Archive for the ‘Bulkheads’ Category

Priming Parts and Bending Longerons – 9 hrs

May 21, 2011 Leave a comment

Saturday May 21, 2011

I was planning to start priming parts first thing thins morning but it was overcast and humid so I decided to wait for better conditions. So next in order is the longerons. Like others, I was a little anxious about bending the longerons. Vans says you need to get this right and it can be “maddening”. So I started preparing by marking the bend lines, top, left, right and overall length. Then after double checking measurements I cut the end to the final length plus about 1/8 inch which i will trim later. I clamped both longerons back to back in my vise and found that there is already a bow to the parts. That will make it more interesting.

Marking and cutting longerons to length

Then the real fun began. I started at the aft most bend line for the shallow curve and began using the Vans method. I applied pressure to the end of the angle and whacked it several times near the vice. Then moved down two inches and repeated. After stepping all the way to the forward bend line I checked the result. It was bent, but not enough. So I repeated, checking the shape of the bend with the drawing template frequently. When it was close to the final shape I checked the twist and it was. So I used a crescent wrench to twist it back. That worked pretty well.

Making the long bend

Then I checked the straightness in the other axis and it was curved downward. So I unbent it using the Vans method. That caused the original bend to relax a bit so I spent the next half hour iterating the shape in each axis until the so called “shallow curve” was “to spec”.

One down and one to go

By this time the sky is clearing and the sun is coming out but I am on a roll so I continued with the second longeron. I think it took about 45 minutes to bend the second longeron shallow curve to final shape. Here are both parts laid back to back.

Big bends complete!

With the shallow curves done I feel confident i can do the other two bends but with the weather now bright and sunny I shifted back to  priming so I can finish the bulkheads.

Given my limited priming space it took almost three hours to get the spray gun loaded and prime all the bulkhead parts. That includes tacking time and multiple light coats.

Lotta parts primed

After lunch and a break for a haircut I started assembling the bulkheads. The F-706 is the most complicated. The vertical channel is partially riveted to the angle. The instructions are unclear but  I may have to drill those rivets out to all the vertical channel to be drilled to the bulkhead later.

F-706 bulkhead assembled

The F-70 and F-708 bulkheads go together easily.

F-707 and F-708 bulkhead assembled

The F-711 and F-712 bulkheads are also pretty straightforward to rivet.

F-711 and F-712 bulkheads completed

Altogether a very good day of progress.

Categories: Bulkheads, Fuselage, Longerons

More F-709, F-710 and F-712 Prep – 3.0 hrs

May 20, 2011 Leave a comment

Friday May 20, 2011

Tonight my focus was to finish preparing for a big priming session tomorrow. First was to dimple the holes in the F-712 bulkheads for flush head rivets and countersink the AEX tiedown.

F-712 parts dimpled and countersunk

Then I deburred and deglossed the F-710 parts.

F-710 parts deburred and deglossed

Then came the F-708 bulkhead. Nothing but deburr and degloss.

F-709 deburred and deglossed

Then I spent the next couple of hours cleaning and drying this rather large batch of parts with simple green and scotch-brite.

Categories: Bulkheads, Fuselage

F-710 and F-711 Bulkheads – 1.5 hrs

May 19, 2011 Leave a comment

Thursday May 19, 2011

Tonight I started by cutting the AEX tiedown extrusion to length and trimming the corners to the final dimensions called out for F-712. Then I laid out markings for the hole centerlines and drilled them to #30. Next I cleco’d the F-712A and F-712B bulkheads together and aligned the AEX tiedown to the centerline and up 7/16 inch from the bottom (all to the plans). After match drilling through the bulkhead it looked like the picture below.

Then I removed the AEX tiedown and tapped the hole for the tiedown ring to 3/6-16 and about 1.25 deep.

Then I dimpled the holes for flush rivets followed by the obligatory deburring and scotch-brite scrubbing. These are almost ready to prime. Oh, I see I forgot to countersink the holes on the back of the AEX tiedown and dimple the mating holes in the bulkhead. I’ll catch that tomorrow.

I also cut the aluminum angle down to length and trimmed the ends for the F-710B. Final step tonight was match drilling the angle through the bulkhead.

Categories: Bulkheads, Fuselage

Picking Up a Few Missed Details – 1.5 hrs

May 17, 2011 Leave a comment

Tuesday May 17, 2011

While trolling a few of the web sites that other RV7/RV7A builders have posted I noticed that I missed a few small details on the bulkhead drawings. That can happen when the instructions don’t mention those details and there is a lot of small notes on the drawings. It pays to study the drawings carefully and compare them to the instructions. But who does that 100%? That’s why I browse other web sites as well as to pick up tips.

There is a snap bushing hole called out on a small detail view on drawing 21 through the F-706B bulkhead for the manual trim cable. The drawing also says you can put another snap bushing in on the opposite side of the centerline for electrical wiring. I don’t know if I will need that hole now but I decided to go ahead and put it in now because I might need it and it won’t hurt to have it there even if I don’t use it. The tricky part is the hole goes through the F-706B and two other parts mounted directly behind it. I tried to drill them all simultaneously but the unibit wants to drift to the side because the flange behind the bulkhead only partially overlaps the hole. So I ended up finishing the holes separately. Here is the F-706B with the F-730 behind it. The ribs are not shown.

Missed these two snap bushing holes last time

After drilling and cleaning up the partial holes with a rotary tool and a file, I deburred the edges again for priming. I had also missed a callout for flush head rivets on the F-706B so I machine countersank the angle and dimpled the other parts as required. Here are all the modified parts.

Parts modified

Before packing it in for the night I started checking the fit of the main longerons to the bulkheads. There are intricate notches cut in the bulkheads but they are too small as delivered by Vans. I got heads up on this from Brad Oliver’s web site. So I started filing the slots out carefully so the longerons will slip in without binding.

Improving longeron fit through the bulkheads

Categories: Bulkheads, Fuselage

More F-711 Work – 1.5 hrs

May 16, 2011 Leave a comment

Monday May 16, 2011

Week nights don’t afford a lot of time to work on the project but I like to try to make some tangible progress as many nights as I can. Tonight I started by tapering the F-711C bars on the F-711 bulkhead as described on drawing 21. I rough cut them on the band saw (man, that new blade cuts way better than the old one), and finished the edges on the disc sander and scotch-brite wheel. Here they are for a fit check on the bulkhead.

F-711 bars tapered

Then I cut the F-711D angle from stock and tapered the ends per the drawing. It was then aligned flush to the top of the bulkhead and centered across the width. Then I drilled two hole from the bulkhead side through the angle.

F-711D match drilling

Then I did the deburr, and deglossing routine to prepare the parts for priming.

Parts deglossed and ready to prime

Categories: Bulkheads, Fuselage

F-706 and F-711 Bulkheads – 6 hrs

May 15, 2011 Leave a comment

Sunday May 15, 2011

It was another good day in the shop. I started by making several parts using 3/4 x 3/4 angle aluminum. Then after drilling one hole in each for initial positioning I jigged up the parts with clecos and clamps to make sure I had everything assembled and aligned correctly. This portion of the assembly is an L shape with the F-728 rib going to the right and the F-729 going to the left in this picture. They each have an angle that attaches to one side of the channel.

F-706 bulkhead parts ready for drilling

This closeup shows the alignment of the F-729C angle before drilling.

Being careful to align parts correctly

Then I match drilled all the parts together including the angles that were fabricated earlier. After that I attached the F-706A and F-706B parts which form the outline of the fuselage at this cross section. I match drilled these parts together and to the L-shaped rib structure that will support the elevator bellcrank. This is going together pretty fast. If I keep this pace up this thing should look like an airplane by 2015.

F-706 Bulkhead fully cleco'd and match drilled

Next it was time to take it all apart again and prepare for priming. Holes and edges were deburred and each part was buffed with scotch-brite to get the surface ready to receive primer. While I was at it I prepared the parts for the F-707 and F-708 bulkheads as well so I can prime those at the same time.

Parts ready for priming

With that done it was too late to try to prime today so I started on the F-711 bulkhead. This one goes at the aft end of the tail cone and includes bars that attach to the empennage. There are two bulkhead pieces that mate back to back and there are two thick aluminum bars that mount to the bulkhead in a V pattern. First you have to cut the aluminum bars to the correct length, then a line is drawn down the center of each bar and they are clamped to the bulkhead so you can see the line centered on the pre-drilled holes in the bulkhead. The end of each bar sticks out a prescribed distance above the top of the bulkhead. Then you just drill through the parts. In this photo one side is already drilled and the other is aligned and ready to drill.

Drilling the bars for the F-711 bulkhead

Next the instructions say to cur out a section of each bulkhead at the top for the pushrod to pass through. Here it is after cutting the material out.

Section cut out for elevator pushrod

Finally, I marked the bars for trimming. This is only for A version tri-gear models. The tail draggers retain the full bar profile.

Bars marked for trimming (next time)

Categories: Bulkheads, Fuselage

F-705 Bulkhead Done! – 3 hrs

May 14, 2011 Leave a comment

Saturday May 14, 2011

My plan today was to finish the F-705 bulkhead. All rivets here can be squeezed so the work went pretty quickly. First step is to rivet the center support bar onto the lower channel. There is one rivet on each end that is under the doubler so you have to start with that rivet before installing the doublers. In this photo you can see that rivet installed. Don’t forget to install the uprights before riveting these together. Ask me how I know. Yes, I forgot at first and had to drill out the rivet to put the upright in.

The first rivet in the F-705B Center Section Bar

The rest of the riveting went smoothly, paying close attention to the holes that should not be riveted at this stage. They will be used when installing this subassembly into the fuselage. The upper channel (bottom in this picture) will not be riveted until the skins are attached.

F-705 Bulkhead complete

With the F-705 completed I switched back to the F-704 bulkhead. My sanding disc was pretty well worn out and I just got a set of three new discs so I had postponed sanding my spacer blocks until I could get a new disc installed. With that done this morning the cleanup of my 1.437 blocks took only a few minutes to complete. Then I located and drilled two 1/2 inch holes in each one for the main wing spar bolts and assembled the F-704 with the temporary wood blocks and the permanent tubular spacers. This assembly looks good (those main spar bolts are a snug fit though) so its ready to put aside until later.

F-704A and F-704B interface check

Before wrapping up I located the parts for the F-706, F707, and F-708 bulkheads and cleco’d those together.

Started F-706, F-707, and F-708 bulkheads

Categories: Bulkheads, Fuselage

Started Riveting F-705 Bulkhead – 2 hrs

May 13, 2011 Leave a comment

Friday May 13, 2011

Today is not your average Friday for me. My oldest daughter graduates from college tonight. So I took the day off from work which gave me the chance to work a couple of hours in the shop this morning. So I started riveting the F-705 bulkhead together. But just before squeezing that first rivet my corrosion conscience got the better of me and I decided to put a light coat of primer on the mating surfaces of the channel and center support bar. Necessary? No, but these parts are structural and they will be at the lowest part of the cabin under the seats and not visible. A little extra corrosion protection here can’t hurt. So I masked the parts and sprayed them with Dupli-Color self-etch.

A little primer on mating faces

Then I riveted the F-705J Angle, F-705K Plate, and F-705L seat adjustment supports to the top of the F-705F channel which is the beam that runs right behind the seats at about shoulder level.

Riveted F-705J Angle, F-705K Plate and F-705-L seat adjustment supports to the F-705F Channel

Categories: Bulkheads, Fuselage

Alodined F-705 Bulkhead Parts – 2.5 hrs

May 12, 2011 Leave a comment

Thursday May 12, 2011

On the way home from work I stopped at Home Depot and picked up a couple of 1x4s to make an alodine tank with.  I made a 4 foot by 4 inch box and lined it with plastic sheet. Its pretty cheapo but it works OK.

Cheapo alodine tank

I decided to drill and dimple the holes on the uprights and doublers that mate with the skins. The instructions don’t mention this but I can’t see how to dimple them after they are riveted together – at least it will be tough.

Drilled and dimpled the uprights and doublers

Then I cleaned all the aluminum parts with Simple Green and water, rinsed, then soaked in alumiprep, then soaked in Alodine solution. Here are all the parts laid out to dry and set before I rivet them together.

F-705 parts alodined

Categories: Bulkheads, Fuselage

More Prep of F-705 Parts – 2 hrs

May 10, 2011 Leave a comment

Tuesday May 10, 2011

More deburring, buffing, and scrubbing of F-705 bulkhead parts tonight trying to get this stuff ready for final assembly. I deburred the lower F-705A channel, the F-705D uprights, the F-705E side doublers, and the upper F-705F channel. I also machined countersinks on the uprights for nutplates and I put in two machine countersinks on the F-705B section bar for flat head rivets although I could have omitted those because I already trimmed the seat belt anchors to clear the rivets. Oh well, stick to the plans.

Continued parts prep

I started applying alodine to some of the small parts to get those done and out of the way. I need to make a tank or a bath of some sort to process the larger parts. I’m getting this process down pretty well now. I’m getting nice uniform coverage at just the right color (i.e. coating thickness). We will see how it goes when I start processing bigger parts in a shallow bath.

Started applying alodine with these small parts

The flap bearing blocks are match drilled to the pre-drilled holes in the uprights. I measured the hole spacing on the upright first, then marked approximate center marks on the bearing block at that spacing so I could see the marks through the holes in the upright. Then I clamped the parts together using the center marks to make sure I had the blocks aligned parallel to the upright and centered. Then I match drilled a shallow hole into the bearing blocks to locate the hole centers. Then I unclamped the parts and put the bearing block under my drill press to complete the drilling through the full depth of the bearing to make sure I had the hole true and perpendicular to the block face. That all worked fine except I used a #12 drill (.189 dia). The plans call for a #10 (.194 dia) because the plastic flexes just enough that a AN3 bolts won’t go into a hole drilled with a #12. I’ll have to see if I can find a #10 drill somewhere.

Flap bearing blocks match drilled

Categories: Bulkheads, Fuselage