Percival Vega Gull

[Ron Gray]

1 hour ago, John Rickett 102 said:

it will be good enough for what is essentially a sport model.

What! 😲 I'd love to see a scale model of yours if that's the case John 🤣

[Richard Crapp]

  The F/S ones were metal screwed on to  the fuselage.

I used  'fairing compound' from Bucks Composites. I ran two layers of electrical tape along both edges to provide some definition then sanded in the shape. you can sand down to the tape for a fine finish .

 

As Ron said; Sports model ??  !!!!

[John Rickett 102]

Thanks for the compliments, unfortunately for this project I haven't been able to find any reliable drawings, most of the design has come from photographs - an inherently unreliable method as the pictures are rarely taken at right angles to the subject, so I doubt it would pass muster in a scale comp.

 

Thanks also Richard for the tip about fairing compound, I'll probably use that over the top of blue foam which will form the bulk of the fairing.

 

A trial fit of the 'test' foothold. This would definitely not pass muster as I'm sure the floor should be level with the ground, but I couldn't get it to fit any deeper as the inner flap was in the way. For the one further forward there is nothing in the way but installing one foothold level and one at an angle may look a bit silly so it may be best to keep the same (incorrect) angle.....I said earlier its a sports model!     

 

 

 

[Richard Crapp]

I meant to add that I filled in the blanks on my model with the Brian Taylor plan .

Probably the only plan artist that can be relied on for accurate shapes and outlines.

[John Rickett 102]

It was fortunate that Brian Taylor produced a plan for the Gull 4, I've not been so lucky. I have a book which describes the evolution of the Gull series including the widening, stretching and enlarging of the areas and control surfaces from Gull 4 to Proctor although there are no meaningful drawings. 

 

With the fuselage inverted in its cradle the wing centre section could be placed in position and checked for alignment before the dreaded no-going-back-from-here operation of gluing.

 

 

After allowing the glue to dry overnight a milestone was reached with the model being able to sit on its wheels unaided.

 

 

The next jobs are to blend in the line from the bottom of the cowl to the main spar and also make the wing fillets. Completing the footholds has had to be delayed until some gelcoat activator arrives.  

[stu knowles]

I am really impressed by your production of small fibreglass parts such as the foot steps on this model and the cylinder heads on the Se5.  Until you showed the way I would not have considered glass parts for anything much less than cowls and wheel spats.

 

Can I ask what resins you use for the moulds and for the parts themselves.    I have made mould for a large cowl, followed by the cowl itself and used skinning epoxy throughout - which is expensive.  I did wonder after if I should have used a polyester resin for the mould, which would have been much cheaper and then just used epoxy for the production part.

 

I would appreciate hearing your take on the different resins

[John Rickett 102]

Thank you for the compliment Stuart.

I use epoxy resins for everything, buying from Bucks Composites usually as Graham Buckingham trades at shows and provides prompt and helpful service when ordering online. His Formula 50 or L285 will cure in 24 hours at room temperature (20C), though probably best to leave for a couple of days before cutting back to a smooth finish with wet & dry cloth.

Stored in a dry, warm place part-used bottles or cans seem to have an indefinite shelf life. I try to be careful with measuring so that not much is wasted and really don't find it an excessive expense, particularly in the overall scheme of how much a model costs to make!

[John Rickett 102]

Four footholds have now been taken from the plug and the excess dry cloth removed. Each took about 15 minutes to lay up and then a wait of 24 hours before one could be released from the plug and the next one started.

 

 

The excess depth and length of the plug allowed for easier handling but most of the fibreglass needed to be cut away leaving quite small parts to be glued into the wing, this will be done once the wing is glassed. The combined weight of the castings is 5 gm, I’m well pleased with that as I doubt another method would have yielded a similar practical, lightweight result.  

 

 

 

I had assumed that the bases of the footholds would have been at the same angle, parallel to the ground, on closer inspection it appears they are different, the rear ones slope upward more than the front ones. The front ones can now be made deeper………an exciting revelation for an anorak modeller.   

 

 

Blue foam would be a suitable material for the wing fairings, or so I thought, however having cut some and tried to bend it to follow the rib outline I found it to be too stiff, it’s also quite difficult to sand without galling. Instead, the eurothane core recovered from Recticel flooring insulation (same as the cowl plug) was used. This cuts, bends and sands easily while still being light.

 

All but the curve around the leading edge was formed from the eurothane, the front part was completed with lightweight fairing compound mixed with fibreglass resin. Once cured this can be sanded but it’s quite a hard material, it’s easy to sand away the softer adjacent balsa so care must be taken.

 

The first intention was to apply filler to the surface of the eurothane and sand down to feather edges but rejected that idea given how hard the cured filler is, compared to balsa. Instead, the fairing was covered in 2 layers of 50 gm glass cloth, one layer just covering the fairing and a wider piece overlapping onto the fuselage and wing. This provides a resilient surface on the fairing and allowed for easier blending at the edges.

 

 

As the fuselage is to be covered in Ceconite and the wing centre section in glass cloth, I wondered how best to achieve a neat join between the dissimilar materials. A flash of inspiration was to mould fairings on top of the existing fairings. By being removeable, at least initially, the Ceconite/glass cloth join could be hidden under the top fairing and, being fitted after painting, would definitely look like a removeable item. Cutting the moulding into 3 sections (the same as the fullsize) and adding some small screws at about a scale 6” pitch, glued into pre-drilled holes will hopefully complete the illusion.

 

 

Here, the area to be moulded is masked off with release wax being applied - 6 coats, buffing in between, usually does the trick.

 

 

2 layers of 80 gm cloth made the fairing, it seems to be of adequate rigidity so not worth adding more layers when the other side is done. The fairing weighs 10 gm, it now needs a further coat of resin to fill the weave then it can be rubbed down with wet & dry paper and trimmed to final size, the black outline.

 

Given how easy this was to do, I’m motivated to do something similar for the wide straps which cover the wing fold.      

[John Rickett 102]

 

Returning to the filler, lightweight fairing compound is as the name suggests light, however the resin that has to be mixed with it, isn’t light. I tried a comparison test of cured filler versus eurothane. A convenient block of eurothane lying on the bench measured 3505 cc and weighed 95 grammes. I patted some left-over filler into a block which measured 2.45 cc and weighed 3 gm. My schoolboy maths calculated that, by volume, the filler is 15.5 times heavier than the eurothane. This doesn’t take into account the protective covering of fibreglass required, though I’m pleased now the eurothane was handy!

 

 

Attention has reverted to the wing outer panels to get the left panel to the same stage of completion as the other. Part of the process was to get the dihedral the same. Having set the right hand wing, it was a case of adjusting the left wing to be the same.

 

 

The coarse adjustment, if it could be called that, was bolting the inner parts of the hinges in place and then with the M4 bolts inserted, chocking the wing to the correct angle. The fine adjustment was to position the outer parts hinge on their ply supports and drill one hole through the ply and insert its M3 screw, then release the chock so that the wing took the weight. An error meant making another hinge part with the hole slightly offset, then drilling through the second hole to lock into position. Fortunately I only had to do this once, both wings now have a dihedral of 3 degrees, measured along the centre line of the ribs. Its actually difficult to know what the true dihedral of the wings is as the washout tilts down the leading edge and therefore affects the measurement – provided they are the same I’m sure all will be well. It’s possible that the dihedral is less than scale, however as a gyro (wonderful things!) will be part of the radio installation I’m not particularly concerned about a lack of lateral stability.

 

The picture above shows the model inverted with the bolts in position, lots of balsa will be required to fill the gap and perhaps some plastic padding as well to close the gaps completely.

 

 

A great tool to use for making sure all is aligned, is a laser level. I had bought one of these when carrying out some DIY electrical installation a few years ago and have found it invaluable for checking squareness during model building. Here, the wings are being checked for equal dihedral.

 

 

Before getting too far ahead with the wings, the landing light recesses needed sorting out. Although far from scale, modern LEDs provide a source of decent light intensity and can be powered by a small 3s lipo. I’ve used encapsulated lamps before, the type with a G4 (2 pin) base, these work well but are relatively heavy at 17gm for the 36mm diameter ones. This time I’m going to give surface mounted Cree LEDs a try. These lamps are supplied without reflectors so the plan is to line each recess with plasticard and  spray the whole area with chrome paint to enhance the brightness. Beryl Markham’s aircraft, or more accurately the one she borrowed for her Atlantic crossing, didn’t have landing lights fitted, nevertheless I think they are a nice touch when on an approach, so will be incorporated.

 

 

As much as I enjoy the summer months, being in the workroom when the weather takes a turn also has its attractions. Surely those who don’t build are missing something in the hobby, or perhaps not, given that building isn’t nearly as popular as it once was – I’m convinced though that it has a therapeutic value.        

 

 

With the dihedral set and (hopefully) confident that there is no further adjustment necessary to the hinges, completion of the wing sheeting and gap closing can continue. Here the wings are attached and the right wing gaps filled in. Some filler is required to get the sheeting level across the join the same.       

 

                         

 

 

 

 

 

[Richard Crapp]

I think the dihedral of the outer panels is 5 deg.

 

A freind has visited my subject aircraft in Australia and sent me 80 nice  photos. So anything you want ?

[John Rickett 102]

Thanks Richard. I’m unsure how similar the Gull 4 is to the Vega Gull. The Gull 4 evolved into the Gull 6 and then into the Vega Gull. Both iterations involved widening and lengthening, although I don’t know if the dihedral changed during the process, possibly not. I have a scale drawing of the Proctor, which was a further development and if this drawing is to be believed, the dihedral was 5 degrees when measured along the bottom of the wing. Of course, as the wing thickness tapers along its length, the dihedral would be less if measured along the centre line and even less if measured along the top of the wing.  From measuring along the bottom of the model wing, at the main spar position, the tangent is 4.33 degrees. When comparing the model to photographs it doesn’t look to be wildly out so I’ll happily live with the probable reduced dihedral.     

 

As exciting as it is to watch glue dry, there are jobs that ought to  be done during the interim to maintain progress. In order to keep the radio equipment out of immediate view,  yet still be accessible, the main components have been mounted on a removeable tray which sits at floor level below the instrument panel, the batteries are attached to the underside. Beryl, the instrument panel and the tanks are all held in place with small neodym magnets so it should be a relatively easy job to gain access to the radio gear when required.

 

 

 

A couple of wiring looms were made up using Ashlok connectors, principally to make the wing connections a single operation at the field, the connectors also ensure I don't make the silly mistake of crossover errors with flaps and ailerons.

 

 

There is a gap of approximately 3/8” between the ribs, this was closed by adding a ¼” profile to the centre section rib and 1/8” to the outer section, then gently swinging the wing and sanding down where necessary. A strip of paper acted as a feeler gauge to locate the exact point of binding, The top was done first, then the bottom to make sure I knew exactly where binding was occurring. A bit more may have to be eased later all the way round to allow for the overlap of the covering.

 

 

 

 

 

With the outer wing portions seated, gaps closed and footholds fixed into position, the underside of the centre section has now been boxed in completely plus a trial fit of the fixed half of the spats to make sure all is well.

 

[John Rickett 102]

With the bulk of the work on the fuselage out of the way which required it to be first right way up and then upside down, attention can be turned to attaching the tailplane and fin.

The laser level comes into its own once again for checking squareness. Here the fuselage is checked for level on the board, then by raising the tripod mast the tailplane can be checked.

 

 

 

Similarly, the fuselage is chocked up and levelled along its datum line (the upper stringer), then raising the tripod mast checks that the tailplane incidence is at 0 degrees – I’m quite pleased with that, better glue it while its looking good!    

 

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