The HLVOLSDP (Heavy Lift Vehicle Operational Launch Service Demonstration Payload) or
DemoSat is only a 5993 kg instrumented mass to record multiple ride characteristics
of the Delta-4H to be plugged into future
military satellite and OSP designs. The vehicle flew a typical geosynchronous
orbit-insertion mission profile and was to deliver the payload into an orbit above the
geostationary orbit.
It was based on a demonstration payload constructed for the maiden Delta-4 flight,
which was not used, as a real payload was available. DemoSat is a cylindrical outer
aluminium structure 1.95 m high and 1.38 m diameter. The inner ballast consists of sixty
brass rods, stiffeners, fasteners and fittings.
Two criteria had to be met in the construction of this demonstration payload:
- specific mass and center of gravity representing a real payload
- in case of reentry complete burn up (met by the use of brass rods and aluminium for the
construction)
As the structure is very robust, a late addition of the 3CS
(Nanosat-2) payload to the DemoSat was possible. The dispenser was side-mounted on
DemoSat.
The DemoSat reached a lower than planned orbit as the Delta-4H under-performed with shorter than planned
CBC burn times, leading to a fuel shortage of the second stage during the last burn.
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