The research aircraft would have Avon engines but in service the RB.153/61 then under development for Germany would be substituted.

Thanks T-21!;)

But would that not leave it rather under powered? I thought that the RB.153 was a scaled down spey with only about 7000lb of thrust. After burning Avons were turning out nearyl 17,000lb by this time and RR had proposed the Thames as a direct replacement. I thought the 583 was a pretty large aircraft?:confused: