Archive for May, 2011

Fitting the F-623 Corner Rib – 2 hrs

May 31, 2011 Leave a comment

Tuesday May 31, 2011

Tonight I set about to fit and drill the F-623 corner ribs. I studied the plans on this a while because they are certainly not clear on what to do and where to do it. I ended up following the lead of Jason Beaver who has some pretty clear pictures on his web site. First I cut the ends of the left F-623 corner rib to be flush with the F-705 bulkhead in the front and half way between the skin holes in the aft end. For alignment I just made sure the outboard edges of the rib were flush with the edges of the skin and the elbow of the rib lined up with the corner of the skin. I had to flute the rib a little to get it to lay flat to the skin. Then I measured and made the doublers out of scrap .032 aluminum alclad. Here is the aft doubler plate after I drilled through the skin from the far side. It is a little bigger than shown in the plans to give a little more edge distance on the small end.

Here is the forward doubler after I drilled through from the far side. It is also little bigger than shown in the plans to allow all five holes to be picked up, not just the three on the left.

In this shot I have drilled through all the skin holes and this side is done. I made the doublers for the other side and trimmed the rib the same way but I did not have time to drill it tonight.

Categories: Center Section, Fuselage

Assembling the Center Section – 6 hrs

May 30, 2011 Leave a comment

Monday May 30, 2011 (Memorial Day)

Major big progress today on the center section. I didn’t really expect to get as far as I did in one day. I started by drilling out a few holes for snap bushings. The placement of these are all described on the drawings.

Then I fluted the F-716 seat ribs along the bottom flange. At this point its hard to tell if the top flanges need fluting so I will wait to see. Then came the big fun of clecoing nearly the entire center section together starting with the ribs to the F-704 and F-705 bulkheads with the F-916C spacers at the appropriate locations.  Then came the F-725, F-726, and F-727 baggage ribs. Here is a photo. This thing looks impressive!

Next I turned it over with some help from Denise so I could put on the bottom skin.

Here is the skin cleco’d in place and all the holes have be drilled through.

Next I flipped it back over onto the bench and here is where I departed from the assembly order in the plans. The plans say “the skin holds the F-715 and F-716 seat ribs in correct alignment” but that is clearly not the case for the F-715 ribs. In fact the F-715s are unusual in that they will be curved to match the curvature of the side skin. I say “will be” because you have to flute them to achieve the right shape – and there are no pre-drilled holes in the bottom flange to force the ribs into correct alignment. Well looking further ahead in the plans it says to draw a centerline down bottom flange and align that to the pre-drilled holes in the skin. So I placed the rib loosely on the skin and marked the locations of the skin holes along the side of the rib. That is how I knew where to flute the rib so I didn’t make a depression right where a hole is located.

Then I fluted the rib to match the curvature of the skin hole pattern so the centerline was visible through the holes with the rib cleco’d in place.  The last hole or two on the forward end were off the centerline a bit because the rib joggle at that end doesn’t quite put the center of the flange at the hole center but I assume that is OK since that is how the rib is designed.

I also had to trim about 1/8 inch off of the forward end flange of the rib because it was too long overall and it jammed up against the inside radius of the bulkhead. Then I drilled through the skin and the rib flange. Here is a shot showing the left F-715 outboard rib after drilling. I hope I don’t come to regret doing this out of order. It is possible I am not aware of some other reason to do it later.

Then I drilled through the flange of the F-704H side doublers, F-704 bulkhead and the F-715 rib forward flange.

Here is the assembly after both F-715 ribs were aligned the same way.

Categories: Center Section, Fuselage

Finished Drilling Aft Fuselage (Almost) – 5 hrs

May 29, 2011 Leave a comment

Sunday May 29, 2011

I intended to start back drilling the aft fuselage skins and bulkheads first thing this morning but as I gave everything a final look-over I wasn’t happy with the shape of the side skins in the F-711 and F-712 area. The surface had a visible wave between those two bulkheads that I could really see when I put the rudder stops in place. After studying it a few minutes I discovered that the flanges of the F-711 and F-712 bulkheads needed to be bent to follow the angled contour of the skin. So I spent the next hour or so removing the F-711 and F-712 bulkheads and aft bottom skin and I bent all the flanges to match the angle that the skin passes the bulkhead. Wish I had done this before clecoing this together the first time. Here is a view of the flanges on the F-711 after tweaking.

Tweaked flanges on the F-711

When I put it back together again the skin wave was almost entirely gone and the rudder stops now sit flush to the skin so I guess it was time well spent.

Side skins lay much flatter now

Then I went back to the baseline plan and match drilled all the skin to bulkhead holes except the F-706 which the plans say will be drilled later. Here it is. It doesn’t look any different than it did before I drilled it.

Skins and bulkheads drilled

At this point I would be ready to take it apart and prep the skins for riveting (deburr and dimple) but I intend to install a Dynon pitch servo in this thing and it will be easier to do it now since it mounts to the bellcrank support rib and is match drilled to the bottom skin. Unfortunately it snuck up on me and I did not realize it needed to be done until this week, so I placed and order for a pitch servo and mounting kit and it should be arriving next week. So I will hold here on this assembly until then and continue working on the center section in the mean time. That is why drilling is “almost” done.

So the next step on the center section was to make two additional F-716B access plates for the seat ribs. The kit has two of these but builders say it is easier to remove the control column if you install four so following the pack I marked off the outline of the two plates on a piece of scrap .063 aluminum.

Making two more F-716B seat rib access plates

Then I cut out the rough profiles with the band saw, clamped them together and finished the edges with the belt sander to end up with four that match.

Sanded to the final shape

Back to the plans, I modified one of the seat ribs to enlarge the cutout with a 0.75 inch radius at the top as you can see here comparing one of the unmodified ribs. Then I marked the cut lines on the rib which the access plates will span.

Modifying the F-716 seat ribs

Here is how I modified the ribs. Instead of using a hole cutter in my drill press I just drilled an array of #30 holes around the inside edge of the cutout line and cut the excess material out with a cut-off wheel on my rotary tool. Then I filed the flat edges flush and used a small drum sander on the rotary tool to clean up the radius.

Shaping the hole the "hard" way?

After cutting the rib it looks like this with the access plate cleco’d on.

One down, three to go

Here is the set of four modified ribs.

Seat ribs modified for control column access

Drilled J-Channels – 4 hrs

May 28, 2011 Leave a comment

Saturday May 28, 2011

At the crack of dawn this morning I started work again on the fuselage. But since I didn’t have a plumb bob yet I started on the first step of the center section which is to make four P-916C spacers from aluminum bar stock. My new band saw blade cuts so much better than the old one it was breeze to knock these out.

F-916C Spacers

Then I made the two F-963 rudder stops. I still need to drill the holes in these.

Update: I learned later that it was a waste of time making these stop now because I had to remake them on March 17, 2012 when I installed the rudder on the fuselage and discovered that the rudder travel with these stops was too large.

Rudder stop angles

Later I went to Harbor freight and picked up a few things including a nice pointy plumb bob. Here you can see how I put it to use on the forward end of the aft fuselage. After a small adjustment to level it, this side looks good.

Checking plumb on the fwd end

On the other end it took another small adjustment to get it vertical.

And plumb on the aft end

With that I started drilling the J-channel stiffeners. I thought this would go fast but it took longer than expected. There are lots of holes and the stiffeners are not straight and require tweaks to keep the holes aligned to the center line.

J-channels drilled

Here is a picture of one of the stiffeners from the inside. You can see the holes along the flange.

Interior shot of a J-channel

Categories: Aft Fuselage, Fuselage

Tweaking Aft Section – 2 hrs

May 27, 2011 Leave a comment

Friday May 28, 2011

Tonight I worked on improving the fit of the aft bottom skin to the side skins and the F-711 and F-712 bulkheads. As many have reported, the aft bottom skin is thick and comes under bent in the kit. The upper edges don’t want to lay down flush against the bulkhead and it causes the side skins to lift up. So I endeavored to improve the fit by removing the aft bottom skin and working the bend radius. This was a pain because the fit is tight all over and removing and replacing all those clecos is somewhat difficult.

At first I tried to bend the aft bottom skin tighter with minimal success. Then I used my hand seamers to bend the skin inward slightly along a line at the edge where the side skin overlaps. That helped the most I think. When I put it all back together the side skins now tucked up much tighter against the surface of the aft bottom skin as I think you can see in this picture. Click on it to zoom in.

Aft bottom skin fit much improved

Now I am about ready to start match drilling but first I need a good plumb bob that I can use to check the straightness of the assembly. I’ll pick up one of those tomorrow at Harbor Freight.

Categories: Aft Fuselage, Fuselage

Assembling Aft Fuselage – 3 hrs

May 26, 2011 Leave a comment

Thursday May 26, 2011

Well assembling the aft fuselage turned out to be quite a pain. As others have reported, some of the parts don’t fit together perfectly and getting some of the holes to align, particularly at the aft end, was tough. I spent the better part of three hours getting it together and trimming the j-channel stiffeners to fit the bulkheads. I still plan to do a little more work on the aft bottom skin to make it fit more flush to the side skins.

Aft fuselage assembled

My neighbors are starting to give me double takes when they look in the garage and see this thing.

Another view

My approach to the J-channel stiffeners was to trim the forward end per the drawing dimensions, then insert the stiffener and mark it in place for trimming at the aft end. I did this because I was not sure how the aft ends were supposed to be trimmed. After inserting I could see from the mating parts how they needed to be trimmed. Here is one of the forward ends.

Forward end J-channel trim

Categories: Aft Fuselage, Fuselage

Began Aft Fuselage Assembly – 1.5 hrs

May 24, 2011 Leave a comment

Tuesday May 24, 2011

After getting home later than usual I was ready to start aft fuselage assembly. But the fuselage shipping crate was taking up too much room in the garage so I spent the first 45 minutes breaking down the crate and moving the pieces out of the garage. With that done there was room to set up two saw horses and start clecoing the aft fuselage pieces together. This is the fun part – seeing big pieces come together. At this point with only the bottom skin cleco’d to the bulkheads it’s pretty flimsy. I assume it will stiffen up when the side skins are cleco’d on.

Aft fuselage assembly begins

Categories: Aft Fuselage, Fuselage

Finished Longeron Bends – 1.5 hrs

May 23, 2011 Leave a comment

Monday May 23, 2011

Feeling mentally prepared tonight, I dove into bending the sharp downward bends on the longerons. I started by using the Orndorff method (search the Vans Airforce site on Orndorff) where both longerons are clamped back to back in the vice and you simply pull one from the end sideways until it is 2.75 inches from the other longeron. Then you pull the other the other way until its 5.5 inches from the first. The problem was after the first bend on the left longeron I found that the curve was spread out over about 3 inches instead of being localized at the 28 1/4 inch line. As a result when I put the longeron up against the skin the bend did not track the edge of the skin as well as I wanted. The skin line is completely straight right up to the 28 1/4 line where it jogs 5.6 degrees. So I used the Vans method to bend the right longeron with better results. By applying preload to the longeron and whacking it with a mallet the bend is more localized at the point where the longeron is clamped in the vice. In other words, the bend is sharper.

Sharp downward bend on right longeron

So after getting better results on the right longeron I went back and partially unbent the left longeron and rebent it with the Vans method to localize the bend at the 28 1/4 line. So it turned out fine in the end. Then I used a large crescent wrench to put the 17 degree twist into the first 28 inches of each longeron. As a check, I clamped both longerons back to back and placed them on the floor to see how well the two profiles matched. The curvature upward from the floor is due to the shallow bend, then the Y-split is due to the sharp downward bends. They match as mirror images surprisingly well.

Both longerons back to back

Then I marked and trimmed the F-721B aft deck extrusions for trimming as illustrated on the drawing. Be careful here because the tip-up and slider required different trimming.

F-721 B aft deck marked for trimming

Here is the right F-721B after trimming. It matches the picture on the lower right. I also trimmed the left F-721B.

After trimming

Last but not least was cutting the j-channels to length as shown on the drawing. This is in preparation for starting to assemble the tail cone of the aft fuselage.

J-channels cut to length

Drilled F-721 B Aft Deck – 2 hrs

May 22, 2011 Leave a comment

Sunday May 22, 2011

After a good long day on the project yesterday, today was comparatively brief. I had tickets to the Angels game today so Scott and I went to see them beat the Atlanta Braves 4 to 1. Seats were directly behind home base, 2nd row up from the field. Sweet! Thanks Desi!

But on the project I aligned and match drilled the F-21B aft deck parts to the longerons. Most of the time was clamping a couple of scrap pieces of .032 aluminum sheet to the outboard edge of the longeron to simulate the skin and aligning the F-721B to be flush with that and 28 1/4 inches back from the front edge. Then I just drilled through the F-721-B holes. Here you can see the set up.

Match drilling F-721 B aft deck to the right longeron

And here is the completed set. I did the same thing on the left longeron as well.

Match drilled and cleco'd

Categories: Fuselage, Longerons

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