Back under way (for a short while)

The last few months have been frustrating with little progress as my hand healed.  Anyway, it's good enough now to get some work done.  Unfortunately everything will come to a halt in late May when I have a shoulder operation so I'm trying to get as much done before that as I can manage.

First job is to progress the canopy and get the fibreglass skirt laid-up.  It's a job I've not been looking forward to at all.

Here the paper template is laid on the fuselage the mark the correct lay-up position.  The template is then used to cut 5 layers of glass cloth for each side.  Across the centre of the windscreen there will be 10 layers of fabric.

Lot's of masking up is needed to protect the canopy perspex and to create the correct outline of the finished fibreglass.  The parcel tape is covered in car wax to act as a release agent so the finished lay-up can be removed from the aircraft.  Below the yellow tape line, the perspex has been scuffed to create a surface the fibreglass resin will stick to.   To the left of the pivot bolt is an area of foam which has been glued to the canopy frame and sanded to match the fuselage profile.  The fibreglass will stick to this as well as to the windscreen.

This is the first layer of the fabric and epoxy on the right side.  Very messy job!   The left and right sides are done first and allowed to cure overnight and then the centre is laid-up the next day.

After all five layers have been placed, a sheet of peel-ply is placed on top and liberally coated with resin.  When dry, it easily peels away (hence the name) and leave a surface ready for filling or sanding.

This is after the peel-ply has been removed and the initial sanding has taken place.   Next I have to fill any areas that have sunk (where not supported underneath).  The filler is epoxy resin with micro-balloons added to make it light  and easily sandable. 

Here's the filler in the midst of being sanded to final shape. 

After more coats of resin and lots of sanding, this is the final finished canopy skirt having been trimmed to the template dimensions.  The holes for the canopy bolts have been cut out and the foam inside reinforced with more epoxy.

A view with the canopy refitted.  Overall it turned out pretty well.  There are a few small areas that need additional filler and I've completed them using P38 instead of expoxy -  much quicker and no need for additional strength.  It's taken around 3 weeks to do this job and I'm glad it's over!

So on the the engine and preparing it for installation.  I have to install carburettor drip trays so that any overflowing fuel from the float chambers doesn't drip onto the hot exhaust.  I'm also adding a Skydrive carburettor heat system.  This isn't a requirement, but for me just seems like common sense.  Unlike the system on Lycoming or Continental aero engines, it doesn't use hot air from the exhaust shroud into the intake, so there's no loss of power.  Instead it uses small hot water heaters to warm the butterfly ate of the carburettor body.

Here are the carbs on the bench with the heater units installed.  These are pressed onto the  carburettor bodies in a big vice and a risky business if they don't go on square.  There's no way to get them off again if it goes wrong!

This is the left drip tray installed and ready for the carburettor to be refitted. 

And now the carburettor is installed and the fuel pipe reconnected.   Not clear in the picture, but I've also fitted the recently released throttle torsion springs instead of the previous tension springs which were prone to breaking.

The engine mount ring is fitted and the engine is ready to be installed.  Hopefully that'll happen next week.

Final job this time was to install the heater door to the firewall as it's easier to rivet before the engine is fitted.

The tape is holding the heater door shut whilst an RTV gasket cures, which will provide a good air-tight seal.  You can also see the two lower engine mounts which are temporarily fitted to hold the nose landing gear in place.

That's it for the moment.  Stage inspection is due shortly and once the engine is fitted, I can complete the wiring and finally fit the instrument panel 

Un-planned workstop

Sadly I've had to leave work on hold on my RV12 since just after the last post in November.  I started suffering with tennis elbow and shoulder pain and was putting up and trying to keep going, then to make matters worse, fell on the garage stairs and damaged my right hand.  Things are gradually improving so hopefully back to some light jobs in the next few weeks.

I did manage a bit more work on the lower cowling before it all went wrong, and got the painted canopy frame installed and ready for the perspex.

Here are a few pictures of the engine cowling preparation.

Once the two halves of the cowling were trimmed and temporarily pinned to the bulkhead I drilled off the positions for the hings that join the top and bottom halves together.   Here I'm about to rivet the lower left side hinge.

I borrowed this pneumatic squeezer from John at work to aid in riveting, as the tennis elbow precludes using the normal manual squeezers.  Still a bit of a task due to the weight of it with a painful shoulder!

So here are the upper and lower parts fastened together with all side hinges installed and hinge pins cut to size.  I haven't drilled the holes for the cowling-to-bulkhead interface yet - that will wait until the engine is installed so I can ensure the propellor cut-out at the front is in alignment to the spinner and do any additional trimming as necessary.  Looks pretty good so far!

So a view from the right showing the area to cut out for the oil filler/dipstick door.

Here with the upper cowling back on the bench and I've made the opening and fitted the Camlock receptacles.  Note the deliberate mistake? The  Camlock rivets should be parallel to the outer edge of the moulding and not aligned to the diagonal cut-outs in the corners.

Finally with the oil door fitted.  You can see the consequence of mis-aligned Camlock receptacles is that the wings of the Camlock fasteners aren't in line. They'll do for the time being but I plan to change these to stainless steel versions with a screwdriver slot when the aircraft is painted.  I have some more work to do on the oil door as the hinge causes the door to catch on the fibreglass as it's opened, so an additional or thicker packer is required.

Next job is to install the canopy perspex and to lay-up the fibreglass canopy-to-fuselage skirt.

Some unscheduled progress was made yesterday.   My recently delivered Rotax engine is unfortunately subject to a mandatory service bulletin for potentially incorrect push rods.  Having contacted the UK distributor to discuss warranty, they quickly dispatched Andy to inspect it and he changed the faulty parts there and then.  Excellent work CFS Aero!

So here's the engine out of it's box on a work stand.  It should have been installed by now but hopefully that'll still happen in the next month or two.

Power-on!

It;s about a month since my last post and lots of little things have been progressing and a few milestones achieved.

Firstly, I completed the main electrical system wiring - battery distribution and circuit breakers.  I also completed the G3X display system (less engine sensors) and got power on for the first time.  So now it both rolls around and lights up!

These are the circuit breakers, which replace the standard Vans' supplied fuses along with the Vans' switching unit.  I've actually mounted the breakers on a sub-panel which can be easily removed from the main instrument panel for ease of maintenance.

Rear view of the wired circuit breaker panel - this is before the sub-panel was completed with anchor nuts and painted.  The final version also has insulating strips between each row of breakers as the terminals are all very close together and I need to prevent any shorts.  Now I understand why Jerry's aircraft has the circuit breakers set at 45 degrees and not vertical!

For those that have seen a standard RV12 with the Vans' control unit, this will seem very empty - it's the avionics bay behind the pilot's instrument panel.  My wiring is directly unit-to-unit so cuts out a large number of junction box connectors and consequently also the amount of wire used.   Hopefully it'll make for a more reliable and lighter installation.  However, going off-piste has probably added over 100 additional hours and a couple of months to the build, not including the new instrument panel which is necessitated by the need  to fit UK-mandated standby flight instruments.

And so power-on for the first time.  You can't see the master switch here but the ignition module that takes up the 5 holes on the left is connected up behind the panel.  The only wiring not yet done is for the 6 switches in the centre and I won't complete this until the instrument panel has been covered and labelled, and also wiring a traffic detection system (I have the provisions in place but don't know which box to put on the end of the wires at present).  There is a 25-way disconnect plug for the switches to allow for easy instrument panel removal, so for the moment I'm just using jumpers across pins to simulate each switch as I run through testing.  A bit of the old day job for a change and thankfully no wiring errors!

Here I've got all of the G3X running and most of the configuration complete.  I started with the basic set-up supplied as a down-loadable file by Vans on their website and then modified the config in-situ to suit my specific differences: I have a Nav/Comm radio instead of just a Comm, I have added an extra warning discrete for standby battery activation, and my ammeter shunt is not the Vans version.  I've also chosen to configure the fuel flow feature as Vans has you install the transducer, so why not use it?

The G3X uses a CAN bus for all of the boxes to talk to each other (originally developed by Bosch for cars) and this worked fine first time, but unfortunately it also allowed me to see instantly that both autopilot serves were defective as they reported 'HARDWARE FAULT'.  This was a know issue to Garmin back in February but they didn't issue any recall of service bulletin - it was down to individuals to see if they had problematic units.  Garmin have supplied me with a brand new pair of servos under warranty (not service-exchange items)  which is a relief as I don't want to start out with used components.

At this point I've taken all of the units and instrument panel back out of the aircraft so I can complete the panel itself - it will be covered in Carbon Fibre film and then labelled.  I've temporarily installed the version 1 (scrap) panel as the outer profile is correct and this will allow me to progress with the canopy installation.

Here's the perspex canopy on the left next to the engine cowlings.  The upper and lower cowlings are sitting inside the canopy frame.   I'm not relishing this next stage!  One mistake or mis-handling and I could scrap the perspex bubble and it'll be very expensive to get another shipped from Oregon.

The first task is to prepare the frame (de-burr etc) and fit the gas-struts which hold it open, and then fit this assembly to the fuselage.  My garage ceiling isn't high enough to do this indoors so outside we go.

Here's the view indoors with the canopy resting against the ceiling - it's going to be awkward if I need to get in and out much!

This is a view of the right-side gas strut.  My kit came with the original gas-strut version that had plastic end fittings.  There have been a number of incidents of the end fittings snapping and in one instance, the canopy rotated forwards into the propeller.  Therefore I've bought and installed the up-rated metal-ended struts.

The rear window has to be installed to ensure the canopy is correctly aligned over the roll bar.    Here I've got the canopy in place and held with tape ready to drill the fixing holes.  Finger crossed I don't crack anything!  Getting to this stage is long-winded in adjusting the canopy position, trimming and polishing the edges to ensure the correct clearance all round.  It must have gone on and off a dozen times before I was happy.

So finally the canopy holes in the roll bar and front tube are all drilled and the side skirts have been temporarily fitted.  I've also made the two small handles used to list the canopy. 

Just visible in the pilot's seat (actually on a pile of dust sheets and blankets!) is Deborah who was helping me to drill the canopy sides.

Now it all comes apart again so the frame and all metal parts can be painted before final assembly.  The last and probably most difficult part is to make the front skirt which requires a wet lay-up of fibreglass between the screen and the avionics bay cover.  This will have wait for a couple of weeks so I'm moving on to the engine cowlings.

I started by trimming and sanding the cowling mouldings back to the scribed lines.  This took several hours to do both halves and there wasn't much to photograph.  I got covered in dust but at least I wore a mask so din't inhale it! 

Here's the first trial-fit of the lower cowling.  I needed a lot more space on the garage floor to work on the cowlings as the canopy is now occupying the work bench so the aircraft had to be outside on the drive for most of the day.  That generated a few surprises for passers-by!

This picture shows the alignment of the lower cowling to the right side of the firewall and hinges which will secure it.  It's pretty close already so hopefully not much more sanding needed to get an accurate fit.

That's it for the moment.  More cowling and canopy work over the next few weeks and also a trial-fit of the wings so I can drill the flaperon arms and then fit the fuel tank. 

It's mobile!

My RV12 has finally moved on it's own wheels!  Still loads to do though, so here's a brief update.

First job after the fuselage-joining inspection was to prepare all of the undercarriage parts - the main legs, wheel fairing brackets, nose wheel fork etc.  Unfortunately I didn't take any pictures of the pre-installed parts!

Here's the first part installed - the left main undercarriage leg together with axle and fairing bracket.  Note to self:  Next time, put the brake caliper on BEFORE fitting the fairing bracket!   Installing and tightening the undercarriage bolts is a bit of a headache and I needed to drill a couple of holes in the belly skin, which are listed in an old service bulletin which weren't already present in my kit.  These holes are needed to get a 1/4" drive extension bar and socket onto the bolt heads.

Here's the right main leg with the brake caliper correctly installed.

Next it's time for the nose leg and fork to be fitted.  Although my kit came with an un-used standard fork, I've bought the up-rated nose fork as there have been many reports of the original design cracking.   The bolt with a stack of washers is where the tow bar attaches for ground handling.  The two black fixings at the top of the leg onto the firewall are 3/16" skin pins - being used as temporary fixings until the lower engine mount is bolted on to this location.  These holes will eventually be drilled out to 3/8".

The nose-wheel is free-castoring - there is no directly-coupled steering, so you change direction by use of rudder and differential brakes.

So onto the wheels.  I chose the paint the wheel halves as they'll be hidden inside fairings and open to corrosion if the aircraft eventually ends up living outside.  I used a Lazy Susan (used for cake decorating) to allow the wheels to be rotated when painting and this allowed for a decent finish.

I have no prior experience of assembling split-rim aircraft wheels with tubed tyres so it took a bit of reading the manual and fiddling to get the valve stem in the right place and not pinch the tubes, but finally they all went together OK.   What I also learnt was that I needed some new hex bits in sockets so I could correctly torque the bolts.

 So it's finally on it's wheels!

I just had to take the aircraft outside for it's first view of daylight! 

So moving on, I've continued with the electrical and avionics systems in readiness to fit the instrument panel.  This is needed before the canopy can be installed.

I completed the instrument panel itself by riveting stiffeners above each main screen cut-out, added some anchor nuts and drilled all of the circuit breaker holes.  Now it's primed and ready for the carbon-fibre film to be fitted.

More work proceeding on wiring.  Intercom, both PFDs (pilot and co-pilot main screens), autopilot, transponder and radio are now finished.  The main items to complete are the circuit breakers, switches and the engine interface unit (top left on the bulkhead).

A plan view of the part-completed avionics bay wiring.  Everything starts from the centre where the main aircraft harness comes up through the avionics bay shelf.

This is the Garmin GEA24 - the interface between the engine/airframe sensors and the EFIS screens.  Once the wiring is completed it'll be clipped to the bulkhead to allow the top cover to be installed without chafing. 

This is some of the electrical wiring in the engine bay - for the battery and start contactors, and the ammeter shunt.  The shunt is normally inside the Vans switch/fuse panel but I'm not using that.  Also in the picture are the manifold pressure sensor (top centre) and fuel pressure sensor on the right of the picture with the yellow cap on the pipe fitting. 

I've also temporarily installed the battery - merely to add some weight to the nose now the aircraft is on it's wheels.  Without this it wanted tip onto its tail! 

I took some time away from wiring to finish the braking system by installing the main leg brake pipes and attaching the rigid plastic pipes from the park-brake valve to the undercarriage brackets in the centre section.  I've chosen to use after-market braided flexible hoses on the legs instead of the Vans-specified aluminium pipes as this allows for removal of the brake calipers without needing to bend rigid pipes. 

Finally I completed the internal controls for the flaperons in readiness to trial-fit the wings.  With the wings installed, the flaperon control arms can be match-drilled whilst the controls are locked in a rigging position.  Hopefully I can get the aircraft out of the garage again in the next week and complete this step.

This view is looking down and aft on top of the flaperon controls - the white tubes exit the fuselage sides and engage with the flaperons on the trailing edge of the wings.  The green rods connect to the mixer between the seats which in turn connects to the pilots' control sticks.

I wasn't happy that the two bolts on the end of the green push-rods were in alignment when the controls were in neutral so took the lot out and re-measured/adjusted the rod ends until everything was aligned accurately.  It's difficult to get the price dimension stated in the build manual and surprising how a quarter turn either way on opposite rods can have a dramatic effect.

I'm not proceeding as quick as expected but hopefully will complete the electrics/avionics in the next couple of weeks and start on the canopy.