A gas turbine engine comprising: a rotatable first shaft; a first disk connected to the first shaft, the first disk including: a row of low pressure compressor blades; and a row of high pressure turbine blades connected to a radially outer end of the row of low pressure compressor blades; a second disk connected to the first shaft, the second disk including: a first row of high pressure compressor blades; and a row of low pressure turbine blades connected to a radially outer end of the row of high pressure compressor blades; a third disk connected to the first shaft between the first disk and the second disk, the third disk including a second row of high pressure compressor blades; a first row of compressor vanes between the first disk and the third disk; a combustor radially outward from the first disk and the second disk; and a heat exchanger connected to the combustor aft of the second disk; characterized in that the gas turbine engine further comprises: a fourth disk connected to the first shaft between the third disk and the second disk, the fourth disk including a third row of high pressure compressor blades; a second row of compressor vanes between the third disk and the fourth disk; and a third row of compressor vanes between the fourth disk and the second disk. a rotatable first shaft; a first disk connected to the first shaft, the first disk including: a row of low pressure compressor blades; and a row of high pressure turbine blades connected to a radially outer end of the row of low pressure compressor blades; a row of low pressure compressor blades; and a row of high pressure turbine blades connected to a radially outer end of the row of low pressure compressor blades; a second disk connected to the first shaft, the second disk including: a first row of high pressure compressor blades; and a row of low pressure turbine blades connected to a radially outer end of the row of high pressure compressor blades; a first row of high pressure compressor blades; and a row of low pressure turbine blades connected to a radially outer end of the row of high pressure compressor blades; a third disk connected to the first shaft between the first disk and the second disk, the third disk including a second row of high pressure compressor blades; a first row of compressor vanes between the first disk and the third disk; a combustor radially outward from the first disk and the second disk; and a heat exchanger connected to the combustor aft of the second disk; characterized in that the gas turbine engine further comprises: a fourth disk connected to the first shaft between the third disk and the second disk, the fourth disk including a third row of high pressure compressor blades; a second row of compressor vanes between the third disk and the fourth disk; and a third row of compressor vanes between the fourth disk and the second disk. a fourth disk connected to the first shaft between the third disk and the second disk, the fourth disk including a third row of high pressure compressor blades; a second row of compressor vanes between the third disk and the fourth disk; and a third row of compressor vanes between the fourth disk and the second disk.