The Thorad-Agena is a two-stage launch vehicle consisting of a Thorad first-stage and an Agena second-stage, connected by a booster adapter. The composite vehicle, including the shroud and the booster adapter, is about 33 meters (109 ft) long. The total weight at lift-off is approximately 91 625 kilograms (202 000 lbm)

Coffey, E. E.

Geye, R. P.

English

NASA Technical Reports Server

111. LAUNCH VEHICLE DESCRl --- PTlON 
I 
by Eugene E. Coffey and Richard P. Geye 
The Thorad-Agena is a two-stage launch vehicle consisting of a Thorad first-stage 
and an Agena second-stage, connected by a booster adapter. The composite vehicle 
(fig. 111-1) including the shroud and the booster adapter is about 33 meters (109 ft)  long. 
The total weight at lift-off is approximately 91 625 kilograms (202 000 lbm). Fig- 
ure III-2 shows the Thorad-Agena lift-off with Nimbus III. 
The Thorad (fig. In-3) stage consists of a long-tank Thor and three Castor 11 
solid-propellant rocket motors located 120' apart and attached to the long-tank Thor 
near the aft end. The long-tank Thor is 2 1 . 4  meters (70.3 ft)  long and is 2 . 4  meters 
(8 ft) in diameter, except for the conical forward section which tapers to a diameter of 
about 1 . 6  meters  (5. 3 ft). The Thorad is approximately 4 . 3  meters (14 ft) longer than 
Thors previously used resulting in approximately 50 percent greater propellant tank 
volume. The additional propellant provides for an increased main engine thrust duration 
of approximately 72 seconds. The solid-propellant rocket motors are each about 
7 meters (24 ft) long and are 0 . 8  meter (2. 5 f t )  i n  diameter with a conical forward end. 
3 The Thorad is powered by a main engine with a sea-level rated thrust of 756x10 newtons 
(170 000 lbf), two vernier engines with a total sea-level rated thrust of 89x10 newtons 
(2000 lbf) and the three solid-propellant rocket motors with a total sea-level rated thrust 
of 6 9 6 ~ 1 0 ~  newtons (156 450 lbf). The total impulse of these solid-propellant rockets is 
3 3 approximately 3829x10 newton-seconds (861x10 lbf -sec) greater than the total im- 
pulse of the solid-propellant rocket motors previously used on the Thrust Augmented 
Thor vehicle. The propellants for the Thorad main engine and the vernier engines are 
liquid oxygen and high grade kerosene. The propellant for the solid-propellant rocket 
motors is basically a solid grain of polybutadiene acrylic acid and ammonium perchlo- 
rate. The vernier engines, the main engine, and the solid-propellant rocket motors 
are ignited in sequence prior to lift-off. The fixed-nozzle solid-propellant rocket 
motors burn for  approximately 39 seconds. They are jettisoned at T + 102 secon'ds in 
order to insure that the cases for  the solid propellant impact in a safe area (water 
impact). The Thorad main-engine thrusts until the desired velocity for the planned 
suborbital ellipse is achieved as determined by the radio-guidance system, o r  until 
propellant depletion. During powered flight, the Thorad main engine is gimbaled for  
pitch and yaw control, and the vernier engines are gimbaled for roll control. After 
Thorad main engine cutoff, the vernier engines continue to  thrust for 9 seconds to 
2 
5 
https://ntrs.nasa.gov/search.jsp?R=19700021342 2020-03-17T01:40:41+00:00Z
provide for vehicle attitude control and for  fine trajectory corrections. After vernier 
engiie cutoff, the Thorad is severed from the Agena by the firing of a Mild Detonating 
Fuse system located on the forward end of the booster adapter. The firing of a retro- 
rocket system, mounted on the booster adapter, then separates the Thorad with boost- 
er  adapter from the Agena. 
The second stage Agena and the shroud protecting the Nimbus 111 spacecraft are 
shown in figure 111-4. The diameter of the Agena is 1.52 meters (5 ft) ,  and the length 
of the Agena and shroud is about 12 meters (40 ft) .  The Agena engine has a rated 
vacuum thrust of 71.17X10 newtons (16 000 lbf). This engine uses unsymmetrical 
dimethylhydrazine and inhibited red fuming nitric acid as propellants. During powered 
flight, pitch and yaw control are provided by gimbaling the Agena engine, and roll  
control is provided by a cold p s  (mixture of nitrogen and tetrafluoromethane) attitude 
control system. During periods of nonpowered flight, pitch, yaw, and roll control are 
provided by the cold-gas system. The cold-gas attitude control system is also used to 
perform a 75' pitchup maneuver prior to Nimbus IKI separation and a coning (combined 
yaw and roll) maneuver subsequent to Nimbus III separation. For this mission a cold- 
gas retrothrust system provided the impulse (two separate thrust periods) required to 
perturb the Agena orbit after the coning maneuver. A fiber glass laminate clamshell 
shroud was used to provide environmental protection for the spacecraft during ascent. 
This shroud was  jettisoned approximately 10 seconds after Agena engine first start. 
The Nimbus I11 is shown in figure 111-5. 
payload capability than was provided by the Thrust Augmented Thor used for previous 
NASA missions. 
3 
The Thorad used for the Nimbus III mission provided approximately 20 percent more 
6 
Stations 
463.5 
5. 7 m 
(IS. 7 A) 
Hgena 6.2m : 
I 
ft) 
T 
21.4 m' 
ft) 
557 
__-Clamshell shroud 
/ __--- 
688.9 
729.4 
- ______- - -Agena 
825.9 
-- ____--- Booster adapter 
934.1 
978 
1018.1 
1230.5 
1263.5 
B- 
EG--- 
c 
1476.4 
-Thorad 
/ ~ - I~lid-propellant - _/-- rocket motors (3) 
-1722 - - 
1775 
€ 
Figure 111-1. -Composite space vehicle. Nimbus 111. 
7 
~~ 
Figure 111-2. - Thorad-Agena lift-off with nimbus 111. 
8 
Stations 
978.049- 
t 1018.1 ___ 
A 
1 2 3 0 . 5 4  
1263.5 
1536.8- 
1722- 
Flight termination system 
antennas ( f lush mounted); \ ’ / 
four equally spaced places-,/. 
___ & 
,Transition 
G section t 
A 
,-Fuel tank .. 
4 
. 
‘-Centerbody 
section 
,-Oxidizer tank 
,- Solid-propellant 
,// rocket motor (one 
’ of three) 
-Aft skir t  section ,’ 
_,-Engine and 
accessories 
section 
1778 
\ 
LMain engine 
Section A-A 
r Telemetry antenna; 
I (blade type) two places 
I 
Section B-B 
No. 2 No. 3 
Solid motor 
No. 1 
(down range) 
End view 
Figure 111-3. - Thorad general configuration, Nimbus 111. 
9 
rRetrorockets (2), 
Retrorocket fairing ; 180Oapart 
\ 
mosier dudpier structure -, 
\ 
\ 
Lsel f -destruct  c charge 
Mild Detonating 
Fuse separation ring 
\ 
7, Gas storage sphere for retrothrust system 
\ 
Gas storage sphere for 
attitude control system-,, 
I 
I 
I 
I 
Forward section-, 
, I 
I 
I 
I 
LTank section 
Figure 111-4. -Agena, shroud, and booster adapter, Nimbus 111. 
10 
Solar paddle 
'&S-band 
antennas 
Figure 111-5. - Nimbus 111 spacecraft in deployed configuration. 
' 
11 


Launch Vehicle Description

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server