THE FORWARD FUSELAGE

 

 

The first thing the plans have you do on the forward fuselage is to make and install the F-904 attach strips.  These attach the F-704C-L & -R and the F-704D-L & -R vertical angles to the upper longeron.  There were three rivets on each side between these verticals that I had not shot yet. I decided to wait until the forward fuselage was complete before tackling these clips and these rivets because I wasn’t sure how to tackle them.  (See the Cabin section, bottom of page for more details).  I proceeded on to the rest of the forward fuselage first.  Below left is a photo of the bulk of the parts that has to be added to the forward fuselage.  Not shown is the firewall assembly which also will be added in this chapter.   The first thing that I did was to clamp the firewall in.  That brought out the first of many problems to be solved.  The upper longerons were not bent enough.  They would not lay on the top engine mount fittings properly.  I spent a couple of hours bending and re-bending the longerons until I was satisfied that the fit was acceptable.  I used a pair of vice grips and two pieces of scrap aluminum to persuade the longeron to take the shape I wanted it to.  Why did I not use one of the 2 wide mouth straightening pliers I possess?  I left my toolbox in Tennessee and the fuselage is in Florida.  The photo at right shows the reforming process.  It was not difficult to do but it would have been better if I had bent this angle to the proper “toe-in” prior to installing it.  But at that time, I could not figure out a useful procedure to check the proper angle of the forward end of this part.  I struggled through it, however and the upper engine fitting nestles into the inside of this angle pretty well now.

 

Forward fuselage parts Reforming the upper longeron

 

Here is the next problem.  Both longerons are too long.  The plans give you a total length but then they have you trim these parts again.  The line on angle in each photo below is the amount that needs to be trimmed.

 

RH upper longeron trim line LH upper longeron trim line

 

After the longerons were trimmed I put the firewall and bottom skin in place.

 

Firewall in place Bottom skin in place

 

I had to clamp the engine mount fittings in both directions prior to drilling firewall.  The wood is to keep from wrinkling the skin and also to keep from scratching the paint on the longeron.

 

Engine mount fitting clamped to longeron Another clamp on the same fitting

 

While I was tapping the lower skin in to place the fuselage dropped about 1/8".  When I got my heart started again, I realized that this was a wake-up call about the precarious way I had supported the forward end of the fuselage.  I am fairly sure that the center sawhorse would have supported the weight of the forward fuselage by itself but the assembly did move noticeably when I was tapping the lower skin into position with my hand.  I figured that it was about time to get rid of the telescoping roller stand and make something a little more permanent.  I made a new stand for the front from 5/8” interior plywood.  The photo at lower left shows the new stand.  There are more photos in the tool section.  The photo at right is of the level I checked the stand with.  It is level with the rear sawhorse.  Having the sawhorses and/or adjustable roller stands move is one of the fears that I had about having too much of this structure cleco'd and not riveted which is why I deviated from Vans' assembly sequance.  Since a lot of the structure was riveted already I probably was not in danger of twisting any thing when the fixture moved.

 

New fuselage stand Checking that stand is level

 

I worked on the stand quite late on the 10th.  My reward was the second nasty cold I have had since the beginning of the year.  Oh well.  On the 11th I picked up where I left off after I leveled the fuselage assembly.  I drilled the rivet holes in the firewall from the side skin and the bottom skin.  I drilled the rivet holes in the lower longeron (not including the holes in the lower engine mount fittings) and I drilled the holes in the upper engine mount fittings to the upper longerons. 

 

Firewall flanges drilled Upper and lower longerons drilled

 

The photo below left shows the firewall and lower fuselage skin from the inside.  This is really a nice milestone but there is a wagonload of work to be done to finish the forward fuselage.  The next step that I set out to accomplish was to locate the auxiliary longerons, F-713-L & -R, to the F-770 side skin.  After these two parts were drilled I put the F-7101-L & -R in place and began drilling the rivet holes. (Photo below right).  The edges of the F-7101 need to be rounded where they lay in the radius of the F-713 aux. longerons.  The same is true of the lower edge where they eventually lay in the radius of the F-717-L &-R lower longerons.  I did not take a picture of these edges but I did make sure that the edges had adequate radii to insure that they do not “dig in” to the angles. 

 

Inside of forward fuselage F-713-L and F-7101-L in place

 

After the aux longerons are drilled and the F-7101’s are drilled the lower longerons F-717-L & -R can be positioned and drilled.  Clamp them tight to the engine mount attach fitting because there are four bolts that get installed in the horizontal leg of the fitting and the longeron (arrows below right).  Next item is the F-719-L & -R stiffeners.  These parts also get a clip put on the front to attach them to the firewall (next page).  After the F-719’s, come the vertical stiffeners F-902-L & -R.  Vans calls these “bulkheads.” These parts that have a 9 in the number (i.e. F-904) are probably common to the RV 9.  Below left is a photo of the longerons and stiffeners in place.

 

LH longerons, stiffeners and F-7101 Bolt holes in horizontal flanges of longerons

 

Below left is a shot of all of the stiffeners and longerons drilled and cleco’d in place.  Before I tackled the clips at the front of the F-719’s I decided to drill the four stiffeners that help support the lower skin, F-772.  The picture below right shows the left center stiffener F-772B-L in place.  These parts come from Vans with a joggle at both ends.  The larger of the two joggles goes to the front.  The stiffeners were severely distorted at these joggles.  I reworked them the best I could without breaking them but the distortion is still there.  Also the vertical leg of both of the center stiffeners require some trimming at the front to get clearance from the vertical stiffeners on the firewall in the same location.  I did not photo this but it is self explanatory.

 

All stiffeners and longerons cleco’d on LH inboard lower skin stiffener

 

The next part I installed was the left outboard lower skin stiffener.  The part number of this piece is F-722B-R.  This is one of those times that the right hand part goes on the left hand side.  I put the skin in place prior to drilling the 2 holes in each end of the part. (Not shown.)  I did not want to drill the part to the wrong set of holes in the firewall and lower flange of the F-704.  I repeated the procedures for the 2 right hand skin stiffeners.  The photo at lower right shows all four skin stiffeners cleco’d in place.  This portion of the forward fuselage was pretty straightforward.  In all reality the whole project is pretty straight forward.

 

LH inboard and outboard stiffeners All four lower skin stiffeners

 

The 2 F-719B clips are manufactured per drawing 23.  They look simply enough to install but due to their size and the small gap between them and the skin they are complicated to drill.  Not even my angle drill would get into this gap.  After studying the problem I came up with a workable solution.  First I clamped one of the clips in place.  By the way, the front of the F-719 stiffeners need to be trimmed.  They do not fit between the angle on the firewall and the skin.  They need to be trimmed at an angle too.  One of the skin rivets is behind the rear edge of the vertical angle on the firewall.  Photo at left below shows the RH clip  clamped to the angle .  I then drilled a pilot hole in it to the vertical angle on the firewall.  At this point I removed the clip, cleaned it thoroughly and put some “superglue” on it.  I then re-installed  it with the cleco and the clamp.  After about 10 minutes I removed the F-719R with the F-719B glued to it.  (Right photo below.) 

 

F-719B in place with “superglue” & cleco Stiffener with F-719B glued on

 

I drilled two pilot holes where the clip attaches to the stiffener.  (Lower left)  I cleco’d the assembly back on to check for fit.  Everything was OK so I removed the assembly and drilled the pilot holes to #30.  I cleco’d the assembly back on and drilled the hole in the firewall angle to # 30. (Lower right photo).  I removed the assembly once more.  I removed the clip and cleaned all the glue off.  I repeated this procedure on the left stiffener.

 

Drilling pilot holes Assembly cleco’d, holes to final size

 

Well, we’re moving right along.  It’s time to work the F-695-L and F-695-R.  These gussets add strength to the joint where the upper longeron attaches to the upper engine mount attach fittings.  They are pretty straightforward.  In the photo below left it is hard to see but I have one of the gussets drilled.  Before the other one can be drilled it needs to be re-formed a little.  The photo on the right shows me gently persuading the left gusset to take a slightly different shape.  This bend is along the fore and aft leg of the gusset.  The horizontal leg need a little movement also.

 

F-695-L and F-695-R gussets Re-forming a gusset

 

When the angles were just right I drilled the longitudinal rivet holes to #40.   When the part was cleco’d on through these holes it was apparent that there was a gap between the gusset and the lateral angle on the firewall.  This gap was more than one should ignore so I made and installed a shim.  As you can see in the photo below left, the gap is probably at least the thickness of the gusset.  I made a shim from some .063 2024T3 aluminum.  The right photo below shows the shim in place with clecos.  The next step was to drill all of these holes up to #30 for the AN470AD4 rivets that would ultimately be installed.  I did not realize it yet but the most outboard holes on the lateral rows would give me a hard time later.  I repeated the whole process, shim and all, on the left side of the aircraft.

 

Gap between gusset and firewall angle Shim installed in the gap

 

Below left is one more photo of the F-695-R attached with 3/32” clecos.  After this picture was taken I drilled all of the holes to their final size of 1/8” (#30).  I did the same on the F-695-L (Not shown.).  Below right is a picture of the gusset that helps to re-enforce the right lower engine mount attach fitting with the firewall removed. The left fitting gets one too (not shown).  These gussets need some trimming before they are drilled.  The way the dimensions are given for the trimmed off material is odd but if you analyze the dimensions carefully before cutting it works out OK.  I removed the firewall assembly to drill these two gussets.

 

A picture of the F-695-R from below F-684-R installation

 

Below left is a picture of the F-684-L gusset, which helps to re-enforce the attachment of the left lower engine mount fitting.  It is cleco’d to the vertical stiffener on the firewall.  The photo was taken looking outboard with the firewall removed.  The dimension of the trim at the arrow is what was done in an odd fashion on drawing 23.  These 2 parts are ready to prime.  The next step was to transfer the holes in the F-772 lower skin to the lower F-772B stiffeners.  The photo at right shows all of the holes picked up in these four stiffeners.  We are getting closer to riveting but we are not quite there yet.  Mary is starting to ask me every day, "Will we be riveting tonight?”  She is a lot more enthused about this project than she was in the beginning.  I think that is because I got her involved when I needed someone's help.

 

F-684-L after trim F-772 in place. All holes transferred

 

This is a tricky part here.  I ran across the two parts shown in the photos immediately below (arrows) several months ago.  I wasn’t sure where they went at the time for sure, but it was obvious that they were part of the wing attach from the size and location of the holes.  I primed them with some other parts along the way and put them aside.  I had sort of forgotten about them but I spotted them on the storage workbench while I was working on the forward fuselage.  Drawing 23 makes no mention of them.  I thumbed through drawings and plans until I came across drawing 34 title, “Center Cabin Cover.”  Yes sir, that’s where I would put wing attach re-enforcements , on a drawing titled, “Center Cabin Cover.”  Any way I drilled them for bolts per this drawing.  They get attached to the lower longeron with AN3-6A bolts.  These gussets should have been on drawing 11 or 23.  Oh well.

 

F-7114-L (arrow) F-7114-R (arrow)

 

The next thing I tackled was out of sequence a little.  The firewall does not get riveted to the F-770 side skins or the F-772 lower skin until the cowling attach hinges are installed, sometime after the engine is in place.  I decided to put these hinges on now so that the firewall could be riveted to the side and lower skins wet with sealer to prevent dissimilar metals corrosion.  The photo below shows the left lower hinge drilled and cleco’d in place.  Photo at right shows the shim that goes under the hinge.  I drilled both lower side hinges and the 2 bottom hinges to the firewall.  I checked Dan Checkoway's site, www.rvproject.com to get the placement of the hinges.  The cowling drawing was vague.

 

Cowling attach hinge Cowling attach hinge with shim

Press the link, "The Forward Fuselage Page 2" below to read the rest of the narrative on this section.