Upper forward fuselage drama [21.5 hours]

I decided to go ahead and assemble the upper forward fuselage, since I had enough cleco’s, I needed a larger priming batch, and it gets a bunch of drilling / countersinking out of the way. It turns out there is a problem with two of the ribs in this assembly, as noted in this VAF posting, and I have the same problem. Either the holes in the front of the F-1045 ribs are incorrectly punched, or the corresponding holes in the firewall are wrong. During assembly, the ribs are first riveted to the top skin. If this is done, then the holes in the front flange will not line up with the firewall.

If the front flange holes are cleco’d to the firewall, there is a 1/8″ gap between the top flange and the top edge of the firewall. I can’t adjust the firewall flange – then the cowl would not fit. I tried cleco’ing down the top skin, and it sortof goes down OK, but the forward most cleco doesn’t actually close the gap between the flange and the top skin. The rest of the skin is “pulled down” to the flange, resulting in the skin curving inward. The front flange holes can’t be re-drilled, the correct position would overlap (just) with the existing holes.

The fix recommended by Van’s is to put a new flange on the front of the F-1045 left and right ribs. I bent up some 0.032″ Alclad to use as replacement front flanges. The pictures show the modification to the F-1045L (left side) rib. I removed the rib and made up a simple frame on the bench that the rib fitted into snugly. This allows installing and match drilling the new flange in the exact same forward position on the rib. I carefully cut the old front flange off, de-burred the resulting edge, and using the bench frame match drilled the new flange into place, finally trimming the bottom of the flange to match the front of the rib.

The rib with replacement flange can then be cleco’d back in place, with a reference line drawn on the flange so it can be sighted through the firewall holes and lined up properly. The front flange is a bit tight because the holes in the firewall are already dimpled. There are seven holes that now have to be carefully match drilled. The rib was removed again, all holes were de-burred, and the front flange holes were dimpled.

Finally, the rib was re-installed, and with the front flange holes now in the right place, the top skin sits flat on the top flange of the rib, and a straight edge held on the skin shows no gap.

With the two F-1045 ribs fixed up, the entire upper forward fuselage assembly can now be match drilled.

  • f13a
    Front flange holes in F-1045 rib are wrong
  • f13b
    Skin pulled down onto F-1045 flange
  • f13c
    F-1045 rib misalignment
  • f13d
    F-1045L rib removed from forward fuse
  • f13e
    New angle to trim and place on front of F-1045L
  • f13f
    F-1045L nested in blocks
  • f13g
    Removing front flange from F-1045L
  • f13h
    Match drilling new flange to front of F-1045L rib
  • f13i
    Match drilling complete
  • f13j
    New front flange on F-1045L
  • f13k
    Ready to match drill new front flange with F-1045 re-installed
  • f13l
    Four done, three to go
  • f13m
    New F-1045L front flange in place
  • f13n
    No more gap - top skin is now straight
  • f13o
    New front flange matches firewall exactly


Bending fuselage side skins [13.5 hours]

The next step in section 29 of the build manual was to bend the four side skins, hit them with a mallet, twist several other structures, and fit everything together onto the fuselage. Sounds simple enough … not.

To bend the skins I made up a clamping block per the plans, finding out in the process that the blade on my ancient radial arm saw was blunt – hence all the burn marks in the pictures. It turns out you really need to apply a lot of grunt to the skins in order to produce the required conical bends. Once I stopped being timid things went better, and the aft skins went on really well. The aft skin match drilling didn’t take long either.

To bend the front skins, I bought a new saw blade and modified the clamping block in accordance with the plans. The front skins seemed a bit more difficult than the aft skins, and I wound up finishing the bends with larger pieces of clamping Aluminium than the plans called for. Both of the front skins went on well. There’s now a fairly long list of match drilling to do associated with the front skins and firewall, before I tear it all apart for de-burring, dimpling and priming.

  • f12a
    Preparing to bend right aft side skin
  • f12b
    Right aft side skin after bending
  • f12c
    Right aft side skin cleco'd in place
  • f12d
    Rear of right aft side skin
  • f12e
    Both aft side skins fitted
  • f12f
    After match drilling aft skins
  • f12g
    Front structure in place
  • f12h
    Front structure in place
  • f12i
    Ancient radial arm saw ready to modify clamping block
  • f12j
    Ripping the clamping block
  • f12k
    New blade rips through hardwood better...
  • f12l
    Rounding off the edge
  • f12m
    Marking bend lines on right forward side skin
  • f12n
    Ready to bend the right forward side skin
  • f12o
    Bending the right forward side skin
  • f12p
    Right forward side skin
  • f12q
    Right forward side skin cleco'd in place
  • f12r
    Left forward side skin cleco'd in place
  • f12s
    Forward skins cleco'd in place

Fuselage stand [5.5 hours]

I built a fuselage stand. Nothing special about it, just something strong enough to hold the fuselage through to the point where the gear can go on. On wheels of course so I can move the fuselage around in the workshop.

The fuselage is quite heavy now that the front and mid sections are together. I thought about using a second person and lifting each side, while a third person moves the workbenches out and the stand in, but thought it would be safer to not rely on grunting humans so I used the tractor for the lift. This was thankfully uneventful, and the fuselage is now on its temporary stand for the next few months as the build progresses.

Now I have my workbenches back – so I can start bending the side skins.

  • f11a
    Fuselage stand
  • f11b
    Universal airframe lifting machine
  • f11c
    Lifting fuselage off workbenches
  • f11d
    Lifting fuselage off workbenches
  • f11e
    Fuselage on stand