Wing inspection and flaperons

Jerry popped down last week and my completed wings were inspected and signed off without issue, so that's a relief.  Now to move on to the flaperons.  However, before I start I need to make the garage more usable for the winter.  Last year it was far too cold so I was wrapped up like an Eskimo and had the heater running full blast and it made only a marginal difference. I decided to insulate at least the garage door which is just thin sheet steel.  I've stuck on a 25mm layer of Celotex and filled any gaps in the frame with expanding foam. The difference is pretty remarkable - the heater will actually cycle on its thermostat!  Perhaps I should try some roof insulation as well.

With the garage a bit more bearable, it's on with the flaperons. 

To start with, there is some trial assembly of the nose ribs, counterbalance weight (a four-foot length of stainless steel tube) and the outboard leading-edge skin.  This is to allow the holes in the counterbalance to be marked and match-drilled to the pre-punched holes in the leading edge skin and nose ribs.  Worried about wrecking the skin (it's only 0.015" thick) by match-drilling in-situ, I chose just to mark the holes with a spring centre-punch and then drill the holes using the pillar drill and a vee block, and this worked well.  No picture unfortunately!

Here's the outboard end of the left flaperon temporarily assembled after match-drilling. 

A view of the same flaperon showing the inboard end of the counterbalance.

Next job is to prep the parts.  There are 24 trailing edge ribs, 2 main spars and 10 skins as well as all of the small brackets.  Time consuming is an understatement - this prep is probably the least interesting yet most labour-intensive part of building this kit. 

 4 trailing edge skins prep'd and painted.

 All of the small parts on the paint table.  You can see the counterbalance tubes hanging down from the ceiling.

One set of small parts and a section of the spar for one flaperon.

Once painting was complete I could move on with assembly.  I started by fitting all of the small brackets and nose ribs to the front face of the spars

 This is the inboard end of the left flaperon.  It's very tight to get a rivet set onto the end of the solid rivets due to the machined radius in the plate and I need to tidy the paint where I've scuffed it!  The tab where the red L is marked is the interface to the moving control in the fuselage and will make the flaperon rotate around the pivot hole.   

 Another view of the inboard end with the nose rib installed and the remaining tab holes now filled as there's a trailing edge rib also fitted.  The gap between the nose rib and actuating tab is precisely 0.5" and will have the inboard of three pivot bearings installed.

This is one of the other two pivot-bearing mounts.  

 The outboard end of the completed right flaperon structure ready to be skinned.  You can see the outboard bearing bracket behind the counterbalance tube.  I finished the left one to the same stage before moving on.

 Firstly the trailing edge skins are fitted and then the outboard leading edge as shown here.

 You can get an idea of the length of the flaperon here - they are just about 11 feet long!

This is the final view of where I'm up to - the right flaperon with trailing edge skins and the outboard leading edge complete.  Actually there has been a recent change in the plans so I need some additional special rivets for the last rib hole in the trailing edge.  These can wait until until I have an order together for other parts.

Both wings completed.

A bit sooner than expected (nothing before has gone to plan!), I've finally completed the wings.  I do still have the flaperons to do but nevertheless it does feel like a milestone has been reached.

The outstanding items were the right wingtip structure and then completing the nav light fairings and wiring on both wings.

 I started off with the upper and lower tip skins and the hand-hold frame - very straightforward.

 Next is the aft end rib.  It's a pre-formed U-section and simple to install.

 The forward tip rib it much more awkward.  It has complex curves and a twist and needs fluting on the top and bottom edges to make it follow the correct profile.  

This is the finally formed forward tip rib installed.    In reality the fit looks like a smoother curve than in the photo.

 Now the bottom skin goes on.  Loads of small tabs along the bottom inboard edge have to be bent at different angles from 18 to 136 degrees.  In the end it worked out better than the left wing.  I cut the nav light access hole whilst the skin was still on the bench.

 A view of the completed wing-tip from the trailing edge looking forwards.

 A bit of the design that I don't really like.  There is a step in the leading edge profile where tip rib and skins don't really line up.  It is in accordance with the plans but nonetheless I'm going to smooth this section out with some epoxy/flox mix when I deal with the nav light fairings.

 This is the trimmed nav light fairing secured for match-drilling.  I failed to record any of this for the left wing!

 Another view of the cut-out to get access to the nav light wiring and the holes all drilled for the fairing attachment.  The two holes marked in red were meant to be left vacant when riveting the skin.  I still managed to put a rivet in one and had to drill it out again! I'll prime this area before fitting the fairing.

 Here the wing has been up-turned and the fairing temporarily attached with epoxy/flox mix inside, below the black line to ensure a snug fit the the outboard tip rib.  Flox is fine shredded cotton fibres that are mixed into an epoxy resin to make it stiff so it will act as a filler without running out.  The wing tip has car wax on it to act as a release agent so I can get the fairing off again.  You can see a blob of blutack through the fairing - this is to keep this area clear for a nut which secures the nav light assembly.

 Inside the fairing once the epoxy/flox mix has set.  I sanded the excess epoxy off using a rotary sander to save some weight!

 Finally, the fairing is installed and riveted.  The dark edge is the PRC between the fairing and skin (Fuel tank sealant as called out in the plans).  I really dislike PRC - it stinks, gets everywhere and is difficult to remove!  I'd previously left this stage on the left wing until I could mix one batch of sealant for both wings.   On the outside of the fairing is the mounting bracket for the nav/strobe light and the completed wiring disconnect.

Two completed wings on the stand and with the nav/strobe lights installed.  You might be able to see by the uppermost rivet where I blended-in the step in the leading edge.  Time to move onto something else after 10 months of just wings!

 A view of the completed wings from the inboard (root) end showing the electrical connectors.  The pipe sticking out of the left wing is for the angle of attack (AOA) sensor.

 Before moving on with more building, I needed to update the plans.  Loads of revisions have been issued, although fortunately none affecting anything I've done so far.    I will need to buy some improved parts to replace existing but unused bits for the fuselage.  Hopefully not too much expense but best to start with the aircraft having the most recent build standard and product improvements when it first flies.

Here's the next step - parts for the two flaperons.  Whilst these are in build, I have an inspection scheduled for the completed wings.  Hopefully nothing shows up that I've got wrong! 

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.

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.