FINISHING THE FORWARD FUSELAGE

 

Finishing the forward fuselage is basically the assembly of the structure that holds the fuselage tops and.  This structure consists among other things of the instrument panel, the sub panel, the support structure and the forward fuselage top skin.  in the first two pictures below I have temporarily installed the structure of the upper forward fuselage.   In the left photo below is the instrument sub panel P/N F-7105A.  The instrument panel will be supported by the two frames that are shown in the right photo below.  There will be a third frame in between the two.  Obviously the distance between the instrument panel and the sub panel is such that more than likely the sub panel will get a modified when instruments start getting installed.   

 

F-7105A Sub panel F-7107-L and -R

I have seen several photos of firewalls for the RV 7.  In most of these photos it is obvious that there is a slight forward bend in the firewall at about the level of the upper longerons.  Nowhere in the plans did I find a procedure to put this bend in the firewall (maybe I did not look hard enough).  When I installed the F-7107 frames it was apparent that the firewall needed to be bent.  At first I thought that this timing sucks.  But after thinking about it for a while I decided that bending the firewall at this point are only shouldn't be too tough.  The photo below left shows the firewall from the side prior to bending it.  In the photo below right you can see that I have clamped two 2 X 4's to the firewall and am bending the firewall with a large pair of channel locks.      

Un bent firewall Bending the firewall

 

The photo below left shows the slight bend that is now in the firewall.  The photo below right shows this slight bend from another view. 

 

Side view of bend in firewall View of firewall bend looking aft

The F-7105A also needed to have a slight bend.  I clamped it between a 2 X 4 and the table top.  I then very gently formed the band with my hands (photos below).   I did the same thing  to the outboard sub panels P/N F-7105B-L and F-7105B-R. 

Bending the F-7105A and ............ ...............the F-7105B-L and -R

 

The next thing that I did was to make the F-7108B angle.  it is made from 3/4" x 3/4" .125 "L" Angle.  The bottom leg of the angle needs to be trimmed and bent because it attaches to the firewall at an angle.  The photo below left shows that I put a couple of pieces of scrap in a vise to keep from scratching, gouging or otherwise marring the angle.  The photo below right shows a close up of the banding process .  

  

Bending the F-7108B Close up view

Photo below left shows me checking the proper bend angle on the F-7108B with a machinist protractor.  In the photo below right , the F-7108B is in place on the F-7108A frame (the frame in the center).

Checking the F-7108B F-7108B on the F-7108A

 

Up to two this point the fuselage has been up side down.  I have left it that way as long as possible to make it easier to work on.  Sitting on a roll around seat and working overhead seemed to me to be easier than bending over.  But today I finally decided that it was time to roll the fuselage upright.  In the picture below left you can see that I have made two additional fixtures.  The taller of the two is obviously made to hold the tail.  My neighbor from across the street came over and between him, myself, and my wife we easily rolled the fuselage upright and set it on the fixtures. 

 

Two more fuselage stands The fuselage right side up

With the fuselage upright I cleco'd forward fuselage top skin and two the fuselage structure shown in the previous photos on this page (below left).  Next, I installed the roll bar assembly temporarily (below right).

Forward fuselage top skin cleco'd Roll bar temporarily installed

 

you are probably wondering why I have the skin rolled up and taped back.  The forward flange of the F-7108A is drilled but the firewall is not drilled. I had two choices.  Number one, for all on my back underneath the panel with an angle drill.  Or, number two, roll the skin up and drill standing up.  I chose number two.  Whenever you will the skin like this you have to be very careful for you will put a kink in it at a cleco.  If you look at the photo below right you can see several number 40 clecos in the firewall.  This is where an eye transferred the holes from the frame to the firewall.   

 

Skin rolled back for access to frame Holes in frame transferred to firewall and

While I had the skin rolled back and I clamped the F-7108B to the upper cross brace on the firewall and transferred the holes from the frame to it. at about this time I started looking at the center brace for the roll bar where it attaches to the F-7108A.  It is sandwiched between this frame and and the F-7108B angle.  the problem is that the plans do not call out for any kind of a sham.  They have this part sandwiched between two relatively heavy parts with not a lot of give to them.  Installing this brace this way there will be some serious distortion in the lighter of the 3 pieces,  which is the frame itself.  I decided that a shim was needed between the F-7108A and the F-7108B.  I measured the thickness of the brace and it is .100",  therefore I needed a shim of at least that thickness.   since I do not have any .100" material lying around I made the shim in two pieces.  I made one .063" and one .040" (below right).

F-7108A with F-7108B angle The two shims

 

next I put the skin back down on the right and cleco'd it in place and.  I removed the clecos from the left side of the skin and and walled this skin back.  This allowed me to get access to the F-7108B and drilled the hole where it attaches to the upper cross brace on the firewall (below right). 

 

Left side of skin rolled back Drilling hole from F-7108A to F-601L-1

Below left is a picture of a cleco in the hole where the F-7108B angle is attached to the F-601L-1 upper firewall cross brace.  There is a small angle and that attaches the F-7108A frame to the F-7105A center sub panel.  The P/N is F-7108C.  The photo and below right shows me drilling the rivet holes in the forward flange with a 6in. drill bit.   

F-7108B cleco'd to the F-601L-1 Drilling the F-7108C angle

 

In the two photos below, I am attaching angles to the instrument panel.  Two of these angles get made her drawing 24.   They are P/N F-7103C-L and F-7103C-R. The other two angles P/N F-7103B-L and F-7103B-R come with the kit.

 

Attaching angles ........... ........to the instrument panel 

The instrument panel also gets attached to the F-721A-L and F-721A-R forward canopy decks.  The problem is that the skin needs to be cleco'd down and you need to gain access to the area just inside the skin on the forward canopy deck at the same time.  The way I solved this problem was to take a piece of scrap aluminum and transfer the holes from the upper skin to the scrap at the intersection of the instrument panel and the upper longeron.  The picture below left shows this piece of scrap cleco'd in position.  This allowed me to drill the F-721C and the F-721D angles with out crawling under the panel.  The F-721D angles get bent to a 72.6 degree angle.  The photo below right shows one of the angles undergoing a measurement with the machinist protractor.

Aluminum scrap to simulate top skin Measuring an F-721D attach angle

 

One of the simpler problems that I had to solve was how to hold the angles in place while I drilled the holes.  In the picture below left a bottle of "Super Glue."  I glued the F-721D-L to the F-721A-L while the instrument panel was in place.  I then removed the panel below right and transferred the holes from the F-721D-L to the F-721A-L.  I repeated this process on the right side. 

 

"Super Glue" to hold angle in place Panel removed giving access to holes

Earlier in this assembly I showed a picture of the attachment of the F-7108C to the F-7108A and the F-7105A.  Well guess what?  It turns out that the F-7106 top skin needed to be in place to locate this angle properly.  After I made another F-7108C angle, I took a piece of scrap aluminum, cut it to a "T" shape and transferred the holes from the skin at the intersection of the F-7105 and the F-7108A to it.  I cleco'd this in place (below left).  I transferred the holes from the F-7105 and the F-7108A to this new angle (below right).  Also pictured in the right photo is the F-7109 plate that gets riveted to the F-7108A assembly.  You can see that two of the holes in the plate are considerably larger than the others.  These holes are for two bolts that hold the center brace of the roll bar.  The plate helps transfer the load from the center brace to all of the F-7108A and the F-7108B.  Vans went through a lot of trouble to try to protect the occupants in the event of a roll-over.  After I drilled this new angle I put the F-7106 top skin back in place with clecos.  This time the fit was fine.  

Scrap simulating skin at intersection "New" angle drilled and cleco'd in place

 

The next step was to de-burr all of the parts.  I found a new use for the mini-mill.  I chucked up a the de-burr bit and turned the mill on.  I then held the parts to be de-burred up to the bit and de-burred holes.  This didn't work on all of the parts but it did work on a lot of them.  The box in the picture at right below contains all of the smaller parts that are ready for etch, alodine and prime.

 

De-burring holes on the mini-mill Forward upper fuselage parts to be primed

Before the priming process began I dimpled the skin.  A picture below right shows all of these parts after they were primed. 

Dimpling the F-7106 top skin Upper fwd. fuselage parts primed.