11.
E6B Flight Computer
1
0
1 1
1 2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
20
2 1
22
2
3
2
4
2
5
3
0
3
5
40
45
50
55
70
8
0
9
0
60
65
7
5
8
5
9
5
5
3.
T
U
A
N
0
4.
T
AT
S
1
0
1
1
1
2
1 3
1 4
1 5
1 6
1 7
1 8
1 9
20
2 1
22
23
24
25
3
0
4
5
50
55
7
8
9
MPH
C H A S E - D U R E R
30
2
0
1
0
8
4
12
6
2
10
60
4
0
2
0
1
0
30
5
0
You can probably guess how many, because
15
miles in
2.5
hours is obviously too little and
1500
is
obviously too much. So the answer must be
150
miles.
¤
Let’s try another example:
Again, you’re going down the freeway at
70
miles-per-hour. You’ve been traveling at that speed for
110
minutes. How far have you traveled?
¤
Solution:
Turn the dial so that the numeral
60
(which represents 60 minutes) on the dial is right above the
number
7
(which represents 70 miles-per-sixty minutes). Now find the numeral
11
on the dial and
look directly below it on the face. You will note that the
11
is between the numerals
12
and
13
on the
face. We must now interpolate. First we must decide whether the numerals
12
and
13
on the face
represent
12
and
13
,
120
and
130
,
1200
and
1300
, etc. It’s obvious that
12
is too little and
1200
is
too big, but sometimes it’s not so obvious. So here’s another method.
At
70
miles-per-hour (70 miles in 60 minutes), you would
have to travel over
14
hours to go further than
1000
miles.
14
hours is
840
minutes. So the answer must have more
than
2
and less than
4
digits. In other words, it must
have
3
digits until you get above
14
hours or
840
minutes.
After using the Flight Computer for a while these
mental estimates will become second nature (i.e. intuitive).
Now that we’ve done the mental calculation, we know that
the answer must have
3
digits. Therefore
12
must
represent the number
120
and
13
must represent the
number
130
. Since there are nine ticks between the
12
and
13
, there are ten divisions between them. Since they
represent the difference between the numbers
120
and
130
, which is
10
, each tick must represent
1
. Since the
numeral
11
on the dial is above the eighth tick after