Sunday 23 October 2016

More right wing wing

After much discussion with the airframe guys at work on drilling perspex, I was none the wiser about using specialist bits or what speed to drill at!  I couldn't locate any suitable drill bits in the UK but importing a $3 drill from the US meant a £35 freight charge!  I therefore decided I'd have a go at grinding 1/8th and 5/32nd drills to the recommended 60 degree end with zero rake and see how it would work on a piece of scrap (an old side-screen from my MG). Behold it worked perfectly!  So I took the plunge and started on the landing light lens.

After masking the main lens area to try and minimise scratching, I match-drilled the 8 fixing holes through the wing skin and then marked the overall size of the finished lens using the plans instructions.  Drilling the holes before trimming should minimise the risk of a crack running from a hole to the edge.  Then I trimmed the excess material to within about 0.5 mm of the required size using the high speed cutting disk.  So far so good.

 The trimmed lens with edges polished and holes countersunk.  I used a coarse  sanding block initially followed by wet'n'dry paper stuck down on a flat surface and finally fine paper on a hand block.  This took about 3 hours!

 Next the screw holes in the skin are dimpled to match the countersinks in the lens.  The brackets are riveted in place and the previously installed wiring is terminated.  All wiring will be identified using heat-shrink sleeves.

 This is the view from inside the wing looking forwards, with the landing light fixed to the bracket and all wired up.  Just need to test it!

Finally the lens is installed through the front of the wing, with great care to prevent cracking.  I was fortunate that I could get behind the lamp to assist in lining up the lens with the screw holes.  I hope it doesn't have to come out in the future as there's no rear access when the wing skins are installed!

Now I can move on and complete the the top of the right wing.  I first needed to prepare the skins - file and polish all the edges to remove cutting marks etc and then prime the inside and all mating surfaces.  I also took the opportunity to prepare the walkway doubler and the wingtip lower skin.


Here I'm painting the outer surface of the right wingtip lower skin - just the tabs that will mate to the outboard wing rib and trim panels.  The inside of the skin is fully painted.

Here all of the prepared and painted main skins are lying roughly in place ready to be installed.    You may just see some of the yellow edges that'll be overlapping the adjacent skins, so need some means of keeping trapped moisture from the skin to prevent corrosion.

 Right wing inboard top skin cleco'd and ready to rivet.


 Inboard skin now riveted (excluding the walk-way area) and outboard skin ready to secure.  The leading edge can't be finished until the final middle skin is installed.

All three main upper wing skins completed and the wing-walk doubler ready to rivet.
You can see the additional wing ribs which are closely spaced to take a person's weight from the extra rows of clecos.  The leading edge along the whole wing is also cleco'd in preparation for riveting.


 The wing walk doubler completed.  Now just the leading edge of all skins to finish.


And finally all main skins completed! 

Just the wing tip now to complete for the right wing.  All the parts are ready including the fibreglass nav. light mount, so hopefully it'll be pretty straightforward.  After the wing tip is finished, I start on the flaperons.


Wednesday 5 October 2016

Finishing the wings by the end of the first year (Not!).

At the end of my last post I had great expectations of completing both wings by the time I'd had the kit for a year.  Unfortunately it hasn't happened as planned, but I have recently managed to get back into the garage for a few hours and make some good progress on the right wing.  My repaired left knee is holding up well and I'm using a stool as much as possible.  Just worried that the right knee will go next and add another huge delay.

Anyway - a summary of recent progress.

Here's the right wing upside down on the bench showing the bottom skins being fitted.  No dramas here - just a repeat of the left wing.  It's very time-consuming to install, match-drill, remove, debur, refit and finally rivet, but doing it properly now should reduce the chance of cracks developing.  My hands ache horribly from all of the cleco installation and removal!  At least I have a pneumatic pop-rivet gun.

The last bottom skin waiting to be riveted in place.

The wing turned the right way up and the first 6 rivets aft of the leading edge now installed in each rib to create the proper profile.  There are no rivets at the inboard end yet (above the blue electrical connector) where the wing-walk doubler has to be fitted in conjunction with the top skin.

Here's a view inside the wing near the root, with the bottom skin wrapping around the leading edge.  It continues to amaze me how accurate the kit production is, such that all of the holes in ribs that I've fluted still line up with the pre-punched skins!


Now I need to install the landing light near the right wing tip.  It's much easier to do before the top wing skins are fitted (I can't figure out how you'd do it on an aircraft that's already built).  UK LAA aircraft currently aren't approved for night flying and I don't intend to fly at night even if approval is ever granted.  I'm having nav, strobe and landing lights to improve the chance of other pilots seeing and avoiding me!

The supplied template is aligned with existing rivet holes and then marked-though using a spring punch for new screws and rivets.  The lamp lens cut-out is also marked.  I'm not looking forward to cutting this out by hand!

 The punch-marked holes are drilled out #40 and then match-drilled #30 to the lens brackets.

The lens hole cut out and the lamp brackets cleco'd in place.
 
 I used a 1mm-thick cutting disc in an air-grinder for the long edges of the cut-out and then an air nibbler  for the corners.  It was then down to careful filing and finally wet/dry paper on a piece of dowel to get the final shape accurate.  I'm pretty pleased with the final result!

Here are the lamp brackets and lens retaining plates with doublers and anchor nuts and cable grommets fitted as required.

Now I need to drill the Perspex lens and then trim it to final size before everything can be assembled.  At this point I'm stuck as I need to source special drill bits for the Perspex. Using standard metal drill bits can cause the plastic to chip or crack, so not worth the risk of rushing with the wrong tools.

That's it for the moment.  Hopefully more updates later this month.