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Archive for the ‘Fitting Empennage’ Category

Mostly Canopy Stuff – 4 hrs

April 28, 2012 Leave a comment

Saturday Apr 28, 2012

Today I completed a number of tasks leading up to the final alignment of the aft canopy frame to the roll bar and the forward canopy frame. I marked locations for and drilled holes for the C-613 splice plates that join the side rails to the canopy frame weldment. There is one hole in each plate that would be very close to  existing holes in the F-702 skin so I left out those holes. You can see that in the photo below.

I also made the C-731 lift handle which will mount to the left side of the canopy. I rounded the corners a bit to make it more sleek than the stock design.

Then I located and drilled the pilot holes in the WD-725 side rail weldments for the attachment to the bow frame.

I finally started mocking up the avionics layout on the instrument panel today. I started with the main instruments; a 10-inch Skyview PFD, a 7-inch Skyview backup display, a PS Engineering audio panel, SL-30 radio, and GTN-650 WASS GPS. That really starts to put some context to the cockpit.

Next I made one of the C-723 wedges. These things are a pain in my opinion. I messed up the first one when it go sucked down into disc sander which I was using to trim down the material from a 3/16 inch piece of stock. The piece is small and gets hot really fast so I had to keep dunking it in water to cool it off.

The second try turned out pretty well. You can see the wedge slipped in under the left edge of the splice plate in this view. I still need to finish the second one for the left side.

I also installed the three rivets in the F-712D elevator stop on the aft deck. I had a note to myself to finish that since the day I removed the vertical stabilizer.

So work this weekend was somewhat productive but intentionally a little slow and non-committal on the aft canopy frame alignment. I have been making the parts I will need but not drilling things together. That is because I have been researching the options on mounting the canopy. Basically the decision is to screw or bond the canopy to the frame. Screwing is the Vans standard method but I don’t like the increased risk of cracking the canopy with all those holes and stress points. I also like the clean look of the Sika Flex approach along the bow frame son I am leaning that way but as yet not committed. Each approach has implications on the alignment of the frame components.

My options are:

1) Screw the plexiglass canopy on according to the standard method. This approach requires no modifications for mounting – just follow the plans.

2) Use Sika Flex to bond the canopy to the bow frame and front deck but use screws on the side rails. This will require modifications to the bow frame to allow 1/8 inch minimum bond gap.

3) Use Sika Flex to bond the canopy to the bow frame,  front deck, and side rails. This method requires modifications to the bow frame and the side rails to allow 1/8 inch minimum bond gap.

Some builders ignore the 1/8 inch bond gap recommended by Sika when attaching to the side rails but I am not sure that is a good idea. The joint in question is shown on this view for the standard mounting. The option 3 modification would be to offset the side rails inboard by 1/8 inch to provide space between the rail and the inside surface of the canopy where the Sika bond will go in place of screws.

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More Empennage Fairing Trimming – 1 hr

March 20, 2012 Leave a comment

Tuesday Mar 20, 2012

Tonight I only had about an hour to spend on the project so I did some more progressive trimming of the empennage fairing.

The Proseal from last night was still soft because it has been cold in the garage. I’ll give it more time to set up.

Empennage Fairing and NACA Vent – 4 hrs

March 18, 2012 Leave a comment

Sunday Mar 18, 2012

I continued work on the empennage fairing today. Here is a shot of the notch I cut for the elevator bellcrank tube tube. I iterated this notch until I got 1/4 inch clearance on both sides. Cutting fiberglass sure throws up a lot of dust.

I also took a small amount of material off the front where the vertical stabilizer leading edge mates. This was to try to get it to mate more tightly at the leading edges of the horizontal stabilizer.

Underneath the vertical stabilizer is a gap fairing called the F-794. Unfortunately I have to drill out five rivets on each side for this part. I don’t recall any mention of this in the fuselage plans when I riveted the longerons to the side skins. It would have been nice. Anyway, I had to trim about 1/4 inch off the upper edge in some areas of this part to achieve 1/8 inch clearance to the vertical stabilizer bottom skin which is for the rubber seal that you see inserted in this view. I got the left side trimmed and fit but I still need to do the right side.

I started drilling the fairing mounting holes to the empennage at the leading edge and worked aft. The first hole was marked and drilled with the fairing pushed flush against the vertical stabilizer leading edge. The holes in the vertical stabilizer are already drilled so I had to sight through the fiberglass fairing which is semi-transparent enough to spot them.

Then I just continued aft one hole at a time to drill and cleco to the vertical stabilizer holes. I used electrical tape to mark a trim line about 1/2 inch from the holes. The tape allows me to define a nice smooth curve which I’ll use to mark a line for trimming.

Back on the NACA vent installation, I located and marked the position for the right side NACA scoop and prepared the surface of the fuselage skin for Proseal. I also sanded the mating surface of the plastic vent scoops to give them good surfaces for bonding. I did not bond them today because it was really cold in the garage plus I wanted to think about painting these before installing.

Oh, I also made eight little doublers from .025 aluminum sheet for the vent scoops so the rivets don’t compress down into the plastic.

Aligned Rudder and Remade Stops – 8 hrs

March 17, 2012 Leave a comment

Saturday Mar 17, 2012

First order of business this morning was to get the hinge bolts installed on the rudder. When I originally installed the hinge bearings on the rudder I aligned them to the dimensions shown on the rudder drawing. When I installed the rudder two days ago I could only get two hinge bolts in. The third bearing was significantly misaligned. Oddly enough the written instructions in the fuselage section tell you to initially set the hinge bearings to dimensions that are different than the rudder drawing. So I removed the rudder and reset the middle and lower bearings to the dimensions specified in the instructions. When I reinstalled the rudder the two upper bolts went in easily but the lower one was still off but not nearly as much as before. That’s when I remembered that I had not installed the washer between the vertical stabilizer main spar and the aft bulkhead of the fuselage on the left side to account for the .25 inch left twist of the rudder. So I unbolted the vertical stabilizer spar and inserted the one lone washer between the facing surfaces and bolted it back together. To my amazement, the hinge bolt then slipped right into the lower bearing. And the rudder now operates very smoothly.

Next up was installing the rudder stops I pre-made a long time ago and checking the angle range. Well like many other builders I found that the stock dimensions of the stops allows significant over-travel of the rudder. The distance from the rudder to the corner edge of the elevator is supposed to be 1 – 1/8 inch. As you can see in this photo the distance was more like 0.4 inch.

So I set about to remake the rudder stops. After making a few measurements I ended up with a new left stop that is about 0.2 inches longer than the original stock stop. In this photo the new left stop is placed back to back with the right stock stop for comparison.

With the new stop installed the distance is right at the 1 – 1/8 inch mark as desired. It’s a little tricky understanding this photo because the rudder is so reflective.

So made a similar stop for the right side and I drilled them to the fuselage at all four holes. Here you can see the left stop installed. I still need to prime these new stops and rivet them on.

Then I started fitting the empennage fairing. Back to messy fiberglass work. I had to trim the aft end to clear the elevator bellcrank tubes but you can’t really see that in this picture. There is going to be a considerable amount of work to get this part completely installed.

I also worked on the alignment of the trim tab. Last time I drilled holes for the Wd-415 in the wrong place in the E-616PP cover plate. So today I made a new cover plate out of 0.025 stock. It was a piece of cake and only took about 20 – 30 minutes to complete. Then I played with the alignment of the Wd-415 on the trim cable to get the desired +25/-35 degrees of trim flap motion. In this photo you can see it in the full up position although I understand that I will never need anywhere this much deflection in actual use.

Then I moved on to the NACA vent installation. Some people just use Proseal to hold these on. I feel more comfortable with a few rivets to add a mechanical attachment in addition to proseal so I drilled four holes in the flange of each vent. I placed the vent on the fuselage and aligned it by eye at the outside opening then marked the perimeter of the flange on the inside. I put electrical tape around that outline and then removed the primer with a combination of MEK and scotchbrite. Here is what the left one looked like after preparing the surface.

Then I put the left vent back into place and match drilled through the NACA vent flange and the fuselage side skin. I dimpled the skin holes and countersank the flange of the vent. Here is the left side ready to be bonded with Proseal.

Finished Drilling Vertical and Horizontal Stabilizers – 1.5 hrs

March 15, 2012 Leave a comment

Thursday Mar 15, 2012

I got some help from my daughter Jennifer and her friend Joel tonight as I finished drilling the vertical and horizontal stabilizers to the fuselage. In order to drill the holes on the lower portion of the vertical stabilizer rear spar I had to take the elevators back off. Then I could just barely get the 90 degree angle drill down into the cavity and drill through the rear spar using the pre-drilled holes in the AEX tiedown bracket. I always worry about getting the holes perpendicular to the surface with this drill but they turned out fine. I drilled with a 1/8 inch bit first to make pilot holes through the spar, then I opened up the holes from the outside with a #12 bit for the AN3 bolts. We put bolts with temporary nuts in those holes.

Then we marked the locations for and drilled the holes through the aft spar of the horizontal stabilizer. I used a 12 inch long #30 drill first to make pilot holes then opened those up with a #12. For the two lower holes I had to drill from the front side with the #12 because the vertical stabilizer was in the was from the rear with the shorter #12 bit. In this photo you can see only the left side because the vertical stabilizer is in the way.

Installing the rudder was a challenge. Our initial attempts to get the bolts in were frustrating until I realized that I had never chased the holes in the brackets with a #12 drill to clean out the powder coating. After I chased the holes we got bolts into the upper and lower bearings but the center bolt would not go in because the bearing alignment is a little off. Next time I’ll have to determine if the center bearing needs to be adjusted aft or one of the other two bearings need to be adjusted forward. That’s Jennifer posing with the rudder.

Drilled Vertical Stabilizer – 2.5 hrs

March 13, 2012 Leave a comment

Tuesday Mar 13, 2012

I was all set up to drill the F-781 attach plate to the vertical stabilizer tonight after getting it aligned yesterday. I double checked the vertical stabilizer forward and side to side to side tilt and then began to drill through the pre-drilled holes in the F-781. After drilling four holes with the 90 degree angle drill because of the limited space I noticed that the edge distance on the F-781 at the lower edge where the holes will be drilled through the horizontal stabilizer front spar  looked suspect. So I measured as best as I could and concluded that the edge distance would be well under the 3/8 inch called for with AN3 bolts. So I stopped drilling to consider the options.

Not wanting to take a chance with the strength of this joint I decided I had two choices; shift the F-781 down and abandon those four holes in the upper joint and drill four more slightly shifted from the originals, or make another F-781 plate. Since I had nothing to loose by trying I removed the F-781 and marked and drilled four new pilot holes offset from the originals. The stock holes are pretty far apart so the new holes are not that crowded. However, after looking at the resulting pattern I decided to go ahead and make a new F-781 since I had .063 thick 2024-T3 stock on hand. It took about an hour to make the new plate and bend it. The hardest part was the bending since I don’t have a bending brake. I used a bench vice, and block of wood and a hammer. But it turned out almost exactly matching the stock plate. I transferred the locations of the original holes to the new plate except for the ones that were already drilled in the vertical stabilizer spar which I will drill from the aft side using the stabilizer holes as the guide. The old and new F-781 plates are shown below. The crossed out holes are the ones I did not want to transfer to the new plate.

Then I clamped the new F-781 plate in and aligned the vertical stabilizer again, double checking the side to side and fore and aft tilts including making sure the rudder hinges are all in a straight line. Then I drilled again. I drilled two rows of holes in the upper section and I drilled through the horizontal stabilizer for the AN3 bolts that attach the F-781.

I installed free-running nuts temporarily to secure it all together.

Then I drilled the holes in the elevator up stop that secure it to the longerons. I secured that with AN3 bolts and nuts.

Fitting Vertical Stabilizer – 4.5 hrs

March 11, 2012 Leave a comment

Sunday Mar 11, 2012

Since I plan to call Vans on Monday about my concerns over the tooling hole measurements on the horizontal stabilizer I decided to move on to the vertical stabilizer. I had to rearrange the fuselage in the garage to get it so I could clamp the vertical stabilizer to the fuselage without it being hit by the garage door. Boy, I love that 3-car garage. Here is a photo after I mounted the vertical stabilizer for the initial alignment.

First I adjusted the vertical position of the aft spar to the dimension from the longerons down to the top of the lower hinge at 7 – 11/32 inches and I clamped that in place. Then I deburred and clamped in the F-781 attach plate which holds the vertical stabilizer forward spar to the horizontal stabilizer forward spar. Then I measured the distances from the ends of the horizontal stabilizer to the top tip of the vertical stabilizer to make sure it was perpendicular to the horizontal stabilizer. The two distances initially were initially only off by about 1/16 inch so the adjustment to make them match was simple. There is a small gap between the vertical stabilizer front spar and the attach plate so I made a .063 shim to go in that gap. You can see it in the picture below.

Then I made the F-712D up elevator stop from a piece of aluminum angle stock including drilling the pilot holes.

Then I aligned the F-721D in front of the vertical stabilizer aft spar on the aft deck and drilled through the vertical stabilizer spar using a #30 in my 90 degree angle drill. First was the hole on the left which I clecoed after drilling.

This next shot is just a view from the back so you can see how the spar is clamped.

Then I drilled the other hole the same way then opened each one up to #12 for an AN3 bolt which I installed temporarily with some non-locking nuts.

Then I located a marked a line down the centerline of the fuselage aft top skin using the rivet holes as my reference. I also drew a line 1/4 inch to the left of centerline which is where the vertical stabilizer should be aligned to counteract P-factor. And not to forget the check of the straightness of the vertical stabilizer aft spar, I used a long piece of straight steel pipe against the back of the hinge brackets and adjusted the clamp on the attach bracket to get the spar straight. You have to raise the nose of the vertical stabilizer enough to counteract the weight hanging on the aft spar.

After a number of minor tweaks and adjustments it looks like the forward spar attachment is ready to be drilled.