A drive architecture comprising: a rotor (20; 120; 220) and a gearbox (22; 122; 222) for driving said rotor (20; 120; 220); and a pair of input gears (26, 30; 126; 130; 226, 230) for providing rotational drive to said gearbox (22; 122; 222), a first recuperative cycle engine (18; 118) driving one of said pair of gears (26, 126, 226) and a second engine (19; 119) driving the other of said pair of gears (30; 130; 230), wherein said first recuperative cycle engine (18; 118) and said second engine (19; 119) are gas turbine engines, with a power takeoff (72; 172; 272) from a drive shaft (28; 128) of said second engine (19; 119) supplying rotational drive to drive at least one component in said first recuperative cycle engine (18; 118), wherein said power takeoff (72; 172; 272) from said second engine (19; 119) serves to provide rotational input to drive a compressor (32; 132; 232) in said first recuperative cycle engine (18; 118); characterised in that: air downstream of said compressor (32; 132; 232) in said first recuperative cycle engine (18; 118) is directed through a heat exchanger (40; 140; 240) downstream of a turbine section (35; 135; 235) in said first recuperative cycle engine (18; 118), where the air is heated, and is then returned into a combustor section (42; 142; 242), which is intermediate said compressor (32; 132; 232) and said turbine section (35; 135; 235) in said first recuperative cycle engine (18; 118); and air is tapped from said second engine (19; 119) downstream of a compressor (54; 182; 282) in said second engine (19; 119) and passed into a second heat exchanger (50; 150; 250) where it additionally provides heat to the air from said compressor (32; 132; 232) in said first recuperative cycle engine (18; 118) before the air in said first recuperative cycle engine (18; 118) is returned to said combustion section (42; 142; 242). a rotor (20; 120; 220) and a gearbox (22; 122; 222) for driving said rotor (20; 120; 220); and a pair of input gears (26, 30; 126; 130; 226, 230) for providing rotational drive to said gearbox (22; 122; 222), a first recuperative cycle engine (18; 118) driving one of said pair of gears (26, 126, 226) and a second engine (19; 119) driving the other of said pair of gears (30; 130; 230), wherein said first recuperative cycle engine (18; 118) and said second engine (19; 119) are gas turbine engines, with a power takeoff (72; 172; 272) from a drive shaft (28; 128) of said second engine (19; 119) supplying rotational drive to drive at least one component in said first recuperative cycle engine (18; 118), wherein said power takeoff (72; 172; 272) from said second engine (19; 119) serves to provide rotational input to drive a compressor (32; 132; 232) in said first recuperative cycle engine (18; 118); characterised in that: air downstream of said compressor (32; 132; 232) in said first recuperative cycle engine (18; 118) is directed through a heat exchanger (40; 140; 240) downstream of a turbine section (35; 135; 235) in said first recuperative cycle engine (18; 118), where the air is heated, and is then returned into a combustor section (42; 142; 242), which is intermediate said compressor (32; 132; 232) and said turbine section (35; 135; 235) in said first recuperative cycle engine (18; 118); and air is tapped from said second engine (19; 119) downstream of a compressor (54; 182; 282) in said second engine (19; 119) and passed into a second heat exchanger (50; 150; 250) where it additionally provides heat to the air from said compressor (32; 132; 232) in said first recuperative cycle engine (18; 118) before the air in said first recuperative cycle engine (18; 118) is returned to said combustion section (42; 142; 242). air downstream of said compressor (32; 132; 232) in said first recuperative cycle engine (18; 118) is directed through a heat exchanger (40; 140; 240) downstream of a turbine section (35; 135; 235) in said first recuperative cycle engine (18; 118), where the air is heated, and is then returned into a combustor section (42; 142; 242), which is intermediate said compressor (32; 132; 232) and said turbine section (35; 135; 235) in said first recuperative cycle engine (18; 118); and air is tapped from said second engine (19; 119) downstream of a compressor (54; 182; 282) in said second engine (19; 119) and passed into a second heat exchanger (50; 150; 250) where it additionally provides heat to the air from said compressor (32; 132; 232) in said first recuperative cycle engine (18; 118) before the air in said first recuperative cycle engine (18; 118) is returned to said combustion section (42; 142; 242).