October 2009 Archives

Wings off of the Jig!

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Jenn helped me pull the wings down off of the jig this morning and put them in the cradle.  This is a big milestone in the construction of the wings, and it feels really good to reach this point.



I did the ceremonial tearing down of the jig tonight after work.  The garage feels so much bigger now.  It's been about 4 1/2 months since I erected the wing jig, which seems to be faster than most.  Given my pace, it looks like I'm on track to fly sometime in the first half of 2011.



I started out by fitting the aileron hinge brackets on the right wing.  One of the rivets interfered   with the hinge bracket slightly.  A few seconds on the scotchbrite wheel took care of that and the hinge bracket now fits perfectly.



I finished up deburring the aileron components and started working on dimpling the various components.  Dimpling the spar is tight, so I ground part of my 1/8" female dimple die to allow me to fit in there.



I also ended up grinding off part of my 1.5" yoke so that it wouldn't scrape along the spar.



Here you can see that I can easily reach the spar dimples now without scraping the spar web or hitting the flange radius.



My shipment from Aircraft Spruce showed up today, so I used a couple of the adel clamps to secure the roll servo wiring harness.  You'll also notice that I added heat shrink material over the connection to not only hold it together and keep it from being exposed to the elements, but it also prevents it from scraping the spar.



I cleaned, etched, and primed all of the aileron components.



First up is to rivet on the spar reinforcing plates.  The inboard ends each get a K1000-03 nutplate riveted on with flush rivets.  The inner row of holes on each reinforcing plate get riveted now as well since there is nothing else that attaches there.



The nose ribs get blind riveted to the counterweight.



Then the nose ribs get dropped into the leading edge skins and the spars are riveted to them (the closer row of three rivets here just above the nutplate).



Finally, the trailing edge skin is clecoed along the top side of the spar.  It's far too late to think about riveting this tonight (almost 2 am as I'm writing this), so I'm done for the night.



Tech Counselor Visit

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My first tech counselor, Dan Checkoway, moved out of the area since he visited during my empennage construction, so I needed to find someone new.  Several people recommended Brian Dal Porto, a local RV-7 builder who is also an A&P mechanic, so I called him last week to schedule a visit.  He stopped by today to check out the progress on my wings.  He didn't find anything that needed to be redone, but it was great to be able to run a few questions by him.  He said the quality of my work was very good and well above average.
I cut the large push tubes using the cut-off saw.  This was really the wrong tool for the job as it didn't make a perfectly straight cut.  Fortunately, I was able to square up the end and still have it be the correct length.  I cut the other one using a pipe cutter which worked much better.



Here are the two large push tubes cut to length.  The extra is because the RV-8 push tubes are about 5" longer each.



The push tubes get threaded aluminum fittings in each end.  Here, I've pressed the ends into the tube in preparation for drilling.



Using a piece of masking tape cut to fit exactly around the circumference of the push tube, I used a rivet fan to lay out six rivets evenly spaced around the tube.



Putting the tape back on the push tube, I marked for the rivet holes.



These were then drilled on the drill press using a #30 drill bit.



After disassembling and deburring, I sealed each end with tape and sprayed in some self-etching primer to coat the inside of the tube.  The ends were then pressed back into place and blind riveted together.



I suspended the push tubes between a couple of solvent cans using some pieces of wire so that they could be primed on the outside.



The push tubes are installed on the bellcranks using some long bolts and some bushings that have to be fabricated to the correct length.



The ends of the push tubes stick out of the inboard ends of the wings since they will stick into the fuselage and attach to the control sticks.



I also cut the smaller push tubes to length using the pipe cutter.  Unlike the larger push tubes, there is virtually no extra material.  The tiny piece at the bottom is all that is left.



The rod ends have to be pressed into place and either riveted or welded.  The plans call for aluminum rivets which a number of people have questioned.  Since these parts are all steel, aluminum rivets could corrode and cause these rod ends to loosen in the push tubes.  Needless to say, I'm going to have these welded.



Here is one of the rod ends pressed into place.  It shouldn't take them more than a few minutes to put a quick bead around this joint using a tig welder.



I had a little more time this evening, so I pulled down all of the parts for the flaps, stripped the plastic off of the spars and ribs and deburred the main spars.



I drilled the ribs to the spars and then clecoed on the bottom skins.



Spacers of various thicknesses need to be cut and inserted between the ribs and flange that forms the rear spar.  These were then match drilled along with the rib to the hole already in the rear flange of the bottom skin.



My son and I were both sick today, but I was feeling enough better by this evening to put a little time in on the project.  I started by drilling the hinge to the flap skin and spar.  I'm using the recommended 1/4" edge distance.  If it turns out I don't have enough edge distance on the other side once the flaps are aligned with the ailerons, I'll switch the wing side out with the P4 hinge material that has a longer leg.



I had just ordered these long reach cleco clamps and they worked beautifully for holding the hinge material on while I drilled it.  I only ordered two, but they were so handy that I wish I had ordered several more.



I put the top skin on and drilled all of the holes to final size.  I didn't take any pictures of it, but I also needed to make four 0.024" shims for the inboard and outboard ribs to take up the space between the top skin and the rib where the bottom skin stops short.



Here's a closeup of the inboard end of the right flap.  A bracket will rivet around this corner that connects the flap pushrod to the flap and transfers the load from the rib and spar into the pushrod.  The hinge along the lower right (where the hinge pin is sticking out) will rivet to the flap brace and bottom skin of the wing.  The curved top edge will tuck under the trailing edge of the top wing skin.  I can see why they say this is the easiest control surface to build.  I only started on this last night, and with the exception of the bracket I just described, this is ready for disassembly, deburring, priming and reassembly.



The portion of the bracket that rivets to the flap spar has to be fabricated out of a long piece of the aluminum angle on the right.  I cut two pieces to length and cut off part of the short leg to get the two pieces on the left.  It's late, so I'll match drill these to the rest of the bracket tomorrow.



Flap Brackets

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The flap brackets needed to be bent to 6.3º.  I used my fancy digital level to zero out the angle before bending and beat on this with a deadblow mallet until it read 6.3º.  I then repeated this for the other bracket.



Here are the two brackets clecoed back together.  You can see the angle clearly here.  I need to diassemble the flaps and match drill these to the spars and inboard ribs, but I don't have time tonight.



I drilled the flap brackets to the inboard ribs and spars, then disassembled the flap components for deburring.  I made it through most of the ribs before calling it a night.



Deburred Flap Components

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No pictures tonight since it would just be another shot of a pile of parts on my bench.  I finished deburring all of the flap ribs, brackets, and shims and dimpled/countersunk everything.  Once I get the spars ready, the flap components can be primed.

Deburred Flap Parts

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The bottom edge of the spar needs to be machine countersunk because the flap hinge mounts on the inside surface of the spar.



The top edge can be dimpled to receive the skin dimples.



Here are the flap skins, spar, and hinges, all deburred and ready for priming.



The flap ribs, brackets and shims are also all ready for deburred, dimpled/countersunk, etc. and ready for priming.



Prepped Flaps for Riveting

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I primed all of the flap spars, ribs, brackets and shims.



This picture looks a lot like the one from last night; the difference is that now all of the skin holes have been dimpled.  The flaps are now ready for riveting.



Started Riveting Flaps

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I started tonight by riveting part of the flap brace to the spars (except for the holes that also attach the inboard ribs).



I riveted the remaining part of the flap brace to the inboard ribs.  The nutplates have to be riveted on with flush rivets (AN426 on the top and NAS1097 on the bottom) to clear the rod end on the flap pushrod.



I also fabricated the spacers that are used to take up the extra space between the ears of the  brackets (yes I know that the order of one of these is backward, but these have to come apart to bolt these brackets to the ailerons).



I built a couple of v-blocks to hold the flaps while riveting.



I clecoed the flaps together.  Andre is stopping by in a couple of days to help me rivet the ailerons and flaps, so I'm trying to get everything ready so that we can hit the ground running.



I spent probably 15 minutes per flap to get the trailing edge bend perfect so that the flap skin is straight from the spar to the trailing edge radius.



I also fabricated the other two spacers that attach the aileron hinge brackets to the aileron.  The shiny object near the left is an extra COM-3-5 bearing that I used for spacing.  I didn't take a picture of it, but the outboard brackets just use AN960-10 and AN960-10L washers, so I didn't need to fabricate spacers for them.



Wingtip Landing Lights

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I decided to get started on the wingtip landing lights tonight.  I'm using the Van's landing light kit which provides two 75W halogen bulbs in each wingtip (one each for taxi and landing).  I may upgrade the landing lights to HID lights if these don't provide enough light and I do enough night flying to matter, but I don't see any reason to do that before I'm flying.

First up is to trim extra material from the rear part of the bulb holders.  Here you can see the extra material sticking out from around the front part of the bulb holders.



After trimming and running these over the scotchbrite wheel, these are nice and flush.



Next up is to fabricate a dozen tapered spacers from some tube stock.  These have a 70º slope to them to allow the bulb attach screws to sit flush against the spacer even though the wingtip surface that these screws go through is swept back 20º.  This will all become clear when I start attaching the lights to the wingtips.



My friend Andre stopped by tonight and helped me rivet the parts of the flaps and ailerons that are easier with two people.  We started on the ailerons by screwing them down to a couple of boards clamped to the bench.  This made the ailerons rigid enough to rivet.  We only drove the rivets along the top of the spar that must be shot/bucked.  The end ribs can be squeezed and the bottom of the spar uses blind rivets.



We shot and bucked all of the rivets holding the flap skins together and to the ribs.  We then planned on riveting the top of the spar, but I really need to get the hang of shooting and bucking by myself since there will be a lot more of that with the fuselage.  Since Andre has always been so willing to stop by and give me a hand (which I'm eternally grateful for), I really haven't done much solo work with the rivet gun.  I set a few just to see how they turned out, and they all look great.  I can easily finish these by myself.



The aileron brackets would be a little tougher though, so I had him give me a hand riveting these on.  Once the ailerons are done, they will be ready to hang on the wing.



I picked up my aileron pushrods from the welder today, and they look fantastic.  They had to grind off some of the powder coat and machined the cadmium plating off of the mating surface of the rod end before TIG welding them.  I'm going to clean these up and then put a fresh coat of epoxy primer on them before installing them on the wing.



I'm hoping to get the ailerons and flaps completed this weekend, so I got started tonight by squeezing the rivets on the top side of the leading edge and trailing edge ribs.  The next step is to weight these down to a flat surface before putting in all of the rivets on the bottom of the aileron.  My benches are not as flat as I would like, so I'm planning on using our kitchen countertops to do the final riveting.  It's too late tonight to start that, so I'm done for the evening.



Finished Ailerons

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I moved the ailerons to the kitchen since our granite countertops are the flattest surface in our house.  I weighted them down with some books.



I set the pop rivets in the counterbalance weight wet since these are aluminum rivets holding on a galvanized steel pipe.



These are pop riveted on first.



Then the nose rib rivets are set, followed by the rivets on the main ribs.  Finally, blind rivets are used to fasten the nose and trailing edge skins to the bottom of the spar.



After everything is riveted on, the hinge brackets can be bolted to the spar.  I've added some torque seal so that I can confirm these bolts are still tight during preflights.



The outer bolts get torque seal on the nut side.  The bolt above with torque seal threads into a nutplate on the other side of this rib.



Finished Flaps

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After shooting and bucking the rivets along the top of the spar (the left side of this picture), I weighted down the flaps on the kitchen countertop just like the ailerons, and squeezed the rivets along the bottom of the spar that holds on the flap hinge.  This picture looks funny because the top skin is reflecting (and distorting) the spar lightening holes.



The plans call for LP4-3 rivets here, but I'm running short, so I set AN470AD4-4 rivets here instead.  I shot and bucked these solo using a double offset rivet set since you can't get a squeezer in here.



The two flap brackets are riveted together using 5 AN470AD4-7 rivets.  These rivets help transfer the force from the flap pushrod into the spar.



Finally, a few MK319-BS rivets are used near the trailing edge of the flaps (where there is no access to buck these).  I had to use one additional MK319-BS rivet on the bottom of each flap (shown here near the top of this picture) when the flap pushrod nutplate interferes with bucking this rivet.



I finished deburring the aileron braces and dimpled for the holes that attach them to the skin.  I decided to prime under the aileron braces, so I clecoed them on, taped around them, and scuffed the area with a scotchbrite pad.

I'm trying to avoid getting primer on parts of the airplane that will later be painted with the exterior color since I will have to reprime then anyway (since the top coat has to be applied to the primer within a limited window of time).



I also scuffed the backside of these braces with a scotchbrite pad since I'm not going to be etching these.



I think tonight will be the last priming session for the wing.  I mixed up some epoxy primer and injected a few ccs into each aileron push tube through the hole that the welder drilled to relieve pressure during welding.  I then swirled the tubes around to coat the entire inside with the primer.



I then primed the outside of the tube except for the threaded ends.



I then primed the back side of the flap and aileron braces.



And finally, I primed the parts of the rear spars and skins that will be covered up by the braces.



I installed the aileron braces tonight.  All of these rivets could be squeezed, so I could do this after the kids went to bed without making too much noise.



Here is a closeup of the outboard part of the flap brace.  The relief cut on the left allows the brace to step up onto the rear spar doubler, and the complicated shape on the right allows it to follow the outboard aileron hinge bracket closely.  The brace is riveted onto the rear spar with universal rivets, but is riveted to the top skin with AN426AD3-3 rivets which are the shortest rivets I've had to use on the project so far (and I assume the shortest I will have to use).  I assume these rivets are so short so that there is clearance here for the aileron.



I also clecoed on the flap brace, but couldn't rivet it on because these will have to be shot and bucked since the brace blocks access with the squeezer.



I assembled the rear pushrods.  The jam nuts are not torqued down yet since I will have to adjust these to final length once they're installed.



I went ahead and loosely installed the left aileron on the wing.  None of the bolts are tightened down since this may have to come back off at some point.



Here is a closeup of how the pushrod comes through the rear spar.  It's clear now why the hole is oddly shaped as the pushrod traces a curved arc as the the aileron is swung through full travel.  I verified with the digital level that the aileron can exceed the maximum allowable up/down travel.  I still need to fabricate the aileron stop that will limit the travel to the recommended amount.



Here is how the pushrod attaches to the bellcrank.  Again, nothing is torqued down until I know that it's on for good.



After dropping the kids off the morning, I stopped back by the house and riveted on the flap braces.  I'm definitely getting the hang of riveting with the gun solo.  I slightly overdrove a couple of rivets (though not badly enough to drill out), but virtually all were perfect.



After work tonight, my wife was hosting a Bunco party at our house, so I was on kid duty.  After they went to bed, I had a little time before the ladies left, so I snuck out to the garage and mounted the other aileron.



I also safety wired the autopilot roll servo's mounting bolts.  I'm still getting the hang of safety wiring.  It's tricky to estimate how much extra wire to leave before twisting since the wire segment shortens as you twist it.  It only took two tries to get this properly secured.



First step in rigging the ailerons is to place the aileron alignment bracket over the bellcrank with a bolt through it and the rear aileron push tube's end bearing.



Next is to adjust the length of the rear pushrod until the trailing edge of the aileron lines up with two tooling holes in the main wing rib.  I placed a couple of AN3 bolts through these holes and then put the straight edge against both sides of the bolts until the trailing edge was centered between them.  I loosened the rear aileron push tube end bearings evenly so that I will have the same amount of threads showing at each end.



Next up, I clecoed on the bottom skins and put the right flap in place.  I spent awhile adjusting the position of the end clamps to get the trailing edges in perfect alignment.



I think I said it before, but these clamps have come in super handy.  I would highly recommend getting some if you're building.



As I was aligning the trailing edges, I noticed something funny.  The trailing edge radiuses of the flaps and ailerons are not the same.  Here is one shot looking along the edge.  The aileron is the lower trailing edge with the smaller radius and the flap is the upper trailing edge with the larger radius.



Here is a shot looking down on the trailing edges.  The problem is that with the trailing edges aligned front to back, the skin surfaces no longer align.  If I make the top skin surfaces flush, then the flap skin on the bottom of the wing will be proud of the aileron bottom skin.

I don't think I can just squeeze the flap trailing edge either since the flap skins nicely follow the angle defined by the end ribs.  If I squeeze the trailing edge, the skin will have to bend inward as it crosses the trailing edge of the end ribs.  I'm going to see if anyone on vansairforce.net has any ideas.

Update: It turns out that the scale drawings on the flap and aileron plan pages clearly show that the flaps and ailerons have different trailing edge radii, so I'm not going to do anything about this.



Drilled Right Flap

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After triple checking all of the measurements, I drilled the flap hinge to the wing.  I ended up using the P3 hinge that ships with the kit, and I'm well over the minimum 3/16" edge clearance for AD3 rivets (I'm less than 1/32" beyond the recommended 1/4" edge clearance).



Here's a shot of the whole wing.  The control surfaces add considerable area to the wings.



Drilled Left Flap

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I got up this morning and drilled the left flap before work.  This side didn't end up quite as good as the right side (the flap trailing edge ended up about 1/64" below the aileron trailing edge as it's standing vertically like this).  I looked around at a bunch of builders websites and this is apparently a really common problem and 1/64" is actually better than most.  I don't think I'm going to replace the hinge since it could easily end up worse.  I may be able to tweak a few things to make it just about disappear when finally riveted together. 



Van's offers a couple of suggestions for securing the flap hinge pin.  The first is to drill a hole in the inboard aileron bracket that's intentionally slightly out of alignment with the hinge pin.  The hinge pin is then inserted through this hole and the misalignment prevents the pin from sliding back out.  The other suggestion (which most builders including me go with) is to remove several of the hinge loops near the center of the hinge and then secure the hinge pins  against the flap brace.  Here I've removed one loop on the flap side and two on the wing side.  You can also see here how close the rivet holes ended up to my line drawn at 1/4" from the lower edge.



I drilled the flap brace for the #8 nutplate and riveted it on with a couple of oops rivets.



Here you can see how the hinge pins are secured.  The bends in the hinge pins prevent the pins from migrating toward the ends of the flaps and interfering with either the ailerons or the fuselage.  The clip (which I made by cutting a couple of loops off of some extra hinge material) will keep the hinge pin from migrating inboard.  I'll cut off the extra pin material that's sticking out beyond the clip the next time I have the flap off of the wing.



Fuselage has Shipped!

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My fuselage was scheduled to ship next week some time, but on a fluke I checked my credit card online today and noticed I had been charged for the fuselage.  I called Van's to see if I could get an estimate on when it would ship and was told it had shipped yesterday.  I called FedEx freight and they told me that it will be here tomorrow!  Holy lack of notice Batman!  If I hadn't checked, I wonder when I would have found out.

I didn't do any work on the plane tonight, but I did spend a couple of hours cleaning up the garage and making room for the fuselage crate.  The crate is pretty big (about 8' long, 3.5' wide and 1.5' thick and it weighs over 300 lbs), so once I get it into the garage, I still need room to get around it and unpack it.
My fuselage kit showed up today.  I wasn't home when the driver showed up, but Jenn opened the garage door and the driver placed the kit inside.



My buddy Andre stopped by tonight and we cracked the crate open.



Van's does a great job of packing these crates so there's no wasted space.  About the only empty space in the whole crate was inside the rolled up skins on the left here.



We unwrapped all of the parts and stacked them around the garage.  My workbenches are completely covered now.



A bunch more parts are stacked on my other workbench.



And parts are leaned up against the wings.



...or set on the floor.



The pile of paper and cardboard is pretty substantial.  My son Matthew thought the empty crate was a great thing to play in.



Here is the inventory.  10 sheets with probably 30 items each.



I made it through all of the larger parts and placed them up on my shelves.  I still have to inventory all of the small bags, but that can wait until tomorrow.  So far I've only found a couple of items that were supposed to be in one subkit but weren't.  I'll see if they happened to be placed in one of the bags, but otherwise I'll have to call Van's about them.  There were also a couple of backordered items, so I'll need another shipment from them anyway.



Finished Inventory

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I was up until 3 AM finishing the fuselage inventory.  I found the two parts I thought I was missing.  I only found one mistake where Van's sent me some of the wrong kind of screws.  I'll give them a call on Monday to get this corrected.

I still need to reorganize my storage bins to get everything put away, but that can wait until tomorrow; I'm beat.
Even though there is work left to do on the wings, I was excited to get started on the fuselage.  First up is to fabricate the firewall.  There are several parts that have to be fabricated from rough stock.  These are fabricated from some beefy 0.187" thick angle stock.



This stiffener is fabricated from some 0.063" angle stock.



These attach angles tie together the lower firewall stiffener, two upper firewall stiffeners and later the forward floor stiffeners of the fuselage.  These need to be spaced 3/32" from the flange of the lower stiffener.  The easiest way to do this is to use a #40 drill bit to position the angle.  Behind the angle are a couple of shims that are scotch taped in place so that all of these can be drilled together to the firewall.



Using plenty of boelube, these are match drilled using the firewall as a guide.



After fabricating a couple of additional stiffeners, I clecoed all of the stiffeners and weldments to the firewall.  The four gray brackets in each corner are powder coated steel weldments that will eventually tie the fuselage longerons directly to the engine mount through some beefy bolts.



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