From Wikipedia, the free encyclopedia
The
Allison T38
(company Model
501
) 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.
[1]
Design and development
[
edit
]
Developed as a stand-alone single section of the
T40
(Model 500) 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.
[2]
Initially rated at 2,000 shp (1,500 kW) 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 2,250 shp (1,680 kW). Problems with gearbox vibration and combustion were dealt with during the test program and were mirrored by problems in the
Allison T40
programme. The engines fitted to the
Convair CV-240-21 Turboliner
were rated to 2,750 shp (2,050 kW) equivalent.
[2]
In 1951, the
United States Air Force
decided that the production version of the
Beechcraft XT-36
trainer?then in the
mockup
stage and designed for the
Pratt & Whitney R-2800
?would be retrofitted with the T38 when the engine entered full-scale production, which was anticipated to occur in 1955?1960. This decision ultimately doomed the aircraft, as the design changes required to accommodate the T38 delayed the project and rendered the aircraft overweight and over budget.
[3]
Although the only other 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
(the CV-240-21 Turboliner, a project that would be abandoned due to engine problems), 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
.
[2]
Variants
[
edit
]
- Model 501-B7
- commercial version of the T38-A-6
[4]
- XT38
- prototypes of the engine, single engine section of the T40, to assist in the development of the T40.
[5]
- XT38-A-2
- [6]
- XT38-A-5
- Turboprop fitted to the
McDonnell XF-88B
.
- T38-A-6
- Military version of 501-B7
[4]
- T38-A-10
- 1,800 shp (1,300 kW) turboshaft version for the
Piasecki YH-16A Transporter
- T39
- (Model 504) A projected 9,000 shp (6,711.30 kW) development of the T38 which was cancelled before hardware had been produced.
[7]
[2]
- T40
- (Model 500) The 4,100 shp (3,057.37 kW) turboprop origin of the T38,
[5]
composed of two power sections driving a common gearbox.
[2]
[8]
- T44
- (Model 503) large turboprop with three T38 engine sections.
- T56
- (Model 502) enlarged and improved version of the T38, destined to enter service by the tens of thousands.
Applications
[
edit
]
Specifications (T38-A-6 / 501-B7)
[
edit
]
Data from
Aircraft engines of the World 1953
[4]
General characteristics
- Type:
Turboprop
/
Turboshaft
- Length:
84 in (2,100 mm) engine section only
- Diameter:
28.1 in (710 mm) (
gearbox
diameter); 20 in (510 mm) engine section diameter
- Dry weight:
1,225 lb (556 kg) with extension shaft and gearbox
Components
- Compressor:
17-stage
axial
- Combustors
:
8 tubular inter-connected stainless steel combustion chambers
- Turbine
:
4-stage
axial
discs of Timken 16-25-4 alloy with special alloy blades
- Fuel type:
MIL-F-5572 100/130
Octane
Gasoline
- Oil system:
Dry sump
, gear pump at 65 psi (4.5 bar) with
scavenge pump
; MIL-O-6081A
Performance
See also
[
edit
]
Related development
Related lists
References
[
edit
]
- ^
Gunston, Bill (2006).
The Development of Jet and Turbine Aero Engines, 4th Edition
. Sparkford, Somerset, England, UK: Patrick Stephens, Haynes Publishing. pp. 204?205.
ISBN
0-7509-4477-3
.
- ^
a
b
c
d
e
f
g
h
Kay, Anthony L. (2007).
Turbojet History and Development 1930-1960 vol.2
(1st ed.). Ramsbury: The Crowood Press. pp. 119?121.
ISBN
978-1-86126-939-3
.
- ^
a
b
Report on Review of Contracts for T-36A Trainer Aircraft
(PDF)
(Report).
General Accounting Office
. 18 October 1955. pp. 10?13. B-118676
. Retrieved
28 July
2021
.
- ^
a
b
c
Wilkinson, Paul H. (1953).
Aircraft engines of the World 1953
(11th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 66?67.
- ^
a
b
c
Nolan, D. J. (8 August 1952).
"TURBO-LINER : Development of the Allison T-38 Engine in a Convair 240"
(pdf)
.
Flight
.
LXII
(2272): 157?159
. Retrieved
5 January
2019
.
- ^
Wilkinson, Paul H. (1950).
Aircraft engines of the World 1950
(11th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 50?51.
- ^
"Designations Of U.S. Military Aero Engines: 3 Jet and Turbine Engines, 1946 - 1968"
.
www.designation-systems.net
. Retrieved
5 January
2019
.
- ^
Wilkinson, Paul H. (1953).
Aircraft engines of the World 1953
(11th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 68?69.
Further reading
[
edit
]
- Leyes II, Richard A.; William A. Fleming (1999).
The History of North American Small Gas Turbine Aircraft Engines
. Washington, DC: Smithsonian Institution.
ISBN
1-56347-332-1
.