Orbital Pegasus - Manual (Page 40)

Release 7.0 Apr 2010 29
Pegasus User’s Guide
The separation ring to which the payload attaches
is supplied with through holes. The weight of
hardware separated with the payload is
approximately 4.0 kg (8.7 lbm) for the 97 cm (38
in.) system and 2.7 kg (6.0 lbm) for the 59 cm (23
in.) system. Orbital-provided attachment bolts to
this interface can be inserted from either the
launch vehicle or the payload side of this interface
(NAS6303U, dash number based on payload
flange thickness). The weight of the bolts, nuts,
and washers connecting the separation system to
the payload is allocated to the separation system.
Orbital will supply a detailed drawing of the bolt
circle to allow accurate machining of the fastener
holes and will supply all necessary attachment
hardware to payload specifications. The flight
separation system shall be mated to the
spacecraft during processing at the VAB.
At the time of separation, the flight computer
sends commands to activate the redundant bolt
cutters, which allows the titanium clamp band and
its aluminum shoes to release. The clamp band
and shoes remain attached to the avionics
structure by retention springs. The payload is then ejected by matched push-off springs with sufficient
energy to produce the relative separation
velocities shown in Figure 5-9. If nonstandard
separation velocities are needed, different springs
may be substituted on a mission-specific basis.
5.3. Payload Electrical Interfaces
As a standard service, Orbital provides a basic
electrical interface between the payload, the
launch vehicle and any electronic support
equipment located in the L1011 carrier aircraft. As
a mission-unique service, Orbital can provide a
wide variety of electrical services to the payload
and a significantly increased number of pass
through circuits between the payload and support
equipment located in the carrier aircraft.
Figure 5-5. Payload Fairing Access Door Placement Zones (shown with optional second door
shown)