Europa "egg" door latch.
I've installed a wooden egg to prevent the cabin doors from bulging in flight.
A wooden egg is trimmed and affixed to each door so that as the door closes the
pointy end of the egg inserts into a circular hole in the fuselage. The shape
of the egg draws the door to an exact fit with the fuselage and holds it there
securely.
Here's how.
Buy a wooden egg at your wife's favorite craft store and while you're there get
some modeling clay too if you don't have some already. It takes a chunk about
the size of your fingers tightly squeezed. A glue gun might be the third
purchase.
They're inexpensive and really helpful in all kinds of tasks around the
shop. Hot glue sets much faster than 5-minute epoxy so it's really great for
holding
things in place.
Drill a hole into the fuselage at the center, half way between the shoot bolts
that hold the door closed and centered on the fuselage lip. The width of the
hole
is determined by how far you want the egg to drop into the hole. I used ~
1"circumference so the hole squeezes the egg about a third of the way up it.
To determine what to cut away from the egg to shape it into a plunger put the
egg
pointy side down into the hole you've cut. Warm up some modeling clay and
squeeze
it around the implanted egg. Pull, twist and cajole the egg out of the
clay. Close the door tightly on the eggless clay. This presses the clay and
defines
the space you have between the fuselage and the door. When you open the
door the egg's hole has been squished back into where the egg used to be,
partially
filling the hole. Being an artist, razor out the hole in the clay so you
can place the egg's pointy end back into the clay. Push the egg back into the
clay. With a marking pen draw a line around the outer half to three quarters
of the egg where the clay contacts it. Take the egg out again and close the
door.
Look down through the window and note on the clay where the egg should not
be trimmed so that it will be flush with the inside of the door for added
adhesion
contact. Open the door, push an indent into the clay where the egg should
not be trimmed. Put the egg into the clay, mark the egg's forward and rear side
where you made the indentation into the clay. Take the egg out and freehand
a vertical arch on the egg giving you a cut line.
I used a belt sander to trim the egg to gross fit. Just hold it against the
front
of the belt sander as the sander is held upside down in a vise. The cylindrical
front of a belt sander grinds away most of the wooden egg you don't want.
To fine-trim the egg hot glue it into the hole in the fuselage. Use a dremel
of the door. Close the door gently on the egg while you hold the disclosing
paper in the gap between the egg and the door. Pull the disclosing paper slowly
out thereby leaving a mark on the egg where you need to grind it back. Grind
away where the disclosing paper shows the egg contour is high. When you have
the egg contoured enough to completely close the door feel the bottom of the
door
to be sure it is flush with the fuselage. If it's not, then use a couple of
studs, wooden studs - not masculine buffoons, and some carpenter's wooden door
wedges to squeeze the fuselage-door planes to proper fit.
If your egg is still hotglued to the fuselage twist it out leaving the remaining
hotglue on the surface of the egg so it can be reinserted into the fuselage
correctly. When you're satisfied with how everything goes together, mix up the
smallest accurate batch of Epibond 420 to affix the eggs to the doors. It
doesn't
take much at all. Add a little cotton fiber to make some stiff flox. Paint
some Epibond onto the carved out egg and onto the area on the door where the
egg will be affixed. Smear some Vaseline wherever the Epibond could foul up this
whole project! Put the egg into the fuselage hole, smear on some flox and
close the door. Leave it to dry completely.
Open the door. Use some more Epibond and Bid to secure the egg onto the door. I
didn't glass up the fuselage hole to make an egg-holding cup. I don't think it's
necessary and besides it'd add weight.
The egg solution weighs ounces, has no moving parts and works like a charm. Who
could ask for anything more?
Rob Neils, Ph.D.
A162 Tri-MG
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