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This page shows the construction of the wings. That includes the main spars, rear spars, ribs, wing skins, flaps, ailerons and several other little things that goes into aircraft wings. And yes, there are two, so we get to do this exercise twice. With the exception of a few details, most of the pictures here are from the construction of the L/H wing.
The Sonex is designed with detachable wings. Among other things, this allows for easy transportation and storage. It also allows the builder to finish one item, store it and move on to the next. You really don't need a big workshop to complete a Sonex.
The major parts of L/H main spar layed out on the bench and pilot drilled on a few places. At this stage, we've aligned the spar caps with the spar web. We used the alignment tools supplied in the kit.
We made a few wooden blocks that fit nicely under the spar assembly. This way we could secure positive support under both spar caps while drilling both to the pre-drilled spar web. This is a critical step in the spar construction that requires everything to line up perfectly. Make one tiny mistake here, and you will find your self ordering a new set of spar caps from Sonex
These are the pre made aluminum strips included in the kit. They simply cleco to the spar web and the correct spar cap distance is automatically set. Truly smart and a real time saver.
This is how we boxed up the spar assembly to enable drilling all the holes in both upper and lower spar caps. A drill press secures all holes being drilled straight and consistently. At this stage we're at pilot hole size #40. Once completed, we'll have to do it all over again with #30 and then again with #21. Hand drilling this sequence would have been much faster, but using the drill press provides for real peace of mind knowing all these important holes are drilled straight.
#40 being drilled. Keep everything straight and pay close attention to not scratch the spar cap.
The inner part of the left main spar will overlap the corresponding parts of the right main spar. Thus, some rivets and bolts must be countersunk
The countersunk part of the main spar is overlayed by a thinner plate that must be formed to match the countersunk holes. This is called dimpling
These are all the parts that goes into one of the main spars. The upper and lower spar caps and the spar web effectively forms an I-beam. The shorter plates and the smaller items are doublers and stiffening parts for the inboard end of the main spar where the flight loads are greatest
L/H spar assembly drilled at #40 size with all stiffener parts fitted. All the stiffener angles are mounted where the two spars will overlap inside the fuselage. It makes for a real beefy structure
Here are both main spars temporarily assembled. Approximately 390 holes for rivets and bolts must be drilled in each main spar. All the holes are drilled through three steps, with increasing size every time. Effectively, we have drilled close to 2400 holes on the two spars
Inboard attachment block clecoed in place. The drawings calls for these blocks (4ea) to be drilled prior to assembly. We will complete this drilling exercise only on one of the spars. This way we can mate the two spars using alignment holes, clamp both tight together and drill a hole through the opposite block using the other as drillguide
Inboard and outboard attachment blocks drilled for one of the main spars
This is showing the flush side of the main spars. The spars will overlap each other inside the fuselage tunnel and bolt together and into the airplane structure
Locating the rear spar attach bracket accurately on the spar channel is important. This was achieved be clamping the spar channel to a piece of wood, extending a help line from the channel and on to the wood piece. A size 40 bit was drilled into the wood at the correct distance from the spar. This positions the attach bracket perfectly and alignment could easily be adjusted prior to drilling
Another view of the attach bracket alignment exersise
The inboard end of left and right rear spar. The spar to fuselage attach bracket, attach angle for root rib and the hole for the flap pushrod is showing.
Half way out on both rear spars there are holes for the aileron pushrod. These are both reinforced with doubler plates
Probably due to the standard channel stock for the rear spar is too short, an extension made from the same stock channel is spliced to the rest of the spar. The cut out is for the aileron counter balance weight
Preassembled rear spars
R/H main spar with all aft ribs preassembled
All 12 ribs are lined up perfectly
Fwd and aft ribs 1-4 have the little gussets attached for strength
Attention to details. The inboard ribs need a cutout to clear the spar caps
The center spacer sandwiched between the rib and the spar web
Fwd and aft ribs up-drilled and pre assembled to the main spar. Now everything needs to come apart for deburring and and cleaning
Just had to line up the rear spar for motivation. Now it really starts to look like something that belongs to an aeroplane
The right hand aileron bellcrank pivot assembly. Mounts on rib #9 and connects the aileron push rod to the push rod from the stick
Both left and right aileron bellcrank assemblies shown
A stock angle is cut into smaller pieces....
...and made into tiny clips that will support the aileron bellcrank asembly fitted to rib #9 on both wings.
Wing parts piling up on our work bench.
Left and right wing rib #9 showing with aileron bellcrank and supporting structure. The vertical channels on the opposite side of the bellcrank also attaches to the wing skin and stiffens up the rib where the push-pull forces to the aileron is transferred
Aileron bellcrank assembly riveted in place
Aileron bellcrank assembly
Hans Otto hard at work. The scotchbrite wheel does the job effectively
Stig sorts out every last little detail on the ribs
The four attachment block assemblies pre-assembled with 1/4" AN 4-15A bolts. The 3/16" holes in the blocks are pilot holes for the 5/8" bolts that will join the two main spars inside the fuselage carry through channel
Spars mated and aligned with three long reach wing nut clecos
Perfect alignment 1
Perfect alignment 2. Never mind the castle nuts, this will all come apart for cleaning and deburring. Reassembly will be with the specified nylock nuts and correct torque
Stig and Hans Otto completed the two aileron drive horn assemblies. Note the solid rivets, we use them whenever we can
Prior to final assembly of the main spar, we cleaned out all holes with a Q-tip dipped in Acetone.
Mating of left and right main spar. We opted to do this exercise prior to riveting. Plenty of clecos, stiffner angles bolted in place and clamps secured a perfect result. After mating and updrilling of all alignment and bolt holes we could disassemble and deburr all parts. Reassembling afterwards proved perfect alignment. Riveting next.
Solid riveting with pneumatic rivet gun and custom made bucking bar for those hard to reach areas
More riveting
Shop head of solid rivets. Strong, simple and lightweight connection. Aluminium is truly natures gift to the aircraft industry
Details of L/H main spar root end
L/H main spar rot end details and stiffner angles
Completed L/H main spar
L/H wing skeleton assembled for the first time
L/Hwing skeleton on stands and aligned. Lower aft skin clamped in place
To make sure there is no twist in the wing, a thin steel rod was used as a plumb bob, and alignment was checked in both ends of the wing by using the tooling holes in the ribs. Perfect aligned in both ends, means no twist. This is inboard end.
Alignment in the outboard end of the wing. As seen, the hole is not lining up perfectly, a little more shim under the main spar, and its perfect.
Pilot holes in wing skin matches the sharpie mark on the underlying rib perfectly. Amazing how everything comes together. Attention to details and accuracy in every building step pays of.
Every measurement and alignment checked many times, and drilling wing skin to ribs can start. Excellent team work, and the entire skin was drilled and clecoed in less than half an hour.
Holes are lining up perfectly along the center line of the rib flanges.
left wing with upper and lower aft skin clecoed in place. temporarily stored on the workbench while the aerobatic aileron and flap are being built
pitot tube assembly completed.
Detail of pitot tube assembly. Static port and the rivet used to plug the tube
aileron bob weights and rib assemblies under construction
L/H flap in progress. Drilled to final size and ready for rivets.
Detail of L/H flap. Solid rivets on the drive horn.
L/H flap and aileron. We built the aerobatic aileron which is significantly larger than standard. Should provide sufficient roll rate to keep Carl happy.
L/H wing getting skinned.
Pilot holes for aft skinn drilled in main spar cap. The Cobalt drill bits are highly appreciated.
Root rib being fitted.
Leading edge skin maches holes in spar cap and rear skin perfectly.
Top side of leading edge skin and ribs drilled. Wing flipped over, and skin ready to be wrapped around the nose of the ribs.
Fwd root rib in place as well. See the small 1/4" tube through the tool holes of the ribs. Makes for easy alignment of the rootrib prior to being drilled to the skin.
A few cargo straps and two wooden beams made this exersize easy. Amazed once again of how well everything matches up. First line of pilot holes in the ribs closest to the main spar is drilled on this picture.
Root rib assembly
Aileron bellcrank and pushrod assembly
Aileron bellcrank and pushrods, as seen through inspection hatch opening
L/H Lower Aft Skin riveted in place
Final assembly top skin
Extra powerful Clecos comes in handy on the leading edge skin.
The remaining clecos are where the root doubler will be installed. This need adjsutment to fit the fuselage side of the aircraft, hence it will be installed at a later stage. Now this wing wil go into storage, and we will start work on the R/H wing.
L/H wing prepared for storage in wingstand
L/H wing prepared for storage in wingstand
Pitot assembly from the inside of the fwd skin
pitot assembly from the outside of the fwd skin
plastic tubing for the pitot system (yellow) and for wing tip light circuit (transparent).
Aluminium wing tips rather than the original fiberglass version
Tabs for riveting on the wing tips
Nav and strobe light mounted on a removable plate
Back side of removable light plate. The removable plate serves a dual purpose by improving the accessability for inspection inside the wing tip
Mer infoLiker
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