Roee Kalinsky's RV-7A Project

2006.05.02: (1.0) On the QuickBuild fuselage, the aft bulkhead comes attached using just a few temporary pop rivets so that the tail cone could be completed for a tri-gear or taildragger configuration.  I removed the aft bulkhead and adjusted the flanges for a better fit (it came with all flanges perpendicular to the web, should fit the conical and tapering skins).

2006.05.04: (0.5) Greg Larson came over to help me buck a couple of missing rivets inside the tail cone, at the bottom of the F-711C bars attachment to the F-711 bulkhead.  They leave these open in the QB so that the non-'A' builders can attach their misplaced nose wheels.

2006.05.19: (1.5) Fabricated the tie down block and fitted it to the aft bulkhead.

2006.06.30: (0.5) Alodined the aft tie down block.  Prepped the aft bulkhead for primer (it came primed in the QB kit, but not very well).

2006.07.01: (1.0) Sprayed AKZO primer on the aft bulkhead and tie down block.

2006.07.02: (2.0) Riveted the tie down block to the aft bulkhead.  Drilled a clearance hole in the aft skin for the tie down eye bolt (see note below).  Started riveting the aft bulkhead to the fuselage.

Note: the manual says to drill the tie down clearance hole to 5/8". But the diameter of the shoulder of the tie down rings from Van's is even bigger.  So a 5/8" hole would be much bigger than needed to clear the 3/8" threaded part, but the shoulder would still bottom out against the skin rather than the extruded block.  As there is a gap between the skin and the extruded block, this would tend to bend the skin inward.  Not good.  The same situation exists in the wings.  And as the wings were delivered in the QB kit, the clearance holes in the skin are just big enough to clear the 3/8" threads.  I decided to replace the tie down rings from Van's with something that doesn't have that shoulder, and could get through an (approx) 3/8" hole and then bottom out against the block at the end of the threads.  A quick trip to Home Depot yielded the perfect solution.  3/8" x 4" stainless steel eye bolts, rated for a safe working load of 350lb.  I'll have to shorten them by about an inch to the ideal length, but that's no problem.  The eye bolts are manufactured by The LeHigh Group, product #7134, UPC code 071514002385.  At Home Depot they were located near the ropes and chains, NOT near all the bolts and general hardware.  They were $1.99 each (Van's tie down rings are $4.25 each).

Pictured: Van's tie down rings on the left, Home Depot on the right and center.

2006.09.17: (0.5) Now with the fuse off the ground, I can finish riveting the F-712 bulkhead to close out the tail cone.  Squeezed the ones on the aft flange.  Will need some help to drive/buck the rivets on the forward flange.

2006.10.??: (0.0) My neighbor Buzz, who's a professional welder, was kind enough to weld the eye loops on my Home Depot tie down rings.  He used a TIG torch, and it came out great!

2006.11.20: (1.0) Finished closing out the F-712 bulkhead with Garnet on the gun and me on the bucking bar.  These were not a great fit, and for a couple we had to enlarge the hole and use a NAS1097, or "oops" rivet.

2006.12.18: (4.0) Fitting the elevators to the horizontal stabilizer.  Made a couple of "gauges" from some scrap aluminum to help set the depth of the rod end bearings precisely to 13/16".  Trimmed the HS skins at the outboard edges to remove interference with the elevator counterbalance arms.  This required extending the clearance area forward by about 1-1/16", providing the specified 1/8" clearance.

(Photo below is after rough cut and fit check, before making it "nice".  And the apparent "jaggies" are just artifacts of rescaling the photo.)

2006.12.19: (2.5) Noticed that the center elevator bearing assembly wasn't perfectly perpendicular to the HS rear spar web.  Removed it and found that the flange on the right side was a little off from square, and was also slightly offset in depth from the left side flange.  When bolted to the rear spar of the HS, the bolts pull it in flat to the spar, which therefore causes the assembly to lean slightly to the right.  I fixed this by adding a 0.010" stainless steel shim under the right side flange.

As noted in the manual and plans, the bottom flange of the HS rear spar channel interferes with the elevator control horns, limiting elevator down deflection to about 15º.  The elevator control limit should be between 20º and 25º down deflection (builder's manual, section 15), and should be limited by the down elevator stop (F-711E), not the rear spar flange.  And so the bottom flange of the HS rear spar channel has to be trimmed back to provide additional clearance.  I cut a notch just over 2" wide (sufficient to clear the outsides of the horns), and about 11/32" deep (target depth determined using the "eyeball" method).  I measured after making the notch and found that this allows for approximately 30º of down deflection, so it'll have 5º to 10º margin past the stop.  Perfect!

Also measured the max up deflection, which came out to about 40º, limited by the elevator hitting the aft edge of the HS skins.  The final max up deflection required is 25º to 30º, limited by the up elevator stop (F-???), so all is good.

2006.12.22: (3.0) Drilled the elevator horns for the center bearing.  To do this I got a piece of 1/4" aluminum tubing from Marshall's, which had an inner diameter just about right for a #27 drill bit.  I actually had to reduce the tube's outer diameter by about 0.002" to get it to fit through the bearing (poor man's lathe: spun it in the drill press while applying a red scotchbrite pad), and then used it as a drill bushing for perfectly aligned pilot holes.  Used a unibit to enlarge the holes to final size.

Installed the elevators with all five bearings, and clamped the elevator counterbalance arms to the HS for "in trail" alignment.  (Note: used 1/2" thick balsa wood under the clams, which provided enough rigidity so there's no slop, but enough give to not damage the elevators or HS.)  Found that the right elevator horn was angled slightly aft of the left elevator horn, by about 1/8" at the tips.  This is normal (per builder's manual) for the elevator weldments to not be perfectly matched.  The right elevator horn was also slightly shorter at the tip.  So the right elevator horn will be used to position the hole for the pushrod bearing bolt, which will thereby ensure sufficient edge margin on both left and right horns.  Drilled a #30 pilot hole in the right horn.  Found that the distance between the horns is approximately 1-1/32", and amazingly enough I had a block of scrap delrin of that exact thickness.  Drilled a #30 hole through it, using a drill press / drill vise to ensure it is perfectly perpendicular.  Clamped it between the horns, using a the #30 drill bit to align the holes, and then used it as a drill guide to drill the left elevator horn.  Removed the elevators and enlarged the holes to final size with a unibit.

2006.12.30: (12.0) [This log entry is for the past week] Made spacers for the bolt that attaches the push rod bearing to the elevator horns.  The total span was approx 1.0385", and the bearing is 0.5", so I made two identical spacers of length approx 0.269".  I first rough-cut them from some aluminum tube stock, then spun them in the drill press while pressing them down into sand paper to get them to final size.  This works pretty well, but that is about as short as it will work because of how the drill press chuck is designed.  I then attempted to make spacers for the the bolt that attaches the horns to the center hinge bearing, but these are too short to make using the drill press.  Hopefully Vay's lathe can handle the job.  These spacers need to be 0.226" long.  (Pretty amazing that the distance came out identical to within 0.001" between the center bearing and the left and right horns!)

Now the really fun stuff -- fitting the HS to the fuselage.  I started by measuring and marking important reference lines on the aft deck.  I found that there is some amount of slop in how this area was constructed (QB of course!) in that the aft deck is not quite centered with respect to the longerons, the bulkheads are not exactly perpendicular to the centerline of the airplane, etc.  Real close, but different enough that for this purpose I wanted to make sure I used the most appropriate structures for reference.  Anyway, I measured, measured, and measured some more until I had everything sorted out.  I measured and verified the corresponding bolt locations on the front spar of the HS and the mating structures on the fuselage (longerons and bulkhead reinforcements).  After literally hours of this tedious measuring and drafting, I, with Stacey's help, finally placed the HS on the fuselage for a real live fit check.  [Note that despite what the manual says, you really need to have the shims to do all the fit checks and drilling.  Otherwise, the HS fwd spar will be resting on top of dome rivet heads.]  Got everything centered up, and verified symmetry by measuring from identical locations on the tips to identical locations in the fwd fuselage.  I also leveled the fuselage laterally, and then verified that the HS is level.  With good fit verified, I removed the HS and on the bench drilled pilot holes for the bolts in the fwd spar.  Clamped the HS to the fuselage again, did another symmetry check, and started drilling.  Did the outboard  holes using long drill bits, then the inboard holes using an angle drill.  Finally, I located the holes on the F-711C bars and drilled them through the bars and aft spar.  With everything now bolted down, I did one more symmetry check, which matched within about 1mm, or about 0.25º of sweep.  I also checked again for level, which was perfect as best as I could tell with my 4' bubble level.

With the HS still on the fuselage, I installed the elevators with Stacey's help.  Initial fit is pretty good, but I'll want to make a couple of minor adjustments.  The cutout in the aft deck for the elevator horns was cut 2" wide (QB).  This is marginally sufficient, providing about 1/32" clearance to the left horn and just slightly more to the right horn.  Problem is that the elevator down deflection limits out with the horns hitting the radiused corner of the cutout instead of the straight bar of the stop.  As is, they limit out at about 21º, which is within spec (20º to 25º), but I want them to limit out properly against the bar.  Will widen the cutout to fix this problem next time I remove the HS from the fuselage.  The up deflection limit is currently about 30º, with the horns hitting the aft bulkhead.  This will allow me to set the stop within spec (25º to 30º).

2007.01.07: (16.0) [This log entry is for the past week] Fitting the vertical stabilizer to the fuselage.  Firstly, I removed the HS from the fuse and fitted the F-781 VS attach plate to the front spar of the HS (much easier done on the bench than in assembly).  While I had the HS on the bench I took care of other loose ends from the HS that were more easily done disassembled (see previous entry).  Re-installed the HS on the fuse and continued with the VS.  In fitting the VS rear spar to the fuse, I deviated somewhat from the sequence described in the builder's manual.  I made the F-712D angle (VS mount and up-elevator stop), but only drilled the holes, did not trim the legs yet (this will turn out to have been good foresight).  Bolted it to the fuse.  I carefully measured and marked references on the VS rear spar, and clamped it to the F-712D.  Got it perfectly vertical by measuring from the VS tip to the HS tips, and match-drilled the upper two mounting holes using F-712D as the drill guide.  I then drilled the lower four mounting holes using the VS rear spar as the drill guide, since I've already installed the tie down block.  This is the deviation from the manual, which worked out really well.  The key to it though was very careful measuring to ensure that the mounting holes ended up in the right spot on the tie down block.  Not much room for error.

I proceeded to the VS fwd spar, which turned out to be a little more tricky than I thought.  Firstly, I found that I had to make an 0.040" spacer between the spar and the F-781 (this possibility is noted in DWG 27A).  I then very carefully found the centerline on the VS leading edge, and likewise on the top of the fuse.  I then marked another longitudinal line on the fuse, 1/4" left of center.  The leading edge of the VS should be offset by that much to counteract the plane's left turning tendencies.  Got everything clamped down and rechecked all the measurements.  Then checked the the hinge line in the back, because the VS rear spar is actually quite flexible and can easily be made non-straight by mounting the front spar higher or lower.  I checked the hinge line first by holding a taught string through the centers of all three hinge brackets.  Then checked with the real thing by mounting the rudder.  The rudder fit perfectly and swung freely with now discernable resistance.  I started drilling the holes through the front spar using the pre-punched holes in F-781 as a drill guide.  This area is cramped and requires use of an angle drill, which was very awkward.  Unfortunately, 3 of the 11 holes turned out quite elongated.  This is a structurally important area, so I'll really want to fix it right.

2007.01.13: (4.0) [This log entry is for the past week] The three holes in the F-781 were pretty bad, but the holes in the thinner VS spar and spacer looked ok.  I though of a few ways to fix it:

1. Drill out the holes for AN470AD5 (5/32") rivets.  That should be big enough to get back to nice round holes.  But I don't have any 5/32" rivets or squeezer sets, and they might take a lot of force to squeeze.

2. Drill out the holes for AN3 (3/16") bolts.  That should work, but adds weight.  Last resort.

3. Get a new F-781 and see how closely the pre-punched holes fit the holes already drilled in the VS spar.  If they're not close enough, then

4. Get or make a new F-781 without pre-punched holes.  Use the VS as a drill guide.

I shot an email to Van's describing all this to get their recommendation.  Their answer was to the effect that 3 messed up holes out of 8 is ok.  Rivet them and don't worry about it.  I wasn't satisfied with that.  I went for a multi-pronged approach to see which of my ideas would work best.  I got some 5/32" rivets and a squeezer set.  I was able to squeeze down a rivet almost to spec, but not quite.  The squeezer yokes aren't stiff enough, so they just flex out.  Still, I got the shop head almost to spec, probably good enough.  I also bought a new F-781 from Van's, and found that the holes lined up pretty well.  I used the original F-781 to located the four HS attach bolt holes in the new F-781, and moved on.

Lessons learned:

1. Be even more careful with the angle drill.  Enlist a helper as another pair of eyes to make sure it's straight.

2. Clamp the VS to the F-781 and remove together from the fuselage.  On the bench I still would have had to use the angle drill, but perhaps it would have been less awkward.

3. Van's should not have made the holes in F-781 pre-punched.  Had they not been pre-punched, they could have been drilled in assembly from the other side.  I.e. from aft to front, from the VS spar, through the spacer, through the F-781.  This is much more accessible and would not require an angle drill even in assembly.  And better yet, on the bench it would be a piece of cake.

2007.01.14: (4.0) Removed the VS and reinstalled the elevators for another fit check after increasing horn clearance through the aft deck.  Looking good.  Removed the F-712D elevator stop for trimming.  In studying the plans (DWG 27A) I found that the dimension callouts would violate edge distance on the bolt holes.  Doesn't look like added length would interfere with anything, so I decided to adjust the dimensions for good edge clearance.  Also before trimming I did a fit check of the elevator up deflection, and found that as is (F-712D un-trimmed) it was spot on at about 27.5º (specified range 25º to 30º).  Had I trimmed it per DWG27A, the elevator horns wouldn't even hit the stop.  They would bottom out on the aft bulkhead first.  Score another one for "measure twice, cut once".

Did a first fit check of the elevator pushrod.  Attached it to the elevator horns, so far so good.  Attempting to attach the fwd end to the bellcrank, I found that the "fork" of the bellcrank was way too narrow (required: 0.500", actual: 0.395").  The width of the fork is set by bends that were done at the factory, and can't easily be adjusted in assembly.  When I make a new bellcrank, I'll check and adjust them before riveting.  (I planned on making a new bellcrank anyway for two other reasons: 1. The flange bearing has side-to-side play.  Others have reported the same problem, hopefully I can get a new good bearing from Van's.  2. I'll want to make provisions for a third pushrod that will attach to an autopilot servo.)

2007.01.21: (8.0) [This log entry is for the past week] Started making the rudder stops.  On my fuse, the lower forward rivet that attaches the rudder stop is already installed, so I decided to extend the rudder stop forward and add two more rivets (upper and lower).  Otherwise, I made the stops per-plans, although initially I didn't trim the part that'll make contact with the rudder horn, so I can fine tune it to my fuse.  That turned out to be good foresight, but still not enough.  To achieve the correct travel limits (1.125" from the aft inboard corners of the elevators) the contact point on the stops would be about 1/4" further aft than shown on the plans.  Searching the web forums, I found that this is common.  The problem is that this leaves only a very small contact area between the stop and edge of the rudder horn.  That would cause a high stress area on the rudder horn, and potentially the rudder horn could even slip past the stop with enough flexing.  So I decided to throw away the stops and make new ones that also extended further aft.  This worked out nicely.  Note also that the fuselage is not flat where the stops attach, so that leg of the angle has to be shaped to match the contour of the skin.  Not so easy on 1/8" thick aluminum angle.  I did this by putting the angle in a vice and beating on it with a mallet.  That was fun!  Drilled the stops to the fuselage and trimmed them for the correct rudder travel.  More trimming and finishing still needs to be done for smooth interfaces to the fuselage.

2007.04.17: (40.0) [This log entry is for the past several weeks.  Time logged is a gross estimate.  I've been very busy at my day job, so work on the plane has slowed down considerably, but I have been working on it little by little.  Just haven't kept up in logging every work session.]

Adjusted the fit on the rudder.  With the rod end bearings set to the depth shown on the plans, there was a considerable gap between the rudder and VS.  I was able to bring it in closer by about two half-turns on the rod end bearings for a closer fit, without creating any interference.  Note that at the extreme left deflection, the rudder does contact the left aft VS skin slightly (both before and after adjusting the fit, no difference) but with no potential for binding so I won't worry about it.  I also fitted the fiberglass rudder bottom, just to make sure it doesn't create any interference.  See section on fiberglass fairings.

After several times of installing and removing empennage pieces from the fuse, the aft deck had a few minor scuffs and scratches.  This was a good excuse for me to strip off Van's "wash primer" and give it a coat of AKZO.  Also sprayed the inside skin aft of the aft bulkhead, and the outside skin where the rudder stops will mate.  Sprayed the stops themselves and the other miscellaneous brackets, shims, and spacers used in the empennage attach.

Before riveting the rudder stops to the fuse, I decided to make and fit a rudder gust lock.  My design is simple and compact: a piece of 5/32" music wire (a high-carbon steel alloy) bent to a square U shape, that gets inserted one end into a hole in the left rudder stop and the other end into a hole in the left rudder control horn.  The span of the lock is 3", and the "pins" are 2.25" long (somewhat arbitrary).  It inserted from the top, and held in by gravity.  Before making the final bend, I slipped a piece of aluminum tubing (OD: 3/8", ID: 1/4", L: 0.400" ) around the rod that will be held captive when the bends are done.  A key chain ring can then be put through that ring to attach a "REMOVE BEFORE FLIGHT" flag.

Finished the rudder stops and riveted them to the fuselage.  Note a few deviations from Van's plans: Extended the stops aft of the edge of the skin, so that they actually make solid contact with enough material on the rudder horn (many builders have found this necessary).  Extended the material forward to add another pair of forward rivets, because one of the forward rivets called out has already been installed.  Added another pair of rivets at the very aft end of the skin (past the bulkhead) to hold everything together nice and tight (the fit in this area is otherwise loose and sloppy on many RV's).  Beveled the the stop to create a smoother interface with the skin on the forward, aft, and bottom sides (maybe that's worth another 0.1 knot, and it also looks better).  Anyhow, I've spent a surprising number of hours on this little part, but I'm very pleased with the results.

2010.11.10: (0.0) Although I've checked this while I first fit the empennage, I thought I'd take the opportunity again, while I've got the fuselage leveled and the HS installed, to check that the HS is laterally level.  It is.