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 . <EOS>