Castaibert IV (oz14981)

About this Plan

Castaibert IV. Radio control sport scale model, for electric power.

Quote: "Castaibert IV. Urugyan pioneer monoplane for electric power."

Direct submission to Outerzone.

Update 12/12/2023: Added article, thanks to RFJ.

Quote: "Castaibert IV. A sport scale model of a little-known Uruguayan pioneer monoplane, designed for electric-power by Peter Rake, and built and flown by Ian Easton.

When I first saw the small, rubber power plan for the Castaibert IV (oz12290), I simply knew that I was going to have to scale her up for electric R/C operation. So, during a spell when I was unable to get into my modelling room, the dining table was commandeered, and a selection of plans drawn up, the Castaibert being just one of them. Unfortunately, as I began to work my way through them, more pressing modelling ideas presented themselves and the poor Castaibert plan was left languishing in a drawer.

Then during an e-mail conversation with Ian Easton, a Scot now residing in California, I asked him if there were any of my designs that he fancied building. For some reason known only to himself, he jumped at the opportunity and the Castaibert IV was resurrected. I would undoubtedly have built her one day, but now you don't have to wait for that!

The model: As previously stated she is, and was only ever intended to be, a sport scale rendition of the original aircraft. Firstly because the aforementioned plan was the only reference material I had, but mainly because I try, wherever possible, to keep my models easy to build and pleasant to fly. True, there is more scope for detail on this particular model, especially if you decide to fit the fuselage rigging, but she can equally well be kept fairly simple.

Why pick the Castaibert, rather than something better-known, like a Bleriot? Simply because she lends herself to the task so much better. Forget that horrendous bedstead undercarriage of the Bleriot, or the ridiculously short nose. With the Castaibert you have a simple, and admirably functional, undercarriage that still retains a degree of character because of its skids, and the nose is just ideal for getting the balance right. Other than those points, yes, she is very much like a Bleriot - which is probably why she appealed to me in the first place.

Construction: Although I have tried to keep the structure of the model as simple as possible, it isn't without its minor complications. These have been kept to a minimum, however, by making her a one-piece model.

Most of the complications aren't actually to do with the actual building, but are more concerned with the number of choices the builder has to make. The tail surfaces may be either cut from sheet, as shown, or built up from 1/8 sheet and strip balsa.

You may choose to omit the fuselage rigging, but the undercarriage and pylon bracing should be included. The main wing rigging is essential, though. It is all that takes the flying loads off the wing/fuselage joints. Equally so, I would strongly recommend fitting the small aluminium plates at each of the fuselage longeron/upright/cross-brace junctions. They will help to reinforce the uncovered section of the fuselage. Ian used pieces cut from a soft drink can for his - he did say that a beer can could be used but he only drinks beer from bottles. While he marked each plate with two small ink dots to represent bolts, they could also be embossed, from behind, with the tip of a ball pen. Ian points out that this task is well worthwhile, not only for the added strength it imparts, but for the character it adds to the model, too.

Equipment and installation: It is in this area that you have to make what is probably the largest decision of all - which motor unit to use in your model. The ply motor plate shown on the plan is intended for the Multiplex geared 400, but the Graupner 2.33:1 geared unit would be just as good. However, although the position of the motor plate remains the same, its shape and size would need to be modified to suit.

Moving on to the battery pack, there are several options, the lightest choice being a seven-cell pack of 500AR Ni-Cads, but an 1100 mAh or 1300 mAh eight-cell pack of NiMHs would increase flight times quite dramatically. Although both do carry their weight penalty.

The control functions of the model are catered for by a mini or micro four-function receiver, a 15-20 amp rated ESC and two of the 9 gram micro servos that are available under a variety of trade names.

For those of you who like to know the exact equipment used in a model, this is what Ian fitted to the prototype: He chose a Graupner 2.33:1 geared 400, fitted with a 10 x 5 APC prop and powered by a seven-cell pack of 500AR Ni-Cads. The receiver is a Hitec 555, servos are HS55s and the ESC is a Jeti 140.

Linkages to the control surfaces should be via closed-loops of 20 lb breaking strain nylon fishing line. These may be run either directly from the servo output arms or via a short pushrod from remote, internal cranks. Personally, I prefer the latter option since it means that the servos may be removed without having to leave the output arms attached to the model.

While the motor is screwed to the ply plate, and the servos screwed to 1/8 x 3/8 spruce rails, the receiver and ESC are secured to the sheet fuselage sides using servo tape. Just how you mount your battery pack is entirely a matter of personal choice, but I prefer mine permanently fixed with silicone sealer to prevent any chance of getting it in the wrong place whilst changing packs. Whichever system you choose, use the weight of the pack to assist with balancing the model.

Fuselage: Just for a change, begin the instructions with details of building the fuselage. Since it's the only complicated part of the entire model, we may as well get it done first. So, you've decided, as Ian did, to go for the fully-rigged version and to use the Multiplex motor unit or, like Ian, have at least made a modified motor plate to suit your motor/gearbox.

Make up a full set of fuselage parts, including the pylon and undercarriage wires, before starting to build - things will progress pretty swiftly once we do start gluing.

Cut your longerons to length and drill a small hole in the front end of each. That's the bit that will be glued to the sheet sides. Now, tie a knot in the end of the fuselage rigging threads and cyano them into the drilled holes. Pin down the sheet side, over the plan, and glue one pair of longerons to it, trapping the knotted thread in the process. Pin down the longerons and add the fuselage uprights, once again trapping the rigging at each point, but without pulling it so tight that it will distort the fuselage frames..."

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