change in motor speed of five percent or more
from the preceding rotation, the pressure value
should be rejecteq. A slow, continuous change
in speed from minute to minute may be neglected
since it is probably a unifonn change through•
out the rotation period. The motor speed will
decrease during the flight, as a resul~ of the
low temperatures and the drop in battery voltage.
This of itself does not decrease the value of
the record, as long as the speed does not nhange
suddenly.
(e) Olland.Cycle Pressure Element Specific«tions
(1) Pressure range: 1050 to 5mb.
(2) Desired accuracy: Surface to 300 mb ts mb.
300 mb to 50 mb t2 mb.
50 mb to 5 mb leu than t2 mb, il mb if
possible.
Highest accuracy and readability desired
on low pressure end. Temperature compensa-
tion, as required to meet pressure accuracy
requirements for temperature, range •30°
to -7000 or equivalent for medium and high
altitude flights. Mean operating tempera-
ture required more than 0°C.
(3) Helix:
Cylinder--made of insulating material with
low temperature coefficient.
Diameter 3/4 inch to l inch, length 2!
inch.
Spiral--made of nickel or other metal which
does not corrode in the atmosphere, .010
inch or less in diameter.
Eight turns per inch on cylinder.
Check-points--Six points located between
turns of spiral, starting with 9th turn,
60 degrees apart.
Made of the same material as the spiral.
In the electrical circuit of .the pressure
signal.
Suggested shape 1/16 inch diameter, round
pin, flush with surface of helix.
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