FIREWALL AND BULKHEADS PAGE 2

Now that the snap bushing holes are all taken care of, I can work on the other tasks concerning the F-704 center section bulkhead.  But first I just had to cleco a couple of seat bottom brackets in place to see what they look like (LH lower photo).  Enough fantasizing, time to get back to productive work.

Seat brackets cleco’d in place for show only Aileron control attach brackets.

Locating the aileron control support brackets was no big deal.  After they were drilled, I trimmed excess material from the forward flange per the plans.  There was not enough weight saved to make it worthwhile but the look much better.  I etched, alodined and primed them but have not installed them permanently yet. 

Brackets on the forward web Mario and Renatto

The forward web needed to have some brackets installed.  Each bracket has three different sized snap bushings in it.  The outboard brackets are removable and have a re-enforcement riveted to the aft side of the web.  These forward brackets are visible in the photo at upper right, just to the right of Mario.  Mario is the chief pilot of a company that operates a Learjet, Model 35, out of Guayaquil Ecuadoor.  The man behind him is Renatto, his co-pilot.  These guys fly a multi-million dollar business jet and they are fascinated with this little homemade airplane, wow!  They are here for a party.  That is all the work for today. 

Brackets ready for primer My outdoor paint booth

It is Sunday.  The party’s over, I am hung over but progress must continue.  The LH picture above shows the forward F-704 web brackets alodined and ready for primer.  The RH photo shows my outdoor paint booth again.  I miss my paint booth.

The photo at left shows me putting primer in rivet holes for nutplates on the upper flange of  the forward F-704 web.  I am using a cotton swab.  At this point , I am leaning toward priming the entire center section.  These parts have a beautiful gold anodize finish.  No one primes these parts.  I am leaning towards it.  I don’t trust un-painted aluminum.

Priming rivet holes for nutplates.

 

As I debated whether or not to prime the spar carry-through (center section), I decided to at least prime the area between these two assemblies and  the F-704C-L & -R, the F-704D-L & -R center section attach angles.  The two pictures below show these parts.  I masked off the areas that contacted each other and applied the primer with a brush.

Front Spar Primed Rear Spar Primed

In the photo at left below, I am riveting the RH rear center section flange to the aft spar carry-through, or center section as Vans calls it.  The masking tape I installed prior to prime is still in place to protect the parts from damage.  The right picture shows the aft carry-through sub-assembly completed.

 

Riveting the center section Aft center section sub-assembly

Next item on the agenda for the aft center section was to install the nutplates used to attach the floor panels.  Note that I primed each rivet hole as I did on the forward center section.  While I am doing this I know that I will ultimately prime the entire assembly.  Notice that these two photos make the flange look white.  I have been taking pictures for years and there is still a lot to learn about photography.

Aft center section (F-704B) flange Priming the nutplate rivet holes on F-704B

The photo at left below shows one of the center section spacers being checked for length.  These 2 spacers are used on the center section assembly to space the rear assembly (F-704B) from the front (F-704A).  The RH picture shows the two assemblies bolted together with these 2 spacers in between.  These spacers are a permanent part of the assembly. There is a little "c" in the date on several photos.  I am not sure what happened but somehow when I copied and pasted the date on several photos at the same time, some of them ended up with this little "c".  ?????????

F-904J center section spacer Spacers installed

Here are 4 more spacers (below).  The plans suggest that the two center section parts be spaced apart exactly 1 7/16” apart during the rest of the fuselage assembly.  No actual instruction is given on what the material the spacers need to be made out of, though they suggest that you may make them out of wood.  I decided to make the spacers from aluminum so that I did have to worry about heat and moisture changing the dimensions.  Humidity is a big problem in Florida.  The picture at left below shows the 4 spacers I made from thick walled aluminum.  I rough cut them and made them on a Lathe.  The photo at right shows the spacers installed.  I used hardware store bolts for now.  I also only tightened the nuts on the ¼” wing attach bolts and I tightened only barely more than snug.  At this point these two major assemblies are only being spaced out and not attached permanently.

1 7/16” spar simulation spacers Spacers installed. Only the ¼” bolts tightened

Now its time to move onto the F-705 bulk head.  Here you can see the assembly cleco’d together for the initial trial and fit.  As with the rest of the kit so far, everything fit together like a glove.  The first thing that needs to be accomplished on this assembly is to fabricate the center section bar, F-705B, made from AB4-125 X 1 ½ per drawing 20.  The right photo shows the bar in the process of being drilled on the mini-mill.

Trial assembly of F-705 bulkhead Drilling the F-705B center section bar

More fabrication.  The photo at left below shows the F-605C doublers made from the same material as the center section bar.  These in combination with the F-705B center section bar become the rear fuselage to wing attach fittings later.  Some other items that get fabricated for this assembly are the 2 F-705K seat back fittings, the 2 F-705L shims for these fittings, the 2 F-705H spacers f that go between the 2 F-605C fittings and the F-705B center section bar.  Two F-705J angles must also be made.  The photo below right shows the parts of the F-705 bulkhead just about ready to be etched, alodined and primed.

F-605C doublers (rear spar attach) F-705 bulkhead parts ready for prime process

Here is my outdoor paint booth again.  I miss my booth but to be honest, so much of the garage is being used now, I wouldn’t have a place to put it.  Anyway, at this point the F-705 bulkhead parts are etched, alodined, and primed.  At right below is a photo of the beginning stage of the final assembly of the F-705 bulkhead.  Notice that I have two tubs of clecos laying on the bulkhead.  These cleco buckets are being used as weights to help hold the bulkhead so that I stays square while it is being riveted together.  I don’t even need this thing to be twisted for the final assembly of the fuselage.

F-705 parts primed in outdoor “paintbooth” F-705 bulkhead initial assembly

The photo below left shows the F-705 bulkhead is coming along nicely.  The RH picture shows the bulkhead completed.  I spent a few minutes basking in this milestone.  I knew that the center section was going to take shape soon.  The center section ribs form the bottom of the seats.  The pile of blue plastic coated aluminum shapes is about to take on the characteristics of an airplane.  For some unexplained reason this simple square shape fascinated me more than the spar carry-through which is really the anchor for the entire airplane.  When wooden ships were built the first assembly to be constructed was the keel.  The spar carry-through on this machine like that keel is the single most important structural piece of this “ship.”  The F-705 bulkhead is the first structure built that will allow the rest of the “ship” to be attached to “keel.”

F-705 bulkhead assembly continues F-705 bulkhead complete

After a few minutes of admiring the milestone, I could wait no more.  I assembled the seat ribs to the spar center section and then the F-705 bulkhead to check for fit.  From now on every time I set a rivet I will be adding to the shape of the airplane.  It is not like I invented this machine or designed it, however with the addition of each part of it I feel some ridiculous sense of accomplishment.  There have been over 3000 of these things flown and yet I feel the same degree of giddy accomplishment as if I was building the first one.  There is no doubt in my mind now that when and if I ever fly it that will be an ant-climatic event.  Building the bird is what is important.

View of seat ribs cleco’d to the center section Another view of the temporary assembly

Now I have to get out of dreamland and back to reality.  The drudge of “etch, alodine and prime” returns.  Am I taking too much time with this fanatical obsession with treating and priming all of the parts?  I don’t think so.  I intend to place my thoughts on this subject in another part of this narrative, but I will say this here.  All aluminum corrodes.  The best you can hope for is to slow that inevitability down.  Treating and priming the parts is time consuming, but I feel it has its rewards.  The pictures below show the seat ribs and the rest of the bulkhead parts in the process of etch and alodine.

Etch, alodine and prime center section parts Center section parts drying

The picture at left shows the seat ribs and the rest of the bulkhead parts after they have been primed.  I primed these parts in the temporary paint booth that we have at our main hangar.  We are only allowed to spray one quart a day per the EPA so I only paint a few parts at one time.  I usually paint on weekends but if we are not priming other parts at the time, I will paint at night during the week. 

Seat ribs and bulkhead parts