vV—2 ROCKETS—KRAUSE 
wind-tunnel tests, the pressure is 
within a very small percentage of 
ambient. Since a pressure range of 
108 is covered in a normal flight, it is 
necessary to use various types of 
gages. —The range from atmospheric 
pressure down to about 1 cm. of 
mercury is covered with a bellows 
gage; the range of 2 cm. mercury 
to 10-* mm. mercury is measured with 
Pirani gages (31) while the region of 
10- to 10—' mm. mercury is studied by 
means of Philips gages (32) and 
ionization gages (33). The most com- 
plete measurements to date were 
obtained on flights in October 1946 
and March 1947 (34, 35). 
I would like to discuss briefly the 
March flight in which a total of 15 
pressure and 2 skin-temperature gages 
were installed. Ambient pressures 
were measured up to about 80 km. 
with gages mounted on the side of the 
V-2, just forward of the tail section. 
Pirani gages mounted in similar posi- 
tions on opposite sides of the rocket 
gave readings which agree within ex- 
perimental errors, indicating that no 
appreciable error was introduced by 
yaw of the missile up to this altitude. 
A single Philips gage was mounted on 
the 15° cone of the warhead. The 
readings of this gage, when reduced 
to ambient pressures by use of the 
theories of Taylor and Maccoll (36), 
gave values up to 120 km. altitude. 
Pressure measurements obtained by 
these two methods are shown in 
figure 7. 
Temperature measurements are of 
two types: 1, measurement of ambient 
temperatures; and 2, measurement of 
skin temperatures and temperatures 
within the missile. The direct meas- 
urement of ambient temperatures from 
a rocket has not yet been successfully 
accomplished. The temperature of 
the atmosphere was calculated from 
the slope of the pressure vs. altitude 
curve and from the ratio of ram to 
ambient pressures. Pitot tube theory 
was used to obtain Mach number from 
the ratio of ram pressure to ambient 
pressure. The velocity of the rocket 
201 
divided by Mach number gave the 
velocity of sound, from which tem- 
perature was calculated. Figure 8 is 
a plot of the temperatures derived by 
these methods. Shown also are the 
temperatures measured by means of 
a weather balloon released within an 
hour of the time of the rocket’s flight. 
For comparison, the NACA estimated 
mean temperature (37) is included on 
the curve. Probable error is +25° 
from 50 to 60 km., +15° at 65 to 70 
km,)-and--1-202-at-72.52kme)" The 
probable error above 100 km. is+ 40°. 
Temperatures calculated from ram 
pressures for altitudes between 10 and 
20 km. are 5 to 20° lower than the 
expected temperature. This discrep- 
ancy is possibly caused by errors in 
the velocities calculated from the poor 
radar data obtained during the first 
20 km. of the flight. 
Two platinum resistance tempera- 
ture gages were installed to measure 
the temperature of sections of the 15° 
nose cone. The temperature rise on 
the 0.1-inch-thick aluminum forward 
section of the nose was 120+5° C. 
On the 0.1-inch steel section immedi- 
ately behind the aluminum, the tem- 
perature rise was 85+5° C., 
Ionosphere 
It is now possible to extend further 
our knowledge of the ionosphere (38) 
by utilizing rockets to make measure- 
ments within the ionized region of the 
upper atmosphere. 
The value of experimental methods 
utilizing rockets may be shown by a 
consideration of the parameters in- 
volved in the simple approximate ex- 
pression for the index of refraction in 
an ionized medium, neglecting the 
earth’s magnetic field. 
/ 4nN? 
(1) ba, ae i 
: Index of refraction. 
: Ion density. 
: Charge on the ion. 
: Mass of ion. 
: Angular frequency of radia- 
tion. 
FSa Ss 
