January 1983:the Titan launch vehicles

Introduction

During the 1950’s the cold war between the United States
and the Soviet Union was at its height. Work had already
started on developing the United States’ first 1CBM (Inter¬Continental Ballistic Missile), the Atlas; but progress was slow.
Because of the urgent need to acquire a large missile, the
United States Air Force (USAF) decided to start work on a
new missile. In 1955 the Martin Company was awarded a
contract to design and develop a two-stage liquid propellant
rocket. Taking its name from Greek Mythology, the giant
rocket was named after the children of Uranus and Gaea -
Titan.

Titan I

Titan got the go-ahead in 1957, and by late 1958 it was ready
for ground tests. Titan I was a 98.4 ton missile, 27 m
(88.6 ft) tall and 5.05 m (10 ft) in diameter. It used liquid oxygen
and RP-1 (Kerosene) in both stages. The first stage carried two
Aerojet-General LR-87 engines, giving a combined thrust of
1361 kT (300,000 lb). The second stage used a single Aerojet-
General LR-91 engine, with a thrust of 36 t (80,000 lb).

The first successful attempt at launching Titan I came on
6 January 1959 using an inert second stage. Titan I eventually
entered service with the Strategic Air Command in April 1962.
However, Titan I saw only three years of service before being
replaced by the Titan II.

Titan II

As far back as mid-1959, the disadvantages of using non-storable propellants were being discussed. Like the Atlas, Titan had to be set up from its horizontal before it could be fuelled
and launched. This did not meet the requirements for a
strategic ICBM. What was required was a retaliatory weapon
that could withstand a pre-emptive attack of severe bombardment - an ICBM with storable propellants and launched from
an underground silo.
Considering these requirements, the decision was made to
expand the promising technology of Titan I and use it as a
basis for a new version: Titan II. Development began in June

Titan II was a two stage missile 3.05 m (10 ft) in diameter
and 31 m (102 ft) tall, of which 21.5 m (70 ft) was the first stage.
Two Aerojet-General YLR-87 rocket motors giving a com¬
bined thrust of 195 t (430,000 lb) were used in the first stage,
while a single Aerojet-Ceneral YLR-91 rocket motor, giving
a thrust of 45.4 t (100,0001b) was used to power the second
stage. These engines ran on storable hypergolic propellants; a
blend of hydrazine and unsymmetrical dimethylhydrazine
(UDMH) as fuel, with nitrogen tetroxide as oxidizer. Since this
combination is hypergolic - fuel and oxidizer ignite on contact
- Titan II required no ignition system. Since both fuel and
oxidizer can be stored and used at normal temperatures -
instead of the supercold liquid oxygen of Atlas and Titan I -
Titan II needed no cold storage and handling facilities.

A total of 35 Titan II test flights were conducted, the first
on 16 March 1962. After a number of problems, of which
longitudinal oscillation was the greatest, Titan II was declared
to be operational in December 1963. By 1965 all of the Titan
l's had been withdrawn from service and replaced by Titan II
and Minuteman. Today there are about 52 Titan II missiles,
each carrying nuclear warheads.

Gemini

Early in 1961, at the same time that the Martin Company
was developing the Titan II as an ICBM, NASA was working
on an improved Mercury manned spacecraft, later to be known
as Gemini. NASA began to investigate the possibilities of
using the Titan II as a launch vehicle for the two man Gemini spacecraft.

In December 1961 NASA announced Project Gemini and
the selection of Titan II as the launch vehicle. The USAF,
acting as contractor, took responsibility to ensure that NASA
got its Titan II launch vehicles.
Titan II was the most logical choice for Gemini because it
was the most powerful and advanced rocket the United States
had under development at that time and it could also be
brought up to manned spacecraft launcher standard. Other
factors in Titan's favour were its use of storable propellant,which made it capable of standing for considerable lengths of
time on the launch pad; also the Air Force had done considerable work in designing and testing Titan as a launch vehicle
for the Dyna-Soar programme.

In order to uprate it into a man-carrying launch vehicle, the
USAF had to make a number of modifications. The main
modifications were:

(i) a new Malfunction Detection System (MDS) and a
backup flight control system,

(ii) an electrical system with backup circuits for guidance,
engine shutdown, and staging,

(iii) substitution of radio guidance for inertial guidance.

The first test flight came on 16 March 1962 from the Cape
Canaveral Missile Range. One and a half minutes after lift-off,
when the first stage engine was still firing, the missile began
to vibrate lengthwise at about 11 times a second for about 30
seconds. This trouble would not have been too serious for a
missile, but in the case of a manned launcher it was dangerous.
Accelerations of two and a half times that of gravity were
recorded in this first flight. It took almost two years to analyse
and solve the problem.
Efforts to solve the Pogo problem had been in progress since
early 1962 and the problem of instability in the second-stage
engine was being tackled by Aerojet-General. They began in
October 1963 and 18 months later their new design for the
engine was a complete success. NASA installed the new engines
with modified propellant injectors in the last six Gemini launch
vehicles; the previous six flew with the old style injectors.

Due to NASA’s pressure, the Air Force began a drive in
September 1963 to bring the manufacturing of parts up to the
higher standard that NASA required. They spent $11 million
on design improvements, improving welding techniques, and
better assembly and quality control standards.

By the early spring of 1964, all three major problems that
NASA had stated must be reduced to tolerable levels before
Titan II could be fully man-rated, had been solved. In fact, the
first Cemini flight occurred on 8 April 1964, the day before
the Titan II research and development programme ended. It
would be another year before Titan carried men. One more Gemini-Titan test flight occurred on 19 January 1965; again
it was successful
On 23 March 1965 a Titan II orbited the first manned
Gemini spacecraft, Gemini 3. Titan proved itself by safely
launching all ten manned Gemini spacecraft.

Titan III

In order to follow the development of Titan, we have to
return to 1962. The Air Force wanted to develop a national
launch capability for a wide variety of manned and unmanned
space missions. In August 1962 the Department of Defense
(DOD) approved the Titan III standard space launch system.

Titan IIIA

The Titan IIIA consisted of a two stage Titan II strengthened
to accommodate a third stage and heavier payload. The new
stage (Transtage) used the same type of storable propellants;
its diameter was 3.05 m (10 ft) and it was 4.57 m (15 ft) high,
with a thrust of 7.1 t (15,600 lb). Transtage had the capability
of multiple restart.
Titan IIIA stood 38 m (124 ft) tall, 3.05 m (10 ft) in diameter,
and could deliver about 2.8 t (6,200 lb) into low Earth orbit. The first IIIA was launched from Cape Canaveral in September 1964. By 6 May 1965 four had been launched, with a
fifth cancelled because research and development objectives
had already been met. After further development, the IIIA
became the central core for the Titan IIIC.

Titan IIIB

In July 1966, the first Titan IIIB was launched from the
Vandenberg Air Force Base in California, and it became the
USAF standard medium-weight launcher.
The IIIB carried an Agena D as third stage with a strengthened Titan II as first and second stages. The total height varied
between 44 m (144 ft) and 52.7 m (173 ft), according to payload.
It could place up to 3.5 t (8,000 lb) into polar orbit or 450 kg
(1,025 lb) into geosynchronous orbit.
The Titan IIIB is presently used by the USAF for launching
reconnaissance satellites.

Titan IIIC

In 1967 the Air Force introduced the Titan IIIC. Basically,
it was a Titan IIIA (as a central core) plus two five-segment
strap-on solid propellant boosters (stage 0) attached to the sides
of the first stage. This configuration made the IIIC more than
9.1 m (30 ft) wide at the extreme.
The IIIC is capable of launching payloads ranging from
13.21 mt (29,000 lb or 12.9 tons) into low Earth orbit; 1.31
my (3,000 lb) into synchronous equatorial orbit; and between
771 kg (1,700 lb) and 1,814 kg (4,000 lb) to Mars or Venus.

Titan IIID

The Titan IIID is essentially a IIIC without the Transtage.
Payload capacity is a minimum of 13,600 kg (30,0001b or
13.4 tons) for low Earth orbit, to 10,890 kg (24,0001b or
10.7 tons) for polar orbit.
Like the IIIB, the IIID is launched from the Vandenberg Air
Force Base and used exclusively for military space operations,
launching mainly surveillance and reconnaisance satellites (Big
Bird and KH-11 being examples).

Titan IIIE-Centaur

Titan IIIE was developed for use as a civilian space launch
vehicle for NASA for launching planetary spacecraft. It is basically a standard Titan IIIC, with a Centaur replacing the
Transtage.
Its most unusual feature is its top heavy appearance. This
is caused by the large payload shroud which covers both the
satellite and Centaur. The main Titan “core” has a diameter
of 3.05 m (10 ft), while the shroud has a diameter of 4.27 m
(14 ft). Total height of the IIIE is 48.8 m (160 ft).

Titan IIIM

In 1964, the Air Force began work on a Manned Orbital
Laboratory (MOL). This vehicle consisted of a modified Gemini spacecraft resting on a cylindrical space laboratory. It was
an experimental programme to study the use of space for
military purposes.
By 1966, the total weight was over 13,600 kg (30,000 lb) and
it therefore required a more powerful booster than the Titan
IIIC. The USAF decided on a modified IIIC design, called the
Titan IIIM. The IIIMwas to use a seven segment solid fuel
strap-on booster, as opposed to the five segment booster used
on the IIIC. First stage engines were to use a new 15 to 1 expansion nozzle. Although an unmanned test flight of a MOL mock-up (reflying the Gemini 2 spacecraft) was launched in November
1966 by a Titan IIIC, the IIIM design was never used. On 10
June 1969, MOL was officially cancelled.

Titan 34D

The Titan 34D is the latest generation of USAF Titan HI
launch vehicles. Apart from two main differences, the Titan
34D is basically the same design as the Titan IIIC. These two
dissimilarities are that the Titan 34D utilises five and one-half segments solid propellant
motors. This extra half segment provides an increased
capability for heavy military payloads. It uses a solid propellant Inertial Upper Stage (IUS) instead
of the Transtage.
The IUS will also be used by NASA’s Space Shuttle in order
to take payloads into higher orbits or interplanetary missions.
Like the Titan IIIC, the Titan 34D will be used to orbit
military satellites for the USAF, using Complex 40 at Cape
Canaveral.