|Now the bottom wings are set to the
proper dihedral angle using a level. This adjustment was made by
tightening or loosening the landing wires. Do you remember
where I said that I didn't like the method that we leveled the fuselage?
Well, this is why. We set the angle perfectly using the bubble level.
Later, we used a smart level and found that the wing dihedral angle was
off by two degrees.
Click Here's a quick story about bubble levels.
My cousin is a highway engineer working for the state highway department.
His responsibility is to check each job, mostly bridge construction, to
ensure the work is going exactly to plan. One day he went to the
hardware store and was checking bubble levels for accuracy before he bought
one for his personal use. He would place the level on a shelf and
look at where the bubble was in relation to the marks. He would then
turn the level around 180 degrees and make the same measurement.
If the level was accurate, the bubble would appear in the exact position
regardless of which way the level was turned. Much to his surprise
he had to go through about fifteen levels before he found one that was
correct. I hope this illustrates the point. Bubble levels can
be way off so to be smart, use a smart level.
To make a short story long, I
met a man at the Springfield, Illinois airport who had built a dragonfly.
The plane was very nicely constructed. He said that every part was
leveled perfectly. The first time he flew the airplane, he
took off and the plane immediately required a full right aileron
to keep the plane upright. He called the tower and said that he was
going to stay in the pattern for a touch and go. When he released
the aileron pressure the plane made a real nice left bank, perfect for
pattern work. He flew around the pattern and brought the plane in
for a landing. After wiping the sweat off of his brow, he took the
plane back to the hangar and started making some more measurements and
found that the wing had a 3/4 inch twist in it which caused the problem
which could have led to a crash. Of course, it was obvious
that he didn't follow proper high speed taxi test prior the the maiden