Allison T38


The Allison T38 was an early turboprop engine developed by Allison Engine Company during the late 1940s. The T38 became the basis for the very successful family of Allison T56 turboprop engine.

Design and development

Developed as a stand-alone single section of the T40 twin engine to aid in development of the T40, the T38 started life with a 19-stage axial compressor, eight can type combustion chambers, a 4-stage turbine driving the compressor and the extension shaft to the reduction gearbox.
Initially rated at the T38 first ran in 1947 and flew in the nose of a Boeing B-17 Flying Fortress test-bed on 19 April 1949, rated at. Problems with gearbox vibration and combustion were dealt with during the test programme and were mirrored by problems in the Allison T40 programme. The engines fitted to the Convair CV-240-21 Turboliner were rated to equivalent.
Although the only aircraft slated to receive the T38 as a production engine, the Convair T-29E, was cancelled, the T38 did power a converted Convair CV-240, and was fitted in the nose of the McDonnell XF-88B to drive experimental supersonic propellers. Further development of the T38 provided the power sections for the Allison T40 as well as forming the basis for the Allison T56/Model 501 and the projected Allison T39.

Variants

;Model 501-B7: commercial version of the T38-A-6
;XT38:prototypes of the engine, single engine section of the T40, to assist in the development of the T40.
;XT38-A-2:
;XT38-A-5: Turboprop fitted to the McDonnell XF-88B.
;T38-A-6: Military version of 501-B7
;T38-A-10: turboshaft version for the Piasecki YH-16A Transporter
;T39 : A projected development of the T38 which was cancelled before hardware had been produced.
;T40: The turboprop origin of the T38, composed of two power sections driving a common gearbox.
;T44: large turboprop with three T38 engine sections.
;T56: enlarged and improved version of the T38, destined to enter service by the tens of thousands.

Applications