Wing tip work

 We continued working on the wing tips.  With the fiberglass pieces glued on for the wingtip lights, we then used a few coats of lightweight filler to smooth the joints between these pieces and the wingtips. 

Filler added to smooth transition to the light mounts

We also discovered an issue where the screw attach holes drilled in the wingtips no longer lined up with the holes in the wings.  This appears to have been caused by the fiberglass modification we made to the front of the wingtips.  While this modification was needed to get the leading edge of the wingtip to line up with the leading edge cuff, it also caused their position to shift slightly so the previously drilled holes just didn't work.  We decided that the simplest fix was to fill in these holes and drill new ones, so that's what we did.  We filled them with epoxy/flox combo, let it dry overnight, and then redrilled the holes the next day, using a hole-locator tool to ensure that the new holes in the wingtip lined up with the existing holes in the wings.

New holes drilled, with screws temporarily installed

We also started working on another wingtip modification to close up a large opening at the back which should improve the aerodynamics a bit.  We are using a few pieces of balsa wood to keep it light, and plan to apply epoxy-varnish to them before installation.   Hours: 10.5

Wing Tips and flap gap work

Several updates since the last post:

After priming the right wing, we realized we hadn't fitted the aluminum piece to seal the flap gap for this wing yet, so we cut the aluminum strip to size, measured and matched the rivet hole locations to the left wing, and then drilled the holes.  Final installation of this piece will occur much later in the build process.

Next we turned our attention to the fiberglass wing tips.  Because we added a leading edge cuff to the wings, the profile of the fiberglass wing tips did not match the profile of our wings, so we needed to do some fiberglass work to get them to look right  (nothing like learning a new skill).  

Leading edge of wing tip did not line up with wing

 We used some pink foam and lightweight filler to carefully form the shape, and applied a layer of epoxy with micro-beads to fill in any small cavities.  We then fiberglassed over the shape with alternating layers of fiberglass and epoxy. After this dried, we applied another thin layer of epoxy with micro-beads to fill small voids, followed by another light epoxy coat.  Once this was done, we applied some more lightweight filler to smooth everything out and sanded it.  This took a bit of time, more so because this was a new skill, but we're happy with the way it came out.

Adding foam to wing tip prior to fiberglass

Wing tip profile modification completed

There was another modification that we still want to do the wing tips, which was to add additional fiberglass pieces for mounting wing tip lights. We purchased these parts, so at least we didn't have to make them ourselves.. but we did need to install them.  We  first cut some holes in the wing tips that will allow us to pass cables through to the lights, and also help to lighten up the pieces a little bit.

Nice big hole cut in fiberglass wingtip

Then we did a little sanding prep work (including slightly beveling the edges of the fiberglass pieces), and glued them in place with Hysol epoxy, then added a bit of weight on top to helps hold them in place while the adhesive cures.  Hours: 15

Fiberglass mount for lights glued in place

Left Wing Priming and Flap Gap-Seal

 We finished priming the left wing, including wet sanding between coats.  We must be getting better (or just getting lucky) because we didn't have to deal with any runs or drips.  We also measured, cut, and drilled a thin aluminum piece that serves to seal the gap between the wing and the flaps.  Hours: 10

Michael sanding the primer on the left wing

 

Left Wing Priming Prep-work

 We retrieved the left wing that was hanging in our shed.  The part was wiped with Isopropyl Alcohol to clean any accumulated dirt.  We also addressed any loose fabric edges and "glue blobs".  We started taping off the ends getting ready for priming.  Hours: 5

Root end of wing, taping off the Fuel Tank

Outer end of wing, taping off

 

Right Wing Priming

The right wing was primed with Superflite fabric primer.  Two cross coats were applied with sanding in-between the coats.  A final sanding and examination on the right wing before we moved it to the shed for storage.   Hours: 10

Ed examining the wing closely

Removable Door on Paint Booth

Wing prep and flap gap seal

We are moving on to the the wing and are prepping it for the primer. The wing was lowered from it's perch in the shed rafters, and moved into the paint booth. We did some clean-up work, including a little ironing on some of the pinked edges, and some acetone to remove a few unwanted glue blobs. We noticed that some of the inspection plate cover areas were a little wavy, so we hit those with the iron too to smooth it all out.

Retrieving a wing from the shed

Right wing moved into the paint booth

We decided to fit and drill for the aluminum flap-gap seal prior to priming.  The rivet holes are a little under 3" apart.  They are (almost) all equally spaced along the length, but the spacing was adjusted a little to ensure none of the rivets fell on a rib.  Once drilled, we removed the flap gap seal and will prime/paint that piece later when we do some of the other metal parts.

Hours: 6

Fitting the flap-gap seal to the right wing

Primed the Elevators

More steady progress in our paint booth, as we have completed priming the elevators.  The second coat went on nicely, probably because we are gaining some experience.  Hours: 9

Elevators before priming

Elevators after priming and a little sanding

Rudder and Horizontal Stabilizers Primed

 We finished priming the rudder and horizontal stabilizers.  We are trying to apply enough primer to fill the weave and smooth things out a bit, but not too much primer because that adds extra unwanted weight to the airplane.  Priming takes a bit of time with all the prep and sanding required, but we are making steady progress.  I forgot to take a picture while the parts were hanging in the paint booth, but I took a snapshot of the three parts after they were primed.  Hours: 12

  

Rudder & Horiz Stabilizers Primed

Primed the Ailerons and Trim Tab

 We primed the ailerons and trim tab using the same method as the flaps.  This work included using irons to help glue down any pinked edges that had popped up, cleaning excess glue with acetone, cleaning the parts with alcohol, priming (we are using a Devilbiss Finishline 4 paint gun) , and wet sanding (with 400 grit) between coats.  Did a little better this time around with just a few runs that needed sanding out, but we are still learning.  Hours 10

Ailerons and trim tab after a 2nd coat of primer

Sanding the ailerons between coats

Priming Flaps

 Have not updated the blog recently, but we finished priming the test parts, including some sanding in between coats.  We experienced some runs because we are newbies and made some mistakes, but that was the whole reason of doing this on test parts, first. 

Priming the flaps

Next we decided to prime the flaps. First we did some prep work to remove some glue blobs, iron down any of the pinked tape edges that were slightly raised, and also smooth out the glue lines a bit.  We cleaned the parts with alcohol, and hung them up in the paint booth.  Next we sprayed a vertical pattern of primer, then waited about 45 minutes, and applied the cross-coat.  

We took the parts down and sanded them with 320 grit sandpaper (wet sanding).  This also allowed us to remove a run or two that occurred.  We hung them back up and applied a second coat of primer.  We noticed a few issues in the paint (a run, for example), so we did some more sanding after this.  We applied a very light 3rd touch-up coat after the sanding, but only in areas that were thin as we didn't want to add any more weight than we have to. 

Overall, we are happy with the first parts we primed, and think they are looking pretty good.

Hours: 10

Putting Primer on Test Parts

 We decided to go all out and get a good fresh air system for our painting.  We bought a dual air system from Turbine Products (https://www.turbineproducts.com/) and went with the hood setup due to Michael's glasses and full protection.

All protected, Covid-19 Safe too!

We were able to spray our first practice parts with primer.

Hours: 10

First coat of Primer

Paint Booth cont.

A little more progress on the paint room.  The front of the room is built out of two large panels (each about 7' tall and 5' wide) that will serve as removable doors that will allow us to move large plane parts into the booth.  We found that they were a bit leaky around the edges, so we added some cheap window gasket around the periphery, and also added some clamping blocks which allow us to pull the pieces together better with some inexpensive Harbor Freight clamps.  Removing the panels will be simple, we just have to remove a few hand clamps and 2 bolts to free them. We added a few door handles to make it easier to move the panels around, and also added some small wood blocks to help retain the filters in place.  

Front Door panels with clamps

We sealed off some AC ductwork in one corner of the room with plastic and duct tape, and also installed a block that is used as a pass-thru for the fresh air hoses.  You can see the paint hoods hanging from hooks and the white hoses that will bring in fresh breathing air from outside.  The paint has some nasty chemicals (isocynates) which are not healthy to breath, so we are playing it safe and bringing in outside air so that we don't risk breathing in anything bad.    Hours: 5.0

 Back corner of room with sealed ductwork and fresh air inlets

Paint booth work

We continue to make progress on the paint booth.  We installed plastic on the ceiling.  This took a few pieces because we wanted clear plastic so that the lights would shine through, and both Home Depot and Lowes only had smaller sheets of plastic that were marginally clear.  Word of caution, just because the label on a box of plastic sheeting says "clear" doesn't mean it's really clear.  It could be gray, and they still call it "clear".  Apparently, the level of transparency can vary wildly depending on the percentage of recycled content in the plastic, which is not listed on the packaging.

Front of paint booth. Outlet vents along bottom. Zipper door in side.

We sealed the sheeting on the walls to the floor and ceiling with duct tape.  We also installed a blue zipper door in the far wall that will allow us to access items from the far wall of the garage.  If we didn't add this zipper, we would always have to open the garage door to access anything on the shelves against the far walls

Back of Paint booth. Inlet vents are at the top right of picture

The inlet vents are 20"x20" which allows us to sue standard home furnace filters.  On the backside of these vents, we installed an bottom board plus three eye hooks.  Bungee cords attach to these hooks to hold the circulation fans in place.  We tested the fans out and they work just fine. 

Two box fans added to the inlets

We installed a couple of hinges and hung a simple hollow core door on the near wall that will give us easy entry and exit to the paint booth, and we added some gasketing to improve the seal.  Didn't have enough gasket, so need to make another run to Home Depot to finish the job.   Hours: 10.0

Side view; Entry door hung on left wall near the front

Paint Booth Construction Continues

We discovered that the walls of the paint booth were not plumb and many corners were not right angles.  We added some bracing in the corners to correct this problem.  Once the walls were corrected we added framing for the inlet air.  We framed two 20"x20" air inlets to accept 20" Box fans and 20"x20" filters.  We also framed in the area around the A/C hoses to isolate them from the room.

Inlet Air Framing

Framing around A/C hoses

On the front of the paint booth, we will have two removable doors to bring the large pieces of the airplane inside.  We framed these in with 2x4s and we have the provisions for 4 air exit ports if needed.  We'll tune the airflow on the room later.

Ed admiring the two new front doors

Once the framing was done, we started installing Plastic on the walls  Depending on the location, need for light transmission, and viewing pleasure we installed various thicknesses of plastic.  2mil plastic with the best clarity will be used on the ceiling.  Our 4mil plastic is the cloudiest and was installed on the back wall and the left wall.  The right wall got a section of 4mil plastic around the inlet air filters. Between that section and the small entry doorway clear 2mil was used so that work could be monitored outside the paint booth.  And finally, a small section near the front of the paint booth was covered with 4mil to finish the walls.

The two front doors were covered with a 6mil plastic we had laying around who's clarity was somewhere between the 2mil and 4mil plastic we bought recently. 

Plastic Going Up on Walls

Front Doors with Plastic Covering

One trick we found while watching someone build a paint booth with plastic, was to put duct tape underneath every staple used to secure the plastic.  This will help keep the plastic from ripping at the staple points.  Hours: 14.5

Paint room mod and back wall

We made a slight adjustment to the top of the paint room to prevent interference with the garage door by rotating four of the ceiling 2x4's by 90 degrees.  Sure, the ceiling will have more flex, but that doesn't really matter for a paint booth since it isn't holding any weight.

We also added some 2x4's to form a back wall.  The back wall will be a little trickier to seal since we have ducts for a portable air conditioner running out the back wall.   Hours: 3.0

Current state of the paint booth

Paint Booth Work

Now that we've got the fuselage out of the garage, it is time to start construction of the paint booth so we can finish the covering job.  A large load of lumber was bought from the local hardware store.  Our paint booth will be roughly 10ft x 20ft.  Due to the garage door there will be two heights to the paint booth.  The taller section will accommodate the tail section and the lower section will accommodate the cockpit area of the fuselage.

We first constructed one wall to locate where we would need to place the steps in the ceiling.  We had many trial and error moments to get the wall height near the garage door correct.  We finally settled on all the dimensions.  Ed precut the boards for the second wall.  We assembled the second wall, which went together much quicker with the precut lumber.

Assembling the Second Wall

Second wall complete and ready to lift into place

Finally we raised the second wall into place.  We had to be careful around the A/C intake/output hoses and condensation drain lines.  Once the wall was in place, the 10ft rafters were installed one at a time.  We ran into one issue that will have to solved.  The garage door has a bracket in the middle that the garage door opener attaches to and as it travels it hits the installed rafters.  It may be as simple as rotating the rafters 90 degrees.  Hours: 12

Rafters being installed

Paint Booth coming together

Fuselage moved to hangar

We needed to move the fuselage to the airport so that we had room to build a paint booth in the garage, so wrapped up the fuselage to prepare it for the move, and then the next morning we loaded it up on the trailer and towed it away.  The move went very smoothly with no issues.  We always have to watch out for low hanging limbs when pulling out of the driveway, and also when driving (very slowly) down the narrow road leading up to the hangar.   With Michael's expert driving skills, and my unmatched talent at lifting low branches with a broom, the trip went without a hitch.   (Hours: 4.0)

A quick pic of the fuselage before the move

Fuselage in front of the hangar, ready to be unloaded

Turtledeck fasteners, Prep for paint booth

We installed Camloc style fasteners (made by Skybolt) on the turtledeck.  We had an issue, though, because the studs (sized S-2) were too long, and the next smaller size (S-1) were too short.  After some investigation, it appeared that some of the studs we received had a manufacturing issue.  There was supposed to be only a 0.03" difference between the two sizes, but there was twice this (0.06" difference) between the two.  We thought the issue was with the S-2 studs, so ordered some replacements directly from Skybolt to ensure we received the correct ones, but we had the same problem with the new parts.  Luckily, we also ordered some adjustable receptacles as a back-up solution if the new studs didn't work out.   So instead of waiting for new parts once again, we just drilled out the old receptacles and installed the adjustable ones.  This allowed us to dial everything in correctly so that they fit perfectly. 

Turtledeck installed

Close-up of Camloc fastener

The fuselage was taken off the rotisserie and the landing gear was once again installed.  We did this because we now need to move the fuselage back to the hangar (for temporary storage) so that we have room in the garage to build a paint booth. 

Landing gear installed again

We also spent several hours cleaning up and planning how to build a paint booth in the garage, yet still have room for everything we need.  We settled on a plan for a 10'x20' booth, and will have to completely rearrange the garage as well as put some things in the shed for storage.   Lumber for the paint booth was also purchased.  Hours: 9.5

Baggage door and turtledeck

The baggage door work is essentially complete now.  The biggest challenge we had was trying to get all the edges to fit properly.  The upper longeron that it mates to has a slight scallop shape, while the lower edge is flat.  To get the upper edge of the baggage door to seal nicely, we added a stiffening bracket with a gentle bow shape to match the shape of the top longeron.  This took several attempts to get right as it was difficult to get the bracket shaped properly so that the top door edge lined up nicely. The bracket itself isn't the prettiest thing in the world, but it works well.

1st attempt at stiffening bracket with an intentional "bow"

Baggage door with final stiffening bracket installed

We also installed Camlock receptacles on the fuselage, and drilled holes in the baggage door for the camlock latches.  These were tested and adjusted, and are working great.

Camlock receptacles riveted in place

Baggage door exterior, with 2 small Camlock latches

The turtledeck was also trimmed, fitted, drilled, and deburred.  It's starting to look more like an airplane as we get more pieces fitted in place.   Hours: 12.5

Footwell panels and Baggage door

We got some good use out of our bead roller/flanging tool to make flanges along some of the edges on the aluminum side panels for the footwells.  This wasn't really required, but it looks and fits nicer, and should also help seal a bit better around some of the edges.   We made the panels out of 0.025" thick aluminum, and each side was individually measured and cut to fit.  It took a few iterations to flange the edges so that they were rounded just the right amount, but that work actually went quicker than we originally thought. We had some extra aluminum just in case we screwed one up and had to remake it, but we didn't have to dip into these extra supplies.
 

Closeup of right panel with flange shown

Bead Roller/Flanging tool with a Tipping Die installed

Left Panel installed with Clecos

We also made progress on the baggage door.  We made this door out of 0.032" aluminum, and also formed the top edge using the bead roller (with a tipping die) so that it had a flange to better mate against the fuselage.  The bottom edge was also flanged to bend around a stringer.  One half of the hinge was drilled and riveted to the door, and the other half was temporarily installed with Clecos to attach it to the fuselage.  We are also adding a stiffener bracket to help keep the door from flexing which should help it seal better when closed.  We installed this bracket temporarily, but have a bit more work to do on it because we want to introduce a small bit of arc to this stiffener to help seal the door better when it latches closed.  We plan to have two latches (not yet installed).  Hopefully this will be enough (with the stiffener) to seal the door along the top and sides with a gasket.  If not, we will have to tweak the design a bit.    Hours:  14.5

Baggage door with hinge installed on left side

Baggage door partially opened.