From "Hints for Homebuilders" EAA Experimenter,
May, 1999
KNOCKDOWN FUSELAGE CRADLE
Chuck Popenoe EAA #179785
While building my Europa, I soon found that supporting the fuselage on boxes or stacked pallets as suggested in the builder’s manual was not very satisfactory. The fuselage must be leveled longitudinally and laterally. It then must remain stable enough so that the normal bumps and knocks received during an extended construction period would not upset the orientation. I began to think about designing a stable cradle which would facilitate all of this work with the fuselage. I preferred that it should also be inexpensive, quick to build, and able to be quickly knocked down for flat storage, ready to be reassembled when needed. I came up with what I think is a pretty slick design, which can be built in about a day for a few bucks, and is both simple and effective!The result is presented in the attached photos which are fairly self-explanatory. This fuselage cradle can be built from one and one-quarter sheets of ¾" plywood and four 12 ft. 2x4 studs. Total cost was less than 30 US bucks, including the ½ inch pipe insulation used for cushioning!! The 2x4’s are dadoed to fit snugly into slots cut into the plywood sections, and can, if carefully fit, be knocked together with a mallet without fasteners in two or three minutes. Likewise, when not needed, it can be disassembled in even less time. It may be rotated by one person to be stable at 0, 60 and 90 degrees to work on the bottom or insides. I have drilled four holes into the bottom 2x4’s to receive discarded chair casters, so that if I want to roll it around, I simply have to roll it over, plug in the casters, and then back upright, and now it becomes a dolly.
Unless your shop floor is much more even than mine, you will need to shim it up a bit to level the fuselage and provide good contact between the floor, the forms and the fuselage. Once this is done, however, it is very stable and the wings can even be plugged in (with support under the first wing, of course). The horizontal 2x4’s make a good step to climb into the cockpit and make engine noises!
I began by supporting the fuselage at the two ends, leveling it on both axes, and taking measurements from the bottom to the floor at four approximate stations, which I had marked on the fuselage. The stations that I used were at 2", 37", 74" and 127" measured back from the front face of the firewall vertical section. Then, box cardboard is fitted to the inside at the four stations, cutting a little at a time until a good fit is reached. It helps if the cardboard is folded vertically in the middle. One side is marked and trimmed, and then the pattern is folded and the other side is trimmed, since it must be symmetrical. These inside patterns are then transferred to the rough cut plywood supports with the bottom coinciding with the measurements previously made from the station to the floor. These are then cut out with a saber saw for a rough approximation, and are then fit to the actual bottom in several successive trimming operations, until there is an even ¼ inch gap between the fuselage and the vertically held support, which will be about right for the 3/8" thick pipe insulation. I then cut dadoes in some short (2 ft) scraps of 2x4 to temporarily hold the supports vertically, applied the pipe insulation and slid the supports longitudinally until they were a snug fit against the fuselage. Then you can take accurate measurements between the front faces of all of the supports and transfer these values to the 12 ft. 2x4’s. Cut dadoes 23/32" wide x 3/16" deep both sides of the 2x4’s at the station marks. It helps to make a 1-1/8" wide slot jig used to get the dadoes even and a snug fit, and also a dadoed short 2x4 for a jig to ensure an even and snug fit in the slots in the plywood supports. (Don’t worry, if your fits are not quite snug enough to not need fasteners, you can always drill a hole and slip a nail in to lock the pieces together).
That’s about it! It took me about a day and a half, most of which was spent in thinking, shimming and fitting. I hope that this work will be of some help to other builders.