Complex sentence: Positive results in other areas, including payload, range and V/STOL performance, led to the award of a development contract in 1979; the contract called for 12 aircraft in the first batch, and a further 324 thereafter.
Split into simpler sentences: Positive results in other areas, including payload, range and V/STOL performance, led to the award of a development contract in 1979. The contract stipulated that 12 aircraft would be procured in the first batch, and a further 324 thereafter.