Nieuport Build Part 14 - Finishing the Top Wing Centre Section - Part 1

After the top wing panels had been fitted to the fuselage they were removed so that the remaining work could be finished. To be sure that the wing panels retained a good fit at the centre join whilst finishing  them off they would be bolted back together with 2 scrap 6mm thick plywood braces, but first the tubes and .8mm plywood capping were fitted.

The 4 tubes were made rough with coarse abrasive paper so that the epoxy glue would 'key' to the surface.The 2 hardwood dowel 'plugs' were glued in first, these  tubes were marked up 'FRONT' so I didn't stick them in the rear by mistake later.

Wing joining tubes, dowel 'plugs' and epoxy.

Dowel 'plugs' glued in place.

The components of the starboard wing panel less the riblets.

 

The plywood centre section sheeting will not be applied yet until the 'scale' spars have been permanently glued in place. The sheeting has, however, been cut  exact to size and all the short sides have been chamfered. Chamfering the edges now makes blending the plywood into the balsa leading edge and balsa centre section cut-out much easier. If the plywood was applied then blended in you risk the chance of sanding the balsa wood away first before the plywood.

Chamfered plywood before and after.

 

The wing joining tubes and captive nuts were than glued in place with epoxy. The tubes protrude slightly as the plywood capping ribs still require fitting.

Wing joining tubes glued in place and riblets trimmed and ready to fit.

 

The plywood capping and riblets were then glued in place with wood glue. Not forgetting to cut the 2 extra cut-outs to the rear of each capping rib for the 'scale' spars to slide through. Where the riblets touched the aluminium tubes epoxy was used to secure them.

Plywood capping held in place with masking tape while the glue was setting.

To give the plywood centre section sheeting more purchase at the front and to stop the sheet lifting after gluing, it's a good idea to fill in the riblet bays in this area with scrap balsa block.

Balsa block infills will be sanded down later.

Now is a good time to colour the inside of the aileron boxes and the visible section of the 'scale' spar detail. A light oak water based stain was used, light oak being the best colour to replicate 'old pine'.

Aileron box and spar with light oak varnish applied.

The reason for staining the boxes etc now is because the 'scale' spars require gluing in place before the center section sheeting is applied. If the centre section sheeting was applied first you can't get at the spars to glue them in place and these spars are functional.

Also the aileron bell-cranks have to be installed at the same time as the 'scale' spars are glued in. So I best not forget to include those bell-cranks!! I'll cover this in a future post.

Whilst on the subject of ailerons, I also cut the 2 torque tubes to length. These tubes were also marked up on each end so that I would know were to drill the holes for the aileron bell-crank retaining pins, installation details to follow.

Aileron tube being cut to length.

Next the leading edge of centre section was sanded down, this can be done with the wing panels joined together as the wings are flat.

Centre section leading edge sanded down.

Underside view of the centre section showing temporary plywood joiners.

Also seen in the above picture is a white plastic insert placed into the cut-out for the rear mounting bracket fixing. This plastic insert was there to stop filler from getting in the aperture.

A polyester resin '2 part' wood filler will be used to make good the centre section join. The underside was filled first.

Wood filler applied to the underside of the centre section, the easy one.

 

Then came the top of the centre section. Looking at scale reference this area was more square than round in section and therefore needed 'squaring' off.

The filler was added gradually first to the curved section then to the top section, the edge of the filler was finally sanded to a right angle.

Filler sanded at right angles, port wing panel.

Once the filler had been sanded at right angles the sharp edges were then chamfered. The amount you sand off will be determined by the size of radius you require.

Remember the 'shadow sanding' technique, it can be seen to full effect in the following pictures. The shadows cast clearly show your progress during the shaping process.

Sharpe edge sanded off, note the taper of the chamfer

so as to blend in with the trailing edge.

Both sides chamfered to a uniform shape and confirmed by the shadows cast.

And finally the sharp edges of the chamfers were removed until a 'sweet' curve was achieved.

Chamfers rounded off and final shape finished with fine abrasive paper.

All that needed to be done now was to 'split' the 2 sections on the centre join, currently held together by the wood filler. This was done with the aid of a razor saw.

Razor saw being used to separate the wing panels.

Wing panels after separating.

The next post will see the centre section finished...hopefully

To be continued...