March 1982:the Percheron rocket

Non-government sponsored space programmes have been
few and far between. Efforts such as that by the California
rocket pioneer Robert Truax have yet to bear fruit but have
stimulated the interest of others into trying to construct rocket
carriers capable of reaching suborbital and orbital heights.

Space Services, Incorporated (SSI) of Houston is one organisation of entrepreneurs which plans to compete with the major
commercial payload carriers, (the American Space Shuttle and
Delta, and the European Ariane). Its vehicle programme
centres about a rocket module similar in size to the Redstone
that would be mass produced using low cost, high technology
techniques, with only modular variations being required to
produce different orbital configurations.

The Vehicle

The SSI vehicle is known as Percheron (after the French for
workhorse). It is 1.2 m in diameter and almost 14 m tail; the
addition of a nose cone and engine brings the final length to
over 17 m. The pressure-fed engine has a potential thrust of
34,000 kgf, although the first prototype reached only 27,000,
and uses a coaxial pintle system like that on expandable launch
vehicles and in the Apollo lunar module descent engine system.
This particular engine burns JP-4 kerosene as fuel with liquid
oxygen as an oxidizer.

A gas pressurisation system is mounted on the nose to
maintain tank feed pressure at 350 psi for both the kerosene
and the oxidizer. A common bulkhead separates, fuel and
oxidizer; it was the bulkhead which separated during the
August 1981 catastrophe when the first rocket was destroyed
during a static test.

A 4 m long payload section in the shapre of a truncated cone
and capable of surviving reentry is carried. A number of expandable vanes lie at the rear to help to orient the capsule at the proper entry angle, thus controlling the rate of descent
and downtrack/crosstrack imbalance. Parachutes, the reaction
control subsystem for on-orbit adjustment and an avionics bay
make up the remainder of the segment.

Other versions could be created by adding to this basic
production model: a production model plus upper stage, and
a production model/upper stage with strapon boosters. The
upper stage could be either liquid or solid fuelled. Parallel
staging (as in the Space Shuttle) occurs in the third version
when two or more strapons plus the main engine fire simultaneously to increase the overall boost altitude prior to upper
stage burn towards geosynchronous orbit. For a heavy payload,
a cluster of seven modules is linked together; the outer six fire
until four are depleted. These four are jettisoned and the
remaining three fire together.

For the past 25 years the major space countries have used
a wide range of rockets to boost payloads into space. Each of
these countries’ programmes is weighed down with the
encumbrances of government bureaucracies. SSI’s development efforts have concentrated on using rented launch sites,
(eventual) rented tracking stations, minimal.support facilities,
in-house consulting and the construction of partially reusable
rocket components in order to minimise lengthy qualification
and test cycles.

Percheron’s body is formed of a glass filament-wound fibre
mainly because of the optimal weight and cost advantage. Use
of aluminium and stainless steel is provided for in the various
equipment support structures. Purchase of filament winding
equipment is expected to comprise a principal expenditure for
SSI’s production facility.

The SSI programme plans to run at a per flight cost of
one-third that charged by NASA for a user contracted to fly
on the Space Shuttle. In order to achieve this, the following
techniques are employed:

1. Use of identical production engine modules

2. Cluster small systems rather than building large heavy
lift single engines

3. Use of pressure-fed instead of pump-fed fuel systems

4. Use of low cost and easily obtainable fuel

5. Use of lightweight structural material

6. Use of recoverable payload sections

7. Use of "off the shelf" technology rather than existing
military-grade equipment

8. Minimise programme management and personnel costs

9. Contracting with existing ground stations for data link
rental

Space Services’ budget does not permit massive expenditures
on launch sites, so for its first test a 3000 acre area was leased
on Matagorda Island located off the southern Texas coast at
latitude 27.9° North and longitude 97° West. Ironically, the
island is in the same locale that NASA was considering 20
years ago as its prime candidate for a southern launch site.
Cape Canaveral was later selected.

Following the August 1981 setback, Space Services planned
to rebuild in California, estimating only six months completion
time for the second model. Qualifying the propulsion system
seems to be the major problem; its schedule showed about 200
test firings.

An orbital test launch was planned for early 1983 and
preliminary talks have already taken place with the US Air
Force with the intention of using Vandenberg Air Force Base
in California for possible polar low Earth orbit missions, with
future thoughts of lifting up to 2300 kg payloads.