Page 41 - Winter Issue 2018
P. 41

,. , K of World War II caused attention to shift almost exclusively
I)’-L. . - , , to the development of rockets for use as weapons. They be-
. . ‘n:  came such important elements of warfare that had research
 , ‘ ’.;,_ advanced more quickly on Germany’s V-2 rocket, designed
 "92-: "f"’ ‘ ,‘ , A. K by Wernher Von Braun, the course of the war would almost
’_'.'_ ;.f',:, . I ‘ er ’ " certainly have been significantly changed. Similarly, it was
..,_ ‘x is 7: A I  the military as well as the scientific uses of rocket technol-
' :-‘ Q‘ ~4‘.‘.__ ogy that made Sputnik such a historic event. Its successful
\ v V . .‘ E" ."_ " _  V launch caused great anxiety for the Americans who feared
‘i  g 5.1" g ‘Tl’ "\ .. _..   ' ‘ ‘ ' a widening technological gap between the two so-called su-
‘  ‘-\.. hm! ‘.— perpowers, the United States and USSR.
. ‘ ’ zfi -?§E:5.?.' ii n In December 1957, American scientists made their first at-
' "‘" tempt to launch a satellite into orbit. The Vanguard TV3 ig-
  ' ‘ nited and began to rise but immediately lost thrust and fell
‘ B “ back to the launch pad (see bit.ly/lbvmlxp to view the un-
[lb ' — -_ r_ I -d , 'j-. " successful Vanguard TV3 launch). Finally, in early 1958, the
_ . _ _ f I United States successfully launched its first satellite, Explor-
- I h_- ‘ i - \ ' er 1, which returned data for nearly four months and which
- f ____”g‘ V‘  -» g " remained in orbit until 1970 (see bit.ly/2P5dQPy that shows
Figure 1. Dr. Robert H. Goddardgfore t;height7of,l;:fir7sl liquid— the Us (National Aermfautics and S.Pace .Admini5trati0n
propelled rocket in Auburn, MA, on March 16, 1926. Photo available [NASA] Space Expkfranons of 1958’ mdildmg the first five
at gammlgm,/ZMPRSCD‘ US satellites). Following Explorer 1, satellite technology de-
  veloped quickly and by the inid—1960s, satellites were preva-
lent and were being widely used for digital telecommunica-
could be used to lift rockets to higher altitudes, the so- tions. To date, more than 6,600 satellites have been launched
called step rocket, was initially developed in the 16th cen- from 40 countries. There are currently approximately 3,600
tury by a firework maker for enhancing firework displays in orbit, 1,000 of which are operational.
(see bit.ly/2Ln7TLH). Its principles are still fundamental
to the launch of orbital vehicles today. A significant break- And We Have Liftoff...
through came in the 17th century when Sir Isaac Newton Rocket “launch” is the liftoff phase in a rocket’s flight. Or-
developed the scientific foundations for modern rocketry. bital launch vehicles, rockets that are capable of placing pay-
His three laws governing physical motion explained how loads into or beyond Earth orbit, typically lift off vertically
and why rockets work and could be used to inform future (or near vertically) before progressively leaning over as they
rocket design. However, improvements in rocket accuracy use gravity to steer the vehicle onto the required trajectory
were not achieved for another two hundred years, until the in order to exit Earth’s atmosphere. Once rockets have com-
technique of spin stabilization was developed. In spin sta- pleted the transonic climb phase through the atmosphere,
bilization, the exhaust gases strike small vanes, causing the they reach the desired altitude by angling slightly below the
rocket to spin as it travels. This is the same principle that horizontal. This maneuver also increases their horizontal
bullets use today. speed until it reaches orbital speed, at which point the en-
Still, modern rocketry belongs to the 20th century. Although gine “its out‘ Because sing1e'Stage orbital rockets require an
. . . excessive amount of fuel, all current rockets are multistage
early rockets were propelled by solid fuels, modern scientists . _ , I
thought (Tsiolkovsky, 1903; Goddard, 2002) that they could vehicles’ Hfeanmg th_at theylemson hafdware (stages) on the
achieve greater Speed and range by using liquid fuel. Ameri_ way to orbit. The Jettisoried stages are either lost or recovered
can rocketry Pioneer Dr_ Robert H_ Goddard (See Figure 1) and reused as in SpaceXs recently developed Falcon rockets.
achieved the first successfiil liquid-propelled rocket flight The launch environment, which typically lasts only a few
in Auburn, MA, on March 16, 1926 (see bit.ly/2Lr9FeI for minutes, is the most severe dynamic environment that a
video of the first liquid-fiieled rocket launch). The outbreak spacecraft will endure during its normal life (Martinez—Val
Winter 2018 | Acoustics Thday | 35


















































   39   40   41   42   43