McDONNELL DOUGLAS has selected Pratt & Whitney and Alliant Techsystems to provide the second-stage engine and solid-rocket boosters for the new Delta 3 booster, respectively.

The P&W RL10B-2 cryogenic engine will power the vehicle's second stage. This is a derivative of the RL-10 engine, which has been in service for 30 years. Two RL-10A-3-3As are used on the second stages of the four-fleet Lockheed Martin Atlas booster (Flight International, 31 May-6 June).

Up to ten engines, are expected to be ordered initially. The RL10B-2 will be the most powerful version, with a thrust of 106kN (23,800lb), compared with 72kN on the current model.

Alliant will develop the graphite-epoxy strap-on motors for the first stage, which itself will be powered by an uprated Rocketdyne engine used on the current Delta 2, provided with more propellants.

Nine strap-on motors will be used on each Delta 3, which will be 1.1m wider in diameter and 1.2m longer than those provided by Alliant (formerly Hercules Aerospace) for the Delta 2, which also has nine motors per vehicle.

Alliant will build 16 flightsets over the next five years for the Delta 3, which will have its first flight in late 1997. The contract also provides an "authority to proceed" to Alliant to build 16 more flightsets for the Delta 2, maintaining production levels to 2000, with options extending the period to 2005.

The nozzles for the Delta 3 motors will be modified and will be steerable to provide a thrust-vector-control capability not available on the Delta 2.

Source: Flight International