Fihavanana (oz16387)

About this Plan

F1 Havanana. A1 class free flight glider model. Wingspan 51-1/2 in.

Quote: "A thoroughly de-bugged design, Fihavanana is ideal for anyone who has made a few kit-type gliders, got the measure of building and trimming, and would like to break into 'specification' contests. Al events are usually included in meetings for the `mini' classes.

Why the strange name? Well, F1H is FAI-speak for the A1 glider class and FIH are the first three letters of Fihavanana - the name of a house where I used to live. The previous owners had been missionaries in Madagascar, and Fihavanana was where they worked!

This glider might be termed 'mid-tech'. It uses no carbon in the wing and tail and has sensible, easy to assemble structures, even though there are a lot of ribs. While the original has ordinary up-and-off straight tow, a circle tow system could be added by cutting away the fuselage core to accommodate the tow hook, and beginning the fuselage rod at this point. A hardwood skid could then go from the hook forward to the nose. Anyway, if you are new to glider competitions, a normal straight tow model will be quite adequate to get you started - and there's nothing to go wrong!

Building an A1 down to weight is not usually a problem, but choose your wood wisely and remember light wing tips and tail end make for a more lift-responsive model. Ribs and trailing edges should be medium quarter grain balsa - the speckly stuff - and leading edges and spars, medium to hard straight grain.

A word about contest flying. A high-performing model is not enough: it must be consistent ie fly well every time. Consistency comes from practice on the field, accurate building with no unintentional warps, and proper storage. Don't chuck your models down where they can twist and deteriorate. Store wings on their leading edges on a flat shelf. Tails can be banded to each other or onto an anti-warp board, and fuselages can be hung vertically from a picture rail.

Let's get buildingl If you haven't yet used it, get some of John Hook's (Flite Hook) thin transparent film. It's like the cellophane used to cover cigarette packets, and is wonderful for putting over the plan to stop things sticking to it - much better than soap!

The tail: Shape the trailing edge (TE) before construction and the leading edge (LE) after, when it is easier to carve and blend in by sanding to the airfoil. Trailing edges should be notched slightly to give a little tolerance when fitting fibs, preventing distortion and subsequent warping. However, a notched LE is asking for trouble, creating a weak point should the model hit anything.

Make a 1mm ply template with spar notches and cut out the ribs accurately. This template can later be used as the centre rib to take the strain of the [VT peg etc.

Pin down the LE, complete with 1mm centre reinforcing strip, lower spar and TE. Glue the ribs using a non-shrinking adhesive - I use aliphatic resin. Now add the webs between the ribs, then, when dry, the top spar. In theory, the grain of the webs should be vertical, but in practice, short sections of 1/32 sheet are very difficult to cut without splitting. Horizontal webs are quite permissible if your patience is limited! Add the sheet reinforcement at the LE in the centre flush with the under surface, and the gussets to the TE, flush with the top surface. Add roughly shaped 1/16 sheet cap ribs to the tips. When dry, trim and sand smoothly into the structure. Finally, add the D/T peg from 1/8 dia hardwood dowel. Sand a flat where it fits on the tail and glue with 5 minute epoxy.

The wing: A jig to fit the under surface is a great aid. This can be hot-wired from foam, or built up from 1/bin. balsa top stuck over closely spaced rib shapes. If you can't be bothered with all this, then the TE can be packed up with a strip of 3/32 balsa to maintain the aerofoil section while building.

Starting with the centre section simplifies lining-up the wing joiner tubes. Assembly is like a larger version of the tail, but as there are more ribs, you could make two ply templates and produce them by the sandwich method. Don't bother with the extra spar slots for the wing root doublers at this stage. They are best cut in situ when the main spar has been fitted..."

F1Havanana from Aviation Modeller International, November 1999.

Direct submission to Outerzone.

Supplementary file notes

Article pages, thanks to RFJ.

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