Fantasy 2 (oz16218)

About this Plan

Fantasy 2. Radio control sport model. Wingspan 52 in, for .25 engines.

Quote: "A 50 in span R/C sportster for .25 engines, Fantasy 2, by Peter Miller.

Some years ago I designed a nice little low wing, semi-scale sports model for .15 engines, which I called Fantasy. I spent two weeks of an Easter holiday doing a really fancy spray job on the model, and it looked great and flew really well - until I gave 'up' elevator whilst in the inverted attitude.

Feeling the urge to design a new model, I decided on a slightly enlarged and simplified version of the original: more of a lookalike than a true scaling up of the original.

The main design criteria were for the model to be fully aerobatic, yet forgiving in flight. Capable of being flown slowly, combined with easy construction and good looks. This inevitably meant light weight and a large wing area, plus a thick wing section, for low wing loading and gentle stall characteristics.

I feel that I have met all those design parameters, as Fantasy 2 was very quick to build, I (as unbiased as ever!) think that it looks good - and as for the flying, judge for yourself in the relevant section.

Fuselage: The construction is conventional, 1/8 sheet balsa sides with 1/32 ply doublers and formers from assorted materials. Glue the doublers to the sides, then add formers Fl to F4 to one side, making sure that they are at 90 degrees. When the glue has set, add the other side and when all is dry, pull-in and glue at the rear, add all the remaining formers.

It does pay to do all the drilling on F1 before fitting, and the undercarriage should be fitted to F2 before that former is glued in place. However, this means that you have to assemble the fuselage on the edge of the bench to allow the undercarriage leg to hang down, no problems.

The turtle deck is angular, because it is quicker and easier to produce than rolled sheet balsa, and looks quite smart. I incorporated a hatch under the nose between formers F1 and F2 as it makes access to the tank much easier: you could omit this and have a suitable access hole in F2, but you will not be happy if you have to get the tank out on the flying field.

Holding the wing in place is a dowel at the front and a bolt at the rear, with the nut bonded to the 1/4in. ply plate.

Fit the snake outers before covering the bottom of the fuselage. Note that the holes for the snakes in F3 are slots: this is because they are very close to the servo and the snakes needs to be able to move sideways as the output arm rotates. Glue the snake outers to the next former back. The headrest can be carved to shape now, but don't glue it down until the model has been covered.

Tailplane and fin: These are made from sheet, you can use medium sheet for the tailplane and harder sheet for the fin. I made mine from very soft wood, but then I had to add lead to the tail to get the CG right. You might as well benefit from the extra strength of harder and heavier balsa!

I like to leave the tail off the model until it is covered, as then you don't have to try and get the film to form sealed joints in tight corners.

Wings: These are the most vital part of any model, if they are warped the model will never fly well, so take a lot of care in their construction.

The wing design follows full size practice in that the main spar is the main load bearing member, while the leading and trailing edges take a little load, but are not intended to carry a significant amount. Note how the main spar is tapered in strength and is laminated so that the root (where the highest loads are) is the strongest area.

Because there is no leading edge sheeting, the spar is webbed on both sides. It is important that the webs are a good fit to both the spars and ribs, because this makes a sealed box which is much stiffer. It won't prevent warps, but it helps.

The aileron servo is laid on its side and operates the ailerons through bellcranks, which makes for a little more room in the fuselage, and applies the operating force to the aileron in the best place - the middle.

Cut out all the ribs and the webs before starting. Laminate the spars, noting the tapered end to the inner lamination, which is important. You can cut each spar and inner lamination from one 36 in length.

Build the wings as two separate panels. Pin down the lower spar over the plan: also pin down a piece of 1/4 in square near the trailing edge to support the rear of the ribs during assembly - use a couple of ribs to position this correctly.

Glue on the tip rib, making sure that it is vertical. Next, position all the ribs (without gluing) and fit the top spar -which should only be glued to the tip rib. Fit the first pair of webs, then slide the next rib up to them, gluing all joints. Now fit the next set of webs and slide the next rib up to them, and so on right up to the rib at the side of the servo bay..."

From Aviation Modeller International October 1999.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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