length being 1.5" more than shown). At first it was thought that the Plan was at fault, but it became apparent that the two main formers housing the wing dowels were of the same width as the plan.

The only solution was to cut down the servo tray which is designed to impart the desired curvature to the fuselage sides in the canopy area and also to cut down the top and top and bottom sheets and canopy parts after assembly. Therefore, the trouble and expense of the pre-shaped parts is largely wasted.

When constructing the wing it is necessary to make up each of the four wing skins from foue pieces of pre-printed sheet. Cutting to the printed lines with a straight-edge gave perfect scarf joints in all cases which merits a word of congratulation to the designer.

Unfortunately, another snag did crop up in the wing construction. Pre-shaped trailing edge material is supplied. for adding to the rear of each wing panel. This is nowhere near thick enough for the job and it is necessary to sand away a considerable amount of the wing sheeting to produce a match.

To produce the characteristic slight undercamber on the bottom surface of the wing, the front portion of the sheeting is 1/8" thick while the remainder is only 1/16" thick. It is then necessary to shape the 1/8" sheet to a reflex curve which I personally found to be a unsatisfactory (and not very accurate) way of producing the desired result. I would have found it easier to fit constant thickness sheet onto a curved rib underside.

Tail surfaces are of solid sheet and only require sanding to section. The wings and tailplane were covered with clear Kwikcote after decorating with a felt pen. After building up the wing fillets from micro balloons and epoxy. the fuselage was covered with heavyweight tissue, followed by two coats of sanding sealer. After rubbing down, two coats of dark blue polyurethane were applied.

Radio Installation

Linkages supplied comprise of a nylon in nylon snake for the elevator linkage (which suffers from the slight lost motion common to all such systems) and a closed loop cable for the rudder. Having read on numerous occasions that a closed loop system will not work with a linear rack servo, I used just such a servo for the rudder with perfect results This set-up does, in fact, give exactly the same result as an exponential R/C option. As the model was coming out a little on the tail heavy side, the receiver was mounted in front of the servos rather than behind them as shown on the plan. If I decide to use the canopy airbrake at a latter date, the canopy servo will have to go in this area and the receiver will have to be moved back to the suggested position.

Flying

Two ounces of noseweight were required to bring the C of G to the recommended position and this gave an all-up weight of three pounds and a loading of 10 oz./sq.ft.

A few test glides established that the suggested starting point for the tail incidence was about right, as were the control movements.

The first attempts at towing, however, revealed that rather more elevator movement was required since once the nose dropped a lot of height was lost before recovery. Rudder response was more than adequate, but as with all high aspect ratio, rudder controlled models, there is a noticeable lurch before starting to turn.

Even without ballast, the model can be flown quite fast, and needs a fair breeze to tow it up (unless you have an Olympic standard runner available). The releasable tow hook - worked from down elevator in this case - is a useful feature and would be particularly helpful when using a bungee.

Conclusions

A beautifully engineered kit with superb wood which produces a competitive 100S or F3B class glider. Some extra care is needed during fuselage assembly due to conflicts between pre-cut wood sizes and the plan.

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