November 2009 Archives

I completed the same modification on the left flap hinge pin.  No need to repeat the details, look back a few days if you want to see how I did this.  This did take me about half the time the first one did though.



Received Reservoir Dog

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I've been out sick the last couple of days, so I haven't been able to do anything on the plane, but my order from Peterson Innovation showed up today.  They make a slick little product called the Reservoir Dog that fits on your brake fluid reservoir to keep brake fluid from spilling out when you're inverted.  As you can see in the picture below, it fits between the aluminum reservoir and the breather cap that comes from Van's.  It contains a check valve that allows air into the reservoir when you're upright, but seals tight when inverted.



Bottom Wing Skin Prep

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Now that I'm feeling better, I got started prepping the bottom wing skins for riveting.  I deburred and dimpled two of the skins and installed the nutplates in three of the six cutouts.  After the wing skins, I only have a small punch list of items to complete before I'm ready to rivet the bottom skins on:

    • Put remaining tank bolts in place and torque all tank bolts.
    • Put proseal around conduit where it penetrates each rib to prevent vibration from cutting through them.
    • Reroute roll servo wire through smaller rubber grommet so that the wire can't move as much.
    • Fix a couple of bent rib flanges inside the main spar flanges
    • Fabricate a support angle to tie the pitot tube mount to the adjacent rib to keep the skin from having to carry any flexing load.



I safety wired the remaining two bolts on the autopilot roll servo.  These are the bolts at either end of the short pushrod from the servo to the aileron bellcrank.  These nuts as well as the remaining nuts in the aileron control linkage have been final torqued and torque sealed (orange lacquer).  This is the bolt on the servo end of the pushrod.



This is the bolt at the bellcrank end of the pushrod.  I drilled a tiny #50 hole in the flange of the bellcrank to safety wire the bolt to.



Pitot Tube Mount Support

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I fabricated a short piece of angle to tie the pitot tube mount to the adjacent wing rib.  Positioning this required putting the pitot mount and bottom wing skin in place so that the piece of angle could be clamped to the rib.  After removing the mount and bottom skin, the angle could be drilled to the rib.

Below the large push tube, you can see one of my experiments in keeping the pitot and AOA tubing away from the push tube.  I'm not going with this arrangement, but I'll post something in a few days about how I'm handling this.



Here it is with the mount back in place.  This bit of angle adds considerable rigidity to the mount.



Disassembled Firewall

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I fabricated the F-601TD brake reinforcement doubler and match drilled it to the fuselage.  I also laid out and drilled the 7/16" holes through this and the firewall.  Drilling stainless is pretty hard on cutting tools, but I used some foam that is a tapping lubricant and that seemed to work really well.



Here are all of the components that came off of the firewall.  I deburred all of these except for the steel brackets at the top.  There's still a lot of work to do here as the firewall side of most of these pieces needs to be machine countersunk to receive the dimples in the firewall.



The plans don't make any mention of it, but the F-601Z aux fuel firewall doubler isn't required if you're using a fuel injected engine as I will be.  Leaving this out means a lot fewer unnecessary holes in the firewall.



My mom's in town, so I got her help dimpling the firewall.  I was a little worried that the DRDT-2 dimpler wouldn't make as crisp of a dimple in the stainless (though I didn't even try to see if this fear was warranted).  My buddy Andre has a couple of the traditional Avery style dimplers, so I borrowed one to dimple the firewall.



As you can see, the dimples are perfectly crisp and the material around the dimple is perfectly flat.



I also machine countersunk about half of the holes in the stiffeners before having to call it a day.  Hopefully I can finish these up, prime them and rivet the firewall together in the next couple of days.



Riveted Firewall

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My step-father Curtis was in town and gave me a hand prepping the firewall components for priming and helped me back-rivet everything in place.  We had a little problem with one of the corners because the firewall wasn't sitting flat on the back rivet plate.  I drilled the problem rivets out though and everything looks great now.  Like many other builders, I had to go up a size on some of the rivets to get a sufficiently large shop head (though I don't think it would have mattered to just use the size called out for in the plans).



Started on Center Section

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Now that the firewall is out of the way, I got started on the center section.  First up is to enlarge the holes in the side supports to allow the rudder cables to pass through.  These are drilled out to 5/8" for an SB625-7 snap bushing.



The side supports are then positioned using a couple of close tolerance bolts so that the rivet holes can be precisely match drilled.  These bolts are seriously snug.  Even with some lubricating oil, I had to push these rather firmly to get them through the holes.

I also noticed something odd when laying out all of the pieces.  Van's apparently mismarked the forward and after center sections (the aft section was marked fwd and vice versa).  This may have just been a marking error, but if the center section was flipped end for end when the wing spars were match drilled, then the close tolerance bolt holes may not line up precisely when the wings are mated.  I'll call Van's on Monday to see if they think this is an issue.  Hopefully their drilling jig won't let this sort of mistake happen.

Update: I spoke with Ken at Van's and he's about 99% sure this is simply a marking mistake.  He didn't know if their drilling jig would let them drill the center section backward, but said that if I wanted to be 100% sure, I could simply install the center section onto each wing using the close tolerance bolts to see if the holes lined up.



The aft center section needs some spacer bars match drilled to the spar web.  Using some AN4 bolts, I positioned and clamped the spacer in place.



There is a pilot hole in the spar web and side support, but then you need to drill through the 5/8" spacer.  Since it would be easy to get this hole slightly off of perpendicular to the surface, I broke out my drill cups to ensure that these holes are exactly perpendicular.



There are a few more 5/8" holes that need to be drilled in the forward and after center section spar webs for snap bushings that will allow for wiring runs to penetrate the center section.  Here are the two in the forward center section.  The plans call for SB625-7, but I ordered extra SB625-8 snap bushing to give myself a little more room for wire runs.



Here are the corresponding holes in the aft center section.  The seat ribs rivet here which is why there are two vertical rows of rivets.  Like most builders, I wonder why they didn't just move these over a half inch or so so that they wouldn't interfere with the rib.  As it is, I'll have to cut away part of the rib flange to make room for the snap bushing.  I also ended up with the minimum edge distance on one of these holes (3/16").  Nothing to worry about, but it would have been a non-issue if they have simply moved their holes inboard a bit.



There are also outboard holes in both center sections for snap bushings.  If you zoom in on the picture, you can see that the hole slightly cuts into the side support.  Again it seems odd that they didn't move these holes inboard a tiny amount to eliminate this interference.



Drilled Control Mounts

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I drilled the control mounts to the aft center section.  This basically entailed laying out and drilling the top hole then bolting the mount in place and squaring it to the spar.  After clamping it in firmly in place, the other hole can be back drilled through the spar.



Attached Control Sticks

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I fabricated the control stick bushings and mounted the control sticks tonight.  I'm still not happy with these though.  The pilot's side stick has a little bit of play between the stick and the bushing, and the passenger side is binding a little bit.  It's late though, so I'll work on these more tomorrow.



Center Section

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I started out tonight by finishing the work on the controls.  After a little fiddling with both sides, I got everything working nicely with virtually no play.  I disassembled everything so that I can get the control mounts prepped and primed.

The plans say you can optionally remove the outlined material from the control mounts to save weight.  I'm trying to save weight where I can, so I'm doing most if not all of these optional steps.  I started by drilling some #30 holes to define the radius of the interior angles.



I cut out the bulk of the material using the band saw.  After this picture was taken, I smoothed out the cuts with a vixen file and the scotchbrite wheel so that these are ready for priming.



The center section has 18 K1000-08 nutplates that need to be installed on the top flanges.



I also deburred the edges of the center cover supports and match drilled these to the spar.  Nutplates are installed on the front flange and holes are drilled through the webs for snap bushings, but these can wait until tomorrow.



I started on the cover support ribs.  I didn't have much time tonight, but I did get the edges deburred and drilled the webs for several snap bushings.



Finished Cover Support Ribs

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I fabricated the web stiffeners that go on the other side of the shorter cover support ribs.  The plans don't include the 45º cuts on the opposing flange, but I misdrilled the end holes, so I cut the flanges to remove the holes.



I primed the cover support ribs and installed the nutplates and snap bushings.



I also primed and installed the snap bushings on the web stiffeners.



Here is everything installed.  The web stiffeners are riveted on the other side of the spar web under the two short cover ribs.  The short cover support ribs are screwed to the nutplates installed on the web stiffeners.  The longer cover support ribs are bolted through the spar bars at the top and bottom of the rib and riveted to the spar web through the middle.  If you look closely, you can see that the lower rivet in these ribs is missing.  I'm going to have to use my double offset rivet set to reach these and I'd rather wait until I have a riveting partner to use that.



My Ideal StripMaster wire strippers came with the L-4421 knife blade.  This is fine for typical PVC insulation that most things are wired with, but it isn't ideal for the tefzel insulated wire used in aircraft; the sharp edge can nick the wire.



The correct blades for teflon/tefzel are L-5211, but these are expensive (~$100).  I lucked out and found a set on eBay for $10 though so I picked them up.



Rear Spar Bulkhead

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My buddy Andre stopped by today to give me a hand with the rear spar carrythrough bulkhead.  First up is to shoot the two rivets I couldn't do easily yesterday.  I didn't get a picture of it yesterday, but I also riveted on the main spar uprights.  A few of these rivets could be squeezed, but most needed to be shot and bucked.  I'm definitely getting the hang of doing that solo.



The rear spar bulkhead starts with a could of beefy pieces of 2024-T4 bar stock.  The lower one in this picture runs all the way across the bulkhead and carries the major portion of the load.  Shorter pieces of bar stock with a couple of bends in them are riveted to these to create a socket which will receive the rear wing spar.



The lower seat belt attach points are drilled and bolted to the rear spar carry through structure.  The technique here is to mark and drill one side that then clamp the other side in place with a 3/16" spacer.  An AN3 bolt is exactly 3/16" thick, so clamping one of these between the anchors creates the perfect spacing.  The holes in the top of the anchors (off the top of the picture) are held in alignment with an AN4 bolt.  The other anchor can then be back drilled through the spar.  You can also see here the the outboard seatbelt attach points require the anchors to be cut to clear adjacent rivets.  Here, the left anchor has been cut, but the right one is still full size.



Here are all four seat belt attach points match drilled to the spar.



The shorter spar bars are tapered for weight reduction.  You need to make sure that the last rivet has 1/4" edge distance all around the radius.  By positioning this end first, I could easily ensure that.



Then the other end can be cut flush with the long spar bar.



While I was working on the rear spar, Andre fabricated the upper angles that will receive the canopy latch pins.



The angles fit behind the upper portion of this bulkhead.  I drilled the four corner holes so that I could use rivets to keep the three prepunched pieces in alignment.  The angle could then be clamped in position and the holes match drilled.  I've said it before, but these self-adjusting clamps absolutely rock.



I cut all of the pieces that form the upper seat adjustment.  I started to layout the holes, but I realized that my rivet fan won't adjust wide enough.  Instead of doing this old-school, I'll borrow a large rivet fan from a friend.



The lower bulkhead needs a couple of 5/8" holes for snap bushings to run wires through this area.  Edge distance to the adjacent holes is right at the recommended amount.



The F-705D uprights need 5/8" holes as well for the rudder cable snap bushings as well as a couple of K1000-08 nutplates each.  I installed these before priming because I'm only going to prime parts now that won't get a top coat of the interior color.  I'll also probably use self-etching primer for all of the cabin components so that I can easily wipe off the primer at some point in the future if I need to paint an area.



Pitot/AOA Tube Routing

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I used some self-fusing silicone tape to keep the two fittings on the pitot tube from rubbing against each other or the inside of the pitot tube mount.



I also used a MS21919-DG10 clamp to route the tubes towards the spar so that they don't interfere with the aileron push tube.  The DG10 has enough free play that I can slide the tubing through it if I ever need to take the pitot out.  I'll have quick disconnects in the wing roots that I can disconnect to create the slack to do this.



More Work on F-705 Bulkhead

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I drilled the flap blocks to the sides of the F-705 bulkhead.  These won't be bolted on until much later in the construction, but it's easiest to drill them now.



I also drilled the four holes in the top of the two F-705G angles.



...as well as drilled and filed the elongated holes for the canopy latches.


I managed to get all of the holes in the F-705 bulkhead deburred.  I still need to finish the upper seat back adjustment parts, then this will be ready to prime and rivet together.
I had the day off work, so my buddy Andre dropped by and we got started on the F-706 bulkhead.  First up is to drill some 0.063" angle to a couple of support ribs.  Here is the rib that goes from the back of F-706 back to F-707.



And here is the rib that runs vertically behind F-706.



Here are how all of the pieces fit together.  The reason there is so much structure near the bottom of this bulkhead is that there is a bellcrank mounted here that connects the forward elevator pushrod (from the control sticks) to the rear elevator pushrod (to the elevator horns).  All of this is now match drilled.



Here is a closeup of this area.  The forward elevator pushrod passes through the hole visible here.  The bellcrank mounts between the two ribs near the top of the picture.



I also fabricated the straps that attach the horizontal stabilizer to the F-711 bulkhead.  Near the bottom you can see a taper cut into these to clear the side skin of the fuselage.



These are positioned against the front side of F-711 such that the bottom hole is 5/8" up from the bottom edge and the top edge is 3 19/32" from the top of the bulkhead.



These are then back-drilled through the bulkhead.



I drilled a series of eight holes along the inside edge of the F-708 bulkhead to attach the static tubing.  I also drilled holes in F-706 and F-707 (the two bulkheads forward of this one to pass the static tubing up to the front part of the fuselage.  There are also rudder cable holes in almost all of the bulkheads that require opening to 5/8"  With this, I think I am done with all of the drilling for the bulkheads (for now at least).  Everything can be disassembled, deburred, dimpled and primed in preparation for riveting.



No pictures today.  I spent several hours deburring fuselage bulkheads.  I still have a fair amount to do before priming.

Bent Upper Seat Adjustment

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A couple of pieces of the upper seat adjustment mechanism needs to be bent to 4º.  I tried this without a brake and the bend was pretty poor.  I took advantage of the black friday sale at Harbor Freight to pick up this brake and made perfect bends in just a couple of minutes.



Upper Seat Back Adjustment

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I drilled the upper seat back adjustment pieces.  None of these pieces have any layout holes, so everything has to be measured and drilled.



These pieces allow you to position the upper seat back in two forward positions by sliding the edge of part of the seat back into one of the two slots defined by these pieces.  Here, the seat back piece is positioned in the forward position.



The bulkheads have a bunch of separate flanges because of the tight radius of some of the curves.  Some emery cloth cut into 1/4" wide strips works pretty sell when used like dental floss.



After a lot of sanding, cleaning and priming, the bulkheads are starting to go together.  Here, the F-705 bulkhead is clecoed together.  Double check that this bulkhead is square before riveting since the clecos allow some play in these pieces.  I could change the diagonal measurement as much as 1/4" by racking these pieces from side to side.  After assuring that everything is square, this can be riveted together.  The blue tape signifies the holes that need to be left open right now since they will be riveted together with other parts of the structure at a later time.



Here is the F-705 bulkhead riveted together.  The clecos near the top are there because these pieces are riveted in conjunction with other parts.



This rivet needs to be a flush head since the seat belt attach anchor extends past this point.



Here is a closeup of the upper left portion of the F-705 bulkhead showing how many holes need to be left open for later riveting.



The upper seat adjustment pieces can also be riveted on now.  I used some rattle can primer on these so that I can easily remove it later when I'm ready for final paint.



The rear bulkheads are primed with epoxy primer and just need a few rivets each to join the two halves together.



The F-706 bulkhead is riveted along the bottom, but the top is left clecoed since it is riveted in conjunction with a top skin rib.



The F-711 bulkhead is riveted through the bars and around the lower curved section.  The upper and lower hole in each bar is left unriveted for now.



The F-712 bulkhead is riveted together using flush rivets on the aft side since the vertical stabilizer rear spar attaches here.



The F-728 and F-729 ribs that support the elevator bellcrank are attached and everything except for F-728 is riveted in place.



For fun, I clecoed the F-706, F-707 and F-708 bulkheads to the bottom skin to see how everything fits together.  The hole alignment is pretty poor.  The bulkheads will definitely need some fluting before everything aligns.



Started Longerons

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I started working on the longerons tonight.  First up is to cut them to length.  This is a critical cut because replacing these 15' long angles would be very expensive (both in material cost and in shipping).  These need to be cut to precisely 173 7/16".  Since the ends of tape measures can have some slop in them, a trick to get more precise measurements is to position the tape measure at the 1" mark.  You do have to be sure to add 1" to your measurement to account for this though.



These suckers are long.  They barely fit across my garage widthwise because of the stuff I have lining both walls.



I used my cutoff saw to cut these about 1/8" long and then filed them to the correct length.



The aft ends of the longerons need some material removed.  I misread the plans at first that called for a 1/8" radius and drilled a 1/8" hole (1/16" radius).  I fortunately had drilled the hole far enough away from the lines that I could file the radius to be 1/8" and still not cross the lines (though it doesn't look like it from this picture).



Here are both ends cut and polished.



Next up is to lay out for the bends.  These lines define the forward end of the F-721 side rails and the point at which the longerons bend downward to meet up with the firewall.



The longerons are straight for the next 10+ inches or so, then curve inward to define the shape of the fuselage.



I placed marks every inch or so to help with the alignment during bending.



This is the rear end of the curve.  The longerons are straight from this point back to the tail.  It's nearly midnight, so I'll get started on the bending tomorrow.



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This page is an archive of entries from November 2009 listed from newest to oldest.

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