Doing it this way allows you to sand blast and prime inside the flange to prevent corrosion. During the covering process, the flange will be fabric covered.
The passenger side door flanges are made the same way except the vertical
flange at Station D/N is more of a "J" shape (if you are making the cargo
door). This is because it serves as the rear of the main door and the
front of the cargo door. Previous plans had this flange formed into
a complete"U". Later, the plans were changed to reflect an "L" shape
like on the pilot's side but with a 5/16" flange. as shown below:
Doing it this way allows you to sand blast and prime inside the flange to
prevent corrosion. During the covering process, the flange will be
fabric covered.
Here is the same door flange from the front:
As you can see, it looks just like the pilot's side.
Now we'll get started on the door flanges for the cargo door.
The aft end of the cargo door has a flange formed to blend with the two stringers
that will be there. The plans show the height of each bend area and
the width of the flange from the centerline of the fuselage. The first
bend is located 12" up from the center of the bottom longeron (at Station
F/L). This was measured and a mark made at the 12" point:
A plumb bob was dropped at the fuselage centerline from the top cross tube
of station L. The plans indicate the distance from the fuselage centerline
out to the bend at the 12" height as 16". Using a tape measure, the
flange width was calculated as shown below:
As you can see above, the flange at this point needs to be 1 3/4" wide (the
distance from the tube to the 16" mark).
The next bend of this flange is 22 1/4" above the center of the bottom longeron.
At this point the outer edge of the flange should be 16 1/4" from the
fuselage centerline. Again, measuring from the plumb bob line at the
fuselage center, the flange width was determined as shown below:
As you can see, the flange width at this point needs to be about 2 1/4" (the
distance from the tube to the 16 1/4" mark).
With these measurements, we can layout the aft cargo door flange on the .032" mild steel sheet. Enough extra was included to make 9/16" flanges.
Here is the aft cargo door flange after forming it from one piece of metal:
The flange has been notched to fit at the tube locations.
Here it is clamped to the fuselage and ready for skip welding:
As you can see in the above picture, the flange was properly aligned by clamping
a piece of aluminum angle and a straight edge to the flange and across to
the tube on the opposite side.
As a double check, the flange was again measured from the plumb bob line
at the fuselage centerline, to make sure the measurements are
met:
Note: When we install the two stringers on the opposite side of the airplane,
we will make sure that they are same distance from the fuselage centerline
(16" and 16 1/4"respectively) as this flange at these points.
Click here to go to Door Flanges page 4
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